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Julian Basanovic; Lies Notebaert; Patrick J F Clarke; Colin MacLeod Emotion-in-motion: An ABM approach that modifies attentional disengagement from, rather than attentional engagement with, negative information Journal Article Cognitive Therapy and Research, pp. 1–9, 2020. @article{Basanovic2020, title = {Emotion-in-motion: An ABM approach that modifies attentional disengagement from, rather than attentional engagement with, negative information}, author = {Julian Basanovic and Lies Notebaert and Patrick J F Clarke and Colin MacLeod}, doi = {10.1007/s10608-020-10178-1}, year = {2020}, date = {2020-01-01}, journal = {Cognitive Therapy and Research}, pages = {1--9}, publisher = {Springer US}, abstract = {Background: Individuals with heightened anxiety vulnerability demonstrate a bias favouring attention to negative information, and it has been argued that this reflects a difficulty to disengage from negative information. Methods to manipulate attentional bias have demonstrated inconsistent effectiveness, however such methods have not targeted biases in attentional disengagement specifically. A recently developed approach to attentional bias modification, labelled Emotion-in-Motion, has been proposed to result in facilitated attentional disengagement from information. Thus, the present study empirically investigated whether the Emotion-in-Motion task modifies biased attentional disengagement from negative information using eye-movement recordings. Methods: Forty-four participants completed the Emotion-in-Motion attention manipulation task under conditions designed to enhance attention (Attend Negative) or attenuate attention (Avoid Negative) to negative information. Biased attentional engagement with, and attentional disengagement from, negative information was examined subsequently. Results: Participants in the Avoid Negative condition demonstrated lower levels of biased attentional disengagement from negative information as compared to participants in the Attend Negative condition. No difference in biased attentional engagement with negative information was observed. Conclusions: It is concluded that the Emotion-in-Motion task serves to independently manipulate selective attentional disengagement from negative information and may be useful in investigating the specific role of biased attentional disengagement in emotional vulnerability.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Individuals with heightened anxiety vulnerability demonstrate a bias favouring attention to negative information, and it has been argued that this reflects a difficulty to disengage from negative information. Methods to manipulate attentional bias have demonstrated inconsistent effectiveness, however such methods have not targeted biases in attentional disengagement specifically. A recently developed approach to attentional bias modification, labelled Emotion-in-Motion, has been proposed to result in facilitated attentional disengagement from information. Thus, the present study empirically investigated whether the Emotion-in-Motion task modifies biased attentional disengagement from negative information using eye-movement recordings. Methods: Forty-four participants completed the Emotion-in-Motion attention manipulation task under conditions designed to enhance attention (Attend Negative) or attenuate attention (Avoid Negative) to negative information. Biased attentional engagement with, and attentional disengagement from, negative information was examined subsequently. Results: Participants in the Avoid Negative condition demonstrated lower levels of biased attentional disengagement from negative information as compared to participants in the Attend Negative condition. No difference in biased attentional engagement with negative information was observed. Conclusions: It is concluded that the Emotion-in-Motion task serves to independently manipulate selective attentional disengagement from negative information and may be useful in investigating the specific role of biased attentional disengagement in emotional vulnerability. |
Sarah Bate; Catherine Haslam; Jeremy J Tree; Timothy L Hodgson Evidence of an eye movement-based memory effect in congenital prosopagnosia Journal Article Cortex, 44 (7), pp. 806–819, 2008. @article{Bate2008, title = {Evidence of an eye movement-based memory effect in congenital prosopagnosia}, author = {Sarah Bate and Catherine Haslam and Jeremy J Tree and Timothy L Hodgson}, doi = {10.1016/j.cortex.2007.02.004}, year = {2008}, date = {2008-01-01}, journal = {Cortex}, volume = {44}, number = {7}, pages = {806--819}, abstract = {While extensive work has examined the role of covert recognition in acquired prosopagnosia, little attention has been directed to this process in the congenital form of the disorder. Indeed, evidence of covert recognition has only been demonstrated in one congenital case in which autonomic measures provided evidence of recognition (Jones and Tranel, 2001), whereas two investigations using behavioural indicators failed to demonstrate the effect (de Haan and Campbell, 1991; Bentin et al., 1999). In this paper, we use a behavioural indicator, an "eye movement-based memory effect" (Althoff and Cohen, 1999), to provide evidence of covert recognition in congenital prosopagnosia. In an initial experiment, we examined viewing strategies elicited to famous and novel faces in control participants, and found fewer fixations and reduced regional sampling for famous compared to novel faces. In a second experiment, we examined the same processes in a patient with congenital prosopagnosia (AA), and found some evidence of an eye movement-based memory effect regardless of his recognition accuracy. Finally, we examined whether a difference in scanning strategy was evident for those famous faces AA failed to explicitly recognise, and again found evidence of reduced sampling for famous faces. We use these findings to (a) provide evidence of intact structural representations in a case of congenital prosopagnosia, and (b) to suggest that covert recognition can be demonstrated using behavioural indicators in this disorder.}, keywords = {}, pubstate = {published}, tppubtype = {article} } While extensive work has examined the role of covert recognition in acquired prosopagnosia, little attention has been directed to this process in the congenital form of the disorder. Indeed, evidence of covert recognition has only been demonstrated in one congenital case in which autonomic measures provided evidence of recognition (Jones and Tranel, 2001), whereas two investigations using behavioural indicators failed to demonstrate the effect (de Haan and Campbell, 1991; Bentin et al., 1999). In this paper, we use a behavioural indicator, an "eye movement-based memory effect" (Althoff and Cohen, 1999), to provide evidence of covert recognition in congenital prosopagnosia. In an initial experiment, we examined viewing strategies elicited to famous and novel faces in control participants, and found fewer fixations and reduced regional sampling for famous compared to novel faces. In a second experiment, we examined the same processes in a patient with congenital prosopagnosia (AA), and found some evidence of an eye movement-based memory effect regardless of his recognition accuracy. Finally, we examined whether a difference in scanning strategy was evident for those famous faces AA failed to explicitly recognise, and again found evidence of reduced sampling for famous faces. We use these findings to (a) provide evidence of intact structural representations in a case of congenital prosopagnosia, and (b) to suggest that covert recognition can be demonstrated using behavioural indicators in this disorder. |
Sarah Bate; Catherine Haslam; Ashok Jansari; Timothy L Hodgson Covert face recognition relies on affective valence in congenital prosopagnosia Journal Article Cognitive Neuropsychology, 26 (4), pp. 391–411, 2009. @article{Bate2009b, title = {Covert face recognition relies on affective valence in congenital prosopagnosia}, author = {Sarah Bate and Catherine Haslam and Ashok Jansari and Timothy L Hodgson}, doi = {10.1080/02643290903175004}, year = {2009}, date = {2009-01-01}, journal = {Cognitive Neuropsychology}, volume = {26}, number = {4}, pages = {391--411}, abstract = {Dominant accounts of covert recognition in prosopagnosia assume subthreshold activation of face representations created prior to onset of the disorder. Yet, such accounts cannot explain covert recognition in congenital prosopagnosia, where the impairment is present from birth. Alternatively, covert recognition may rely on affective valence, yet no study has explored this possibility. The current study addressed this issue in 3 individuals with congenital prosopagnosia, using measures of the scanpath to indicate recognition. Participants were asked to memorize 30 faces paired with descriptions of aggressive, nice, or neutral behaviours. In a later recognition test, eye movements were monitored while participants discriminated studied from novel faces. Sampling was reduced for studied--nice compared to studied--aggressive faces, and performance for studied--neutral and novel faces fell between these two conditions. This pattern of findings suggests that (a) positive emotion can facilitate processing in prosopagnosia, and (b) covert recognition may rely on emotional valence rather than familiarity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dominant accounts of covert recognition in prosopagnosia assume subthreshold activation of face representations created prior to onset of the disorder. Yet, such accounts cannot explain covert recognition in congenital prosopagnosia, where the impairment is present from birth. Alternatively, covert recognition may rely on affective valence, yet no study has explored this possibility. The current study addressed this issue in 3 individuals with congenital prosopagnosia, using measures of the scanpath to indicate recognition. Participants were asked to memorize 30 faces paired with descriptions of aggressive, nice, or neutral behaviours. In a later recognition test, eye movements were monitored while participants discriminated studied from novel faces. Sampling was reduced for studied--nice compared to studied--aggressive faces, and performance for studied--neutral and novel faces fell between these two conditions. This pattern of findings suggests that (a) positive emotion can facilitate processing in prosopagnosia, and (b) covert recognition may rely on emotional valence rather than familiarity. |
Sarah Bate; Rachel Bennetts; Joseph A Mole; James A Ainge; Nicola J Gregory; Anna K Bobak; Amanda Bussunt Rehabilitation of face-processing skills in an adolescent with prosopagnosia: Evaluation of an online perceptual training programme Journal Article Neuropsychological Rehabilitation, 25 (5), pp. 733–762, 2015. @article{Bate2015, title = {Rehabilitation of face-processing skills in an adolescent with prosopagnosia: Evaluation of an online perceptual training programme}, author = {Sarah Bate and Rachel Bennetts and Joseph A Mole and James A Ainge and Nicola J Gregory and Anna K Bobak and Amanda Bussunt}, doi = {10.1080/09602011.2014.973886}, year = {2015}, date = {2015-01-01}, journal = {Neuropsychological Rehabilitation}, volume = {25}, number = {5}, pages = {733--762}, abstract = {In this paper we describe the case of EM, a female adolescent who acquired prosopagnosia following encephalitis at the age of eight. Initial neuropsychological and eye-movement investigations indicated that EM had profound difficulties in face perception as well as face recognition. EM underwent 14 weeks of perceptual training in an online programme that attempted to improve her ability to make fine-grained discriminations between faces. Following training, EM's face perception skills had improved, and the effect generalised to untrained faces. Eye-movement analyses also indicated that EM spent more time viewing the inner facial features post-training. Examination of EM's face recognition skills revealed an improvement in her recognition of personally-known faces when presented in a laboratory-based test, although the same gains were not noted in her everyday experiences with these faces. In addition, EM did not improve on a test assessing the recognition of newly encoded faces. One month after training, EM had maintained the improvement on the eye-tracking test, and to a lesser extent, her performance on the familiar faces test. This pattern of findings is interpreted as promising evidence that the programme can improve face perception skills, and with some adjustments, may at least partially improve face recognition skills.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this paper we describe the case of EM, a female adolescent who acquired prosopagnosia following encephalitis at the age of eight. Initial neuropsychological and eye-movement investigations indicated that EM had profound difficulties in face perception as well as face recognition. EM underwent 14 weeks of perceptual training in an online programme that attempted to improve her ability to make fine-grained discriminations between faces. Following training, EM's face perception skills had improved, and the effect generalised to untrained faces. Eye-movement analyses also indicated that EM spent more time viewing the inner facial features post-training. Examination of EM's face recognition skills revealed an improvement in her recognition of personally-known faces when presented in a laboratory-based test, although the same gains were not noted in her everyday experiences with these faces. In addition, EM did not improve on a test assessing the recognition of newly encoded faces. One month after training, EM had maintained the improvement on the eye-tracking test, and to a lesser extent, her performance on the familiar faces test. This pattern of findings is interpreted as promising evidence that the programme can improve face perception skills, and with some adjustments, may at least partially improve face recognition skills. |
Denise Baumeler; Sabine Born; Nicolas Burra; Radek Ptak When left is one and right is double: An experimental investigation of visual allesthesia after right parietal damage Journal Article Vision, 4 , pp. 1–13, 2020. @article{Baumeler2020, title = {When left is one and right is double: An experimental investigation of visual allesthesia after right parietal damage}, author = {Denise Baumeler and Sabine Born and Nicolas Burra and Radek Ptak}, doi = {10.3390/vision4010016}, year = {2020}, date = {2020-01-01}, journal = {Vision}, volume = {4}, pages = {1--13}, abstract = {Illusory visual phenomena, such as palinopsia, polyopsia or allesthesia, are rare manifestations of posterior cortical damage. Symptoms are characterized by illusory perceptions, ranging from isolated stationary objects to scenes and moving persons. Such illusions may appear while the original object is still in view, or become manifest with a delay and last for minutes, hours or even days. Some authors have suggested a disinhibited cortical response underlying visual illusions, but experimental studies supporting this hypothesis are lacking. Here, we examined a rare patient who after focal right parietal injury consistently reported a second stimulus on the left when briefly shown a target in his right hemifield. The patient perceived the illusory stimulus as less intense, and therefore concluded that it must have a different shape than the original stimulus. A masking experiment revealed that the frequency of the illusion was inversely related to the visibility of the original stimulus, suggesting that it depended on early, feedforward visual processing. We propose that illusory perceptions reflect the interplay of two physiological processes: a fast and automatic activation of contralateral, homotopic visual cortex after unilateral stimulation, and the lack of top-down inhibition following damage to the posterior parietal cortex.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Illusory visual phenomena, such as palinopsia, polyopsia or allesthesia, are rare manifestations of posterior cortical damage. Symptoms are characterized by illusory perceptions, ranging from isolated stationary objects to scenes and moving persons. Such illusions may appear while the original object is still in view, or become manifest with a delay and last for minutes, hours or even days. Some authors have suggested a disinhibited cortical response underlying visual illusions, but experimental studies supporting this hypothesis are lacking. Here, we examined a rare patient who after focal right parietal injury consistently reported a second stimulus on the left when briefly shown a target in his right hemifield. The patient perceived the illusory stimulus as less intense, and therefore concluded that it must have a different shape than the original stimulus. A masking experiment revealed that the frequency of the illusion was inversely related to the visibility of the original stimulus, suggesting that it depended on early, feedforward visual processing. We propose that illusory perceptions reflect the interplay of two physiological processes: a fast and automatic activation of contralateral, homotopic visual cortex after unilateral stimulation, and the lack of top-down inhibition following damage to the posterior parietal cortex. |
Denise Baumeler; Josef G Schönhammer; Sabine Born Microsaccade dynamics in the attentional repulsion effect Journal Article Vision Research, 170 , pp. 46–52, 2020. @article{Baumeler2020b, title = {Microsaccade dynamics in the attentional repulsion effect}, author = {Denise Baumeler and Josef G Schönhammer and Sabine Born}, doi = {10.1016/j.visres.2020.03.009}, year = {2020}, date = {2020-01-01}, journal = {Vision Research}, volume = {170}, pages = {46--52}, abstract = {A briefly flashed peripheral cue has been shown to repulse the perceived position of a subsequently presented foveal probe - a bias called the Attentional Repulsion Effect (ARE). While this bias has originally been assumed to reflect attentional capturing by the cue, its attentional nature has recently been questioned. To investigate the ARE's attentional properties, we recorded microsaccades as an attentional marker in the ARE paradigm. Microsaccades, small fixational eye movements performed during fixation, have previously been described to reflect the dynamics of spatial attention deployment. Our results favor an attentional explanation for the ARE: In trials in which an ARE was found, microsaccades were directed more often toward the cue, presumably reflecting the covert shift of attention. In contrast, more cue-incongruent microsaccades were observed in trials in which no ARE was found. Therefore, both repulsion as well as measured microsaccade modulations, are most likely an outcome of the preceding shifts of covert attention.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A briefly flashed peripheral cue has been shown to repulse the perceived position of a subsequently presented foveal probe - a bias called the Attentional Repulsion Effect (ARE). While this bias has originally been assumed to reflect attentional capturing by the cue, its attentional nature has recently been questioned. To investigate the ARE's attentional properties, we recorded microsaccades as an attentional marker in the ARE paradigm. Microsaccades, small fixational eye movements performed during fixation, have previously been described to reflect the dynamics of spatial attention deployment. Our results favor an attentional explanation for the ARE: In trials in which an ARE was found, microsaccades were directed more often toward the cue, presumably reflecting the covert shift of attention. In contrast, more cue-incongruent microsaccades were observed in trials in which no ARE was found. Therefore, both repulsion as well as measured microsaccade modulations, are most likely an outcome of the preceding shifts of covert attention. |
Louise Beattie; Markus Bindemann; Simon D Kyle; Stephany M Biello Attention to beds in natural scenes by observers with insomnia symptoms Journal Article Behaviour Research and Therapy, 92 , pp. 51–56, 2017. @article{Beattie2017, title = {Attention to beds in natural scenes by observers with insomnia symptoms}, author = {Louise Beattie and Markus Bindemann and Simon D Kyle and Stephany M Biello}, doi = {10.1016/j.brat.2017.02.001}, year = {2017}, date = {2017-01-01}, journal = {Behaviour Research and Therapy}, volume = {92}, pages = {51--56}, publisher = {Elsevier Ltd}, abstract = {Attention biases to sleep-related stimuli are held to play a key role in the development and maintenance of insomnia, but such biases have only been shown with controlled visual displays. This study investigated whether observers with insomnia symptoms allocate attention to sleep-related items in natural scenes, by recording eye movements during free-viewing of bedrooms. Participants with insomnia symptoms and normal sleepers were matched in their visual exploration of these scenes, and there was no evidence that the attention of those with insomnia symptoms was captured more quickly by sleep-related stimuli than that of normal sleepers. However, the insomnia group fixated bed regions on more trials and, once fixated on a bed, also remained there for longer. These findings indicate that sleep stimuli are particularly effective in retaining visual attention in complex natural scenes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Attention biases to sleep-related stimuli are held to play a key role in the development and maintenance of insomnia, but such biases have only been shown with controlled visual displays. This study investigated whether observers with insomnia symptoms allocate attention to sleep-related items in natural scenes, by recording eye movements during free-viewing of bedrooms. Participants with insomnia symptoms and normal sleepers were matched in their visual exploration of these scenes, and there was no evidence that the attention of those with insomnia symptoms was captured more quickly by sleep-related stimuli than that of normal sleepers. However, the insomnia group fixated bed regions on more trials and, once fixated on a bed, also remained there for longer. These findings indicate that sleep stimuli are particularly effective in retaining visual attention in complex natural scenes. |
Elizabeth H Beck; Anthony A Amato; Steven A Greenberg; Elizabeth H Beck Improvement of internuclear ophthalmoparesis in multiple sclerosis with dalfampridine Journal Article Neurology, 83 , pp. 192–194, 2014. @article{Beck2014, title = {Improvement of internuclear ophthalmoparesis in multiple sclerosis with dalfampridine}, author = {Elizabeth H Beck and Anthony A Amato and Steven A Greenberg and Elizabeth H Beck}, doi = {10.1212/WNL.0000000000000546}, year = {2014}, date = {2014-01-01}, journal = {Neurology}, volume = {83}, pages = {192--194}, abstract = {Internuclear ophthalmoparesis (INO) in multiple sclerosis (MS) is due to demyelination of the medial longitudinal fasciculus (MLF) and provides an acces- sible model for studying consequences of raised body temperature and fatigue on central demyelination.1,2 Prompted by one of our patient's report of vision improvement after initiating dalfampridine, a potas- sium channel blocker prescribed for gait impairment,3 we measured this drug's effects on 3 patients with MS with bilateral INO. All showed changes in horizontal saccadic conjugacy consistent with improved trans- mission of the neural pulse responsible for adducting movements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Internuclear ophthalmoparesis (INO) in multiple sclerosis (MS) is due to demyelination of the medial longitudinal fasciculus (MLF) and provides an acces- sible model for studying consequences of raised body temperature and fatigue on central demyelination.1,2 Prompted by one of our patient's report of vision improvement after initiating dalfampridine, a potas- sium channel blocker prescribed for gait impairment,3 we measured this drug's effects on 3 patients with MS with bilateral INO. All showed changes in horizontal saccadic conjugacy consistent with improved trans- mission of the neural pulse responsible for adducting movements. |
Valerie M Beck; Timothy J Vickery Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory Journal Article Cortex, 122 , pp. 159–169, 2020. @article{Beck2020, title = {Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory}, author = {Valerie M Beck and Timothy J Vickery}, doi = {10.1016/j.cortex.2018.09.017}, year = {2020}, date = {2020-01-01}, journal = {Cortex}, volume = {122}, pages = {159--169}, publisher = {Elsevier Ltd}, abstract = {Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems. |
Jeffrey S Bedwell; Christopher C Spencer; Chi C Chan; Pamela D Butler; Pejman Sehatpour; Joseph Schmidt The P1 visual-evoked potential, red light, and transdiagnostic psychiatric symptoms Journal Article Brain Research, 1687 , pp. 144–154, 2018. @article{Bedwell2018, title = {The P1 visual-evoked potential, red light, and transdiagnostic psychiatric symptoms}, author = {Jeffrey S Bedwell and Christopher C Spencer and Chi C Chan and Pamela D Butler and Pejman Sehatpour and Joseph Schmidt}, doi = {10.1016/j.brainres.2018.03.002}, year = {2018}, date = {2018-01-01}, journal = {Brain Research}, volume = {1687}, pages = {144--154}, publisher = {Elsevier B.V.}, abstract = {A reduced P1 visual-evoked potential amplitude has been reported across several psychiatric disorders, including schizophrenia-spectrum, bipolar, and depressive disorders. In addition, a difference in P1 amplitude change to a red background compared to its opponent color, green, has been found in schizophrenia-spectrum samples. The current study examined whether specific psychiatric symptoms that related to these P1 abnormalities in earlier studies would be replicated when using a broad transdiagnostic sample. The final sample consisted of 135 participants: 26 with bipolar disorders, 25 with schizophrenia-spectrum disorders, 19 with unipolar depression, 62 with no current psychiatric disorder, and 3 with disorders in other categories. Low (8%) and high (64%) contrast check arrays were presented on gray, green, and red background conditions during electroencephalogram, while an eye tracker monitored visual fixation on the stimuli. Linear regressions across the entire sample (N = 135) found that greater severity of both clinician-rated and self-reported delusions/magical thinking correlated with a reduced P1 amplitude on the low contrast gray (neutral) background condition. In addition, across the entire sample, higher self-reported constricted affect was associated with a larger decrease in P1 amplitude (averaged across contrast conditions) to the red, compared to green, background. All relationships remained statistically significant after covarying for diagnostic class, suggesting that they are relatively transdiagnostic in nature. These findings indicate that early visual processing abnormalities may be more directly related to specific transdiagnostic symptoms such as delusions and constricted affect rather than specific psychiatric diagnoses or broad symptom factor scales.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A reduced P1 visual-evoked potential amplitude has been reported across several psychiatric disorders, including schizophrenia-spectrum, bipolar, and depressive disorders. In addition, a difference in P1 amplitude change to a red background compared to its opponent color, green, has been found in schizophrenia-spectrum samples. The current study examined whether specific psychiatric symptoms that related to these P1 abnormalities in earlier studies would be replicated when using a broad transdiagnostic sample. The final sample consisted of 135 participants: 26 with bipolar disorders, 25 with schizophrenia-spectrum disorders, 19 with unipolar depression, 62 with no current psychiatric disorder, and 3 with disorders in other categories. Low (8%) and high (64%) contrast check arrays were presented on gray, green, and red background conditions during electroencephalogram, while an eye tracker monitored visual fixation on the stimuli. Linear regressions across the entire sample (N = 135) found that greater severity of both clinician-rated and self-reported delusions/magical thinking correlated with a reduced P1 amplitude on the low contrast gray (neutral) background condition. In addition, across the entire sample, higher self-reported constricted affect was associated with a larger decrease in P1 amplitude (averaged across contrast conditions) to the red, compared to green, background. All relationships remained statistically significant after covarying for diagnostic class, suggesting that they are relatively transdiagnostic in nature. These findings indicate that early visual processing abnormalities may be more directly related to specific transdiagnostic symptoms such as delusions and constricted affect rather than specific psychiatric diagnoses or broad symptom factor scales. |
Sara A Beedie; Philip J Benson; Ina Giegling; Dan Rujescu; David M St. Clair Smooth pursuit and visual scanpaths: Independence of two candidate oculomotor risk markers for schizophrenia Journal Article The World Journal of Biological Psychiatry, 13 (3), pp. 200–210, 2012. @article{Beedie2012, title = {Smooth pursuit and visual scanpaths: Independence of two candidate oculomotor risk markers for schizophrenia}, author = {Sara A Beedie and Philip J Benson and Ina Giegling and Dan Rujescu and David M {St. Clair}}, doi = {10.3109/15622975.2011.566628}, year = {2012}, date = {2012-01-01}, journal = {The World Journal of Biological Psychiatry}, volume = {13}, number = {3}, pages = {200--210}, abstract = {OBJECTIVES: Smooth pursuit and visual scanpath deficits are candidate trait markers for schizophrenia. It is not clear whether eye tracking dysfunction (ETD) and atypical scanpath behaviour are the product of the same underlying neurobiological processes. We have examined co-occurrence of ETD and scanpath disturbance in individuals with schizophrenia and healthy volunteers. METHODS: Eye movements of individuals with schizophrenia (N = 96) and non-clinical age-matched comparison participants (N = 100) were recorded using non-invasive infrared oculography during smooth pursuit in both predictable (horizontal sinusoid) and less predictable (Lissajous sinusoid) conditions and a free viewing scanpath task. RESULTS: Individuals with schizophrenia demonstrated scanning deficits in both tasks. There was no association between performance measures of smooth pursuit and scene scanpaths in patient or control groups. Odds ratios comparing the likelihood of scanpath dysfunction when ETD was present, and the likelihood of finding scanpath dysfunction when ETD was absent were not significant in patients or controls in either pursuit variant, suggesting that ETD and scanpath dysfunction are independent anomalies in schizophrenia. CONCLUSION: ETD and scanpath disturbance appear to reflect independent oculomotor or neurocognitive deficits in schizophrenia. Each task may confer unique information about the pathophysiology of psychosis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVES: Smooth pursuit and visual scanpath deficits are candidate trait markers for schizophrenia. It is not clear whether eye tracking dysfunction (ETD) and atypical scanpath behaviour are the product of the same underlying neurobiological processes. We have examined co-occurrence of ETD and scanpath disturbance in individuals with schizophrenia and healthy volunteers. METHODS: Eye movements of individuals with schizophrenia (N = 96) and non-clinical age-matched comparison participants (N = 100) were recorded using non-invasive infrared oculography during smooth pursuit in both predictable (horizontal sinusoid) and less predictable (Lissajous sinusoid) conditions and a free viewing scanpath task. RESULTS: Individuals with schizophrenia demonstrated scanning deficits in both tasks. There was no association between performance measures of smooth pursuit and scene scanpaths in patient or control groups. Odds ratios comparing the likelihood of scanpath dysfunction when ETD was present, and the likelihood of finding scanpath dysfunction when ETD was absent were not significant in patients or controls in either pursuit variant, suggesting that ETD and scanpath dysfunction are independent anomalies in schizophrenia. CONCLUSION: ETD and scanpath disturbance appear to reflect independent oculomotor or neurocognitive deficits in schizophrenia. Each task may confer unique information about the pathophysiology of psychosis. |
Robert J van Beers The sources of variability in saccadic eye movements Journal Article Journal of Neuroscience, 27 (33), pp. 8757–8770, 2007. @article{Beers2007, title = {The sources of variability in saccadic eye movements}, author = {Robert J van Beers}, doi = {10.1523/JNEUROSCI.2311-07.2007}, year = {2007}, date = {2007-01-01}, journal = {Journal of Neuroscience}, volume = {27}, number = {33}, pages = {8757--8770}, abstract = {Our movements are variable, but the origin of this variability is poorly understood. We examined the sources of variability in human saccadic eye movements. In two experiments, we measured the spatiotemporal variability in saccade trajectories as a function of movement direction and amplitude. One of our new observations is that the variability in movement direction is smaller for purely horizontal and vertical saccades than for saccades in oblique directions. We also found that saccade amplitude, duration, and peak velocity are all correlated with one another. To determine the origin of the observed variability, we estimated the noise in motor commands from the observed spatiotemporal variability, while taking into account the variability resulting from uncertainty in localization of the target. This analysis revealed that uncertainty in target localization is the major source of variability in saccade endpoints, whereas noise in the magnitude of the motor commands explains a slightly smaller fraction. In addition, there is temporal variability such that saccades with a longer than average duration have a smaller than average peak velocity. This noise model has a large generality because it correctly predicts the variability in other data sets, which contain saccades starting from very different initial locations. Because the temporal noise most likely originates in movement planning, and the motor command noise in movement execution, we conclude that uncertainty in sensory signals and noise in movement planning and execution all contribute to the variability in saccade trajectories. These results are important for understanding how the brain controls movement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Our movements are variable, but the origin of this variability is poorly understood. We examined the sources of variability in human saccadic eye movements. In two experiments, we measured the spatiotemporal variability in saccade trajectories as a function of movement direction and amplitude. One of our new observations is that the variability in movement direction is smaller for purely horizontal and vertical saccades than for saccades in oblique directions. We also found that saccade amplitude, duration, and peak velocity are all correlated with one another. To determine the origin of the observed variability, we estimated the noise in motor commands from the observed spatiotemporal variability, while taking into account the variability resulting from uncertainty in localization of the target. This analysis revealed that uncertainty in target localization is the major source of variability in saccade endpoints, whereas noise in the magnitude of the motor commands explains a slightly smaller fraction. In addition, there is temporal variability such that saccades with a longer than average duration have a smaller than average peak velocity. This noise model has a large generality because it correctly predicts the variability in other data sets, which contain saccades starting from very different initial locations. Because the temporal noise most likely originates in movement planning, and the motor command noise in movement execution, we conclude that uncertainty in sensory signals and noise in movement planning and execution all contribute to the variability in saccade trajectories. These results are important for understanding how the brain controls movement. |
Christopher G Beevers; Michael C Mullarkey; Justin Dainer-Best; Rochelle A Stewart; Jocelyn Labrada; John J B Allen; John E McGeary; Jason Shumake Association between negative cognitive bias and depression: A symptom-level approach Item Journal Article Journal of Abnormal Psychology, 128 (3), pp. 212–227, 2019. @article{Beevers2019, title = {Association between negative cognitive bias and depression: A symptom-level approach Item}, author = {Christopher G Beevers and Michael C Mullarkey and Justin Dainer-Best and Rochelle A Stewart and Jocelyn Labrada and John J B Allen and John E McGeary and Jason Shumake}, doi = {10.1037/abn0000405}, year = {2019}, date = {2019-01-01}, journal = {Journal of Abnormal Psychology}, volume = {128}, number = {3}, pages = {212--227}, abstract = {Cognitive models of depression posit that negatively biased self-referent processing and attention have important roles in the disorder. However, depression is a heterogeneous collection of symptoms and all symptoms are unlikely to be associated with these negative cognitive biases. The current study involved 218 community adults whose depression ranged from no symptoms to clinical levels of depression. Random forest machine learning was used to identify the most important depression symptom predictors of each negative cognitive bias. Depression symptoms were measured with the Beck Depression Inventory-II. Model performance was evaluated using predictive R-squared (R pred2 ), the expected variance explained in data not used to train the algorithm, estimated by 10 repetitions of 10-fold cross-validation. Using the self-referent encoding task (SRET), depression symptoms explained 34% to 45% of the variance in negative self-referent processing. The symptoms of sadness, self-dislike, pessimism, feelings of punishment, and indecision were most important. Notably, many depression symptoms made virtually no contribution to this prediction. In contrast, for attention bias for sad stimuli, measured with the dot-probe task using behavioral reaction time (RT) and eye gaze metrics, no reliable symptom predictors were identified. Findings indicate that a symptom-level approach may provide new insights into which symptoms, if any, are associated with negative cognitive biases in depression.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cognitive models of depression posit that negatively biased self-referent processing and attention have important roles in the disorder. However, depression is a heterogeneous collection of symptoms and all symptoms are unlikely to be associated with these negative cognitive biases. The current study involved 218 community adults whose depression ranged from no symptoms to clinical levels of depression. Random forest machine learning was used to identify the most important depression symptom predictors of each negative cognitive bias. Depression symptoms were measured with the Beck Depression Inventory-II. Model performance was evaluated using predictive R-squared (R pred2 ), the expected variance explained in data not used to train the algorithm, estimated by 10 repetitions of 10-fold cross-validation. Using the self-referent encoding task (SRET), depression symptoms explained 34% to 45% of the variance in negative self-referent processing. The symptoms of sadness, self-dislike, pessimism, feelings of punishment, and indecision were most important. Notably, many depression symptoms made virtually no contribution to this prediction. In contrast, for attention bias for sad stimuli, measured with the dot-probe task using behavioral reaction time (RT) and eye gaze metrics, no reliable symptom predictors were identified. Findings indicate that a symptom-level approach may provide new insights into which symptoms, if any, are associated with negative cognitive biases in depression. |
Francesca Beilharz; Andrea Phillipou; David J Castle; Susan L Rossell Saccadic eye movements in body dysmorphic disorder Journal Article Journal of Obsessive-Compulsive and Related Disorders, 25 , pp. 1–6, 2020. @article{Beilharz2020, title = {Saccadic eye movements in body dysmorphic disorder}, author = {Francesca Beilharz and Andrea Phillipou and David J Castle and Susan L Rossell}, doi = {10.1016/j.jocrd.2020.100526}, year = {2020}, date = {2020-04-01}, journal = {Journal of Obsessive-Compulsive and Related Disorders}, volume = {25}, pages = {1--6}, publisher = {Elsevier B.V.}, abstract = {Body dysmorphic disorder (BDD) is characterised by a preoccupation with perceived flaws in appearance, which significantly disrupts functioning and causes distress. The difference in self-perception characteristic of BDD has been related to a bias in visual processing across a variety of stimuli and tasks. However, it is unknown how BDD participants perform on basic saccade tasks using eye tracking. Eighteen BDD and 21 healthy control participants completed a battery of saccadic eye movement tasks (fixation, prosaccade, anti-saccade, and memory guided). No significant differences were noted between the groups regarding behavioural performance or patterns of eye movements; however, there was a trend for BDD participants to make increased anticipatory errors on the prosaccade task. Overall, BDD participants demonstrated largely intact saccadic eye movement characteristics which may differentiate BDD from other obsessive-compulsive related disorders, although future research using larger samples is required. It is consequently argued that abnormalities in visual processing apparent among people with BDD may reflect abnormalities in higher-order visual systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Body dysmorphic disorder (BDD) is characterised by a preoccupation with perceived flaws in appearance, which significantly disrupts functioning and causes distress. The difference in self-perception characteristic of BDD has been related to a bias in visual processing across a variety of stimuli and tasks. However, it is unknown how BDD participants perform on basic saccade tasks using eye tracking. Eighteen BDD and 21 healthy control participants completed a battery of saccadic eye movement tasks (fixation, prosaccade, anti-saccade, and memory guided). No significant differences were noted between the groups regarding behavioural performance or patterns of eye movements; however, there was a trend for BDD participants to make increased anticipatory errors on the prosaccade task. Overall, BDD participants demonstrated largely intact saccadic eye movement characteristics which may differentiate BDD from other obsessive-compulsive related disorders, although future research using larger samples is required. It is consequently argued that abnormalities in visual processing apparent among people with BDD may reflect abnormalities in higher-order visual systems. |
Judith Bek; Ellen Poliakoff; Karen Lander Measuring emotion recognition by people with Parkinson's disease using eye-tracking with dynamic facial expressions Journal Article Journal of Neuroscience Methods, 331 , pp. 1–7, 2020. @article{Bek2020, title = {Measuring emotion recognition by people with Parkinson's disease using eye-tracking with dynamic facial expressions}, author = {Judith Bek and Ellen Poliakoff and Karen Lander}, doi = {10.1016/j.jneumeth.2019.108524}, year = {2020}, date = {2020-01-01}, journal = {Journal of Neuroscience Methods}, volume = {331}, pages = {1--7}, abstract = {Background: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. New method: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. Results: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. Comparison with existing methods: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. Conclusions: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. New method: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. Results: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. Comparison with existing methods: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. Conclusions: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area. |
Judith Bek; Emma Gowen; Stefan Vogt; Trevor J Crawford; Ellen Poliakoff; Emma Gowen; Stefan Vogt; Trevor J Crawford; Ellen Poliakoff Action observation and imitation in Parkinson's disease: The influence of biological and non-biological stimuli Journal Article Neuropsychologia, 150 , pp. 1–11, 2021. @article{Bek2021, title = {Action observation and imitation in Parkinson's disease: The influence of biological and non-biological stimuli}, author = {Judith Bek and Emma Gowen and Stefan Vogt and Trevor J Crawford and Ellen Poliakoff and Emma Gowen and Stefan Vogt and Trevor J Crawford and Ellen Poliakoff}, doi = {10.1016/j.neuropsychologia.2020.107690}, year = {2021}, date = {2021-01-01}, journal = {Neuropsychologia}, volume = {150}, pages = {1--11}, publisher = {Elsevier Ltd}, abstract = {Action observation and imitation have been found to influence movement in people with Parkinson's disease (PD), but simple visual stimuli can also guide their movement. To investigate whether action observation may provide a more effective stimulus than other visual cues, the present study examined the effects of observing human pointing movements and simple visual stimuli on hand kinematics and eye movements in people with mild to moderate PD and age-matched controls. In Experiment 1, participants observed videos of movement sequences between horizontal positions, depicted by a simple cue with or without a moving human hand, then imitated the sequence either without further visual input (consecutive task) or while watching the video again (concurrent task). Modulation of movement duration, in accordance with changes in the observed stimulus, increased when the simple cue was accompanied by the hand and in the concurrent task, whereas modulation of horizontal amplitude was greater with the simple cue alone and in the consecutive task. Experiment 2 compared imitation of kinematically-matched dynamic biological (human hand) and non- biological (shape) stimuli, which moved with a high or low vertical trajectory. Both groups exhibited greater modulation for the hand than the shape, and differences in eye movements suggested closer tracking of the hand. Despite producing slower and smaller movements overall, the PD group showed a similar pattern of imitation to controls across tasks and conditions. The findings demonstrate that observing human action influences aspects of movement such as duration or trajectory more strongly than non-biological stimuli, particularly during concurrent imitation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Action observation and imitation have been found to influence movement in people with Parkinson's disease (PD), but simple visual stimuli can also guide their movement. To investigate whether action observation may provide a more effective stimulus than other visual cues, the present study examined the effects of observing human pointing movements and simple visual stimuli on hand kinematics and eye movements in people with mild to moderate PD and age-matched controls. In Experiment 1, participants observed videos of movement sequences between horizontal positions, depicted by a simple cue with or without a moving human hand, then imitated the sequence either without further visual input (consecutive task) or while watching the video again (concurrent task). Modulation of movement duration, in accordance with changes in the observed stimulus, increased when the simple cue was accompanied by the hand and in the concurrent task, whereas modulation of horizontal amplitude was greater with the simple cue alone and in the consecutive task. Experiment 2 compared imitation of kinematically-matched dynamic biological (human hand) and non- biological (shape) stimuli, which moved with a high or low vertical trajectory. Both groups exhibited greater modulation for the hand than the shape, and differences in eye movements suggested closer tracking of the hand. Despite producing slower and smaller movements overall, the PD group showed a similar pattern of imitation to controls across tasks and conditions. The findings demonstrate that observing human action influences aspects of movement such as duration or trajectory more strongly than non-biological stimuli, particularly during concurrent imitation. |
Nathalie N Bélanger; Michelle Lee; Elizabeth R Schotter Young skilled deaf readers have an enhanced perceptual span in reading Journal Article Quarterly Journal of Experimental Psychology, 71 (1), pp. 291–301, 2018. @article{Belanger2018, title = {Young skilled deaf readers have an enhanced perceptual span in reading}, author = {Nathalie N Bélanger and Michelle Lee and Elizabeth R Schotter}, doi = {10.1080/17470218.2017.1324498}, year = {2018}, date = {2018-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {71}, number = {1}, pages = {291--301}, abstract = {Recent evidence suggests that deaf people have enhanced visual attention to simple stimuli in the parafovea in comparison to hearing people. Although a large part of reading involves processing the fixated words in foveal vision, readers also utilize information in parafoveal vision to pre-process upcoming words and decide where to look next. We investigated whether auditory deprivation affects low-level visual processing during reading, and compared the perceptual span of deaf signers who were skilled and less skilled readers to that of skilled hearing readers. Compared to hearing readers, deaf readers had a larger perceptual span than would be expected by their reading ability. These results provide the first evidence that deaf readers' enhanced attentional allocation to the parafovea is used during a complex cognitive task such as reading.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recent evidence suggests that deaf people have enhanced visual attention to simple stimuli in the parafovea in comparison to hearing people. Although a large part of reading involves processing the fixated words in foveal vision, readers also utilize information in parafoveal vision to pre-process upcoming words and decide where to look next. We investigated whether auditory deprivation affects low-level visual processing during reading, and compared the perceptual span of deaf signers who were skilled and less skilled readers to that of skilled hearing readers. Compared to hearing readers, deaf readers had a larger perceptual span than would be expected by their reading ability. These results provide the first evidence that deaf readers' enhanced attentional allocation to the parafovea is used during a complex cognitive task such as reading. |
Christian Bellebaum; Irene Daum; B Koch; M Schwarz; Klaus-Peter Hoffmann The role of the human thalamus in processing corollary discharge Journal Article Brain, 128 (5), pp. 1139–1154, 2005. @article{Bellebaum2005, title = {The role of the human thalamus in processing corollary discharge}, author = {Christian Bellebaum and Irene Daum and B Koch and M Schwarz and Klaus-Peter Hoffmann}, doi = {10.1093/brain/awh474}, year = {2005}, date = {2005-01-01}, journal = {Brain}, volume = {128}, number = {5}, pages = {1139--1154}, abstract = {Corollary discharge signals play an important role in monitoring self-generated movements to guarantee spatial constancy. Recent work in macaques suggests that the thalamus conveys corollary discharge information of upcoming saccades passing from the superior colliculus to the frontal eye field. The present study aimed to investigate the involvement of the thalamus in humans by assessing the effect of thalamic lesions on the processing of corollary discharge information. Thirteen patients with selective thalamic lesions and 13 healthy age-matched control subjects performed a saccadic double-step task in which retino-spatial dissonance was induced, i.e. the retinal vector of the second target and the movement vector of the second saccade were different. Thus, the subjects could not rely on retinal information alone, but had to use corollary discharge information to correctly perform the second saccade. The amplitudes of first and second saccades were significantly smaller in patients than in controls. Five thalamic lesion patients showed unilateral deficits in using corollary discharge information, as revealed by asymmetries compared with the other patients and controls. Three patients with lateral thalamic lesions including the ventrolateral nucleus (VL) were impaired contralaterally to the side of damage and one patient with a lesion in the mediodorsal thalamus (MD) was impaired ipsilaterally to the lesion. The largest asymmetry was found in a patient with a bilateral thalamic lesion. The results provide evidence for a thalamic involvement in the processing of corollary discharge information in humans, with a potential role of both the VL and MD nuclei}, keywords = {}, pubstate = {published}, tppubtype = {article} } Corollary discharge signals play an important role in monitoring self-generated movements to guarantee spatial constancy. Recent work in macaques suggests that the thalamus conveys corollary discharge information of upcoming saccades passing from the superior colliculus to the frontal eye field. The present study aimed to investigate the involvement of the thalamus in humans by assessing the effect of thalamic lesions on the processing of corollary discharge information. Thirteen patients with selective thalamic lesions and 13 healthy age-matched control subjects performed a saccadic double-step task in which retino-spatial dissonance was induced, i.e. the retinal vector of the second target and the movement vector of the second saccade were different. Thus, the subjects could not rely on retinal information alone, but had to use corollary discharge information to correctly perform the second saccade. The amplitudes of first and second saccades were significantly smaller in patients than in controls. Five thalamic lesion patients showed unilateral deficits in using corollary discharge information, as revealed by asymmetries compared with the other patients and controls. Three patients with lateral thalamic lesions including the ventrolateral nucleus (VL) were impaired contralaterally to the side of damage and one patient with a lesion in the mediodorsal thalamus (MD) was impaired ipsilaterally to the lesion. The largest asymmetry was found in a patient with a bilateral thalamic lesion. The results provide evidence for a thalamic involvement in the processing of corollary discharge information in humans, with a potential role of both the VL and MD nuclei |
Christian Bellebaum; Klaus-Peter Hoffmann; Irene Daum Post-saccadic updating of visual space in the posterior parietal cortex in humans Journal Article Behavioural Brain Research, 163 (2), pp. 194–203, 2005. @article{Bellebaum2005a, title = {Post-saccadic updating of visual space in the posterior parietal cortex in humans}, author = {Christian Bellebaum and Klaus-Peter Hoffmann and Irene Daum}, doi = {10.1016/j.bbr.2005.05.007}, year = {2005}, date = {2005-01-01}, journal = {Behavioural Brain Research}, volume = {163}, number = {2}, pages = {194--203}, abstract = {Updating of visual space takes place in the posterior parietal cortex to guarantee spatial constancy across eye movements. However, the timing of updating with respect to saccadic eye movements remains a matter of debate. In the present study, event-related potentials (ERPs) were recorded in 15 volunteers during a saccadic double-step task to elucidate the time course of the updating process. In the experimental condition updating of visual space was required, because both saccade targets had already disappeared before the first saccade was executed. A similar task without updating requirements served as control condition. ERP analysis revealed a significantly larger slow positive wave in the retino-spatial dissonance condition compared to the control condition, starting between 150 and 200 ms after first saccade onset. Source analysis showed an asymmetry with respect to the direction of the first saccade. Whereas the source was restricted to the right PPC in trials with leftward first saccades, left and right PPC were involved in rightward trials. The results of the present study suggest that updating of visual space in a saccadic double-step task occurs not earlier than 150 ms after the onset of the first saccade. We conclude that extraretinal information about the first saccade is integrated with motor information about the second saccade in the inter-saccade interval.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Updating of visual space takes place in the posterior parietal cortex to guarantee spatial constancy across eye movements. However, the timing of updating with respect to saccadic eye movements remains a matter of debate. In the present study, event-related potentials (ERPs) were recorded in 15 volunteers during a saccadic double-step task to elucidate the time course of the updating process. In the experimental condition updating of visual space was required, because both saccade targets had already disappeared before the first saccade was executed. A similar task without updating requirements served as control condition. ERP analysis revealed a significantly larger slow positive wave in the retino-spatial dissonance condition compared to the control condition, starting between 150 and 200 ms after first saccade onset. Source analysis showed an asymmetry with respect to the direction of the first saccade. Whereas the source was restricted to the right PPC in trials with leftward first saccades, left and right PPC were involved in rightward trials. The results of the present study suggest that updating of visual space in a saccadic double-step task occurs not earlier than 150 ms after the onset of the first saccade. We conclude that extraretinal information about the first saccade is integrated with motor information about the second saccade in the inter-saccade interval. |
Joachim Bellet; Chih-Yang Chen; Ziad M Hafed Sequential hemifield gating of alpha and beta behavioral performance oscillations after microsaccades Journal Article Journal of Neurophysiology, 118 , pp. 2789–2805, 2017. @article{Bellet2017, title = {Sequential hemifield gating of alpha and beta behavioral performance oscillations after microsaccades}, author = {Joachim Bellet and Chih-Yang Chen and Ziad M Hafed}, doi = {10.1152/jn.00253.2017}, year = {2017}, date = {2017-01-01}, journal = {Journal of Neurophysiology}, volume = {118}, pages = {2789--2805}, abstract = {Microsaccades are tiny saccades that occur during gaze fixation. Even though visual processing has been shown to be strongly modulated close to the time of microsaccades, both at central and peripheral eccentricities, it is not clear how these eye movements might influence longer term fluctuations in brain activity and behavior. Here we found that visual processing is significantly affected and, in a rhythmic manner, even several hundreds of milliseconds after a microsaccade. Human visual detection efficiency, as measured by reaction time, exhibited coherent rhythmic oscillations in the ? - and ? -frequency bands for up to ~650–700 ms after a microsaccade. Surprisingly, the oscillations were sequentially pulsed across visual hemifields relative to microsaccade direction, first occurring in the same hemifield as the movement vector for ~400 ms and then the opposite. Such pulsing also affected perceptual detection performance. Our results suggest that visual processing is subject to long-lasting oscillations that are phase locked to microsaccade generation, and that these oscillations are dependent on microsaccade direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microsaccades are tiny saccades that occur during gaze fixation. Even though visual processing has been shown to be strongly modulated close to the time of microsaccades, both at central and peripheral eccentricities, it is not clear how these eye movements might influence longer term fluctuations in brain activity and behavior. Here we found that visual processing is significantly affected and, in a rhythmic manner, even several hundreds of milliseconds after a microsaccade. Human visual detection efficiency, as measured by reaction time, exhibited coherent rhythmic oscillations in the ? - and ? -frequency bands for up to ~650–700 ms after a microsaccade. Surprisingly, the oscillations were sequentially pulsed across visual hemifields relative to microsaccade direction, first occurring in the same hemifield as the movement vector for ~400 ms and then the opposite. Such pulsing also affected perceptual detection performance. Our results suggest that visual processing is subject to long-lasting oscillations that are phase locked to microsaccade generation, and that these oscillations are dependent on microsaccade direction. |
Marie E Bellet; Joachim Bellet; Hendrikje Nienborg; Ziad M Hafed; Philipp Berens Human-level saccade detection performance using deep neural networks Journal Article Journal of Neurophysiology, 121 (2), pp. 646–661, 2019. @article{Bellet2019, title = {Human-level saccade detection performance using deep neural networks}, author = {Marie E Bellet and Joachim Bellet and Hendrikje Nienborg and Ziad M Hafed and Philipp Berens}, doi = {10.1152/jn.00601.2018}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {121}, number = {2}, pages = {646--661}, abstract = {Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades. In such cases, labeling by human experts is required, but this is a tedious task prone to variability and error. We developed a convolutional neural network to automatically detect saccades at human-level accuracy and with minimal training examples. Our algorithm surpasses state of the art according to common performance metrics and could facilitate studies of neurophysiological processes underlying saccade generation and visual processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades. In such cases, labeling by human experts is required, but this is a tedious task prone to variability and error. We developed a convolutional neural network to automatically detect saccades at human-level accuracy and with minimal training examples. Our algorithm surpasses state of the art according to common performance metrics and could facilitate studies of neurophysiological processes underlying saccade generation and visual processing. |
Caren Bellmann; Mary P Feely; Michael D Crossland; Stamatina A Kabanarou; Gary S Rubin Fixation stability using central and pericentral fixation targets in patients with age-related macular degeneration Journal Article Ophthalmology, 111 (12), pp. 2265–2270, 2004. @article{Bellmann2004, title = {Fixation stability using central and pericentral fixation targets in patients with age-related macular degeneration}, author = {Caren Bellmann and Mary P Feely and Michael D Crossland and Stamatina A Kabanarou and Gary S Rubin}, doi = {10.1016/j.ophtha.2004.06.019}, year = {2004}, date = {2004-01-01}, journal = {Ophthalmology}, volume = {111}, number = {12}, pages = {2265--2270}, abstract = {To determine fixation stability for central and pericentral fixation targets in patients with age-related macular degeneration (AMD). Comparative study. Twelve patients having late-stage AMD involving the fovea and 10 age-matched controls having no other eye diseases and visual acuity better than 20/25. Six different fixation targets (1°cross; 1°filled circle; 1°letter x; small 4-point diamond; large 4-point diamond using dimensions as in a field analyzer; large-crossover whole-image diagonal with open 1°center) were presented on a high-resolution monitor. Before examination, subjects were given verbal instructions to move their eye to see the center of the target best. Fixation stability was measured for the preferred eye, with the fellow eye occluded, using a gaze tracker. Fixation stability was quantified by calculating the bivariate contour ellipse area (BCEA) over 30 seconds for each target. For statistical analysis, BCEA values (minutes of arc2) were converted into their logarithms. The absolute retinal scotoma for the study eye was determined using a scanning laser ophthalmoscope. Bivariate contour ellipse area. Visual acuity in patients (age range, 57-87 years) ranged from 20/32 to 20/600. The lowest BCEA values were found for the 1°letter x in patients (mean, 12052.2%±254.0%) and for the 1°cross in normal subjects (mean, 1286.9%±47.8%); the highest BCEA values were found for the small 4-point diamond in patients (mean, 23109.5%±298.3%) and for the large 4-point diamond in normals (age range, 62-79 years) (mean, 3229.2%±105.4%). The difference between the targets was significant for normal subjects (analysis of variance [ANOVA], Ptextless0.01) but not for patients (ANOVA, Ptextgreater0.05). In normals, BCEA values were significantly lower for central fixation targets than for pericentral fixation targets (Ptextless0.01). Fixation is significantly less stable for pericentral fixation targets in normal subjects, indicating an advantage for central fixation targets. These results are particularly significant for any clinical and experimental testing method that requires the patient to maintain stable fixation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To determine fixation stability for central and pericentral fixation targets in patients with age-related macular degeneration (AMD). Comparative study. Twelve patients having late-stage AMD involving the fovea and 10 age-matched controls having no other eye diseases and visual acuity better than 20/25. Six different fixation targets (1°cross; 1°filled circle; 1°letter x; small 4-point diamond; large 4-point diamond using dimensions as in a field analyzer; large-crossover whole-image diagonal with open 1°center) were presented on a high-resolution monitor. Before examination, subjects were given verbal instructions to move their eye to see the center of the target best. Fixation stability was measured for the preferred eye, with the fellow eye occluded, using a gaze tracker. Fixation stability was quantified by calculating the bivariate contour ellipse area (BCEA) over 30 seconds for each target. For statistical analysis, BCEA values (minutes of arc2) were converted into their logarithms. The absolute retinal scotoma for the study eye was determined using a scanning laser ophthalmoscope. Bivariate contour ellipse area. Visual acuity in patients (age range, 57-87 years) ranged from 20/32 to 20/600. The lowest BCEA values were found for the 1°letter x in patients (mean, 12052.2%±254.0%) and for the 1°cross in normal subjects (mean, 1286.9%±47.8%); the highest BCEA values were found for the small 4-point diamond in patients (mean, 23109.5%±298.3%) and for the large 4-point diamond in normals (age range, 62-79 years) (mean, 3229.2%±105.4%). The difference between the targets was significant for normal subjects (analysis of variance [ANOVA], Ptextless0.01) but not for patients (ANOVA, Ptextgreater0.05). In normals, BCEA values were significantly lower for central fixation targets than for pericentral fixation targets (Ptextless0.01). Fixation is significantly less stable for pericentral fixation targets in normal subjects, indicating an advantage for central fixation targets. These results are particularly significant for any clinical and experimental testing method that requires the patient to maintain stable fixation. |
Stéphanie Bellocchi; Delphine Massendari; Jonathan Grainger; Stéphanie Ducrot Effects of inter-character spacing on saccade programming in beginning readers and dyslexics Journal Article Child Neuropsychology, 25 (4), pp. 482–506, 2019. @article{Bellocchi2019, title = {Effects of inter-character spacing on saccade programming in beginning readers and dyslexics}, author = {Stéphanie Bellocchi and Delphine Massendari and Jonathan Grainger and Stéphanie Ducrot}, doi = {10.1080/09297049.2018.1504907}, year = {2019}, date = {2019-01-01}, journal = {Child Neuropsychology}, volume = {25}, number = {4}, pages = {482--506}, publisher = {Routledge}, abstract = {The present study investigated the impact of inter-character spacing on saccade programming in beginning readers and dyslexic children. In two experiments, eye movements were recorded while dyslexic children, reading-age, and chronological-age controls, performed an oculomotor lateralized bisection task on words and strings of hashes presented either with default inter-character spacing or with extra spacing between the characters. The results of Experiment 1 showed that (1) only proficient readers had already developed highly automatized procedures for programming both left- and rightward saccades, depending on the discreteness of the stimuli and (2) children of all groups were disrupted (i.e., had trouble to land close to the beginning of the stimuli) by extra spacing between the characters of the stimuli, and particularly for stimuli presented in the left visual field. Experiment 2 was designed to disentangle the role of inter-character spacing and spatial width. Stimuli were made the same physical length in the default and extra-spacing conditions by having more characters in the default spacing condition. Our results showed that inter-letter spacing still influenced saccade programming when controlling for spatial width, thus confirming the detrimental effect of extra spacing for saccade programming. We conclude that the beneficial effect of increased inter-letter spacing on reading can be better explained in terms of decreased visual crowding than improved saccade targeting.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The present study investigated the impact of inter-character spacing on saccade programming in beginning readers and dyslexic children. In two experiments, eye movements were recorded while dyslexic children, reading-age, and chronological-age controls, performed an oculomotor lateralized bisection task on words and strings of hashes presented either with default inter-character spacing or with extra spacing between the characters. The results of Experiment 1 showed that (1) only proficient readers had already developed highly automatized procedures for programming both left- and rightward saccades, depending on the discreteness of the stimuli and (2) children of all groups were disrupted (i.e., had trouble to land close to the beginning of the stimuli) by extra spacing between the characters of the stimuli, and particularly for stimuli presented in the left visual field. Experiment 2 was designed to disentangle the role of inter-character spacing and spatial width. Stimuli were made the same physical length in the default and extra-spacing conditions by having more characters in the default spacing condition. Our results showed that inter-letter spacing still influenced saccade programming when controlling for spatial width, thus confirming the detrimental effect of extra spacing for saccade programming. We conclude that the beneficial effect of increased inter-letter spacing on reading can be better explained in terms of decreased visual crowding than improved saccade targeting. |
Sonya Bells; Silvia L Isabella; Donald C Brien; Brian C Coe; Douglas P Munoz; Donald J Mabbott; Douglas O Cheyne Mapping neural dynamics underlying saccade preparation and execution and their relation to reaction time and direction errors Journal Article Human Brain Mapping, 41 (7), pp. 1934–1949, 2020. @article{Bells2020, title = {Mapping neural dynamics underlying saccade preparation and execution and their relation to reaction time and direction errors}, author = {Sonya Bells and Silvia L Isabella and Donald C Brien and Brian C Coe and Douglas P Munoz and Donald J Mabbott and Douglas O Cheyne}, doi = {10.1002/hbm.24922}, year = {2020}, date = {2020-01-01}, journal = {Human Brain Mapping}, volume = {41}, number = {7}, pages = {1934--1949}, abstract = {Our ability to control and inhibit automatic behaviors is crucial for negotiating complex environments, all of which require rapid communication between sensory, motor, and cognitive networks. Here, we measured neuromagnetic brain activity to investigate the neural timing of cortical areas needed for inhibitory control, while 14 healthy young adults performed an interleaved prosaccade (look at a peripheral visual stimulus) and antisaccade (look away from stimulus) task. Analysis of how neural activity relates to saccade reaction time (SRT) and occurrence of direction errors (look at stimulus on antisaccade trials) provides insight into inhibitory control. Neuromagnetic source activity was used to extract stimulus-aligned and saccade-aligned activity to examine temporal differences between prosaccade and antisaccade trials in brain regions associated with saccade control. For stimulus-aligned antisaccade trials, a longer SRT was associated with delayed onset of neural activity within the ipsilateral parietal eye field (PEF) and bilateral frontal eye field (FEF). Saccade-aligned activity demonstrated peak activation 10ms before saccade-onset within the contralateral PEF for prosaccade trials and within the bilateral FEF for antisaccade trials. In addition, failure to inhibit prosaccades on anti-saccade trials was associated with increased activity prior to saccade onset within the FEF contralateral to the peripheral stimulus. This work on dynamic activity adds to our knowledge that direction errors were due, at least in part, to a failure to inhibit automatic prosaccades. These findings provide novel evidence in humans regarding the temporal dynamics within oculomotor areas needed for saccade programming and the role frontal brain regions have on top-down inhibitory control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Our ability to control and inhibit automatic behaviors is crucial for negotiating complex environments, all of which require rapid communication between sensory, motor, and cognitive networks. Here, we measured neuromagnetic brain activity to investigate the neural timing of cortical areas needed for inhibitory control, while 14 healthy young adults performed an interleaved prosaccade (look at a peripheral visual stimulus) and antisaccade (look away from stimulus) task. Analysis of how neural activity relates to saccade reaction time (SRT) and occurrence of direction errors (look at stimulus on antisaccade trials) provides insight into inhibitory control. Neuromagnetic source activity was used to extract stimulus-aligned and saccade-aligned activity to examine temporal differences between prosaccade and antisaccade trials in brain regions associated with saccade control. For stimulus-aligned antisaccade trials, a longer SRT was associated with delayed onset of neural activity within the ipsilateral parietal eye field (PEF) and bilateral frontal eye field (FEF). Saccade-aligned activity demonstrated peak activation 10ms before saccade-onset within the contralateral PEF for prosaccade trials and within the bilateral FEF for antisaccade trials. In addition, failure to inhibit prosaccades on anti-saccade trials was associated with increased activity prior to saccade onset within the FEF contralateral to the peripheral stimulus. This work on dynamic activity adds to our knowledge that direction errors were due, at least in part, to a failure to inhibit automatic prosaccades. These findings provide novel evidence in humans regarding the temporal dynamics within oculomotor areas needed for saccade programming and the role frontal brain regions have on top-down inhibitory control. |
Artem V Belopolsky; Jan Theeuwes Selection within visual memory representations activates the oculomotor system Journal Article Neuropsychologia, 49 (6), pp. 1605–1610, 2011. @article{Belopolsky2011b, title = {Selection within visual memory representations activates the oculomotor system}, author = {Artem V Belopolsky and Jan Theeuwes}, doi = {10.1016/j.neuropsychologia.2010.12.045}, year = {2011}, date = {2011-01-01}, journal = {Neuropsychologia}, volume = {49}, number = {6}, pages = {1605--1610}, publisher = {Elsevier Ltd}, abstract = {Humans tend to create and maintain internal representations of the environment that help guiding actions during the everyday activities. Previous studies have shown that the oculomotor system is involved in coding and maintenance of locations in visual-spatial working memory. In these studies selection of the relevant location for maintenance in working memory took place on the screen (selecting the location of a dot presented on the screen). The present study extended these findings by showing that the oculomotor system also codes selection of location from an internal memory representation. Participants first memorized two locations and after a retention interval selected one location for further maintenance. The results show that saccade trajectories deviated away from the ultimately remembered location. Furthermore, selection of the location from the memorized representation produced sustained oculomotor preparation to it. The results show that oculomotor system is very flexible and plays an active role for coding and maintaining information selected within internal memory representations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Humans tend to create and maintain internal representations of the environment that help guiding actions during the everyday activities. Previous studies have shown that the oculomotor system is involved in coding and maintenance of locations in visual-spatial working memory. In these studies selection of the relevant location for maintenance in working memory took place on the screen (selecting the location of a dot presented on the screen). The present study extended these findings by showing that the oculomotor system also codes selection of location from an internal memory representation. Participants first memorized two locations and after a retention interval selected one location for further maintenance. The results show that saccade trajectories deviated away from the ultimately remembered location. Furthermore, selection of the location from the memorized representation produced sustained oculomotor preparation to it. The results show that oculomotor system is very flexible and plays an active role for coding and maintaining information selected within internal memory representations. |
Artem V Belopolsky; Jan Theeuwes Updating the premotor theory: The allocation of attention is not always accompanied by saccade preparation Journal Article Journal of Experimental Psychology: Human Perception and Performance, 38 (4), pp. 902–914, 2012. @article{Belopolsky2012, title = {Updating the premotor theory: The allocation of attention is not always accompanied by saccade preparation}, author = {Artem V Belopolsky and Jan Theeuwes}, doi = {10.1037/a0028662}, year = {2012}, date = {2012-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {38}, number = {4}, pages = {902--914}, abstract = {There is an ongoing controversy regarding the relationship between covert attention and saccadic eye movements. While there is quite some evidence that the preparation of a saccade is obligatory preceded by a shift of covert attention, the reverse is not clear: Is allocation of attention always accompanied by saccade preparation? Recently, a shifting and maintenance account was proposed suggesting that shifting and maintenance components of covert attention differ in their relation to the oculomotor system. Specifically, it was argued that a shift of covert attention is always accompanied by activation of the oculomotor program, while maintaining covert attention at a location can be accompanied either by activation or suppression of oculomotor program, depending on the probability of executing an eye movement to the attended location. In the present study we tested whether there is such an obligatory coupling between shifting of attention and saccade preparation and how quickly saccade preparation gets suppressed. The results showed that attention shifting was always accompanied by saccade preparation whenever covert attention had to be shifted during visual search, as well as in response to exogenous or endogenous cues. However, for the endogenous cues the saccade program to the attended location was suppressed very soon after the attention shift was completed. The current findings support the shifting and maintenance account and indicate that the premotor theory needs to be updated to include a shifting and maintenance component for the cases in which covert shifts of attention are made without the intention to execute a saccade.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There is an ongoing controversy regarding the relationship between covert attention and saccadic eye movements. While there is quite some evidence that the preparation of a saccade is obligatory preceded by a shift of covert attention, the reverse is not clear: Is allocation of attention always accompanied by saccade preparation? Recently, a shifting and maintenance account was proposed suggesting that shifting and maintenance components of covert attention differ in their relation to the oculomotor system. Specifically, it was argued that a shift of covert attention is always accompanied by activation of the oculomotor program, while maintaining covert attention at a location can be accompanied either by activation or suppression of oculomotor program, depending on the probability of executing an eye movement to the attended location. In the present study we tested whether there is such an obligatory coupling between shifting of attention and saccade preparation and how quickly saccade preparation gets suppressed. The results showed that attention shifting was always accompanied by saccade preparation whenever covert attention had to be shifted during visual search, as well as in response to exogenous or endogenous cues. However, for the endogenous cues the saccade program to the attended location was suppressed very soon after the attention shift was completed. The current findings support the shifting and maintenance account and indicate that the premotor theory needs to be updated to include a shifting and maintenance component for the cases in which covert shifts of attention are made without the intention to execute a saccade. |
Artem V Belopolsky; Stefan Van der Stigchel Saccades curve away from previously inhibited locations: Evidence for the role of priming in oculomotor competition Journal Article Journal of Neurophysiology, 110 (10), pp. 2370–2377, 2013. @article{Belopolsky2013, title = {Saccades curve away from previously inhibited locations: Evidence for the role of priming in oculomotor competition}, author = {Artem V Belopolsky and Stefan {Van der Stigchel}}, doi = {10.1152/jn.00293.2013}, year = {2013}, date = {2013-01-01}, journal = {Journal of Neurophysiology}, volume = {110}, number = {10}, pages = {2370--2377}, abstract = {The oculomotor system serves as the basis for representing concurrently competing motor programs. Here, we examine whether the oculomotor system also keeps track of the outcome of competition between target and distractor on the previous trial. Participants had to perform a simple task of making a saccade toward a predefined direction. On two-thirds of the trials, an irrelevant distractor was presented to either the left or right of the fixation. On one-third of the trials, no distractor was present. The results show that on trials without a distractor, saccades curved away from the empty location that was occupied by a distractor on the previous trial. This result was replicated and extended to cases when different saccade directions were used. In addition, we show that repetition of distractor location on the distractor-present trials results in a stronger curvature away and in a shorter saccade latency to the target. Taken together, these results provide strong evidence that the oculomotor system automatically codes and retains locations that had been ignored in the past to bias future behavior.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The oculomotor system serves as the basis for representing concurrently competing motor programs. Here, we examine whether the oculomotor system also keeps track of the outcome of competition between target and distractor on the previous trial. Participants had to perform a simple task of making a saccade toward a predefined direction. On two-thirds of the trials, an irrelevant distractor was presented to either the left or right of the fixation. On one-third of the trials, no distractor was present. The results show that on trials without a distractor, saccades curved away from the empty location that was occupied by a distractor on the previous trial. This result was replicated and extended to cases when different saccade directions were used. In addition, we show that repetition of distractor location on the distractor-present trials results in a stronger curvature away and in a shorter saccade latency to the target. Taken together, these results provide strong evidence that the oculomotor system automatically codes and retains locations that had been ignored in the past to bias future behavior. |
Alessandro Benedetto; Paola Binda Dissociable saccadic suppression of pupillary and perceptual responses to light Journal Article Journal of Neurophysiology, 115 (3), pp. 1243–1251, 2016. @article{Benedetto2016, title = {Dissociable saccadic suppression of pupillary and perceptual responses to light}, author = {Alessandro Benedetto and Paola Binda}, doi = {10.1152/jn.00964.2015}, year = {2016}, date = {2016-01-01}, journal = {Journal of Neurophysiology}, volume = {115}, number = {3}, pages = {1243--1251}, abstract = {We measured pupillary constrictions in response to full-screen flashes of variable luminance, occurring either at the onset of a saccadic eye movement or well before/after it. A large fraction of perisaccadic flashes were undetectable to the subjects, consistent with saccadic suppression of visual sensitivity. Likewise, pupillary responses to perisaccadic flashes were strongly suppressed. However, the two phenomena appear to be dissociable. Across subjects and luminance levels of the flash stimulus, there were cases in which conscious perception of the flash was completely depleted yet the pupillary response was clearly present, as well as cases in which the opposite occurred. On one hand, the fact that pupillary light responses are subject to saccadic suppression reinforces evidence that this is not a simple reflex but depends on the integration of retinal illumination with complex "extraretinal" cues. On the other hand, the relative independence of pupillary and perceptual responses suggests that suppression acts separately on these systems-consistent with the idea of multiple visual pathways that are differentially affected by saccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We measured pupillary constrictions in response to full-screen flashes of variable luminance, occurring either at the onset of a saccadic eye movement or well before/after it. A large fraction of perisaccadic flashes were undetectable to the subjects, consistent with saccadic suppression of visual sensitivity. Likewise, pupillary responses to perisaccadic flashes were strongly suppressed. However, the two phenomena appear to be dissociable. Across subjects and luminance levels of the flash stimulus, there were cases in which conscious perception of the flash was completely depleted yet the pupillary response was clearly present, as well as cases in which the opposite occurred. On one hand, the fact that pupillary light responses are subject to saccadic suppression reinforces evidence that this is not a simple reflex but depends on the integration of retinal illumination with complex "extraretinal" cues. On the other hand, the relative independence of pupillary and perceptual responses suggests that suppression acts separately on these systems-consistent with the idea of multiple visual pathways that are differentially affected by saccades. |
Alessandro Benedetto; Concetta M Morrone Saccadic suppression is embedded within extended oscillatory modulation of sensitivity Journal Article Journal of Neuroscience, 37 (13), pp. 3661–3670, 2017. @article{Benedetto2017, title = {Saccadic suppression is embedded within extended oscillatory modulation of sensitivity}, author = {Alessandro Benedetto and Concetta M Morrone}, doi = {10.1523/JNEUROSCI.2390-16.2016}, year = {2017}, date = {2017-01-01}, journal = {Journal of Neuroscience}, volume = {37}, number = {13}, pages = {3661--3670}, abstract = {Action and perception are intimately coupled systems. One clear case is saccadic suppression, the reduced visibility around the time of saccades, which is important in mediating visual stability; another is the oscillatory modulation of visibility synchronized with hand action. To suppress effectively the spurious retinal motion generated by the eye movements, it is crucial that saccadic suppression and saccadic onset be temporally synchronous. However, the mechanisms that determine this temporal synchrony are unknown. We investigated the effect of saccades on contrast discrimination sensitivity over a long period stretching over textgreater1 s before and after saccade execution. Human subjects made horizontal saccades at will to two stationary saccadic targets separated by 20°. At a random interval, a brief Gabor patch was displayed between the two fixations in either the upper or lower visual field and the subject had to detect its location. Strong saccadic suppression was measured between -50 and 50 ms from saccadic onset. However, the suppression was systematically embedded in a trough of oscillations of contrast sensitivity that fluctuated rhythmically in the delta range (at ∼3 Hz), commencing ∼1 s before saccade execution and lasting for up to 1 s after the saccade. The results show that saccadic preparation and visual sensitivity oscillations are coupled and the coupling might be instrumental in temporally aligning the initiation of the saccade with the visual suppression.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Action and perception are intimately coupled systems. One clear case is saccadic suppression, the reduced visibility around the time of saccades, which is important in mediating visual stability; another is the oscillatory modulation of visibility synchronized with hand action. To suppress effectively the spurious retinal motion generated by the eye movements, it is crucial that saccadic suppression and saccadic onset be temporally synchronous. However, the mechanisms that determine this temporal synchrony are unknown. We investigated the effect of saccades on contrast discrimination sensitivity over a long period stretching over textgreater1 s before and after saccade execution. Human subjects made horizontal saccades at will to two stationary saccadic targets separated by 20°. At a random interval, a brief Gabor patch was displayed between the two fixations in either the upper or lower visual field and the subject had to detect its location. Strong saccadic suppression was measured between -50 and 50 ms from saccadic onset. However, the suppression was systematically embedded in a trough of oscillations of contrast sensitivity that fluctuated rhythmically in the delta range (at ∼3 Hz), commencing ∼1 s before saccade execution and lasting for up to 1 s after the saccade. The results show that saccadic preparation and visual sensitivity oscillations are coupled and the coupling might be instrumental in temporally aligning the initiation of the saccade with the visual suppression. |
Alessandro Benedetto; Concetta M Morrone Visual sensitivity and bias oscillate phase-locked to saccadic eye movements Journal Article Journal of vision, 19 (14), pp. 1–16, 2019. @article{Benedetto2019, title = {Visual sensitivity and bias oscillate phase-locked to saccadic eye movements}, author = {Alessandro Benedetto and Concetta M Morrone}, doi = {10.1167/19.14.15}, year = {2019}, date = {2019-01-01}, journal = {Journal of vision}, volume = {19}, number = {14}, pages = {1--16}, abstract = {Oscillations in perceptual performance have been observed before and after a voluntary action, like hand, finger, and eye movements. In particular, discrimination accuracy of suprathreshold contrast stimuli oscillates in the delta range (2-3 Hz) phase-locked to saccadic eye movements. Importantly, saccadic suppression is embedded in phase with these long-lasting perceptual oscillations. It is debated whether these rhythmic modulations affect only appearance of high-contrast stimuli or whether absolute detection threshold is also modulated rhythmically. Here we measured location discrimination of a brief Gabor patch presented randomly between 1 s before and after a voluntary saccade and demonstrated that absolute contrast thresholds oscillated at a similar frequency to suprathreshold contrast discrimination. Importantly, saccadic suppression is also embedded in phase with absolute threshold oscillations. Interestingly, response bias was also found to oscillate at the same frequency in both tasks. However, the frequency was in the alpha range for bias, while it was in the delta range for sensitivity. These results demonstrate the presence of perisaccadic delta oscillations in visual sensitivity phase-locked to saccadic onset, and independent from response bias alpha oscillations. Overall, the present findings reinforce the suggestion of a leading role of oscillations in the temporal binding between eye-movement and visual processing timing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Oscillations in perceptual performance have been observed before and after a voluntary action, like hand, finger, and eye movements. In particular, discrimination accuracy of suprathreshold contrast stimuli oscillates in the delta range (2-3 Hz) phase-locked to saccadic eye movements. Importantly, saccadic suppression is embedded in phase with these long-lasting perceptual oscillations. It is debated whether these rhythmic modulations affect only appearance of high-contrast stimuli or whether absolute detection threshold is also modulated rhythmically. Here we measured location discrimination of a brief Gabor patch presented randomly between 1 s before and after a voluntary saccade and demonstrated that absolute contrast thresholds oscillated at a similar frequency to suprathreshold contrast discrimination. Importantly, saccadic suppression is also embedded in phase with absolute threshold oscillations. Interestingly, response bias was also found to oscillate at the same frequency in both tasks. However, the frequency was in the alpha range for bias, while it was in the delta range for sensitivity. These results demonstrate the presence of perisaccadic delta oscillations in visual sensitivity phase-locked to saccadic onset, and independent from response bias alpha oscillations. Overall, the present findings reinforce the suggestion of a leading role of oscillations in the temporal binding between eye-movement and visual processing timing. |
Brittany Benjamin; Christopher Macomb; Alisha Martin; Aaron L Cecala Can color act as a contextual cue in human saccadic adaptation? Journal Article Bios, 87 (1), pp. 9–20, 2016. @article{Benjamin2016, title = {Can color act as a contextual cue in human saccadic adaptation?}, author = {Brittany Benjamin and Christopher Macomb and Alisha Martin and Aaron L Cecala}, doi = {http://dx.doi.org/10.1893/BIOS-D-14-00011.1}, year = {2016}, date = {2016-01-01}, journal = {Bios}, volume = {87}, number = {1}, pages = {9--20}, abstract = {When the head does not move, rapid movements of the eyes called saccades are used to redirect the line of sight. Saccades are defined by a series of metrical and kinematic (evolution of a movement as a function of time) relationships. For example, the amplitude of a saccade made from one visual target to another is roughly 90% of the distance between the initial fixation point (T0) and the peripheral target (T1). However, this stereotypical relationship between saccade amplitude and initial retinal error (jT1-Initial Eye Positionj) may be altered, either increased or decreased, by surreptitiously displacing a visual target during an ongoing saccade. This form of saccadic adaptation has been described in both humans and monkeys. We investigated the effects of a contextual cue (target color) on the magnitude of human saccadic adaptation using an eye tracker to measure our subjects' eye position. Our results indicate that target color cannot be used by the eye movement control system to elicit differential changes in motor output regardless of whether the color cues are randomly intermixed or presented sequentially.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When the head does not move, rapid movements of the eyes called saccades are used to redirect the line of sight. Saccades are defined by a series of metrical and kinematic (evolution of a movement as a function of time) relationships. For example, the amplitude of a saccade made from one visual target to another is roughly 90% of the distance between the initial fixation point (T0) and the peripheral target (T1). However, this stereotypical relationship between saccade amplitude and initial retinal error (jT1-Initial Eye Positionj) may be altered, either increased or decreased, by surreptitiously displacing a visual target during an ongoing saccade. This form of saccadic adaptation has been described in both humans and monkeys. We investigated the effects of a contextual cue (target color) on the magnitude of human saccadic adaptation using an eye tracker to measure our subjects' eye position. Our results indicate that target color cannot be used by the eye movement control system to elicit differential changes in motor output regardless of whether the color cues are randomly intermixed or presented sequentially. |
Philip J Benson; Ute Leonards; Robert M Lothian; David M St. Clair; Marco C G Merlo Visual scan paths in first-episode schizophrenia and cannabis-induced psychosis Journal Article Journal of Psychiatry and Neuroscience, 32 (4), pp. 267–274, 2007. @article{Benson2007, title = {Visual scan paths in first-episode schizophrenia and cannabis-induced psychosis}, author = {Philip J Benson and Ute Leonards and Robert M Lothian and David M {St. Clair} and Marco C G Merlo}, doi = {10.1111/bjd.13740}, year = {2007}, date = {2007-01-01}, journal = {Journal of Psychiatry and Neuroscience}, volume = {32}, number = {4}, pages = {267--274}, abstract = {OBJECTIVE: Patterns of successive saccades and fixations (scan paths) that are made while viewing images are often spatially restricted in schizophrenia, but the relation with cannabis-induced psychosis has not been examined. We used higher-order statistical methods to examine spatiotemporal characteristics of scan paths to determine whether viewing behaviour was distinguishable on a continuum. METHODS: Patients with early acute first-episode paranoid schizophrenia (SCH; n = 11), cannabis-induced psychosis (CIP; n = 6) and unaffected control subjects (n = 22) undertook a task requiring free viewing of facial, fractal and landscape images for 5 seconds while their eye movements were recorded. Frequencies and distributions of saccades and fixations were calculated in relation to image regions examined during each trial. RESULTS: Findings were independent of image category, indicating generalized scanning deficits. Compared with control subjects, patients with SCH and CIP made fewer saccades and fewer fixations of longer duration. In turn, the spatial distribution of fixations in CIP patients was more clustered than in SCH and control subjects. The diversity of features fixated in subjects with CIP was also lower than in SCH patients and control subjects. CONCLUSION: A continuous approach to characterizing scan path changes in different phenotypes suggests that CIP shares some of the abnormalities of SCH but can be distinguished with measures that are sensitive to cognitive strategies active or inhibited during visual exploration.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVE: Patterns of successive saccades and fixations (scan paths) that are made while viewing images are often spatially restricted in schizophrenia, but the relation with cannabis-induced psychosis has not been examined. We used higher-order statistical methods to examine spatiotemporal characteristics of scan paths to determine whether viewing behaviour was distinguishable on a continuum. METHODS: Patients with early acute first-episode paranoid schizophrenia (SCH; n = 11), cannabis-induced psychosis (CIP; n = 6) and unaffected control subjects (n = 22) undertook a task requiring free viewing of facial, fractal and landscape images for 5 seconds while their eye movements were recorded. Frequencies and distributions of saccades and fixations were calculated in relation to image regions examined during each trial. RESULTS: Findings were independent of image category, indicating generalized scanning deficits. Compared with control subjects, patients with SCH and CIP made fewer saccades and fewer fixations of longer duration. In turn, the spatial distribution of fixations in CIP patients was more clustered than in SCH and control subjects. The diversity of features fixated in subjects with CIP was also lower than in SCH patients and control subjects. CONCLUSION: A continuous approach to characterizing scan path changes in different phenotypes suggests that CIP shares some of the abnormalities of SCH but can be distinguished with measures that are sensitive to cognitive strategies active or inhibited during visual exploration. |
Philip J Benson; Sara A Beedie; Elizabeth Shephard; Ina Giegling; Dan Rujescu; David M St. Clair Simple viewing tests can detect eye movement abnormalities that distinguish schizophrenia cases from controls with exceptional accuracy Journal Article Biological Psychiatry, 72 (9), pp. 716–724, 2012. @article{Benson2012, title = {Simple viewing tests can detect eye movement abnormalities that distinguish schizophrenia cases from controls with exceptional accuracy}, author = {Philip J Benson and Sara A Beedie and Elizabeth Shephard and Ina Giegling and Dan Rujescu and David M {St. Clair}}, doi = {10.1016/j.biopsych.2012.04.019}, year = {2012}, date = {2012-01-01}, journal = {Biological Psychiatry}, volume = {72}, number = {9}, pages = {716--724}, publisher = {Elsevier Inc.}, abstract = {Background: We have investigated which eye-movement tests alone and combined can best discriminate schizophrenia cases from control subjects and their predictive validity. Methods: A training set of 88 schizophrenia cases and 88 controls had a range of eye movements recorded; the predictive validity of the tests was then examined on eye-movement data from 34 9-month retest cases and controls, and from 36 novel schizophrenia cases and 52 control subjects. Eye movements were recorded during smooth pursuit, fixation stability, and free-viewing tasks. Group differences on performance measures were examined by univariate and multivariate analyses. Model fitting was used to compare regression, boosted tree, and probabilistic neural network approaches. Results: As a group, schizophrenia cases differed from control subjects on almost all eye-movement tests, including horizontal and Lissajous pursuit, visual scanpath, and fixation stability; fixation dispersal during free viewing was the best single discriminator. Effects were stable over time, and independent of sex, medication, or cigarette smoking. A boosted tree model achieved perfect separation of the 88 training cases from 88 control subjects; its predictive validity on retest assessments and novel cases and control subjects was 87.8%. However, when we examined the whole data set of 298 assessments, a cross-validated probabilistic neural network model was superior and could discriminate all cases from controls with near perfect accuracy at 98.3%. Conclusions: Simple viewing patterns can detect eye-movement abnormalities that can discriminate schizophrenia cases from control subjects with exceptional accuracy. textcopyright 2012 Society of Biological Psychiatry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: We have investigated which eye-movement tests alone and combined can best discriminate schizophrenia cases from control subjects and their predictive validity. Methods: A training set of 88 schizophrenia cases and 88 controls had a range of eye movements recorded; the predictive validity of the tests was then examined on eye-movement data from 34 9-month retest cases and controls, and from 36 novel schizophrenia cases and 52 control subjects. Eye movements were recorded during smooth pursuit, fixation stability, and free-viewing tasks. Group differences on performance measures were examined by univariate and multivariate analyses. Model fitting was used to compare regression, boosted tree, and probabilistic neural network approaches. Results: As a group, schizophrenia cases differed from control subjects on almost all eye-movement tests, including horizontal and Lissajous pursuit, visual scanpath, and fixation stability; fixation dispersal during free viewing was the best single discriminator. Effects were stable over time, and independent of sex, medication, or cigarette smoking. A boosted tree model achieved perfect separation of the 88 training cases from 88 control subjects; its predictive validity on retest assessments and novel cases and control subjects was 87.8%. However, when we examined the whole data set of 298 assessments, a cross-validated probabilistic neural network model was superior and could discriminate all cases from controls with near perfect accuracy at 98.3%. Conclusions: Simple viewing patterns can detect eye-movement abnormalities that can discriminate schizophrenia cases from control subjects with exceptional accuracy. textcopyright 2012 Society of Biological Psychiatry. |
Valerie Benson; Monica S Castelhano; Sheena K Au-Yeung; Keith Rayner Eye movements reveal no immediate "WOW" ("which one's weird") effect in autism spectrum disorder Journal Article Quarterly Journal of Experimental Psychology, 65 (6), pp. 1139–1150, 2012. @article{Benson2012a, title = {Eye movements reveal no immediate "WOW" ("which one's weird") effect in autism spectrum disorder}, author = {Valerie Benson and Monica S Castelhano and Sheena K Au-Yeung and Keith Rayner}, doi = {10.1080/17470218.2011.644305}, year = {2012}, date = {2012-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {65}, number = {6}, pages = {1139--1150}, abstract = {Autism spectrum disorder (ASD) and typically developed (TD) adult participants viewed pairs of scenes for a simple " spot the difference " (STD) and a complex " which one's weird " (WOW) task. There were no group differences in the STD task. In the WOW task, the ASD group took longer to respond manually and to begin fixating the target " weird " region. Additionally, as indexed by the first-fixation duration into the target region, the ASD group failed to " pick up " immediately on what was " weird " . The findings are discussed with reference to the complex information processing theory of ASD (Minshew & Goldstein, 1998).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Autism spectrum disorder (ASD) and typically developed (TD) adult participants viewed pairs of scenes for a simple " spot the difference " (STD) and a complex " which one's weird " (WOW) task. There were no group differences in the STD task. In the WOW task, the ASD group took longer to respond manually and to begin fixating the target " weird " region. Additionally, as indexed by the first-fixation duration into the target region, the ASD group failed to " pick up " immediately on what was " weird " . The findings are discussed with reference to the complex information processing theory of ASD (Minshew & Goldstein, 1998). |
Valerie Benson; Magdalena Ietswaart; David Milner Eye movements and verbal report in a single case of visual neglect Journal Article PLoS ONE, 7 (8), pp. e43743, 2012. @article{Benson2012b, title = {Eye movements and verbal report in a single case of visual neglect}, author = {Valerie Benson and Magdalena Ietswaart and David Milner}, doi = {10.1371/journal.pone.0043743}, year = {2012}, date = {2012-01-01}, journal = {PLoS ONE}, volume = {7}, number = {8}, pages = {e43743}, abstract = {In this single case study, visuospatial neglect patient P1 demonstrated a dissociation between an intact ability to make appropriate reflexive eye movements to targets in the neglected field with latencies of textless400 ms, while failing to report targets presented at such durations in a separate verbal detection task. In contrast, there was a failure to evoke the usually robust Remote Distractor Effect in P1, even though distractors in the neglected field were presented at above threshold durations. Together those data indicate that the tight coupling that is normally shown between attention and eye movements appears to be disrupted for low-level orienting in P1. A comparable disruption was also found for high-level cognitive processing tasks, namely reading and scene scanning. The findings are discussed in relation to sampling, attention and awareness in neglect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this single case study, visuospatial neglect patient P1 demonstrated a dissociation between an intact ability to make appropriate reflexive eye movements to targets in the neglected field with latencies of textless400 ms, while failing to report targets presented at such durations in a separate verbal detection task. In contrast, there was a failure to evoke the usually robust Remote Distractor Effect in P1, even though distractors in the neglected field were presented at above threshold durations. Together those data indicate that the tight coupling that is normally shown between attention and eye movements appears to be disrupted for low-level orienting in P1. A comparable disruption was also found for high-level cognitive processing tasks, namely reading and scene scanning. The findings are discussed in relation to sampling, attention and awareness in neglect. |
Valerie Benson; Monica S Castelhano; Philippa L Howard; Nida Latif; Keith Rayner Looking, seeing and believing in autism: Eye movements reveal how subtle cognitive processing differences impact in the social domain Journal Article Autism Research, 9 (8), pp. 879–887, 2016. @article{Benson2016, title = {Looking, seeing and believing in autism: Eye movements reveal how subtle cognitive processing differences impact in the social domain}, author = {Valerie Benson and Monica S Castelhano and Philippa L Howard and Nida Latif and Keith Rayner}, doi = {10.1002/aur.1580}, year = {2016}, date = {2016-01-01}, journal = {Autism Research}, volume = {9}, number = {8}, pages = {879--887}, abstract = {Adults with High Functioning Autism Spectrum Disorders (ASD) viewed scenes with people in them, while having their eye movements recorded. The task was to indicate, using a button press, whether the pictures were normal, or in some way weird or odd. Oddities in the pictures were categorized as violations of either perceptual or social norms. Compared to a Typically Developed (TD) control group, the ASD participants were equally able to categorize the scenes as odd or normal, but they took longer to respond. The eye movement patterns showed that the ASD group made more fixations and revisits to the target areas in the odd scenes compared with the TD group. Additionally, when the ASD group first fixated the target areas in the scenes, they failed to initially detect the social oddities. These two findings have clear implications for processing difficulties in ASD for the social domain, where it is important to detect social cues on-line, and where there is little opportunity to go back and recheck possible cues in fast dynamic interactions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Adults with High Functioning Autism Spectrum Disorders (ASD) viewed scenes with people in them, while having their eye movements recorded. The task was to indicate, using a button press, whether the pictures were normal, or in some way weird or odd. Oddities in the pictures were categorized as violations of either perceptual or social norms. Compared to a Typically Developed (TD) control group, the ASD participants were equally able to categorize the scenes as odd or normal, but they took longer to respond. The eye movement patterns showed that the ASD group made more fixations and revisits to the target areas in the odd scenes compared with the TD group. Additionally, when the ASD group first fixated the target areas in the scenes, they failed to initially detect the social oddities. These two findings have clear implications for processing difficulties in ASD for the social domain, where it is important to detect social cues on-line, and where there is little opportunity to go back and recheck possible cues in fast dynamic interactions. |
Albert V van den Berg; J A Beintema; Maarten A Frens Heading and path percepts from visual flow and eye pursuit signals Journal Article Vision Research, 41 (25-26), pp. 3467–3486, 2001. @article{Berg2001, title = {Heading and path percepts from visual flow and eye pursuit signals}, author = {Albert V van den Berg and J A Beintema and Maarten A Frens}, doi = {10.1016/S0042-6989(01)00023-2}, year = {2001}, date = {2001-01-01}, journal = {Vision Research}, volume = {41}, number = {25-26}, pages = {3467--3486}, abstract = {The percept of self-motion through the environment is supported by visual motion signals and eye movement signals. The interaction between these signals by decoupling of the eye movement and the pattern of retinal motion during brief simulated ego-movement on straight or circular trajectories was studied. A new response method enabled subjects to report perceived destination and perceived curvature of their future path simultaneously. Various combinations of simulated gaze rotation in the retinal flow and eye pursuit were investigated. Simulated gaze rotation ranged from consistent and larger than, to opponent and larger than eye pursuit. It was found that the perceived destination shifts non-linearly with the mismatch between simulated gaze rotation and eye pursuit. The non-linearity is also revealed in the perceived tangent heading direction and perceived path curvature, although to different extent in different subjects. For the same retinal flow, eye pursuit that is consistent with the simulated gaze rotation reduces heading error and the perceived path straightens out. In contrast, perceived path and/or heading do not become more curved or more biased in the direction opposite to pursuit when the eye -in-head rotation is opposite to the simulated gaze rotation. These observations point to modulation of the effect of the extra-retinal pursuit signal by the visual evidence for eye rotation. In a second experiment, one presented to a stationary eye the sum of a component of simulated gaze rotation and radial flow. It was found that the bi-circular flow component, that characterizes the change in pattern of flow directions by the gaze rotation, induces a shift of perceived heading without appreciable perceived path curvature. Conversely, the complementary component of simulated gaze rotation (bi-radial flow) evokes a percept of motion on a curved path with a small tangent heading error. It was suggested that bi-circular and bi-radial flow components contribute primarily to percepts of heading and path curvature, respectively.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The percept of self-motion through the environment is supported by visual motion signals and eye movement signals. The interaction between these signals by decoupling of the eye movement and the pattern of retinal motion during brief simulated ego-movement on straight or circular trajectories was studied. A new response method enabled subjects to report perceived destination and perceived curvature of their future path simultaneously. Various combinations of simulated gaze rotation in the retinal flow and eye pursuit were investigated. Simulated gaze rotation ranged from consistent and larger than, to opponent and larger than eye pursuit. It was found that the perceived destination shifts non-linearly with the mismatch between simulated gaze rotation and eye pursuit. The non-linearity is also revealed in the perceived tangent heading direction and perceived path curvature, although to different extent in different subjects. For the same retinal flow, eye pursuit that is consistent with the simulated gaze rotation reduces heading error and the perceived path straightens out. In contrast, perceived path and/or heading do not become more curved or more biased in the direction opposite to pursuit when the eye -in-head rotation is opposite to the simulated gaze rotation. These observations point to modulation of the effect of the extra-retinal pursuit signal by the visual evidence for eye rotation. In a second experiment, one presented to a stationary eye the sum of a component of simulated gaze rotation and radial flow. It was found that the bi-circular flow component, that characterizes the change in pattern of flow directions by the gaze rotation, induces a shift of perceived heading without appreciable perceived path curvature. Conversely, the complementary component of simulated gaze rotation (bi-radial flow) evokes a percept of motion on a curved path with a small tangent heading error. It was suggested that bi-circular and bi-radial flow components contribute primarily to percepts of heading and path curvature, respectively. |
Douwe P Bergsma; G J van der Wildt Visual training of cerebral blindness patients gradually enlarges the visual field Journal Article British Journal of Ophthalmology, 94 (1), pp. 88–96, 2010. @article{Bergsma2010, title = {Visual training of cerebral blindness patients gradually enlarges the visual field}, author = {Douwe P Bergsma and G J van der Wildt}, doi = {10.1136/bjo.2008.154336}, year = {2010}, date = {2010-01-01}, journal = {British Journal of Ophthalmology}, volume = {94}, number = {1}, pages = {88--96}, abstract = {BACKGROUND: Multiple studies on recovery of hemianopsia after cerebrovascular accident report visual-field enlargements after stimulation of the visual-field border area. These enlargements are made evident by the difference between pre- and post-training measurements of the visual field. Until now, it was not known how the visual-field enlargement develops. AIM: To study how the enlargement develops as a function of time. METHODS: 11 subjects were trained by stimulating the border area of their visual-field defect using a Goldmann perimeter. The visual-field border location was assessed using dynamic Goldmann perimetry before, after and during training (after each 10th training session). To monitor eye fixation, a video-based eye-tracker was used during each complete perimetry session. RESULTS: It was found that visual-field enlargement during training is actually a gradual shift of the visual-field border, which was independent of the type of stimulus-set used during training. The shift could be observed while eye fixation was accurate. CONCLUSION: Visual-detection training leads to a decrease in detection thresholds in the affected visual-field areas and to visual-field enlargement. Training effects can be generalised to important daily-life activities like reading.}, keywords = {}, pubstate = {published}, tppubtype = {article} } BACKGROUND: Multiple studies on recovery of hemianopsia after cerebrovascular accident report visual-field enlargements after stimulation of the visual-field border area. These enlargements are made evident by the difference between pre- and post-training measurements of the visual field. Until now, it was not known how the visual-field enlargement develops. AIM: To study how the enlargement develops as a function of time. METHODS: 11 subjects were trained by stimulating the border area of their visual-field defect using a Goldmann perimeter. The visual-field border location was assessed using dynamic Goldmann perimetry before, after and during training (after each 10th training session). To monitor eye fixation, a video-based eye-tracker was used during each complete perimetry session. RESULTS: It was found that visual-field enlargement during training is actually a gradual shift of the visual-field border, which was independent of the type of stimulus-set used during training. The shift could be observed while eye fixation was accurate. CONCLUSION: Visual-detection training leads to a decrease in detection thresholds in the affected visual-field areas and to visual-field enlargement. Training effects can be generalised to important daily-life activities like reading. |
Douwe P Bergsma; Joris A Elshout; G J van der Wildt; Albert V van den Berg Transfer effects of training-induced visual field recovery in patients with chronic stroke Miscellaneous 2012. @misc{Bergsma2012, title = {Transfer effects of training-induced visual field recovery in patients with chronic stroke}, author = {Douwe P Bergsma and Joris A Elshout and G J van der Wildt and Albert V van den Berg}, doi = {10.1310/tsr1903-212}, year = {2012}, date = {2012-01-01}, booktitle = {Topics in Stroke Rehabilitation}, volume = {19}, number = {3}, pages = {212--225}, abstract = {OBJECTIVE: Visual training of light detection in the transition zone between blind and healthy hemianopic visual fields leads to improvement of color and simple pattern recognition. Recently, we demonstrated that visual field enlargement (VFE) also occurs when an area just beyond the transition zone is stimulated. In the current study, we attempted to determine whether this peripheral training also causes improvement in color and shape perception and reading speed. Further, we evaluated which measure of VFE relates best to improvements in performance: the average border shift (ABS) in degrees or the estimated amount of cortical surface gain (ECSG) in millimeters, using the cortical magnification factor (CMF). METHOD: Twelve patients received 40 sessions of 1-hour restorative function training (RFT). Before and after training, we measured visual fields and reading speed. Additionally, color and shape perception in the trained visual field area was measured in 7 patients.$backslash$n$backslash$nRESULTS: VFE was found for 9 of 12 patients. Significant improvements were observed in reading speed for 8 of 12 patients and in color and shape perception for 3 of 7 patients. ECSG correlates significantly with performance; ABS does not. Our data indicate that the threshold ECSG, needed for significant changes in color and shape perception and reading speed, is about 6 mm. CONCLUSIONS: White stimulus training-induced VFE can lead to improved color and shape perception and to increased reading speed in and beyond the pretraining transition zone if ECSG is sufficiently large. The latter depends on the eccentricity of the VFE.}, keywords = {}, pubstate = {published}, tppubtype = {misc} } OBJECTIVE: Visual training of light detection in the transition zone between blind and healthy hemianopic visual fields leads to improvement of color and simple pattern recognition. Recently, we demonstrated that visual field enlargement (VFE) also occurs when an area just beyond the transition zone is stimulated. In the current study, we attempted to determine whether this peripheral training also causes improvement in color and shape perception and reading speed. Further, we evaluated which measure of VFE relates best to improvements in performance: the average border shift (ABS) in degrees or the estimated amount of cortical surface gain (ECSG) in millimeters, using the cortical magnification factor (CMF). METHOD: Twelve patients received 40 sessions of 1-hour restorative function training (RFT). Before and after training, we measured visual fields and reading speed. Additionally, color and shape perception in the trained visual field area was measured in 7 patients.$backslash$n$backslash$nRESULTS: VFE was found for 9 of 12 patients. Significant improvements were observed in reading speed for 8 of 12 patients and in color and shape perception for 3 of 7 patients. ECSG correlates significantly with performance; ABS does not. Our data indicate that the threshold ECSG, needed for significant changes in color and shape perception and reading speed, is about 6 mm. CONCLUSIONS: White stimulus training-induced VFE can lead to improved color and shape perception and to increased reading speed in and beyond the pretraining transition zone if ECSG is sufficiently large. The latter depends on the eccentricity of the VFE. |
Douwe P Bergsma; Joris A Elshout; Albert V van den Berg Segregation of spontaneous and training induced recovery from visual field defects in subacute stroke patients Journal Article Frontiers in Neurology, 8 , pp. 1–12, 2017. @article{Bergsma2017, title = {Segregation of spontaneous and training induced recovery from visual field defects in subacute stroke patients}, author = {Douwe P Bergsma and Joris A Elshout and Albert V van den Berg}, doi = {10.3389/fneur.2017.00681}, year = {2017}, date = {2017-01-01}, journal = {Frontiers in Neurology}, volume = {8}, pages = {1--12}, abstract = {Whether rehabilitation after stroke profits from an early start is difficult to establish as the contributions of spontaneous recovery and treatment are difficult to tease apart. Here, we use a novel training design to dissociate these components for visual rehabilitation of subacute stroke patients with visual field defects such as hemianopia. Visual discrimination training was started within 6 weeks after stroke in 17 patients. Spontaneous and training-induced recoveries were distinguished by training one-half of the defect for 8 weeks, while monitoring spontaneous recovery in the other (control) half of the defect. Next, trained and control regions were swapped, and training continued for another 8 weeks. The same paradigm was also applied to seven chronic patients for whom spontaneous recovery can be excluded and changes in the control half of the defect point to a spillover effect of training. In both groups, field stability was assessed during a no-intervention period. Defect reduction was significantly greater in the trained part of the defect than in the simultaneously untrained part of the defect irrespective of training onset (p = 0.001). In subacute patients, training contributed about twice as much to their defect reduction as the spontaneous recovery. Goal Attainment Scores were significantly and positively correlated with the total defect reduction (p = 0.01), percentage increase reading speed was significantly and positively correlated with the defect reduction induced by training (epoch 1: p = 0.0044; epoch 2: p = 0.023). Visual training adds significantly to the spontaneous recovery of visual field defects, both during training in the early and the chronic stroke phase. However, field recovery as a result of training in this subacute phase was as large as in the chronic phase. This suggests that patients benefited primarily of early onset training by gaining access to a larger visual field sooner.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Whether rehabilitation after stroke profits from an early start is difficult to establish as the contributions of spontaneous recovery and treatment are difficult to tease apart. Here, we use a novel training design to dissociate these components for visual rehabilitation of subacute stroke patients with visual field defects such as hemianopia. Visual discrimination training was started within 6 weeks after stroke in 17 patients. Spontaneous and training-induced recoveries were distinguished by training one-half of the defect for 8 weeks, while monitoring spontaneous recovery in the other (control) half of the defect. Next, trained and control regions were swapped, and training continued for another 8 weeks. The same paradigm was also applied to seven chronic patients for whom spontaneous recovery can be excluded and changes in the control half of the defect point to a spillover effect of training. In both groups, field stability was assessed during a no-intervention period. Defect reduction was significantly greater in the trained part of the defect than in the simultaneously untrained part of the defect irrespective of training onset (p = 0.001). In subacute patients, training contributed about twice as much to their defect reduction as the spontaneous recovery. Goal Attainment Scores were significantly and positively correlated with the total defect reduction (p = 0.01), percentage increase reading speed was significantly and positively correlated with the defect reduction induced by training (epoch 1: p = 0.0044; epoch 2: p = 0.023). Visual training adds significantly to the spontaneous recovery of visual field defects, both during training in the early and the chronic stroke phase. However, field recovery as a result of training in this subacute phase was as large as in the chronic phase. This suggests that patients benefited primarily of early onset training by gaining access to a larger visual field sooner. |
Douwe P Bergsma; Mies van Genderen; Carlien Roelofzen; Serge O Dumoulin; Alessio Fracasso; Giorgio L Porro; Marnix Naber Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma Journal Article Frontiers in Neurology, 9 , pp. 1–12, 2018. @article{Bergsma2018, title = {Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma}, author = {Douwe P Bergsma and Mies van Genderen and Carlien Roelofzen and Serge O Dumoulin and Alessio Fracasso and Giorgio L Porro and Marnix Naber}, doi = {10.3389/fneur.2018.00558}, year = {2018}, date = {2018-01-01}, journal = {Frontiers in Neurology}, volume = {9}, pages = {1--12}, abstract = {Background: The pupillary light reflex is weaker for stimuli presented inside as compared to outside absolute scotomas. Pupillograph perimetry could thus be an objective measure of impaired visual processing. However, the diagnostic accuracy in detecting scotomas has remained unclear. We quantitatively investigated the accuracy of a novel form of pupil perimetry. Methods: The new perimetry method, termed gaze-contingent flicker pupil perimetry, consists of the repetitive on, and off flickering of a bright disk (2 hz; 320 cd/m2; 4◦ diameter) on a gray background (160 cd/m2) for 4 seconds per stimulus location. The disk evokes continuous pupil oscillations at the same rate as its flicker frequency, and the oscillatory power of the pupil reflects visual sensitivity. We monocularly presented the disk at a total of 80 locations in the central visual field (max. 15◦). The location of the flickering disk moved along with gaze to reduce confounds of eye movements (gaze-contingent paradigm). The test lasted ∼5min per eye and was performed on 7 patients with cerebral visual impairment (CVI), 8 patients with primary open angle glaucoma (age textgreater 45), and 14 healthy, age/gender-matched controls. Results: For all patients, pupil oscillation power (FFT based response amplitude to flicker) was significantly weaker when the flickering disk was presented in the impaired as compared to the intact visual field (CVI: 12%}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: The pupillary light reflex is weaker for stimuli presented inside as compared to outside absolute scotomas. Pupillograph perimetry could thus be an objective measure of impaired visual processing. However, the diagnostic accuracy in detecting scotomas has remained unclear. We quantitatively investigated the accuracy of a novel form of pupil perimetry. Methods: The new perimetry method, termed gaze-contingent flicker pupil perimetry, consists of the repetitive on, and off flickering of a bright disk (2 hz; 320 cd/m2; 4◦ diameter) on a gray background (160 cd/m2) for 4 seconds per stimulus location. The disk evokes continuous pupil oscillations at the same rate as its flicker frequency, and the oscillatory power of the pupil reflects visual sensitivity. We monocularly presented the disk at a total of 80 locations in the central visual field (max. 15◦). The location of the flickering disk moved along with gaze to reduce confounds of eye movements (gaze-contingent paradigm). The test lasted ∼5min per eye and was performed on 7 patients with cerebral visual impairment (CVI), 8 patients with primary open angle glaucoma (age textgreater 45), and 14 healthy, age/gender-matched controls. Results: For all patients, pupil oscillation power (FFT based response amplitude to flicker) was significantly weaker when the flickering disk was presented in the impaired as compared to the intact visual field (CVI: 12% |
Jean-Baptiste Bernard; Susana T L Chung The role of external features in face recognition with central vision loss Journal Article Optometry and Vision Science, 93 (5), pp. 510–520, 2016. @article{Bernard2016b, title = {The role of external features in face recognition with central vision loss}, author = {Jean-Baptiste Bernard and Susana T L Chung}, doi = {http://dx.doi.org/10.1289/ehp.1002503}, year = {2016}, date = {2016-01-01}, journal = {Optometry and Vision Science}, volume = {93}, number = {5}, pages = {510--520}, abstract = {PURPOSE: We evaluated how the performance of recognizing familiar face images depends on the internal (eyebrows, eyes, nose, mouth) and external face features (chin, outline of face, hairline) in individuals with central vision loss. METHODS: In experiment 1, we measured eye movements for four observers with central vision loss to determine whether they fixated more often on the internal or the external features of face images while attempting to recognize the images. We then measured the accuracy for recognizing face images that contained only the internal, only the external, or both internal and external features (experiment 2) and for hybrid images where the internal and external features came from two different source images (experiment 3) for five observers with central vision loss and four age-matched control observers. RESULTS: When recognizing familiar face images, approximately 40% of the fixations of observers with central vision loss was centered on the external features of faces. The recognition accuracy was higher for images containing only external features (66.8 ± 3.3% correct) than for images containing only internal features (35.8 ± 15.0%), a finding contradicting that of control observers. For hybrid face images, observers with central vision loss responded more accurately to the external features (50.4 ± 17.8%) than to the internal features (9.3 ± 4.9%), whereas control observers did not show the same bias toward responding to the external features. CONCLUSIONS: Contrary to people with normal vision who rely more on the internal features of face images for recognizing familiar faces, individuals with central vision loss show a higher dependence on using external features of face images.}, keywords = {}, pubstate = {published}, tppubtype = {article} } PURPOSE: We evaluated how the performance of recognizing familiar face images depends on the internal (eyebrows, eyes, nose, mouth) and external face features (chin, outline of face, hairline) in individuals with central vision loss. METHODS: In experiment 1, we measured eye movements for four observers with central vision loss to determine whether they fixated more often on the internal or the external features of face images while attempting to recognize the images. We then measured the accuracy for recognizing face images that contained only the internal, only the external, or both internal and external features (experiment 2) and for hybrid images where the internal and external features came from two different source images (experiment 3) for five observers with central vision loss and four age-matched control observers. RESULTS: When recognizing familiar face images, approximately 40% of the fixations of observers with central vision loss was centered on the external features of faces. The recognition accuracy was higher for images containing only external features (66.8 ± 3.3% correct) than for images containing only internal features (35.8 ± 15.0%), a finding contradicting that of control observers. For hybrid face images, observers with central vision loss responded more accurately to the external features (50.4 ± 17.8%) than to the internal features (9.3 ± 4.9%), whereas control observers did not show the same bias toward responding to the external features. CONCLUSIONS: Contrary to people with normal vision who rely more on the internal features of face images for recognizing familiar faces, individuals with central vision loss show a higher dependence on using external features of face images. |
Patricia E G Bestelmeyer; Benjamin W Tatler; Louise H Phillips; Gillian Fraser; Philip J Benson; David St.Clair Global visual scanning abnormalities in schizophrenia and bipolar disorder Journal Article Schizophrenia Research, 87 (1-3), pp. 212–222, 2006. @article{Bestelmeyer2006, title = {Global visual scanning abnormalities in schizophrenia and bipolar disorder}, author = {Patricia E G Bestelmeyer and Benjamin W Tatler and Louise H Phillips and Gillian Fraser and Philip J Benson and David St.Clair}, doi = {10.1016/j.schres.2006.06.015}, year = {2006}, date = {2006-01-01}, journal = {Schizophrenia Research}, volume = {87}, number = {1-3}, pages = {212--222}, abstract = {Visual scanning of face images is widely reported to be abnormal in schizophrenia. This impaired processing has been proposed to be partly responsible for patients' disturbance in social interactions. The present study was designed to determine whether abnormal scanning is specific to images with social content or extends to other types of stimuli. Individuals with schizophrenia (n = 22), bipolar disorder (n = 19) and healthy controls (n = 37) were asked to view a series of 28 images with or without socially important content (i.e. faces, landscapes, fractals and noise patterns) while their eye movements were recorded video-oculographically. Temporal and spatial characteristics of scan paths were compared for each patient group and picture type. Independent of image content, patients with schizophrenia exhibited fewer fixations, longer fixation duration, longer saccade duration and peak velocity, and smaller saccade amplitude compared with healthy controls. Patients with schizophrenia and bipolar disorder did not differ significantly from one another on any of the temporal variables recorded. Fixation location distributions of participants with schizophrenia differed significantly from that of healthy controls on all picture types and from patients with bipolar disorder on all but face images. Abnormal scanning in schizophrenia and also bipolar disorder was independent of stimulus type and therefore reflects a global visual scanning impairment not specific to faces. Spatial scanning characteristics but not temporal ones may serve as biomarkers in the functional psychoses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual scanning of face images is widely reported to be abnormal in schizophrenia. This impaired processing has been proposed to be partly responsible for patients' disturbance in social interactions. The present study was designed to determine whether abnormal scanning is specific to images with social content or extends to other types of stimuli. Individuals with schizophrenia (n = 22), bipolar disorder (n = 19) and healthy controls (n = 37) were asked to view a series of 28 images with or without socially important content (i.e. faces, landscapes, fractals and noise patterns) while their eye movements were recorded video-oculographically. Temporal and spatial characteristics of scan paths were compared for each patient group and picture type. Independent of image content, patients with schizophrenia exhibited fewer fixations, longer fixation duration, longer saccade duration and peak velocity, and smaller saccade amplitude compared with healthy controls. Patients with schizophrenia and bipolar disorder did not differ significantly from one another on any of the temporal variables recorded. Fixation location distributions of participants with schizophrenia differed significantly from that of healthy controls on all picture types and from patients with bipolar disorder on all but face images. Abnormal scanning in schizophrenia and also bipolar disorder was independent of stimulus type and therefore reflects a global visual scanning impairment not specific to faces. Spatial scanning characteristics but not temporal ones may serve as biomarkers in the functional psychoses. |
Richard A I Bethlehem; Serge O Dumoulin; Edwin S Dalmaijer; Miranda Smit; Tos T J M Berendschot; Tanja C W Nijboer; Stefan Van Der Stigchel Decreased fixation stability of the preferred retinal location in juvenile macular degeneration Journal Article PLoS ONE, 9 (6), pp. e100171, 2014. @article{Bethlehem2014, title = {Decreased fixation stability of the preferred retinal location in juvenile macular degeneration}, author = {Richard A I Bethlehem and Serge O Dumoulin and Edwin S Dalmaijer and Miranda Smit and Tos T J M Berendschot and Tanja C W Nijboer and Stefan {Van Der Stigchel}}, doi = {10.1371/journal.pone.0100171}, year = {2014}, date = {2014-01-01}, journal = {PLoS ONE}, volume = {9}, number = {6}, pages = {e100171}, abstract = {Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial and temporal resolution infrared eye-tracker. The fixation-offset paradigm measures release from fixation under different fixation conditions and has been shown useful to distinguish between foveal and non-foveal fixation. We measured eye-movements in nine healthy age-matched controls and five patients with juvenile macular degeneration. In addition, we performed a simulation with the same task in a group of five healthy controls. Our results show that the preferred retinal locus does not adopt a foveal type of fixation but instead drifts further away from its original fixation and has overall increased fixation instability. Furthermore, the fixation instability is most pronounced in low frequency eye-movements representing a slow drift from fixation. We argue that the increased fixation instability cannot be attributed to fixation under an unnatural angle. Instead, diminished visual acuity in the periphery causes reduced oculomotor control and results in increased fixation instability.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Macular degeneration is the main cause for diminished visual acuity in the elderly. The juvenile form of macular degeneration has equally detrimental consequences on foveal vision. To compensate for loss of foveal vision most patients with macular degeneration adopt an eccentric preferred retinal location that takes over tasks normally performed by the healthy fovea. It is unclear however, whether the preferred retinal locus also develops properties typical for foveal vision. Here, we investigated whether the fixation characteristics of the preferred retinal locus resemble those of the healthy fovea. For this purpose, we used the fixation-offset paradigm and tracked eye-position using a high spatial and temporal resolution infrared eye-tracker. The fixation-offset paradigm measures release from fixation under different fixation conditions and has been shown useful to distinguish between foveal and non-foveal fixation. We measured eye-movements in nine healthy age-matched controls and five patients with juvenile macular degeneration. In addition, we performed a simulation with the same task in a group of five healthy controls. Our results show that the preferred retinal locus does not adopt a foveal type of fixation but instead drifts further away from its original fixation and has overall increased fixation instability. Furthermore, the fixation instability is most pronounced in low frequency eye-movements representing a slow drift from fixation. We argue that the increased fixation instability cannot be attributed to fixation under an unnatural angle. Instead, diminished visual acuity in the periphery causes reduced oculomotor control and results in increased fixation instability. |
Elena Betta; Massimo Turatto Are you ready? I can tell by looking at your microsaccades Journal Article NeuroReport, 17 (10), pp. 1001–1004, 2006. @article{Betta2006, title = {Are you ready? I can tell by looking at your microsaccades}, author = {Elena Betta and Massimo Turatto}, doi = {10.1097/01.wnr.0000223392.82198.6d}, year = {2006}, date = {2006-01-01}, journal = {NeuroReport}, volume = {17}, number = {10}, pages = {1001--1004}, abstract = {The direction of microsaccades has been shown to be biased by the allocation of spatial attention. Here, we investigated whether the cognitive processes involved in preparing to respond to an upcoming target can modulate the microsaccadic response. Specifically, we found that optimal manual response preparation, reflected by faster response times, was associated with a reduction in the absolute frequency of microsaccades. The present results are consistent with previous studies suggesting a relationship between oculomotor activity and different sorts of motor responses. Our findings, however, surprisingly demonstrate that the effect of preparation and stimulus expectation extends to an automatic and unconscious oculomotor activity such as microsaccade execution.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The direction of microsaccades has been shown to be biased by the allocation of spatial attention. Here, we investigated whether the cognitive processes involved in preparing to respond to an upcoming target can modulate the microsaccadic response. Specifically, we found that optimal manual response preparation, reflected by faster response times, was associated with a reduction in the absolute frequency of microsaccades. The present results are consistent with previous studies suggesting a relationship between oculomotor activity and different sorts of motor responses. Our findings, however, surprisingly demonstrate that the effect of preparation and stimulus expectation extends to an automatic and unconscious oculomotor activity such as microsaccade execution. |
Elena Betta; Giovanni Galfano; Massimo Turatto Microsaccadic response during inhibition of return in a target-target paradigm Journal Article Vision Research, 47 (3), pp. 428–436, 2007. @article{Betta2007, title = {Microsaccadic response during inhibition of return in a target-target paradigm}, author = {Elena Betta and Giovanni Galfano and Massimo Turatto}, doi = {10.1016/j.visres.2006.09.010}, year = {2007}, date = {2007-01-01}, journal = {Vision Research}, volume = {47}, number = {3}, pages = {428--436}, abstract = {This study examined the relationship between inhibition of return (IOR) in covert orienting and microsaccade statistics. Unlike a previous study [Galfano, G., Betta, E., & Turatto, M. (2004)], IOR was assessed by means of a target-target paradigm, and microsaccade dynamics were monitored as a function of both the first and the second visual event. In line with what has been reported with a cue-target paradigm, a significant directional modulation was observed opposite to the first visual event. Because participants were to respond to any stimulus, this rules out the possibility that the modulation resulted from a generic motor inhibition, showing instead that it is peculiarly coupled to the oculomotor system. Importantly, after the second visual event, a different response was observed in microsaccade orientation, whose direction critically depended of whether the second visual event appeared at the same location as the first visual event. The results are consistent with the notion that IOR is composed of both attentional and oculomotor components, and challenge the view that covert orienting paradigms engage the attentional component in isolation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study examined the relationship between inhibition of return (IOR) in covert orienting and microsaccade statistics. Unlike a previous study [Galfano, G., Betta, E., & Turatto, M. (2004)], IOR was assessed by means of a target-target paradigm, and microsaccade dynamics were monitored as a function of both the first and the second visual event. In line with what has been reported with a cue-target paradigm, a significant directional modulation was observed opposite to the first visual event. Because participants were to respond to any stimulus, this rules out the possibility that the modulation resulted from a generic motor inhibition, showing instead that it is peculiarly coupled to the oculomotor system. Importantly, after the second visual event, a different response was observed in microsaccade orientation, whose direction critically depended of whether the second visual event appeared at the same location as the first visual event. The results are consistent with the notion that IOR is composed of both attentional and oculomotor components, and challenge the view that covert orienting paradigms engage the attentional component in isolation. |
Mario Bettenbühl; Claudia Paladini; Konstantin Mergenthaler; Reinhold Kliegl; Ralf Engbert; Matthias Holschneider Microsaccade characterization using the continuous wavelet transform and principal component analysis Journal Article Journal of Eye Movement Research, 3 (5), pp. 1–14, 2010. @article{Bettenbuehl2010, title = {Microsaccade characterization using the continuous wavelet transform and principal component analysis}, author = {Mario Bettenbühl and Claudia Paladini and Konstantin Mergenthaler and Reinhold Kliegl and Ralf Engbert and Matthias Holschneider}, doi = {10.16910/jemr.3.5.1}, year = {2010}, date = {2010-01-01}, journal = {Journal of Eye Movement Research}, volume = {3}, number = {5}, pages = {1--14}, abstract = {During visual fixation on a target, humans perform miniature (or fixational) eye movements consisting of three components, i.e., tremor, drift, and microsaccades. Microsaccades are high velocity components with small amplitudes within fixa- tional eye movements. However, microsaccade shapes and statistical properties vary between individual observers. Here we show that microsaccades can be formally represented with two significant shapes which we identfied using the mathematical definition of singularities for the detection of the former in real data with the continuous wavelet transform. For characterization and model selection, we carried out a principal component analysis, which identified a step shape with an overshoot as first and a bump which regulates the overshoot as second component. We conclude that microsaccades are singular events with an overshoot component which can be detected by the continuous wavelet transform.}, keywords = {}, pubstate = {published}, tppubtype = {article} } During visual fixation on a target, humans perform miniature (or fixational) eye movements consisting of three components, i.e., tremor, drift, and microsaccades. Microsaccades are high velocity components with small amplitudes within fixa- tional eye movements. However, microsaccade shapes and statistical properties vary between individual observers. Here we show that microsaccades can be formally represented with two significant shapes which we identfied using the mathematical definition of singularities for the detection of the former in real data with the continuous wavelet transform. For characterization and model selection, we carried out a principal component analysis, which identified a step shape with an overshoot as first and a bump which regulates the overshoot as second component. We conclude that microsaccades are singular events with an overshoot component which can be detected by the continuous wavelet transform. |
Mario Bettenbühl; Marco Rusconi; Ralf Engbert; Matthias Holschneider Bayesian selection of Markov Models for symbol sequences: Application to microsaccadic eye movements Journal Article PLoS ONE, 7 (9), pp. e43388, 2012. @article{Bettenbuehl2012, title = {Bayesian selection of Markov Models for symbol sequences: Application to microsaccadic eye movements}, author = {Mario Bettenbühl and Marco Rusconi and Ralf Engbert and Matthias Holschneider}, doi = {10.1371/journal.pone.0043388}, year = {2012}, date = {2012-01-01}, journal = {PLoS ONE}, volume = {7}, number = {9}, pages = {e43388}, abstract = {Complex biological dynamics often generate sequences of discrete events which can be described as a Markov process. The order of the underlying Markovian stochastic process is fundamental for characterizing statistical dependencies within sequences. As an example for this class of biological systems, we investigate the Markov order of sequences of microsaccadic eye movements from human observers. We calculate the integrated likelihood of a given sequence for various orders of the Markov process and use this in a Bayesian framework for statistical inference on the Markov order. Our analysis shows that data from most participants are best explained by a first-order Markov process. This is compatible with recent findings of a statistical coupling of subsequent microsaccade orientations. Our method might prove to be useful for a broad class of biological systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Complex biological dynamics often generate sequences of discrete events which can be described as a Markov process. The order of the underlying Markovian stochastic process is fundamental for characterizing statistical dependencies within sequences. As an example for this class of biological systems, we investigate the Markov order of sequences of microsaccadic eye movements from human observers. We calculate the integrated likelihood of a given sequence for various orders of the Markov process and use this in a Bayesian framework for statistical inference on the Markov order. Our analysis shows that data from most participants are best explained by a first-order Markov process. This is compatible with recent findings of a statistical coupling of subsequent microsaccade orientations. Our method might prove to be useful for a broad class of biological systems. |
Katharina Bey; Lisa Kloft; Leonhard Lennertz; Rosa Grützmann; Stephan Heinzel; Christian Kaufmann; Julia Klawohn; Anja Riesel; Inga Meyhöfer; Norbert Kathmann; Michael Wagner Volitional saccade performance in a large sample of patients with obsessive-compulsive disorder and unaffected first-degree relatives Journal Article Psychophysiology, 54 (9), pp. 1284–1294, 2017. @article{Bey2017, title = {Volitional saccade performance in a large sample of patients with obsessive-compulsive disorder and unaffected first-degree relatives}, author = {Katharina Bey and Lisa Kloft and Leonhard Lennertz and Rosa Grützmann and Stephan Heinzel and Christian Kaufmann and Julia Klawohn and Anja Riesel and Inga Meyhöfer and Norbert Kathmann and Michael Wagner}, doi = {10.1111/psyp.12884}, year = {2017}, date = {2017-01-01}, journal = {Psychophysiology}, volume = {54}, number = {9}, pages = {1284--1294}, abstract = {Recent evidence indicates that patients with obsessive-compulsive disorder (OCD) as well as their unaffected first-degree relatives show deficits in the volitional control of saccades, suggesting that volitional saccade performance may constitute an endophenotype of OCD. Here, we aimed to replicate and extend these findings in a large, independent sample. One hundred and fifteen patients with OCD, 103 healthy comparison subjects without a family history of OCD, and 31 unaffected first-degree relatives of OCD patients were examined using structured clinical interviews and performed a volitional saccade task as well as a prosaccade task. In contrast to previous reports, neither patients nor relatives showed impairments in the performance of volitional saccades compared to healthy controls. Notably, medicated patients did not differ from nonmedicated patients, and there was no effect of depressive comorbidity. Additional analyses investigating correlations between saccade performance and OCD symptom dimensions yielded no significant associations. In conclusion, the present results do not support the notion that volitional saccade execution constitutes an endophenotype of OCD. Possible explanations for inconsistencies with previous studies are discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recent evidence indicates that patients with obsessive-compulsive disorder (OCD) as well as their unaffected first-degree relatives show deficits in the volitional control of saccades, suggesting that volitional saccade performance may constitute an endophenotype of OCD. Here, we aimed to replicate and extend these findings in a large, independent sample. One hundred and fifteen patients with OCD, 103 healthy comparison subjects without a family history of OCD, and 31 unaffected first-degree relatives of OCD patients were examined using structured clinical interviews and performed a volitional saccade task as well as a prosaccade task. In contrast to previous reports, neither patients nor relatives showed impairments in the performance of volitional saccades compared to healthy controls. Notably, medicated patients did not differ from nonmedicated patients, and there was no effect of depressive comorbidity. Additional analyses investigating correlations between saccade performance and OCD symptom dimensions yielded no significant associations. In conclusion, the present results do not support the notion that volitional saccade execution constitutes an endophenotype of OCD. Possible explanations for inconsistencies with previous studies are discussed. |
Katharina Bey; Inga Meyhöfer; Leonhard Lennertz; Rosa Grützmann; Stephan Heinzel; Christian Kaufmann; Julia Klawohn; Anja Riesel; Ulrich Ettinger; Norbert Kathmann; Michael Wagner Schizotypy and smooth pursuit eye movements as potential endophenotypes of obsessive-compulsive disorder Journal Article European Archives of Psychiatry and Clinical Neuroscience, 269 (2), pp. 235–243, 2019. @article{Bey2019, title = {Schizotypy and smooth pursuit eye movements as potential endophenotypes of obsessive-compulsive disorder}, author = {Katharina Bey and Inga Meyhöfer and Leonhard Lennertz and Rosa Grützmann and Stephan Heinzel and Christian Kaufmann and Julia Klawohn and Anja Riesel and Ulrich Ettinger and Norbert Kathmann and Michael Wagner}, doi = {10.1007/s00406-018-0899-x}, year = {2019}, date = {2019-01-01}, journal = {European Archives of Psychiatry and Clinical Neuroscience}, volume = {269}, number = {2}, pages = {235--243}, publisher = {Springer Berlin Heidelberg}, abstract = {Patients with obsessive-compulsive disorder (OCD) show dysfunctions of the fronto-striatal circuitry, which imply corresponding oculomotor deficits including smooth pursuit eye movements (SPEM). However, evidence for a deficit in SPEM is inconclusive, with some studies reporting reduced velocity gain while others did not find any SPEM dysfunctions in OCD patients. Interestingly, psychosis-like traits have repeatedly been linked to both OCD and impaired SPEM. Here, we examined a large sample of n = 168 patients with OCD}, keywords = {}, pubstate = {published}, tppubtype = {article} } Patients with obsessive-compulsive disorder (OCD) show dysfunctions of the fronto-striatal circuitry, which imply corresponding oculomotor deficits including smooth pursuit eye movements (SPEM). However, evidence for a deficit in SPEM is inconclusive, with some studies reporting reduced velocity gain while others did not find any SPEM dysfunctions in OCD patients. Interestingly, psychosis-like traits have repeatedly been linked to both OCD and impaired SPEM. Here, we examined a large sample of n = 168 patients with OCD |
Katharina Bey; Julia V Lippold; Behrem Aslan; René HWIBBLEemann; Ulrich Ettinger Effects of lorazepam on prosaccades and saccadic adaptation Journal Article Journal of Psychopharmacology, 35 (1), pp. 91–99, 2020. @article{Bey2020, title = {Effects of lorazepam on prosaccades and saccadic adaptation}, author = {Katharina Bey and Julia V Lippold and Behrem Aslan and René HWIBBLEemann and Ulrich Ettinger}, doi = {10.1177/0269881120972424}, year = {2020}, date = {2020-01-01}, journal = {Journal of Psychopharmacology}, volume = {35}, number = {1}, pages = {91--99}, abstract = {Background: Benzodiazepines have reliable adverse effects on saccadic eye movements, but the impact of sex as a potential modulator of these effects is less clear. A recent study reported stronger adverse effects on the spatial consistency of saccades in females, which may reflect sex differences in cerebellar mechanisms. Aims: We aimed to further examine the role of sex as a potential modulator of benzodiazepine effects by employing the saccadic adaptation paradigm, which is known to be sensitive to cerebellar functioning. Methods: A total of n=50 healthy adults performed a horizontal step prosaccade task and a saccadic adaptation task under 0.5 mg lorazepam, 1 mg lorazepam and placebo in a double-blind, within-subjects design. Results: In the prosaccade task, lorazepam had adverse effects on measures of peak velocity, latency and spatial consistency. The administration of 0.5 mg lorazepam led to significant reductions in gain-decrease adaptation, while a dose of 1 mg did not impair adaptation learning. Gain-increase adaptation was generally less pronounced, and unaffected by the drug. There were no significant drug×sex interactions in either task. Conclusions: We conclude that a low dose of lorazepam impairs gain-decrease adaptation independent of sex. At higher doses, however, increasing fatigue may facilitate adaptation and thus counteract the adverse effects observed at lower doses. With regards to prosaccades, our findings confirm peak velocity as well as latency and spatial measures as sensitive biomarkers of GABAergic effects.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Benzodiazepines have reliable adverse effects on saccadic eye movements, but the impact of sex as a potential modulator of these effects is less clear. A recent study reported stronger adverse effects on the spatial consistency of saccades in females, which may reflect sex differences in cerebellar mechanisms. Aims: We aimed to further examine the role of sex as a potential modulator of benzodiazepine effects by employing the saccadic adaptation paradigm, which is known to be sensitive to cerebellar functioning. Methods: A total of n=50 healthy adults performed a horizontal step prosaccade task and a saccadic adaptation task under 0.5 mg lorazepam, 1 mg lorazepam and placebo in a double-blind, within-subjects design. Results: In the prosaccade task, lorazepam had adverse effects on measures of peak velocity, latency and spatial consistency. The administration of 0.5 mg lorazepam led to significant reductions in gain-decrease adaptation, while a dose of 1 mg did not impair adaptation learning. Gain-increase adaptation was generally less pronounced, and unaffected by the drug. There were no significant drug×sex interactions in either task. Conclusions: We conclude that a low dose of lorazepam impairs gain-decrease adaptation independent of sex. At higher doses, however, increasing fatigue may facilitate adaptation and thus counteract the adverse effects observed at lower doses. With regards to prosaccades, our findings confirm peak velocity as well as latency and spatial measures as sensitive biomarkers of GABAergic effects. |
R Bibi; Jay A Edelman The influence of motor yraining onhuman express saccade production Journal Article Journal of Neurophysiology, 102 (6), pp. 3101–3110, 2009. @article{Bibi2009, title = {The influence of motor yraining onhuman express saccade production}, author = {R Bibi and Jay A Edelman}, doi = {10.1152/jn.90710.2008}, year = {2009}, date = {2009-01-01}, journal = {Journal of Neurophysiology}, volume = {102}, number = {6}, pages = {3101--3110}, abstract = {Express saccadic eye movements are saccades of extremely short latency. In monkey, express saccades have been shown to occur much more frequently when the monkey has been trained to make saccades in a particular direction to targets that appear in predictable locations. Such results suggest that express saccades occur in large number only under highly specific conditions, leading to the view that vector-specific training and motor preparatory processes are required to make an express saccade of a particular magnitude and direction. To evaluate this hypothesis in humans, we trained subjects to make saccades quickly to particular locations and then examined whether the frequency of express saccades depended on training and the number of possible target locations. Training significantly decreased saccade latency and increased express saccade production to both trained and untrained locations. Increasing the number of possible target locations (two vs. eight possible targets) led to only a modest increase of saccade latency. For most subjects, the probability of express saccade occurrence was much higher than that expected if vector-specific movement preparation were necessary for their production. These results suggest that vector-specific motor preparation and vector-specific saccade training are not necessary for express saccade production in humans and that increases in express saccade production are due in part to a facilitation in fixation disengagement or else a general enhancement in the ability of the saccadic system to respond to suddenly appearing visual stimuli.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Express saccadic eye movements are saccades of extremely short latency. In monkey, express saccades have been shown to occur much more frequently when the monkey has been trained to make saccades in a particular direction to targets that appear in predictable locations. Such results suggest that express saccades occur in large number only under highly specific conditions, leading to the view that vector-specific training and motor preparatory processes are required to make an express saccade of a particular magnitude and direction. To evaluate this hypothesis in humans, we trained subjects to make saccades quickly to particular locations and then examined whether the frequency of express saccades depended on training and the number of possible target locations. Training significantly decreased saccade latency and increased express saccade production to both trained and untrained locations. Increasing the number of possible target locations (two vs. eight possible targets) led to only a modest increase of saccade latency. For most subjects, the probability of express saccade occurrence was much higher than that expected if vector-specific movement preparation were necessary for their production. These results suggest that vector-specific motor preparation and vector-specific saccade training are not necessary for express saccade production in humans and that increases in express saccade production are due in part to a facilitation in fixation disengagement or else a general enhancement in the ability of the saccadic system to respond to suddenly appearing visual stimuli. |
Klinton Bicknell; Roger Levy; Keith Rayner Ongoing cognitive processing influences precise eye-movement targets in reading Journal Article Psychological Science, 31 (4), pp. 351–362, 2020. @article{Bicknell2020, title = {Ongoing cognitive processing influences precise eye-movement targets in reading}, author = {Klinton Bicknell and Roger Levy and Keith Rayner}, doi = {10.1177/0956797620901766}, year = {2020}, date = {2020-01-01}, journal = {Psychological Science}, volume = {31}, number = {4}, pages = {351--362}, abstract = {Reading is a highly complex learned skill in which humans move their eyes three to four times every second in response to visual and cognitive processing. The consensus view is that the details of these rapid eye-movement decisions—which part of a word to target with a saccade—are determined solely by low-level oculomotor heuristics. But maximally efficient saccade targeting would be sensitive to ongoing word identification, sending the eyes farther into a word the farther its identification has already progressed. Here, using a covert text-shifting paradigm, we showed just such a statistical relationship between saccade targeting in reading and trial-to-trial variability in cognitive processing. This result suggests that, rather than relying purely on heuristics, the human brain has learned to optimize eye movements in reading even at the fine-grained level of character-position targeting, reflecting efficiency-based sensitivity to ongoing cognitive processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Reading is a highly complex learned skill in which humans move their eyes three to four times every second in response to visual and cognitive processing. The consensus view is that the details of these rapid eye-movement decisions—which part of a word to target with a saccade—are determined solely by low-level oculomotor heuristics. But maximally efficient saccade targeting would be sensitive to ongoing word identification, sending the eyes farther into a word the farther its identification has already progressed. Here, using a covert text-shifting paradigm, we showed just such a statistical relationship between saccade targeting in reading and trial-to-trial variability in cognitive processing. This result suggests that, rather than relying purely on heuristics, the human brain has learned to optimize eye movements in reading even at the fine-grained level of character-position targeting, reflecting efficiency-based sensitivity to ongoing cognitive processing. |
Hans-Joachim Bieg; Jean-Pierre Bresciani; Heinrich H Bülthoff; Lewis L Chuang Looking for discriminating Is dDifferent from looking for looking's sake Journal Article PLoS ONE, 7 (9), pp. e45445, 2012. @article{Bieg2012, title = {Looking for discriminating Is dDifferent from looking for looking's sake}, author = {Hans-Joachim Bieg and Jean-Pierre Bresciani and Heinrich H Bülthoff and Lewis L Chuang}, doi = {10.1371/journal.pone.0045445}, year = {2012}, date = {2012-01-01}, journal = {PLoS ONE}, volume = {7}, number = {9}, pages = {e45445}, abstract = {Recent studies provide evidence for task-specific influences on saccadic eye movements. For instance, saccades exhibit higher peak velocity when the task requires coordinating eye and hand movements. The current study shows that the need to process task-relevant visual information at the saccade endpoint can be, in itself, sufficient to cause such effects. In this study, participants performed a visual discrimination task which required a saccade for successful completion. We compared the characteristics of these task-related saccades to those of classical target-elicited saccades, which required participants to fixate a visual target without performing a discrimination task. The results show that task-related saccades are faster and initiated earlier than target-elicited saccades. Differences between both saccade types are also noted in their saccade reaction time distributions and their main sequences, i.e., the relationship between saccade velocity, duration, and amplitude.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recent studies provide evidence for task-specific influences on saccadic eye movements. For instance, saccades exhibit higher peak velocity when the task requires coordinating eye and hand movements. The current study shows that the need to process task-relevant visual information at the saccade endpoint can be, in itself, sufficient to cause such effects. In this study, participants performed a visual discrimination task which required a saccade for successful completion. We compared the characteristics of these task-related saccades to those of classical target-elicited saccades, which required participants to fixate a visual target without performing a discrimination task. The results show that task-related saccades are faster and initiated earlier than target-elicited saccades. Differences between both saccade types are also noted in their saccade reaction time distributions and their main sequences, i.e., the relationship between saccade velocity, duration, and amplitude. |
Hans-Joachim Bieg; Jean-Pierre Bresciani; Heinrich H Bülthoff; Lewis L Chuang Saccade reaction time asymmetries during task-switching in pursuit tracking Journal Article Experimental Brain Research, 230 (3), pp. 271–281, 2013. @article{Bieg2013, title = {Saccade reaction time asymmetries during task-switching in pursuit tracking}, author = {Hans-Joachim Bieg and Jean-Pierre Bresciani and Heinrich H Bülthoff and Lewis L Chuang}, doi = {10.1007/s00221-013-3651-9}, year = {2013}, date = {2013-01-01}, journal = {Experimental Brain Research}, volume = {230}, number = {3}, pages = {271--281}, abstract = {We investigate how smooth pursuit eye movements affect the latencies of task-switching saccades. Participants had to alternate their foveal vision between a continuous pursuit task in the display center and a discrete object discrimination task in the periphery. The pursuit task was either carried out by following the target with the eyes only (ocular) or by steering an on-screen cursor with a joystick (oculomanual). We measured participants' saccadic reaction times (SRTs) when foveal vision was shifted from the pursuit task to the discrimination task and back to the pursuit task. Our results show asymmetries in SRTs depending on the movement direction of the pursuit target: SRTs were generally shorter in the direction of pursuit. Specifically, SRTs from the pursuit target were shorter when the discrimination object appeared in the motion direction. SRTs to pursuit were shorter when the pursuit target moved away from the current fixation location. This result was independent of the type of smooth pursuit behavior that was performed by participants (ocular/oculomanual). The effects are discussed in regard to asymmetries in attention and processes that suppress saccades at the onset of pursuit.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate how smooth pursuit eye movements affect the latencies of task-switching saccades. Participants had to alternate their foveal vision between a continuous pursuit task in the display center and a discrete object discrimination task in the periphery. The pursuit task was either carried out by following the target with the eyes only (ocular) or by steering an on-screen cursor with a joystick (oculomanual). We measured participants' saccadic reaction times (SRTs) when foveal vision was shifted from the pursuit task to the discrimination task and back to the pursuit task. Our results show asymmetries in SRTs depending on the movement direction of the pursuit target: SRTs were generally shorter in the direction of pursuit. Specifically, SRTs from the pursuit target were shorter when the discrimination object appeared in the motion direction. SRTs to pursuit were shorter when the pursuit target moved away from the current fixation location. This result was independent of the type of smooth pursuit behavior that was performed by participants (ocular/oculomanual). The effects are discussed in regard to asymmetries in attention and processes that suppress saccades at the onset of pursuit. |
Hans-Joachim Bieg; Lewis L Chuang; Heinrich H Bülthoff; Jean-Pierre Bresciani Asymmetries in saccade reaction times to pursuit Journal Article Experimental Brain Research, 233 (9), pp. 2527–2538, 2015. @article{Bieg2015a, title = {Asymmetries in saccade reaction times to pursuit}, author = {Hans-Joachim Bieg and Lewis L Chuang and Heinrich H Bülthoff and Jean-Pierre Bresciani}, doi = {10.1007/s00221-015-4323-8}, year = {2015}, date = {2015-01-01}, journal = {Experimental Brain Research}, volume = {233}, number = {9}, pages = {2527--2538}, abstract = {Before initiating a saccade to a moving target, the brain must take into account the target's eccentricity as well as its movement direction and speed. We tested how the kinematic characteristics of the target influence the time course of this oculomotor response. Participants performed a step-ramp task in which the target object stepped from a central to an eccentric position and moved at constant velocity either to the fixation position (foveopetal) or further to the periphery (foveofugal). The step size and target speed were varied. Of particular interest were trials that exhibited an initial saccade prior to a smooth pursuit eye movement. Measured saccade reaction times were longer in the foveopetal than in the foveofugal condition. In the foveopetal (but not the foveofugal) condition, the occurrence of an initial saccade, its reaction time as well as the strength of the pre-saccadic pursuit response depended on both the target's speed and the step size. A common explanation for these results may be found in the neural mechanisms that select between oculomotor response alternatives, i.e., a saccadic or smooth response.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Before initiating a saccade to a moving target, the brain must take into account the target's eccentricity as well as its movement direction and speed. We tested how the kinematic characteristics of the target influence the time course of this oculomotor response. Participants performed a step-ramp task in which the target object stepped from a central to an eccentric position and moved at constant velocity either to the fixation position (foveopetal) or further to the periphery (foveofugal). The step size and target speed were varied. Of particular interest were trials that exhibited an initial saccade prior to a smooth pursuit eye movement. Measured saccade reaction times were longer in the foveopetal than in the foveofugal condition. In the foveopetal (but not the foveofugal) condition, the occurrence of an initial saccade, its reaction time as well as the strength of the pre-saccadic pursuit response depended on both the target's speed and the step size. A common explanation for these results may be found in the neural mechanisms that select between oculomotor response alternatives, i.e., a saccadic or smooth response. |
Hans-Joachim Bieg; Lewis L Chuang; Heinrich H Bülthoff; Jean-Pierre Bresciani Asymmetric saccade reaction times to smooth pursuit Journal Article Experimental Brain Research, 233 (9), pp. 2527–2538, 2015. @article{Bieg2015b, title = {Asymmetric saccade reaction times to smooth pursuit}, author = {Hans-Joachim Bieg and Lewis L Chuang and Heinrich H Bülthoff and Jean-Pierre Bresciani}, doi = {10.1007/s00221-015-4323-8}, year = {2015}, date = {2015-01-01}, journal = {Experimental Brain Research}, volume = {233}, number = {9}, pages = {2527--2538}, publisher = {Springer Berlin Heidelberg}, abstract = {Before initiating a saccade to a moving target, the brain must take into account the target's eccentricity as well as its movement direction and speed. We tested how the kinematic characteristics of the target influence the time course of this oculomotor response. Participants performed a step-ramp task in which the target object stepped from a central to an eccentric position and moved at constant velocity either to the fixation position (foveopetal) or further to the periphery (foveofugal). The step size and target speed were varied. Of particular interest were trials that exhibited an initial saccade prior to a smooth pursuit eye movement. Measured saccade reaction times were longer in the foveopetal than in the foveofugal condition. In the foveopetal (but not the foveofugal) condition, the occurrence of an initial saccade, its reaction time as well as the strength of the pre-saccadic pursuit response depended on both the target's speed and the step size. A common explanation for these results may be found in the neural mechanisms that select between oculomotor response alternatives, i.e., a saccadic or smooth response.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Before initiating a saccade to a moving target, the brain must take into account the target's eccentricity as well as its movement direction and speed. We tested how the kinematic characteristics of the target influence the time course of this oculomotor response. Participants performed a step-ramp task in which the target object stepped from a central to an eccentric position and moved at constant velocity either to the fixation position (foveopetal) or further to the periphery (foveofugal). The step size and target speed were varied. Of particular interest were trials that exhibited an initial saccade prior to a smooth pursuit eye movement. Measured saccade reaction times were longer in the foveopetal than in the foveofugal condition. In the foveopetal (but not the foveofugal) condition, the occurrence of an initial saccade, its reaction time as well as the strength of the pre-saccadic pursuit response depended on both the target's speed and the step size. A common explanation for these results may be found in the neural mechanisms that select between oculomotor response alternatives, i.e., a saccadic or smooth response. |
J A Bijvank; L J Van Rijn; L J Balk; H S Tan; Bernard M J Uitdehaag; A Petzold Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia Journal Article Neurology, 92 (20), pp. E2299–E2308, 2019. @article{Bijvank2019, title = {Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia}, author = {J A Bijvank and L J {Van Rijn} and L J Balk and H S Tan and Bernard M J Uitdehaag and A Petzold}, doi = {10.1212/WNL.0000000000007499}, year = {2019}, date = {2019-01-01}, journal = {Neurology}, volume = {92}, number = {20}, pages = {E2299--E2308}, abstract = {Objective: We present an objective and quantitative approach for diagnosing internuclear ophthalmoplegia (INO) in multiple sclerosis (MS). Methods: A validated standardized infrared oculography protocol (DEMoNS [Demonstrate Eye Movement Networks with Saccades]) was used for quantifying prosaccades in patients with MS and healthy controls (HCs). The versional dysconjugacy index (VDI) was calculated, which describes the ratio between the abducting and adducting eye. The VDI was determined for peak velocity, peak acceleration, peak velocity divided by amplitude, and area under the curve (AUC) of the saccadic trajectory. We calculated the diagnostic accuracy for the several VDI parameters by a receiver operating characteristic analysis comparing HCs and patients with MS. The National Eye Institute Visual Function Questionnaire-25 was used to investigate vision-related quality of life of MS patients with INO. Results: Two hundred ten patients with MS and 58 HCs were included. The highest diagnostic accuracy was achieved by the VDI AUC of 15° horizontal prosaccades. Based on a combined VDI AUC and peak velocity divided by amplitude detection, the prevalence of an INO in MS calculated to 34%. In the INO group, 35.2% of the patients with MS reported any complaints of double vision, compared to 18.4% in the non-INO group (p = 0.010). MS patients with an INO had a lower overall vision-related quality of life (median 89.9, interquartile range 12.8) compared to patients without an INO (median 91.8, interquartile range 9.3}, keywords = {}, pubstate = {published}, tppubtype = {article} } Objective: We present an objective and quantitative approach for diagnosing internuclear ophthalmoplegia (INO) in multiple sclerosis (MS). Methods: A validated standardized infrared oculography protocol (DEMoNS [Demonstrate Eye Movement Networks with Saccades]) was used for quantifying prosaccades in patients with MS and healthy controls (HCs). The versional dysconjugacy index (VDI) was calculated, which describes the ratio between the abducting and adducting eye. The VDI was determined for peak velocity, peak acceleration, peak velocity divided by amplitude, and area under the curve (AUC) of the saccadic trajectory. We calculated the diagnostic accuracy for the several VDI parameters by a receiver operating characteristic analysis comparing HCs and patients with MS. The National Eye Institute Visual Function Questionnaire-25 was used to investigate vision-related quality of life of MS patients with INO. Results: Two hundred ten patients with MS and 58 HCs were included. The highest diagnostic accuracy was achieved by the VDI AUC of 15° horizontal prosaccades. Based on a combined VDI AUC and peak velocity divided by amplitude detection, the prevalence of an INO in MS calculated to 34%. In the INO group, 35.2% of the patients with MS reported any complaints of double vision, compared to 18.4% in the non-INO group (p = 0.010). MS patients with an INO had a lower overall vision-related quality of life (median 89.9, interquartile range 12.8) compared to patients without an INO (median 91.8, interquartile range 9.3 |
Jutta Billino; Jürgen Hennig; Karl R Gegenfurtner The role of dopamine in anticipatory pursuit eye movements: Insights from genetic polymorphisms in healthy adults Journal Article eNeuro, 3 (6), pp. 1–13, 2016. @article{Billino2016, title = {The role of dopamine in anticipatory pursuit eye movements: Insights from genetic polymorphisms in healthy adults}, author = {Jutta Billino and Jürgen Hennig and Karl R Gegenfurtner}, doi = {10.1523/ENEURO.0190-16.2016}, year = {2016}, date = {2016-01-01}, journal = {eNeuro}, volume = {3}, number = {6}, pages = {1--13}, abstract = {There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val158Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3′-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There is a long history of eye movement research in patients with psychiatric diseases for which dysfunctions of neurotransmission are considered to be the major pathologic mechanism. However, neuromodulation of oculomotor control is still hardly understood. We aimed to investigate in particular the impact of dopamine on smooth pursuit eye movements. Systematic variability in dopaminergic transmission due to genetic polymorphisms in healthy subjects offers a noninvasive opportunity to determine functional associations. We measured smooth pursuit in 110 healthy subjects genotyped for two well-documented polymorphisms, the COMT Val158Met polymorphism and the SLC6A3 3′-UTR-VNTR polymorphism. Pursuit paradigms were chosen to particularly assess the ability of the pursuit system to initiate tracking when target motion onset is blanked, reflecting the impact of extraretinal signals. In contrast, when following a fully visible target sensory, retinal signals are available. Our results highlight the crucial functional role of dopamine for anticipatory, but not for sensory-driven, pursuit processes. We found the COMT Val158Met polymorphism specifically associated with anticipatory pursuit parameters, emphasizing the dominant impact of prefrontal dopamine activity on complex oculomotor control. In contrast, modulation of striatal dopamine activity by the SLC6A3 3′-UTR-VNTR polymorphism had no significant functional effect. Though often neglected so far, individual differences in healthy subjects provide a promising approach to uncovering functional mechanisms and can be used as a bridge to understanding deficits in patients. |
Jutta Billino; Jürgen Hennig; Karl R Gegenfurtner Vision Research, 141 (170-180), pp. 170–180, 2017. @article{Billino2017, title = {Association between COMT genotype and the control of memory guided saccades: Individual differences in healthy adults reveal a detrimental role of dopamine}, author = {Jutta Billino and Jürgen Hennig and Karl R Gegenfurtner}, doi = {10.1016/j.visres.2016.10.001}, year = {2017}, date = {2017-01-01}, journal = {Vision Research}, volume = {141}, number = {170-180}, pages = {170--180}, publisher = {Elsevier Ltd}, abstract = {The neural circuits involved in oculomotor control are well described; however, neuromodulation of eye movements is still hardly understood. Memory guided saccades have been extensively studied and in particular neurophysiological evidence from monkey studies points to a crucial functional role of prefrontal dopamine activity. We exploited individual differences in dopamine regulation due to the well established COMT (catechol-O-methyltransferase) Val158Met polymorphism to explore the link between prefrontal dopamine activity and memory guided saccades in healthy subjects. The COMT genotype is thought to modulate dopamine metabolism in prefrontal cortex producing differences in dopamine availability. We investigated memory guided saccades in 111 healthy subjects and determined individual genotypes. Accuracy and precision were reduced in subjects with putatively higher prefrontal dopamine levels. In contrast, we found no modulation of saccade parameters by genotype in a visually guided control task. Our results suggest that increased dopamine activity can have a detrimental effect on saccades that rely on spatial memory representations. Although these findings await replication in larger and more diverse sample sizes, they provide persuasive support that specific oculomotor parameters are sensitive to dopaminergic variation in healthy subjects and add to a better understanding of how dopamine modulates saccadic control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The neural circuits involved in oculomotor control are well described; however, neuromodulation of eye movements is still hardly understood. Memory guided saccades have been extensively studied and in particular neurophysiological evidence from monkey studies points to a crucial functional role of prefrontal dopamine activity. We exploited individual differences in dopamine regulation due to the well established COMT (catechol-O-methyltransferase) Val158Met polymorphism to explore the link between prefrontal dopamine activity and memory guided saccades in healthy subjects. The COMT genotype is thought to modulate dopamine metabolism in prefrontal cortex producing differences in dopamine availability. We investigated memory guided saccades in 111 healthy subjects and determined individual genotypes. Accuracy and precision were reduced in subjects with putatively higher prefrontal dopamine levels. In contrast, we found no modulation of saccade parameters by genotype in a visually guided control task. Our results suggest that increased dopamine activity can have a detrimental effect on saccades that rely on spatial memory representations. Although these findings await replication in larger and more diverse sample sizes, they provide persuasive support that specific oculomotor parameters are sensitive to dopaminergic variation in healthy subjects and add to a better understanding of how dopamine modulates saccadic control. |
Paola Binda; Claudia Lunghi Short-term monocular deprivation enhances physiological pupillary oscillations Journal Article Neural Plasticity, pp. 1–10, 2017. @article{Binda2017, title = {Short-term monocular deprivation enhances physiological pupillary oscillations}, author = {Paola Binda and Claudia Lunghi}, year = {2017}, date = {2017-01-01}, journal = {Neural Plasticity}, pages = {1--10}, abstract = {Short-term monocular deprivation alters visual perception in adult humans, increasing the dominance of the deprived eye, for example, as measured with binocular rivalry. This formofplasticitymay depend upon the inhibition/excitation balance in the visual cortex. Recent work suggests that cortical excitability is reliably tracked by dilations and constrictions ofthe pupils ofthe eyes. Here, we ask whether monocular deprivation produces a systematic change ofpupil behavior, as measured at rest, that is independent of the change of visual perception. During periods of minimal sensory stimulation (in the dark) and task requirements (minimizing body and gaze movements), slow pupil oscillations, “hippus,” spontaneously appear. We find that hippus amplitude increases after monocular deprivation, with larger hippus changes in participants showing larger ocular dominance changes (measured by binocular rivalry). This tight correlation suggests that a single latent variable explains both the change of ocular dominance and hippus. We speculate that the neurotransmitter norepinephrine may be implicated in this phenomenon, given its important role in both plasticity and pupil control. On the practical side, our results indicate that measuring the pupil hippus (a simple and short procedure) provides a sensitive index of the change of ocular dominance induced by short-term monocular deprivation, hence a proxy for plasticity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Short-term monocular deprivation alters visual perception in adult humans, increasing the dominance of the deprived eye, for example, as measured with binocular rivalry. This formofplasticitymay depend upon the inhibition/excitation balance in the visual cortex. Recent work suggests that cortical excitability is reliably tracked by dilations and constrictions ofthe pupils ofthe eyes. Here, we ask whether monocular deprivation produces a systematic change ofpupil behavior, as measured at rest, that is independent of the change of visual perception. During periods of minimal sensory stimulation (in the dark) and task requirements (minimizing body and gaze movements), slow pupil oscillations, “hippus,” spontaneously appear. We find that hippus amplitude increases after monocular deprivation, with larger hippus changes in participants showing larger ocular dominance changes (measured by binocular rivalry). This tight correlation suggests that a single latent variable explains both the change of ocular dominance and hippus. We speculate that the neurotransmitter norepinephrine may be implicated in this phenomenon, given its important role in both plasticity and pupil control. On the practical side, our results indicate that measuring the pupil hippus (a simple and short procedure) provides a sensitive index of the change of ocular dominance induced by short-term monocular deprivation, hence a proxy for plasticity. |
Abdullah Bin Zahid; Molly E Hubbard; Julia Lockyer; Olivia E Podolak; Vikalpa M Dammavalam; Matthew Grady; Michael Nance; Mitchell Scheiman; Uzma Samadani; Christina L Master Eye tracking as a biomarker for concussion in children Journal Article Clinical Journal of Sport Medicine, pp. 1–11, 2018. @article{BinZahid2018, title = {Eye tracking as a biomarker for concussion in children}, author = {Abdullah {Bin Zahid} and Molly E Hubbard and Julia Lockyer and Olivia E Podolak and Vikalpa M Dammavalam and Matthew Grady and Michael Nance and Mitchell Scheiman and Uzma Samadani and Christina L Master}, doi = {10.1097/jsm.0000000000000639}, year = {2018}, date = {2018-01-01}, journal = {Clinical Journal of Sport Medicine}, pages = {1--11}, abstract = {OBJECTIVE: Concussion is the most common type of brain injury in both pediatric and adult populations and can potentially result in persistent postconcussion symptoms. Objective assessment of physiologic "mild" traumatic brain injury in concussion patients remains challenging. This study evaluates an automated eye-tracking algorithm as a biomarker for concussion as defined by its symptoms and the clinical signs of convergence insufficiency and accommodation dysfunction in a pediatric population. DESIGN: Cross-sectional case-control study. SETTING: Primary care. PATIENTS: Concussed children (N = 56; mean age = 13 years), evaluated at a mean of 22-week post-injury, compared with 83 uninjured controls. INDEPENDENT VARIABLES: Metrics comparing velocity and conjugacy of eye movements over time were obtained and were compared with the correlation between Acute Concussion Evaluation (ACE) scores, convergence, and accommodation dysfunction. MAIN OUTCOME MEASURES: Subjects' eye movements recorded with an automated eye tracker while they watched a 220-second cartoon film clip played continuously while moving within an aperture. RESULTS: Twelve eye-tracking metrics were significantly different between concussed and nonconcussed children. A model to classify concussion as diagnosed by its symptoms assessed using the ACE achieved an area under the curve (AUC) = 0.854 (71.9% sensitivity, 84.4% specificity, a cross-validated AUC = 0.789). An eye-tracking model built to identify near point of convergence (NPC) disability achieved 95.8% specificity and 57.1% sensitivity for an AUC = 0.810. Reduced binocular amplitude of accommodation had a Spearman correlation of 0.752(P value textless0.001) with NPC. CONCLUSION: Eye tracking correlated with concussion symptoms and detected convergence and accommodative abnormalities associated with concussion in the pediatric population. It demonstrates utility as a rapid, objective, noninvasive aid in the diagnosis of concussion.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVE: Concussion is the most common type of brain injury in both pediatric and adult populations and can potentially result in persistent postconcussion symptoms. Objective assessment of physiologic "mild" traumatic brain injury in concussion patients remains challenging. This study evaluates an automated eye-tracking algorithm as a biomarker for concussion as defined by its symptoms and the clinical signs of convergence insufficiency and accommodation dysfunction in a pediatric population. DESIGN: Cross-sectional case-control study. SETTING: Primary care. PATIENTS: Concussed children (N = 56; mean age = 13 years), evaluated at a mean of 22-week post-injury, compared with 83 uninjured controls. INDEPENDENT VARIABLES: Metrics comparing velocity and conjugacy of eye movements over time were obtained and were compared with the correlation between Acute Concussion Evaluation (ACE) scores, convergence, and accommodation dysfunction. MAIN OUTCOME MEASURES: Subjects' eye movements recorded with an automated eye tracker while they watched a 220-second cartoon film clip played continuously while moving within an aperture. RESULTS: Twelve eye-tracking metrics were significantly different between concussed and nonconcussed children. A model to classify concussion as diagnosed by its symptoms assessed using the ACE achieved an area under the curve (AUC) = 0.854 (71.9% sensitivity, 84.4% specificity, a cross-validated AUC = 0.789). An eye-tracking model built to identify near point of convergence (NPC) disability achieved 95.8% specificity and 57.1% sensitivity for an AUC = 0.810. Reduced binocular amplitude of accommodation had a Spearman correlation of 0.752(P value textless0.001) with NPC. CONCLUSION: Eye tracking correlated with concussion symptoms and detected convergence and accommodative abnormalities associated with concussion in the pediatric population. It demonstrates utility as a rapid, objective, noninvasive aid in the diagnosis of concussion. |
Eileen E Birch; Jingyun Wang; Joost Felius; David R Stager; Richard W Hertle Fixation control and eye alignment in children treated for dense congenital or developmental cataracts Journal Article Journal of AAPOS, 16 (2), pp. 156–160, 2012. @article{Birch2012, title = {Fixation control and eye alignment in children treated for dense congenital or developmental cataracts}, author = {Eileen E Birch and Jingyun Wang and Joost Felius and David R Stager and Richard W Hertle}, doi = {10.1016/j.jaapos.2011.11.007}, year = {2012}, date = {2012-01-01}, journal = {Journal of AAPOS}, volume = {16}, number = {2}, pages = {156--160}, publisher = {American Association for Pediatric Ophthalmology and Strabismus}, abstract = {Background: Many children treated for cataracts develop strabismus and nystagmus; however, little is known about the critical period for adverse ocular motor outcomes with respect to age of onset and duration. Methods: Children who had undergone extraction of dense cataracts by the age of 5 years were enrolled postoperatively. Ocular alignment was assessed regularly throughout follow-up. Fixation stability and associated ocular oscillations were determined from eye movement recordings at ≥5 years old. Multivariate logistic regression was used to evaluate whether laterality (unilateral vs bilateral), age at onset, and/or duration of visual deprivation were associated with adverse ocular motor outcomes and to determine multivariate odds ratios (ORs). Results: A total of 41 children were included. Of these, 27 (66%) developed strabismus; 29 (71%) developed nystagmus. Congenital onset was associated with significant risk for strabismus (OR, 5.3; 95% CI, 1.1-34.1); infantile onset was associated with significant risk for nystagmus (OR, 13.6; 95% CI, 1.6-302). Duration textgreater6 weeks was associated with significant risk for both strabismus (OR, 9.1; 95% CI, 1.9-54.2) and nystagmus (OR, 46.2; 95% CI, 6.0-1005). Congenital onset was associated with significant risk for interocular asymmetry in severity of nystagmus (OR, 25.0; 95% CI, 2.6-649), as was unilateral cataract (OR, 58.9; 95% CI, 5.1-2318). Conclusions: Laterality (unilateral vs bilateral) and age at onset were significant nonmodifiable risk factors for adverse ocular motor outcomes. Duration of deprivation was a significant modifiable risk factor for adverse ocular motor outcomes. The current study demonstrated that reduced risk for nystagmus and strabismus was associated with deprivation ≤6 weeks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Many children treated for cataracts develop strabismus and nystagmus; however, little is known about the critical period for adverse ocular motor outcomes with respect to age of onset and duration. Methods: Children who had undergone extraction of dense cataracts by the age of 5 years were enrolled postoperatively. Ocular alignment was assessed regularly throughout follow-up. Fixation stability and associated ocular oscillations were determined from eye movement recordings at ≥5 years old. Multivariate logistic regression was used to evaluate whether laterality (unilateral vs bilateral), age at onset, and/or duration of visual deprivation were associated with adverse ocular motor outcomes and to determine multivariate odds ratios (ORs). Results: A total of 41 children were included. Of these, 27 (66%) developed strabismus; 29 (71%) developed nystagmus. Congenital onset was associated with significant risk for strabismus (OR, 5.3; 95% CI, 1.1-34.1); infantile onset was associated with significant risk for nystagmus (OR, 13.6; 95% CI, 1.6-302). Duration textgreater6 weeks was associated with significant risk for both strabismus (OR, 9.1; 95% CI, 1.9-54.2) and nystagmus (OR, 46.2; 95% CI, 6.0-1005). Congenital onset was associated with significant risk for interocular asymmetry in severity of nystagmus (OR, 25.0; 95% CI, 2.6-649), as was unilateral cataract (OR, 58.9; 95% CI, 5.1-2318). Conclusions: Laterality (unilateral vs bilateral) and age at onset were significant nonmodifiable risk factors for adverse ocular motor outcomes. Duration of deprivation was a significant modifiable risk factor for adverse ocular motor outcomes. The current study demonstrated that reduced risk for nystagmus and strabismus was associated with deprivation ≤6 weeks. |
Eileen E Birch; Yolanda S Castañeda; Christina S Cheng-Patel; Sarah E Morale; Krista R Kelly; Reed M Jost; Lindsey A Hudgins; David A Leske; Jonathan M Holmes Associations of eye-related quality of life with vision, visuomotor function, and self-perception in children with strabismus and anisometropia Journal Article Investigative ophthalmology & visual science, 61 (11), pp. 1–6, 2020. @article{Birch2020, title = {Associations of eye-related quality of life with vision, visuomotor function, and self-perception in children with strabismus and anisometropia}, author = {Eileen E Birch and Yolanda S Casta{ñ}eda and Christina S Cheng-Patel and Sarah E Morale and Krista R Kelly and Reed M Jost and Lindsey A Hudgins and David A Leske and Jonathan M Holmes}, doi = {10.1167/iovs.61.11.22}, year = {2020}, date = {2020-01-01}, journal = {Investigative ophthalmology & visual science}, volume = {61}, number = {11}, pages = {1--6}, abstract = {Purpose: To evaluate associations between eye-related quality of life (ER-QOL) assessed by the Child Pediatric Eye Questionnaire (Child PedEyeQ) and functional measures (vision, visuomotor function, self-perception) in children with strabismus, anisometropia, or both. Our hypothesis was that children with functional deficits would have lower ER-QOL, and if so, these associations would support the convergent construct validity of the Child PedEyeQ. Methods: We evaluated 114 children (ages 5-11 years) with strabismus, anisometropia, or both. Each child completed the Child PedEyeQ to assess four Rasch-scored domains of ER-QOL: Functional Vision, Bothered by Eyes/Vision, Social, and Frustration/Worry. In addition, children completed one or more functional tests: visual acuity (n = 114), Randot Preschool Stereoacuity (n = 92), contrast balance index (suppression; n = 91), Readalyzer reading (n = 44), vergence instability (n = 50), Movement Assessment Battery for Children-2 manual dexterity (n = 57), and Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (n = 44). Results: Child PedEyeQ Functional Vision domain scores were correlated with self-perception of physical competence (rs = 0.65; 95% confidence interval [CI], 0.35-0.96) and reading speed (rs = 0.47; 95% CI, 0.16-0.77). Bothered by Eyes/Vision domain scores were correlated with self-perception of physical competence (rs = 0.52; 95% CI, 0.21-0.83). Moderate correlations were observed between Social domain scores and vergence instability (rs = -0.46; 95% CI, -0.76 to -0.15) and self-perception of physical competence (rs = 0.43; 95% CI, 0.12-0.73) and peer acceptance (rs = 0.49; 95% CI, 0.18-0.80). Frustration/Worry domain scores were moderately correlated with self-perception of physical competence (rs = 0.41; 95% CI, 0.10-0.71) and peer acceptance (rs = 0.47; 95% CI, 0.16-0.77). Conclusions: Strong and moderate correlations were observed between functional measures and Child PedEyeQ domain scores. These associations provide supporting evidence that the Child PedEyeQ has convergent construct validity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose: To evaluate associations between eye-related quality of life (ER-QOL) assessed by the Child Pediatric Eye Questionnaire (Child PedEyeQ) and functional measures (vision, visuomotor function, self-perception) in children with strabismus, anisometropia, or both. Our hypothesis was that children with functional deficits would have lower ER-QOL, and if so, these associations would support the convergent construct validity of the Child PedEyeQ. Methods: We evaluated 114 children (ages 5-11 years) with strabismus, anisometropia, or both. Each child completed the Child PedEyeQ to assess four Rasch-scored domains of ER-QOL: Functional Vision, Bothered by Eyes/Vision, Social, and Frustration/Worry. In addition, children completed one or more functional tests: visual acuity (n = 114), Randot Preschool Stereoacuity (n = 92), contrast balance index (suppression; n = 91), Readalyzer reading (n = 44), vergence instability (n = 50), Movement Assessment Battery for Children-2 manual dexterity (n = 57), and Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (n = 44). Results: Child PedEyeQ Functional Vision domain scores were correlated with self-perception of physical competence (rs = 0.65; 95% confidence interval [CI], 0.35-0.96) and reading speed (rs = 0.47; 95% CI, 0.16-0.77). Bothered by Eyes/Vision domain scores were correlated with self-perception of physical competence (rs = 0.52; 95% CI, 0.21-0.83). Moderate correlations were observed between Social domain scores and vergence instability (rs = -0.46; 95% CI, -0.76 to -0.15) and self-perception of physical competence (rs = 0.43; 95% CI, 0.12-0.73) and peer acceptance (rs = 0.49; 95% CI, 0.18-0.80). Frustration/Worry domain scores were moderately correlated with self-perception of physical competence (rs = 0.41; 95% CI, 0.10-0.71) and peer acceptance (rs = 0.47; 95% CI, 0.16-0.77). Conclusions: Strong and moderate correlations were observed between functional measures and Child PedEyeQ domain scores. These associations provide supporting evidence that the Child PedEyeQ has convergent construct validity. |
Geoffrey Bird; Caroline Catmur; Giorgia Silani; Chris Frith; Uta Frith Attention does not modulate neural responses to social stimuli in autism spectrum disorders Journal Article NeuroImage, 31 (4), pp. 1614–1624, 2006. @article{Bird2006, title = {Attention does not modulate neural responses to social stimuli in autism spectrum disorders}, author = {Geoffrey Bird and Caroline Catmur and Giorgia Silani and Chris Frith and Uta Frith}, doi = {10.1016/j.neuroimage.2006.02.037}, year = {2006}, date = {2006-01-01}, journal = {NeuroImage}, volume = {31}, number = {4}, pages = {1614--1624}, abstract = {We investigated whether individuals with autism spectrum disorders (ASD) would show attentional modulation for social (face) and non-social (house) stimuli. Sixteen individuals with ASD and 16 matched control participants completed a task in which pairs of face and house stimuli were present on every trial, with one of the pairs randomly assigned to attended locations and the other to unattended locations. Both mass-univariate (SPM) and region of interest analyses suggested that responses to houses were modulated by attention in both groups, but that only the control participants demonstrated attentional modulation of face-selective regions. Thus, the participants with ASD demonstrated a lack of attentional modulation which was particularly evident for the social stimulus. Analyses of effective connectivity indicated that these results were due to a failure of attention to modulate connectivity between extrastriate areas and V1. We discuss how these results may suggest a mechanism to explain the reduced salience of social stimuli in ASD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated whether individuals with autism spectrum disorders (ASD) would show attentional modulation for social (face) and non-social (house) stimuli. Sixteen individuals with ASD and 16 matched control participants completed a task in which pairs of face and house stimuli were present on every trial, with one of the pairs randomly assigned to attended locations and the other to unattended locations. Both mass-univariate (SPM) and region of interest analyses suggested that responses to houses were modulated by attention in both groups, but that only the control participants demonstrated attentional modulation of face-selective regions. Thus, the participants with ASD demonstrated a lack of attentional modulation which was particularly evident for the social stimulus. Analyses of effective connectivity indicated that these results were due to a failure of attention to modulate connectivity between extrastriate areas and V1. We discuss how these results may suggest a mechanism to explain the reduced salience of social stimuli in ASD. |
Elina Birmingham; Moran Cerf; Ralph Adolphs Comparing social attention in autism and amygdala lesions: Effects of stimulus and task condition Journal Article Social Neuroscience, 6 (5-6), pp. 420–435, 2011. @article{Birmingham2011, title = {Comparing social attention in autism and amygdala lesions: Effects of stimulus and task condition}, author = {Elina Birmingham and Moran Cerf and Ralph Adolphs}, doi = {10.1080/17470919.2011.561547}, year = {2011}, date = {2011-01-01}, journal = {Social Neuroscience}, volume = {6}, number = {5-6}, pages = {420--435}, abstract = {The amygdala plays a critical role in orienting gaze and attention to socially salient stimuli. Previous work has demonstrated that SM a patient with rare bilateral amygdala lesions, fails to fixate and make use of information from the eyes in faces. Amygdala dysfunction has also been implicated as a contributing factor in autism spectrum disorders (ASD), consistent with some reports of reduced eye fixations in ASD. Yet, detailed comparisons between ASD and patients with amygdala lesions have not been undertaken. Here we carried out such a comparison, using eye tracking to complex social scenes that contained faces. We presented participants with three task conditions. In the Neutral task, participants had to determine what kind of room the scene took place in. In the Describe task, participants described the scene. In the Social Attention task, participants inferred where people in the scene were directing their attention. SM spent less time looking at the eyes and much more time looking at the mouths than control subjects, consistent with earlier findings. There was also a trend for the ASD group to spend less time on the eyes, although this depended on the particular image and task. Whereas controls and SM looked more at the eyes when the task required social attention, the ASD group did not. This pattern of impairments suggests that SM looks less at the eyes because of a failure in stimulus-driven attention to social features, whereas individuals with ASD look less at the eyes because they are generally insensitive to socially relevant information and fail to modulate attention as a function of task demands. We conclude that the source of the social attention impairment in ASD may arise upstream from the amygdala, rather than in the amygdala itself.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The amygdala plays a critical role in orienting gaze and attention to socially salient stimuli. Previous work has demonstrated that SM a patient with rare bilateral amygdala lesions, fails to fixate and make use of information from the eyes in faces. Amygdala dysfunction has also been implicated as a contributing factor in autism spectrum disorders (ASD), consistent with some reports of reduced eye fixations in ASD. Yet, detailed comparisons between ASD and patients with amygdala lesions have not been undertaken. Here we carried out such a comparison, using eye tracking to complex social scenes that contained faces. We presented participants with three task conditions. In the Neutral task, participants had to determine what kind of room the scene took place in. In the Describe task, participants described the scene. In the Social Attention task, participants inferred where people in the scene were directing their attention. SM spent less time looking at the eyes and much more time looking at the mouths than control subjects, consistent with earlier findings. There was also a trend for the ASD group to spend less time on the eyes, although this depended on the particular image and task. Whereas controls and SM looked more at the eyes when the task required social attention, the ASD group did not. This pattern of impairments suggests that SM looks less at the eyes because of a failure in stimulus-driven attention to social features, whereas individuals with ASD look less at the eyes because they are generally insensitive to socially relevant information and fail to modulate attention as a function of task demands. We conclude that the source of the social attention impairment in ASD may arise upstream from the amygdala, rather than in the amygdala itself. |
Jo Black; David Williams; Heather J Ferguson Imagining counterfactual worlds in autism spectrum disorder Journal Article Journal of Experimental Psychology: Learning, Memory, and Cognition, 44 (9), pp. 1444–1463, 2018. @article{Black2018, title = {Imagining counterfactual worlds in autism spectrum disorder}, author = {Jo Black and David Williams and Heather J Ferguson}, doi = {10.1037/xlm0000500}, year = {2018}, date = {2018-01-01}, journal = {Journal of Experimental Psychology: Learning, Memory, and Cognition}, volume = {44}, number = {9}, pages = {1444--1463}, abstract = {Two experiments are presented that explore online counterfactual processing in autism spectrum disorder (ASD) using eye-tracking. Participants' eye movements were tracked while they read factual and counterfactual sentences in an anomaly detection task. In Experiment 1, the sentences depicted everyday counterfactual situations (e.g., If Joanne had remembered her umbrella, her hair would have been dry/wet when she arrived home). Sentences in Experiment 2 depicted counterfactual versions of real world events (e.g., If the Titanic had not hit an iceberg, it would have survived/sunk along with all the passengers). Results from both experiments suggest that counterfactual understanding is undiminished in adults with ASD. In fact, participants with ASD were faster than Typically Developing (TD) participants to detect anomalies within realistic, discourse-based counterfactuals (Experiment 1). Detection was comparable for TD and ASD groups when understanding could be grounded in knowledge about reality (Experiment 2), though the 2 groups used subtly different strategies for responding to and recovering from counterfactual inconsistent words. These data argue against general difficulties in global coherence and complex integration in ASD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two experiments are presented that explore online counterfactual processing in autism spectrum disorder (ASD) using eye-tracking. Participants' eye movements were tracked while they read factual and counterfactual sentences in an anomaly detection task. In Experiment 1, the sentences depicted everyday counterfactual situations (e.g., If Joanne had remembered her umbrella, her hair would have been dry/wet when she arrived home). Sentences in Experiment 2 depicted counterfactual versions of real world events (e.g., If the Titanic had not hit an iceberg, it would have survived/sunk along with all the passengers). Results from both experiments suggest that counterfactual understanding is undiminished in adults with ASD. In fact, participants with ASD were faster than Typically Developing (TD) participants to detect anomalies within realistic, discourse-based counterfactuals (Experiment 1). Detection was comparable for TD and ASD groups when understanding could be grounded in knowledge about reality (Experiment 2), though the 2 groups used subtly different strategies for responding to and recovering from counterfactual inconsistent words. These data argue against general difficulties in global coherence and complex integration in ASD. |
Jo Black; Mahsa Barzy; David Williams; Heather Ferguson Intact counterfactual emotion processing in autism spectrum disorder: Evidence from eye-tracking Journal Article Autism Research, 12 (3), pp. 422–444, 2019. @article{Black2019, title = {Intact counterfactual emotion processing in autism spectrum disorder: Evidence from eye-tracking}, author = {Jo Black and Mahsa Barzy and David Williams and Heather Ferguson}, doi = {10.1002/aur.2056}, year = {2019}, date = {2019-01-01}, journal = {Autism Research}, volume = {12}, number = {3}, pages = {422--444}, abstract = {Counterfactual emotions, such as regret and relief, require an awareness of how things could have been different. We report a preregistered experiment that examines how adults with and without ASD process counterfactual emotions in real-time, based on research showing that the developmental trajectory of counterfactual thinking may be disrupted in people with ASD. Participants were eye-tracked as they read narratives in which a character made an explicit decision then subsequently experienced either a mildly negative or positive outcome. The final sentence in each story included an explicit remark about the character's mood that was either consistent or inconsistent with the character's expected feelings of regret or relief (e.g., “łdots she feels happy/annoyed about her decision.”). Results showed that adults with ASD are unimpaired in processing emotions based on counterfactual reasoning, and in fact showed earlier sensitivity to inconsistencies within relief contexts compared to TD participants. This finding highlights a previously unknown strength in empathy and emotion processing in adults with ASD, which may have been masked in previous research that has typically relied on explicit, response-based measures to record emotional inferences, which are likely to be susceptible to demand characteristics and response biases. Therefore, this study highlights the value of employing implicit measures that provide insights on peoples' immediate responses to emotional content without disrupting ongoing processing. Autism Res 2019, 12: 422–444 textcopyright 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: Despite known difficulties with empathy and perspective-taking, we found that adults with autism are unimpaired at inferring complex emotions (regret and relief) in others. This finding extends existing evidence showing dysfunctional counterfactual thinking in children with autism. We highlight the value of using implicit measures to identify strengths and abilities in ASD that may be masked by explicit tasks that require participants to interact socially or report their own thoughts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Counterfactual emotions, such as regret and relief, require an awareness of how things could have been different. We report a preregistered experiment that examines how adults with and without ASD process counterfactual emotions in real-time, based on research showing that the developmental trajectory of counterfactual thinking may be disrupted in people with ASD. Participants were eye-tracked as they read narratives in which a character made an explicit decision then subsequently experienced either a mildly negative or positive outcome. The final sentence in each story included an explicit remark about the character's mood that was either consistent or inconsistent with the character's expected feelings of regret or relief (e.g., “łdots she feels happy/annoyed about her decision.”). Results showed that adults with ASD are unimpaired in processing emotions based on counterfactual reasoning, and in fact showed earlier sensitivity to inconsistencies within relief contexts compared to TD participants. This finding highlights a previously unknown strength in empathy and emotion processing in adults with ASD, which may have been masked in previous research that has typically relied on explicit, response-based measures to record emotional inferences, which are likely to be susceptible to demand characteristics and response biases. Therefore, this study highlights the value of employing implicit measures that provide insights on peoples' immediate responses to emotional content without disrupting ongoing processing. Autism Res 2019, 12: 422–444 textcopyright 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: Despite known difficulties with empathy and perspective-taking, we found that adults with autism are unimpaired at inferring complex emotions (regret and relief) in others. This finding extends existing evidence showing dysfunctional counterfactual thinking in children with autism. We highlight the value of using implicit measures to identify strengths and abilities in ASD that may be masked by explicit tasks that require participants to interact socially or report their own thoughts. |
Marius Blanke; Ludwig Harsch; Jonas Knöll; Frank Bremmer Spatial perception during pursuit initiation Journal Article Vision Research, 50 (24), pp. 2714–2720, 2010. @article{Blanke2010, title = {Spatial perception during pursuit initiation}, author = {Marius Blanke and Ludwig Harsch and Jonas Knöll and Frank Bremmer}, doi = {10.1016/j.visres.2010.08.037}, year = {2010}, date = {2010-01-01}, journal = {Vision Research}, volume = {50}, number = {24}, pages = {2714--2720}, publisher = {Elsevier Ltd}, abstract = {Spatial perception is modulated by eye movements. During smooth pursuit, perceived locations are shifted in the direction of the eye movement. During active fixation, visual space is perceptually compressed towards the fovea. In our present study, we were interested to determine the time course of spatial localization during pursuit initiation, i.e. the transition period from fixation to steady-state pursuit. Human observers had to localize briefly flashed targets around the time of pursuit initiation. Our data clearly show that pursuit-like mislocalization starts well before the onset of the eye movement. Our results point towards corollary-discharge as neural source for the observed perceptual effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spatial perception is modulated by eye movements. During smooth pursuit, perceived locations are shifted in the direction of the eye movement. During active fixation, visual space is perceptually compressed towards the fovea. In our present study, we were interested to determine the time course of spatial localization during pursuit initiation, i.e. the transition period from fixation to steady-state pursuit. Human observers had to localize briefly flashed targets around the time of pursuit initiation. Our data clearly show that pursuit-like mislocalization starts well before the onset of the eye movement. Our results point towards corollary-discharge as neural source for the observed perceptual effect. |
Jens Blechert; Ulrich Ansorge; Brunna Tuschen-Caffier A body-related dot-probe task reveals distinct attentional patterns for bulimia nervosa and anorexia nervosa Journal Article Journal of Abnormal Psychology, 119 (3), pp. 575–585, 2010. @article{Blechert2010, title = {A body-related dot-probe task reveals distinct attentional patterns for bulimia nervosa and anorexia nervosa}, author = {Jens Blechert and Ulrich Ansorge and Brunna Tuschen-Caffier}, doi = {10.1037/a0019531}, year = {2010}, date = {2010-01-01}, journal = {Journal of Abnormal Psychology}, volume = {119}, number = {3}, pages = {575--585}, abstract = {We investigated body-related attentional biases in eating disorders by testing whether individuals with anorexia nervosa (AN}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated body-related attentional biases in eating disorders by testing whether individuals with anorexia nervosa (AN |
T M Blekher; Robert D Yee; S C Kirkwood; A M Hake; J C Stout; Marjorie R Weaver; Tatiana M Foroud Oculomotor control in asymptomatic and recently diagnosed individuals with the genetic marker for Huntington's disease Journal Article Vision Research, 44 (23), pp. 2729–2736, 2004. @article{Blekher2004, title = {Oculomotor control in asymptomatic and recently diagnosed individuals with the genetic marker for Huntington's disease}, author = {T M Blekher and Robert D Yee and S C Kirkwood and A M Hake and J C Stout and Marjorie R Weaver and Tatiana M Foroud}, doi = {10.1016/j.visres.2004.06.006}, year = {2004}, date = {2004-01-01}, journal = {Vision Research}, volume = {44}, number = {23}, pages = {2729--2736}, abstract = {We compared oculomotor control among individuals in the early stages of Huntington’s disease (HD), with that of individuals who are presymptomatic HD gene carriers (PSGC) and nongene carriers (NGC). The oculomotor testing paradigm included both traditional tests and a novel experimental procedure to assess visual scanning. Traditional tests elicited saccades, pursuit and optokinetic nystagmus (OKN). HD patients demonstrated marked delay in the initiation of volitional saccades (anti-saccade and memory-guided saccades), a reduced number of correct volitional saccades, reduced velocity of saccades, and a decreased OKN gain. We also studied visual scanning while the participants completed the Digit Symbol Subscale of the Wechsler Adult Intelligence Survey-Revised (WAIS-R). The HD participants demonstrated an abnormal gaze strategy, which may be associated with attention and/or planning deficits.Differences between the PSGC and NGC groups were only observed for two measures: PSGC had a decreased number of memory-guided saccades and a subtle delay in the initiation of volitional saccades. Our results suggest that oculomotor measures are a sensitive biomarker in the early stage of HD and demonstrate that the combination of more traditional oculomotor tests with visual scanning tests is useful in the evaluation of visual performance. textcopyright 2004 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We compared oculomotor control among individuals in the early stages of Huntington’s disease (HD), with that of individuals who are presymptomatic HD gene carriers (PSGC) and nongene carriers (NGC). The oculomotor testing paradigm included both traditional tests and a novel experimental procedure to assess visual scanning. Traditional tests elicited saccades, pursuit and optokinetic nystagmus (OKN). HD patients demonstrated marked delay in the initiation of volitional saccades (anti-saccade and memory-guided saccades), a reduced number of correct volitional saccades, reduced velocity of saccades, and a decreased OKN gain. We also studied visual scanning while the participants completed the Digit Symbol Subscale of the Wechsler Adult Intelligence Survey-Revised (WAIS-R). The HD participants demonstrated an abnormal gaze strategy, which may be associated with attention and/or planning deficits.Differences between the PSGC and NGC groups were only observed for two measures: PSGC had a decreased number of memory-guided saccades and a subtle delay in the initiation of volitional saccades. Our results suggest that oculomotor measures are a sensitive biomarker in the early stage of HD and demonstrate that the combination of more traditional oculomotor tests with visual scanning tests is useful in the evaluation of visual performance. textcopyright 2004 Elsevier Ltd. All rights reserved. |
Tanya Blekher; S A Johnson; James A R Marshall; K White; S Hui; Marjorie R Weaver; J Gray; Robert D Yee; J C Stout; X Berstian; Joanne Wojcieszek; Tatiana M Foroud Saccades in presymptomatic and early stages of Huntington disease Journal Article Neurology, 67 (2), pp. 394–399, 2006. @article{Blekher2006, title = {Saccades in presymptomatic and early stages of Huntington disease}, author = {Tanya Blekher and S A Johnson and James A R Marshall and K White and S Hui and Marjorie R Weaver and J Gray and Robert D Yee and J C Stout and X Berstian and Joanne Wojcieszek and Tatiana M Foroud}, doi = {10.1111/j.1467-8373.2007.00344.x}, year = {2006}, date = {2006-01-01}, journal = {Neurology}, volume = {67}, number = {2}, pages = {394--399}, abstract = {OBJECTIVE:To evaluate quantitative measures of eye movements as possible biomarkers in prediagnostic and early stages of Huntington disease (HD). METHODS:The study sample (n = 215) included individuals both at risk and recently diagnosed with HD. All participants completed a uniform clinical evaluation which included administration of the Unified Huntington's Disease Rating Scale (UHDRS) by a movement disorder neurologist and molecular testing to determine HD gene status. A high resolution, video-based eye tracking system was employed to quantify measures of eye movement (error rates, latencies, SD of latencies, velocities, and accuracies) during a computerized battery of saccadic and steady fixation tasks. RESULTS:Prediagnostic HD gene carriers and individuals with early HD demonstrated three types of significant abnormalities while performing memory guided and anti-saccade tasks: increased error rate, increased saccade latency, and increased variability of saccade latency. The eye movement abnormalities increased with advancing motor signs of HD. CONCLUSIONS:Abnormalities in eye movement measures are a sensitive biomarker in the prediagnostic and early stages of Huntington disease (HD). These measures may be more sensitive to prediagnostic changes in HD than the currently employed neurologic motor assessment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVE:To evaluate quantitative measures of eye movements as possible biomarkers in prediagnostic and early stages of Huntington disease (HD). METHODS:The study sample (n = 215) included individuals both at risk and recently diagnosed with HD. All participants completed a uniform clinical evaluation which included administration of the Unified Huntington's Disease Rating Scale (UHDRS) by a movement disorder neurologist and molecular testing to determine HD gene status. A high resolution, video-based eye tracking system was employed to quantify measures of eye movement (error rates, latencies, SD of latencies, velocities, and accuracies) during a computerized battery of saccadic and steady fixation tasks. RESULTS:Prediagnostic HD gene carriers and individuals with early HD demonstrated three types of significant abnormalities while performing memory guided and anti-saccade tasks: increased error rate, increased saccade latency, and increased variability of saccade latency. The eye movement abnormalities increased with advancing motor signs of HD. CONCLUSIONS:Abnormalities in eye movement measures are a sensitive biomarker in the prediagnostic and early stages of Huntington disease (HD). These measures may be more sensitive to prediagnostic changes in HD than the currently employed neurologic motor assessment. |
Tanya Blekher; Marjorie R Weaver; Xueya Cai; Siu L Hui; Jeanine Marshall; Jacqueline Gray Jackson; Joanne Wojcieszek; Robert D Yee; Tatiana M Foroud Test-retest reliability of saccadic measures in subjects at risk for Huntington disease Journal Article Investigative Ophthalmology & Visual Science, 50 (12), pp. 5707–5711, 2009. @article{Blekher2009, title = {Test-retest reliability of saccadic measures in subjects at risk for Huntington disease}, author = {Tanya Blekher and Marjorie R Weaver and Xueya Cai and Siu L Hui and Jeanine Marshall and Jacqueline Gray Jackson and Joanne Wojcieszek and Robert D Yee and Tatiana M Foroud}, doi = {10.1167/iovs.09-3538}, year = {2009}, date = {2009-01-01}, journal = {Investigative Ophthalmology & Visual Science}, volume = {50}, number = {12}, pages = {5707--5711}, abstract = {PURPOSE Abnormalities in saccades appear to be sensitive and specific biomarkers in the prediagnostic stages of Huntington disease (HD). The goal of this study was to evaluate test-retest reliability of saccadic measures in prediagnostic carriers of the HD gene expansion (PDHD) and normal controls (NC). METHODS The study sample included 9 PDHD and 12 NC who completed two study visits within an approximate 1-month interval. At the first visit, all participants completed a uniform clinical evaluation. A high-resolution, video-based system was used to record eye movements during completion of a battery of visually guided, antisaccade, and memory-guided tasks. Latency, velocity, gain, and percentage of errors were quantified. Test-retest reliability was estimated by calculating the intraclass correlation (ICC) of the saccade measures collected at the first and second visits. In addition, an equality test based on Fisher's z-transformation was used to evaluate the effects of group (PDHD and NC) and the subject's sex on ICC. RESULTS The percentage of errors showed moderate to high reliability in the antisaccade and memory-guided tasks (ICC = 0.64-0.93). The latency of the saccades also demonstrated moderate to high reliability (ICC = 0.55-0.87) across all tasks. The velocity and gain of the saccades showed moderate reliability. The ICC was similar in the PDHD and NC groups. There was no significant effect of sex on the ICC. CONCLUSIONS Good reliability of saccadic latency and percentage of errors in both antisaccade and memory-guided tasks suggests that these measures could serve as biomarkers to evaluate progression in HD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } PURPOSE Abnormalities in saccades appear to be sensitive and specific biomarkers in the prediagnostic stages of Huntington disease (HD). The goal of this study was to evaluate test-retest reliability of saccadic measures in prediagnostic carriers of the HD gene expansion (PDHD) and normal controls (NC). METHODS The study sample included 9 PDHD and 12 NC who completed two study visits within an approximate 1-month interval. At the first visit, all participants completed a uniform clinical evaluation. A high-resolution, video-based system was used to record eye movements during completion of a battery of visually guided, antisaccade, and memory-guided tasks. Latency, velocity, gain, and percentage of errors were quantified. Test-retest reliability was estimated by calculating the intraclass correlation (ICC) of the saccade measures collected at the first and second visits. In addition, an equality test based on Fisher's z-transformation was used to evaluate the effects of group (PDHD and NC) and the subject's sex on ICC. RESULTS The percentage of errors showed moderate to high reliability in the antisaccade and memory-guided tasks (ICC = 0.64-0.93). The latency of the saccades also demonstrated moderate to high reliability (ICC = 0.55-0.87) across all tasks. The velocity and gain of the saccades showed moderate reliability. The ICC was similar in the PDHD and NC groups. There was no significant effect of sex on the ICC. CONCLUSIONS Good reliability of saccadic latency and percentage of errors in both antisaccade and memory-guided tasks suggests that these measures could serve as biomarkers to evaluate progression in HD. |
Tanya Blekher; Marjorie R Weaver; Jeanine Marshall; Siu L Hui; Jacqueline Gray Jackson; Julie C Stout; Xabier Beristain; Joanne Wojcieszek; Robert D Yee; Tatiana M Foroud Visual scanning and cognitive performance in prediagnostic and early-stage Huntington's disease Journal Article Movement Disorders, 24 (4), pp. 533–540, 2009. @article{Blekher2009a, title = {Visual scanning and cognitive performance in prediagnostic and early-stage Huntington's disease}, author = {Tanya Blekher and Marjorie R Weaver and Jeanine Marshall and Siu L Hui and Jacqueline Gray Jackson and Julie C Stout and Xabier Beristain and Joanne Wojcieszek and Robert D Yee and Tatiana M Foroud}, doi = {10.1002/mds.22329}, year = {2009}, date = {2009-01-01}, journal = {Movement Disorders}, volume = {24}, number = {4}, pages = {533--540}, abstract = {The objective of this study was to evaluate visual scanning strategies in carriers of the Huntington disease (HD) gene expansion and to test whether there is an association between measures of visual scanning and cognitive performance. The study sample included control (NC}, keywords = {}, pubstate = {published}, tppubtype = {article} } The objective of this study was to evaluate visual scanning strategies in carriers of the Huntington disease (HD) gene expansion and to test whether there is an association between measures of visual scanning and cognitive performance. The study sample included control (NC |
Tanya Blekher; Marjorie R Weaver; Jason Rupp; William C Nichols; Siu L Hui; Jacqueline Gray; Robert D Yee; Joanne Wojcieszek; Tatiana M Foroud Multiple step pattern as a biomarker in Parkinson disease Journal Article Parkinsonism and Related Disorders, 15 (7), pp. 506–510, 2009. @article{Blekher2009b, title = {Multiple step pattern as a biomarker in Parkinson disease}, author = {Tanya Blekher and Marjorie R Weaver and Jason Rupp and William C Nichols and Siu L Hui and Jacqueline Gray and Robert D Yee and Joanne Wojcieszek and Tatiana M Foroud}, doi = {10.1016/j.parkreldis.2009.01.002}, year = {2009}, date = {2009-01-01}, journal = {Parkinsonism and Related Disorders}, volume = {15}, number = {7}, pages = {506--510}, publisher = {Elsevier Ltd}, abstract = {Objective: To evaluate quantitative measures of saccades as possible biomarkers in early stages of Parkinson disease (PD) and in a population at-risk for PD. Methods: The study sample (n = 68) included mildly to moderately affected PD patients, their unaffected siblings, and control individuals. All participants completed a clinical evaluation by a movement disorder neurologist. Genotyping of the G2019S mutation in the LRRK2 gene was performed in the PD patients and their unaffected siblings. A high resolution, video-based eye tracking system was employed to record eye positions during a battery of visually guided, anti-saccadic (AS), and two memory-guided (MG) tasks. Saccade measures (latency, velocity, gain, error rate, and multiple step pattern) were quantified. Results: PD patients and a subgroup of their unaffected siblings had an abnormally high incidence of multiple step patterns (MSP) and reduced gain of saccades as compared with controls. The abnormalities were most pronounced in the more challenging version of the MG task. For this task, the MSP measure demonstrated good sensitivity (87%) and excellent specificity (96%) in the ability to discriminate PD patients from controls. PD patients and their siblings also made more errors in the AS task. Conclusions: Abnormalities in eye movement measures appear to be sensitive and specific measures in PD patients as well as a subset of those at-risk for PD. The inclusion of quantitative laboratory testing of saccadic movements may increase the sensitivity of the neurological examination to identify individuals who are at greater risk for PD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Objective: To evaluate quantitative measures of saccades as possible biomarkers in early stages of Parkinson disease (PD) and in a population at-risk for PD. Methods: The study sample (n = 68) included mildly to moderately affected PD patients, their unaffected siblings, and control individuals. All participants completed a clinical evaluation by a movement disorder neurologist. Genotyping of the G2019S mutation in the LRRK2 gene was performed in the PD patients and their unaffected siblings. A high resolution, video-based eye tracking system was employed to record eye positions during a battery of visually guided, anti-saccadic (AS), and two memory-guided (MG) tasks. Saccade measures (latency, velocity, gain, error rate, and multiple step pattern) were quantified. Results: PD patients and a subgroup of their unaffected siblings had an abnormally high incidence of multiple step patterns (MSP) and reduced gain of saccades as compared with controls. The abnormalities were most pronounced in the more challenging version of the MG task. For this task, the MSP measure demonstrated good sensitivity (87%) and excellent specificity (96%) in the ability to discriminate PD patients from controls. PD patients and their siblings also made more errors in the AS task. Conclusions: Abnormalities in eye movement measures appear to be sensitive and specific measures in PD patients as well as a subset of those at-risk for PD. The inclusion of quantitative laboratory testing of saccadic movements may increase the sensitivity of the neurological examination to identify individuals who are at greater risk for PD. |
James Blundell; Steven Frisson; Anupam Chakrapani; Shauna Kearney; Suresh Vijay; Anita MacDonald; Paul Gissen; Chris Hendriksz; Andrew Olson Markers of cognitive function in individuals with metabolic disease: Morquio syndrome and tyrosinemia type III Journal Article Cognitive Neuropsychology, 35 (3-4), pp. 120–147, 2018. @article{Blundell2018, title = {Markers of cognitive function in individuals with metabolic disease: Morquio syndrome and tyrosinemia type III}, author = {James Blundell and Steven Frisson and Anupam Chakrapani and Shauna Kearney and Suresh Vijay and Anita MacDonald and Paul Gissen and Chris Hendriksz and Andrew Olson}, doi = {10.1080/02643294.2018.1443913}, year = {2018}, date = {2018-01-01}, journal = {Cognitive Neuropsychology}, volume = {35}, number = {3-4}, pages = {120--147}, publisher = {Taylor & Francis}, abstract = {We characterized cognitive function in two metabolic diseases. MPS–IVa (mucopolysaccharidosis IVa, Morquio) and tyrosinemia type III individuals were assessed using tasks of attention, language and oculomotor function. MPS–IVa individuals were slower in visual search, but the display size effects were normal, and slowing was not due to long reaction times (ruling out slow item processing or distraction). Maintaining gaze in an oculomotor task was difficult. Results implicated sustained attention and task initiation or response processing. Shifting attention, accumulating evidence and selecting targets were unaffected. Visual search was also slowed in tyrosinemia type III, and patterns in visual search and fixation tasks pointed to sustained attention impairments, although there were differences from MPS–IVa. Language was impaired in tyrosinemia type III but not MPS–IVa. Metabolic diseases produced selective cognitive effects. Our results, incorporating new methods for developmental data and model selection, illustrate how cognitive data can contribute to understanding function in biochemical brain systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We characterized cognitive function in two metabolic diseases. MPS–IVa (mucopolysaccharidosis IVa, Morquio) and tyrosinemia type III individuals were assessed using tasks of attention, language and oculomotor function. MPS–IVa individuals were slower in visual search, but the display size effects were normal, and slowing was not due to long reaction times (ruling out slow item processing or distraction). Maintaining gaze in an oculomotor task was difficult. Results implicated sustained attention and task initiation or response processing. Shifting attention, accumulating evidence and selecting targets were unaffected. Visual search was also slowed in tyrosinemia type III, and patterns in visual search and fixation tasks pointed to sustained attention impairments, although there were differences from MPS–IVa. Language was impaired in tyrosinemia type III but not MPS–IVa. Metabolic diseases produced selective cognitive effects. Our results, incorporating new methods for developmental data and model selection, illustrate how cognitive data can contribute to understanding function in biochemical brain systems. |
James Blundella; Steven Frissona; Anupam Chakrapani; Paul Gissenc; Chris Hendriksz; Suresh Vijay; Andrew Olson Oculomotor abnormalities in children with Niemann-Pick type C Journal Article Molecular Genetics and Metabolism, 123 (2), pp. 159–168, 2018. @article{Blundella2018, title = {Oculomotor abnormalities in children with Niemann-Pick type C}, author = {James Blundella and Steven Frissona and Anupam Chakrapani and Paul Gissenc and Chris Hendriksz and Suresh Vijay and Andrew Olson}, doi = {10.1016/j.ymgme.2017.11.004}, year = {2018}, date = {2018-01-01}, journal = {Molecular Genetics and Metabolism}, volume = {123}, number = {2}, pages = {159--168}, publisher = {Elsevier}, abstract = {Niemann-Pick type C (NP-C) is a rare recessive disorder associated with progressive supranuclear gaze palsy. Degeneration occurs initially for vertical saccades and later for horizontal saccades. There are studies of oculo- motor degeneration in adult NP-C patients [1, 2] but no comparable studies in children. We used high-resolution video-based eye tracking to record monocular vertical and horizontal eye movements in 2 neurological NP-C pa- tients (children with clinically observable oculomotor abnormalities) and 3 pre-neurological NP-C patients (children without clinically observable oculomotor abnormalities). Saccade onset latency, saccade peak velocity and saccade curvature were compared to healthy controls (N= 77). NP-C patients had selective impairments of vertical sac- cade peak velocity and vertical saccade curvature, with slower peak velocities and greater curvature. Changes were more pronounced in neurological than pre-neurological patients, showing that these measures are sensitive to disease progress, but abnormal curvature and slowed downward saccades were present in both groups, showing that eye- tracking can register disease-related changes before these are evident in a clinical exam. Both slowing, curvature and the detailed characteristics of the curvature we observed are predicted by the detailed characteristics of RIMLF population codes. Onset latencies were not different from healthy controls. High-resolution video-based eye tracking is a promising sensitive and objective method to measure NP-C disease severity and neurological onset. It may also help evaluate responses to therapeutic interventions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Niemann-Pick type C (NP-C) is a rare recessive disorder associated with progressive supranuclear gaze palsy. Degeneration occurs initially for vertical saccades and later for horizontal saccades. There are studies of oculo- motor degeneration in adult NP-C patients [1, 2] but no comparable studies in children. We used high-resolution video-based eye tracking to record monocular vertical and horizontal eye movements in 2 neurological NP-C pa- tients (children with clinically observable oculomotor abnormalities) and 3 pre-neurological NP-C patients (children without clinically observable oculomotor abnormalities). Saccade onset latency, saccade peak velocity and saccade curvature were compared to healthy controls (N= 77). NP-C patients had selective impairments of vertical sac- cade peak velocity and vertical saccade curvature, with slower peak velocities and greater curvature. Changes were more pronounced in neurological than pre-neurological patients, showing that these measures are sensitive to disease progress, but abnormal curvature and slowed downward saccades were present in both groups, showing that eye- tracking can register disease-related changes before these are evident in a clinical exam. Both slowing, curvature and the detailed characteristics of the curvature we observed are predicted by the detailed characteristics of RIMLF population codes. Onset latencies were not different from healthy controls. High-resolution video-based eye tracking is a promising sensitive and objective method to measure NP-C disease severity and neurological onset. It may also help evaluate responses to therapeutic interventions. |
Hazel I Blythe; Jonathan H Dickins; Colin R Kennedy; Simon P Liversedge Phonological processing during silent reading in teenagers who are deaf/hard of hearing: An eye movement investigation Journal Article Developmental Science, 21 , pp. 1–19, 2018. @article{Blythe2018, title = {Phonological processing during silent reading in teenagers who are deaf/hard of hearing: An eye movement investigation}, author = {Hazel I Blythe and Jonathan H Dickins and Colin R Kennedy and Simon P Liversedge}, doi = {10.1111/desc.12643}, year = {2018}, date = {2018-09-01}, journal = {Developmental Science}, volume = {21}, pages = {1--19}, publisher = {John Wiley & Sons, Ltd (10.1111)}, abstract = {There has been considerable variability within the literature concerning the extent to which deaf/hard of hearing individuals are able to process phonological codes during reading. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). We examined both foveal processing and parafoveal pre‐processing of phonology for three participant groups—teenagers with permanent childhood hearing loss (PCHL), chronological age‐matched controls, and reading age‐matched controls. The teenagers with PCHL showed a pseudohomophone advantage from both directly fixated words and parafoveal preview, similar to their hearing peers. These data provide strong evidence for phonological recoding during silent reading in teenagers with PCHL.}, keywords = {}, pubstate = {published}, tppubtype = {article} } There has been considerable variability within the literature concerning the extent to which deaf/hard of hearing individuals are able to process phonological codes during reading. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). We examined both foveal processing and parafoveal pre‐processing of phonology for three participant groups—teenagers with permanent childhood hearing loss (PCHL), chronological age‐matched controls, and reading age‐matched controls. The teenagers with PCHL showed a pseudohomophone advantage from both directly fixated words and parafoveal preview, similar to their hearing peers. These data provide strong evidence for phonological recoding during silent reading in teenagers with PCHL. |
Hazel I Blythe; Jonathan H Dickins; Colin R Kennedy; Simon P Liversedge The role of phonology in lexical access in teenagers with a history of dyslexia Journal Article PLoS ONE, 15 (3), pp. e0229934, 2020. @article{Blythe2020, title = {The role of phonology in lexical access in teenagers with a history of dyslexia}, author = {Hazel I Blythe and Jonathan H Dickins and Colin R Kennedy and Simon P Liversedge}, doi = {10.1371/journal.pone.0229934}, year = {2020}, date = {2020-01-01}, journal = {PLoS ONE}, volume = {15}, number = {3}, pages = {e0229934}, abstract = {We examined phonological recoding during silent sentence reading in teenagers with a history of dyslexia and their typically developing peers. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). In Experiment 1 we examined foveal processing of the target word/nonword stimuli, and in Experiment 2 we examined parafoveal pre-processing. There were four participant groups-older teenagers with a history of dyslexia, older typically developing teenagers who were matched for age, younger typically developing teenagers who were matched for reading level, and younger teenagers with a history of dyslexia. All four participant groups showed a pseudohomophone advantage, both from foveal processing and parafoveal preprocessing, indicating that teenagers with a history of dyslexia engage in phonological recoding for lexical identification during silent sentence reading in a comparable manner to their typically developing peers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We examined phonological recoding during silent sentence reading in teenagers with a history of dyslexia and their typically developing peers. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). In Experiment 1 we examined foveal processing of the target word/nonword stimuli, and in Experiment 2 we examined parafoveal pre-processing. There were four participant groups-older teenagers with a history of dyslexia, older typically developing teenagers who were matched for age, younger typically developing teenagers who were matched for reading level, and younger teenagers with a history of dyslexia. All four participant groups showed a pseudohomophone advantage, both from foveal processing and parafoveal preprocessing, indicating that teenagers with a history of dyslexia engage in phonological recoding for lexical identification during silent sentence reading in a comparable manner to their typically developing peers. |
Anna K Bobak; Benjamin A Parris; Nicola J Gregory; Rachel J Bennetts; Sarah Bate Eye-movement strategies in developmental prosopagnosia and “super” face recognition Journal Article Quarterly Journal of Experimental Psychology, 70 (2), pp. 201–217, 2017. @article{Bobak2017, title = {Eye-movement strategies in developmental prosopagnosia and “super” face recognition}, author = {Anna K Bobak and Benjamin A Parris and Nicola J Gregory and Rachel J Bennetts and Sarah Bate}, doi = {10.1080/17470218.2016.1161059}, year = {2017}, date = {2017-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {70}, number = {2}, pages = {201--217}, abstract = {Developmental prosopagnosia (DP) is a cognitive condition characterized by a severe deficit in face recognition. Few investigations have examined whether impairments at the early stages of processing may underpin the condition, and it is also unknown whether DP is simply the "bottom end" of the typical face-processing spectrum. To address these issues, we monitored the eye-movements of DPs, typical perceivers, and "super recognizers" (SRs) while they viewed a set of static images displaying people engaged in naturalistic social scenarios. Three key findings emerged: (a) Individuals with more severe prosopagnosia spent less time examining the internal facial region, (b) as observed in acquired prosopagnosia, some DPs spent less time examining the eyes and more time examining the mouth than controls, and (c) SRs spent more time examining the nose-a measure that also correlated with face recognition ability in controls. These findings support previous suggestions that DP is a heterogeneous condition, but suggest that at least the most severe cases represent a group of individuals that qualitatively differ from the typical population. While SRs seem to merely be those at the "top end" of normal, this work identifies the nose as a critical region for successful face recognition.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Developmental prosopagnosia (DP) is a cognitive condition characterized by a severe deficit in face recognition. Few investigations have examined whether impairments at the early stages of processing may underpin the condition, and it is also unknown whether DP is simply the "bottom end" of the typical face-processing spectrum. To address these issues, we monitored the eye-movements of DPs, typical perceivers, and "super recognizers" (SRs) while they viewed a set of static images displaying people engaged in naturalistic social scenarios. Three key findings emerged: (a) Individuals with more severe prosopagnosia spent less time examining the internal facial region, (b) as observed in acquired prosopagnosia, some DPs spent less time examining the eyes and more time examining the mouth than controls, and (c) SRs spent more time examining the nose-a measure that also correlated with face recognition ability in controls. These findings support previous suggestions that DP is a heterogeneous condition, but suggest that at least the most severe cases represent a group of individuals that qualitatively differ from the typical population. While SRs seem to merely be those at the "top end" of normal, this work identifies the nose as a critical region for successful face recognition. |
A R Bogadhi; Anna Montagnini; Guillaume S Masson Dynamic interaction between retinal and extraretinal signals in motion integration for smooth pursuit Journal Article Journal of Vision, 13 (13), pp. 1–26, 2013. @article{Bogadhi2013, title = {Dynamic interaction between retinal and extraretinal signals in motion integration for smooth pursuit}, author = {A R Bogadhi and Anna Montagnini and Guillaume S Masson}, doi = {10.1167/13.13.5}, year = {2013}, date = {2013-01-01}, journal = {Journal of Vision}, volume = {13}, number = {13}, pages = {1--26}, abstract = {Due to the aperture problem, the initial direction of tracking responses to a translating bar is biased towards the direction orthogonal to the bar. This observation offers a powerful way to explore the interactions between retinal and extraretinal signals in controlling our actions. We conducted two experiments to probe these interactions by briefly (200 and 400 ms) blanking the moving target (458 or 1358 tilted bar) during steady state (Experiment 1) and at different moments during the early phase of pursuit (Experiment 2). In Experiment 1, we found a marginal but statistically significant directional bias on target reappearance for all subjects in at least one blank condition (200 or 400 ms). In Experiment 2, no systematic significant directional bias was observed at target reappearance after a blank. These results suggest that the weighting of retinal and extraretinal signals is dynamically modulated during the different phases of pursuit. Based on our previous theoretical work on motion integration, we propose a new closed- loop two-stage recurrent Bayesian model where retinal and extraretinal signals are dynamically weighted based on their respective reliabilities and combined to compute the visuomotor drive. With a single free parameter, the model reproduces many aspects of smooth pursuit observed across subjects during and immediately after target blanking. It provides a new theoretical framework to understand how different signals are dynamically combined based on their relative reliability to adaptively control our actions. Overall, the model and behavioral results suggest that human subjects rely more strongly on prediction during theearly phasethaninthe steady state phase of pursuit.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Due to the aperture problem, the initial direction of tracking responses to a translating bar is biased towards the direction orthogonal to the bar. This observation offers a powerful way to explore the interactions between retinal and extraretinal signals in controlling our actions. We conducted two experiments to probe these interactions by briefly (200 and 400 ms) blanking the moving target (458 or 1358 tilted bar) during steady state (Experiment 1) and at different moments during the early phase of pursuit (Experiment 2). In Experiment 1, we found a marginal but statistically significant directional bias on target reappearance for all subjects in at least one blank condition (200 or 400 ms). In Experiment 2, no systematic significant directional bias was observed at target reappearance after a blank. These results suggest that the weighting of retinal and extraretinal signals is dynamically modulated during the different phases of pursuit. Based on our previous theoretical work on motion integration, we propose a new closed- loop two-stage recurrent Bayesian model where retinal and extraretinal signals are dynamically weighted based on their respective reliabilities and combined to compute the visuomotor drive. With a single free parameter, the model reproduces many aspects of smooth pursuit observed across subjects during and immediately after target blanking. It provides a new theoretical framework to understand how different signals are dynamically combined based on their relative reliability to adaptively control our actions. Overall, the model and behavioral results suggest that human subjects rely more strongly on prediction during theearly phasethaninthe steady state phase of pursuit. |
Richard S Bogartz; Adrian Staub Gaze step distributions reflect fixations and saccades: A comment on Stephen and Mirman (2010) Journal Article Cognition, 123 (2), pp. 325–334, 2012. @article{Bogartz2012, title = {Gaze step distributions reflect fixations and saccades: A comment on Stephen and Mirman (2010)}, author = {Richard S Bogartz and Adrian Staub}, doi = {10.1016/j.cognition.2011.12.014}, year = {2012}, date = {2012-01-01}, journal = {Cognition}, volume = {123}, number = {2}, pages = {325--334}, publisher = {Elsevier B.V.}, abstract = {In three experimental tasks Stephen and Mirman (2010) measured gaze steps, the distance in pixels between gaze positions on successive samples from an eyetracker. They argued that the distribution of gaze steps is best fit by the lognormal distribution, and based on this analysis they concluded that interactive cognitive processes underlie eye movement control in these tasks. The present comment argues that the gaze step distribution is predictable based on the fact that the eyes alternate between a fixation state in which gaze is steady and a saccade state in which gaze position changes rapidly. By fitting a simple mixture model to Stephen and Mirman's gaze step data we reveal a fixation distribution and a saccade distribution. This mixture model captures the shape of the gaze step distribution in detail, unlike the lognormal model, and provides a better quantitative fit to the data. We conclude that the gaze step distribution does not directly suggest processing interaction, and we emphasize some important limits on the utility of fitting theoretical distributions to data.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In three experimental tasks Stephen and Mirman (2010) measured gaze steps, the distance in pixels between gaze positions on successive samples from an eyetracker. They argued that the distribution of gaze steps is best fit by the lognormal distribution, and based on this analysis they concluded that interactive cognitive processes underlie eye movement control in these tasks. The present comment argues that the gaze step distribution is predictable based on the fact that the eyes alternate between a fixation state in which gaze is steady and a saccade state in which gaze position changes rapidly. By fitting a simple mixture model to Stephen and Mirman's gaze step data we reveal a fixation distribution and a saccade distribution. This mixture model captures the shape of the gaze step distribution in detail, unlike the lognormal model, and provides a better quantitative fit to the data. We conclude that the gaze step distribution does not directly suggest processing interaction, and we emphasize some important limits on the utility of fitting theoretical distributions to data. |
Mark S Bolding; Adrienne C Lahti; David White; Claire Moore; Demet GWIBBLEer; Timothy J Gawne; Paul D Gamlin Vergence eye movements in patients with schizophrenia Journal Article Vision Research, 102 , pp. 64–70, 2014. @article{Bolding2014, title = {Vergence eye movements in patients with schizophrenia}, author = {Mark S Bolding and Adrienne C Lahti and David White and Claire Moore and Demet GWIBBLEer and Timothy J Gawne and Paul D Gamlin}, doi = {10.1016/j.visres.2014.07.008}, year = {2014}, date = {2014-01-01}, journal = {Vision Research}, volume = {102}, pages = {64--70}, publisher = {Elsevier Ltd}, abstract = {Previous studies have shown that smooth pursuit eye movements are impaired in patients with schizophrenia. However, under normal viewing conditions, targets move not only in the frontoparallel plane but also in depth, and tracking them requires both smooth pursuit and vergence eye movements. Although previous studies in humans and non-human primates suggest that these two eye movement subsystems are relatively independent of one another, to our knowledge, there have been no prior studies of vergence tracking behavior in patients with schizophrenia. Therefore, we have investigated these eye movements in patients with schizophrenia and in healthy controls. We found that patients with schizophrenia exhibited substantially lower gains compared to healthy controls during vergence tracking at all tested speeds (e.g. 0.25. Hz vergence tracking mean gain of 0.59 vs. 0.86). Further, consistent with previous reports, patients with schizophrenia exhibited significantly lower gains than healthy controls during smooth pursuit at higher target speeds (e.g. 0.5. Hz smooth pursuit mean gain of 0.64 vs. 0.73). In addition, there was a modest (r≈0.5), but significant, correlation between smooth pursuit and vergence tracking performance in patients with schizophrenia. Our observations clearly demonstrate substantial vergence tracking deficits in patients with schizophrenia. In these patients, deficits for smooth pursuit and vergence tracking are partially correlated suggesting overlap in the central control of smooth pursuit and vergence eye movements. textcopyright 2014 Elsevier Ltd.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies have shown that smooth pursuit eye movements are impaired in patients with schizophrenia. However, under normal viewing conditions, targets move not only in the frontoparallel plane but also in depth, and tracking them requires both smooth pursuit and vergence eye movements. Although previous studies in humans and non-human primates suggest that these two eye movement subsystems are relatively independent of one another, to our knowledge, there have been no prior studies of vergence tracking behavior in patients with schizophrenia. Therefore, we have investigated these eye movements in patients with schizophrenia and in healthy controls. We found that patients with schizophrenia exhibited substantially lower gains compared to healthy controls during vergence tracking at all tested speeds (e.g. 0.25. Hz vergence tracking mean gain of 0.59 vs. 0.86). Further, consistent with previous reports, patients with schizophrenia exhibited significantly lower gains than healthy controls during smooth pursuit at higher target speeds (e.g. 0.5. Hz smooth pursuit mean gain of 0.64 vs. 0.73). In addition, there was a modest (r≈0.5), but significant, correlation between smooth pursuit and vergence tracking performance in patients with schizophrenia. Our observations clearly demonstrate substantial vergence tracking deficits in patients with schizophrenia. In these patients, deficits for smooth pursuit and vergence tracking are partially correlated suggesting overlap in the central control of smooth pursuit and vergence eye movements. textcopyright 2014 Elsevier Ltd. |
Sabrina Boll; Marie Bartholomaeus; Ulrike Peter; Ulrike Lupke; Matthias Gamer Attentional mechanisms of social perception are biased in social phobia Journal Article Journal of Anxiety Disorders, 40 , pp. 83–93, 2016. @article{Boll2016a, title = {Attentional mechanisms of social perception are biased in social phobia}, author = {Sabrina Boll and Marie Bartholomaeus and Ulrike Peter and Ulrike Lupke and Matthias Gamer}, doi = {10.1016/j.janxdis.2016.04.004}, year = {2016}, date = {2016-01-01}, journal = {Journal of Anxiety Disorders}, volume = {40}, pages = {83--93}, publisher = {Elsevier Ltd}, abstract = {Previous studies of social phobia have reported an increased vigilance to social threat cues but also an avoidance of socially relevant stimuli such as eye gaze. The primary aim of this study was to examine attentional mechanisms relevant for perceiving social cues by means of abnormalities in scanning of facial features in patients with social phobia. In two novel experimental paradigms, patients with social phobia and healthy controls matched on age, gender and education were compared regarding their gazing behavior towards facial cues. The first experiment was an emotion classification paradigm which allowed for differentiating reflexive attentional shifts from sustained attention towards diagnostically relevant facial features. In the second experiment, attentional orienting by gaze direction was assessed in a gaze-cueing paradigm in which non-predictive gaze cues shifted attention towards or away from subsequently presented targets. We found that patients as compared to controls reflexively oriented their attention more frequently towards the eyes of emotional faces in the emotion classification paradigm. This initial hypervigilance for the eye region was observed at very early attentional stages when faces were presented for 150 ms, and persisted when facial stimuli were shown for 3 s. Moreover, a delayed attentional orienting into the direction of eye gaze was observed in individuals with social phobia suggesting a differential time course of eye gaze processing in patients and controls. Our findings suggest that basic mechanisms of early attentional exploration of social cues are biased in social phobia and might contribute to the development and maintenance of the disorder.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies of social phobia have reported an increased vigilance to social threat cues but also an avoidance of socially relevant stimuli such as eye gaze. The primary aim of this study was to examine attentional mechanisms relevant for perceiving social cues by means of abnormalities in scanning of facial features in patients with social phobia. In two novel experimental paradigms, patients with social phobia and healthy controls matched on age, gender and education were compared regarding their gazing behavior towards facial cues. The first experiment was an emotion classification paradigm which allowed for differentiating reflexive attentional shifts from sustained attention towards diagnostically relevant facial features. In the second experiment, attentional orienting by gaze direction was assessed in a gaze-cueing paradigm in which non-predictive gaze cues shifted attention towards or away from subsequently presented targets. We found that patients as compared to controls reflexively oriented their attention more frequently towards the eyes of emotional faces in the emotion classification paradigm. This initial hypervigilance for the eye region was observed at very early attentional stages when faces were presented for 150 ms, and persisted when facial stimuli were shown for 3 s. Moreover, a delayed attentional orienting into the direction of eye gaze was observed in individuals with social phobia suggesting a differential time course of eye gaze processing in patients and controls. Our findings suggest that basic mechanisms of early attentional exploration of social cues are biased in social phobia and might contribute to the development and maintenance of the disorder. |
Sabrina Boll; Matthias Gamer Psychopathic traits affect the visual exploration of facial expressions Journal Article Biological Psychology, 117 , pp. 194–201, 2016. @article{Boll2016b, title = {Psychopathic traits affect the visual exploration of facial expressions}, author = {Sabrina Boll and Matthias Gamer}, doi = {http://dx.doi.org/10.1016/j.biopsycho.2016.03.010}, year = {2016}, date = {2016-01-01}, journal = {Biological Psychology}, volume = {117}, pages = {194--201}, publisher = {Elsevier B.V.}, abstract = {Deficits in emotional reactivity and recognition have been reported in psychopathy. Impaired attention to the eyes along with amygdala malfunctions may underlie these problems. Here, we investigated how different facets of psychopathy modulate the visual exploration of facial expressions by assessing personality traits in a sample of healthy young adults using an eye-tracking based face perception task. Fearless Dominance (the interpersonal-emotional facet of psychopathy) and Coldheartedness scores predicted reduced face exploration consistent with findings on lowered emotional reactivity in psychopathy. Moreover, participants high on the social deviance facet of psychopathy ('Self-Centered Impulsivity') showed a reduced bias to shift attention towards the eyes. Our data suggest that facets of psychopathy modulate face processing in healthy individuals and reveal possible attentional mechanisms which might be responsible for the severe impairments of social perception and behavior observed in psychopathy.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Deficits in emotional reactivity and recognition have been reported in psychopathy. Impaired attention to the eyes along with amygdala malfunctions may underlie these problems. Here, we investigated how different facets of psychopathy modulate the visual exploration of facial expressions by assessing personality traits in a sample of healthy young adults using an eye-tracking based face perception task. Fearless Dominance (the interpersonal-emotional facet of psychopathy) and Coldheartedness scores predicted reduced face exploration consistent with findings on lowered emotional reactivity in psychopathy. Moreover, participants high on the social deviance facet of psychopathy ('Self-Centered Impulsivity') showed a reduced bias to shift attention towards the eyes. Our data suggest that facets of psychopathy modulate face processing in healthy individuals and reveal possible attentional mechanisms which might be responsible for the severe impairments of social perception and behavior observed in psychopathy. |
Francesca Bonetti; Massimo Turatto Habituation of oculomotor capture by sudden onsets: Stimulus specificity, spontaneous recovery and dishabituation Journal Article Journal of Experimental Psychology: Human Perception and Performance, 45 (2), pp. 264–284, 2019. @article{Bonetti2019, title = {Habituation of oculomotor capture by sudden onsets: Stimulus specificity, spontaneous recovery and dishabituation}, author = {Francesca Bonetti and Massimo Turatto}, doi = {10.1037/xhp0000605}, year = {2019}, date = {2019-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {45}, number = {2}, pages = {264--284}, abstract = {Previous studies have confirmed that visual onsets are very powerful in attracting our gaze. The reflexive saccades triggered by sudden onsets have a high adaptive value because they ensure a rapid inspection of potentially appetitive or dangerous events. Here we showed, however, that such exogenously driven saccades are rapidly attenuated as the exposure to the same irrelevant onset progresses. Crucially, we found that such decrement in oculomotor capture conforms to several key features of habituation, an ancestral and widespread form of learning, consisting in a response reduction to a repeated irrelevant stimulation. In addition, we documented both spontaneous recovery and specificity of habituation, the phenomenon of dishabituation, and that habituation of capture was stimulation-frequency dependent. We also found both short-term and long-term habituation of oculomotor capture. Although we cannot exclude the contribution of top-down strategic inhibitory mechanisms to filter the onset distractors, the oculomotor capture reduction that we have documented finds a straightforward explanation in the neural and cognitive mechanisms underlying habituation of the orienting reflex, as originally suggested by Sokolov. Our study lends support to the idea that habituation plays a key filtering role in regulating the exogenous saccadic response triggered by peripheral onset distractors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies have confirmed that visual onsets are very powerful in attracting our gaze. The reflexive saccades triggered by sudden onsets have a high adaptive value because they ensure a rapid inspection of potentially appetitive or dangerous events. Here we showed, however, that such exogenously driven saccades are rapidly attenuated as the exposure to the same irrelevant onset progresses. Crucially, we found that such decrement in oculomotor capture conforms to several key features of habituation, an ancestral and widespread form of learning, consisting in a response reduction to a repeated irrelevant stimulation. In addition, we documented both spontaneous recovery and specificity of habituation, the phenomenon of dishabituation, and that habituation of capture was stimulation-frequency dependent. We also found both short-term and long-term habituation of oculomotor capture. Although we cannot exclude the contribution of top-down strategic inhibitory mechanisms to filter the onset distractors, the oculomotor capture reduction that we have documented finds a straightforward explanation in the neural and cognitive mechanisms underlying habituation of the orienting reflex, as originally suggested by Sokolov. Our study lends support to the idea that habituation plays a key filtering role in regulating the exogenous saccadic response triggered by peripheral onset distractors. |
Francesca Bonetti; Matteo Valsecchi; Massimo Turatto Cortex, 131 , pp. 251–264, 2020. @article{Bonetti2020, title = {Microsaccades inhibition triggered by a repetitive visual distractor is not subject to habituation: Implications for the programming of reflexive saccades}, author = {Francesca Bonetti and Matteo Valsecchi and Massimo Turatto}, doi = {10.1016/j.cortex.2020.07.013}, year = {2020}, date = {2020-01-01}, journal = {Cortex}, volume = {131}, pages = {251--264}, publisher = {Elsevier Ltd}, abstract = {The oculomotor capture triggered by a peripheral onset is subject to habituation, a basic form of learning consisting in a response decrement toward a repeatedly presented stimulus. However, it is unclear whether habituation of reflexive saccades takes place at the saccadic programming or execution stage (or both). To address this issue, we exploited the fact that during fixation the programming of a reflexive saccade exerts a robust but short-lasting phasic inhibition in the absolute microsaccadic frequency. Hence, if habituation of reflexive saccades occurs at the programming stage, then this should also affect the microsaccadic frequency, with a progressive reduction of the inhibitory phase. Conversely, if habituation occurs only at the later stage of saccade execution, the no change in the microsaccadic pattern is expected. Participants were repeatedly exposed to a peripheral onset distractor, and when eye movements were allowed, we replicated the oculomotor capture habituation. Crucially, however, when fixation was maintained the microsaccadic response did not change as exposure to the onset progressed, suggesting that habituation of reflexive saccades does not take place at the programming stage in the superior colliculus (SC), but at the later stage of saccade execution in the brainstem, where the competition between different saccades might be resolved. This scenario challenges one of the main assumptions of the competitive integration model for oculomotor control, which assumes that competition between exogenous and endogenous saccade programs occurs in the (SC). Our results and interpretation are instead in agreement with neurophysiological studies in non-human primates showing that saccadic adaption, another form of oculomotor plasticity, takes place downstream from the SC.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The oculomotor capture triggered by a peripheral onset is subject to habituation, a basic form of learning consisting in a response decrement toward a repeatedly presented stimulus. However, it is unclear whether habituation of reflexive saccades takes place at the saccadic programming or execution stage (or both). To address this issue, we exploited the fact that during fixation the programming of a reflexive saccade exerts a robust but short-lasting phasic inhibition in the absolute microsaccadic frequency. Hence, if habituation of reflexive saccades occurs at the programming stage, then this should also affect the microsaccadic frequency, with a progressive reduction of the inhibitory phase. Conversely, if habituation occurs only at the later stage of saccade execution, the no change in the microsaccadic pattern is expected. Participants were repeatedly exposed to a peripheral onset distractor, and when eye movements were allowed, we replicated the oculomotor capture habituation. Crucially, however, when fixation was maintained the microsaccadic response did not change as exposure to the onset progressed, suggesting that habituation of reflexive saccades does not take place at the programming stage in the superior colliculus (SC), but at the later stage of saccade execution in the brainstem, where the competition between different saccades might be resolved. This scenario challenges one of the main assumptions of the competitive integration model for oculomotor control, which assumes that competition between exogenous and endogenous saccade programs occurs in the (SC). Our results and interpretation are instead in agreement with neurophysiological studies in non-human primates showing that saccadic adaption, another form of oculomotor plasticity, takes place downstream from the SC. |
Claudia Bonmassar; Francesco Pavani; Wieske van Zoest The role of eye movements in manual responses to social and nonsocial cues Journal Article Attention, Perception, and Psychophysics, 81 (5), pp. 1236–1252, 2019. @article{Bonmassar2019, title = {The role of eye movements in manual responses to social and nonsocial cues}, author = {Claudia Bonmassar and Francesco Pavani and Wieske van Zoest}, doi = {10.3758/s13414-019-01669-9}, year = {2019}, date = {2019-01-01}, journal = {Attention, Perception, and Psychophysics}, volume = {81}, number = {5}, pages = {1236--1252}, publisher = {Attention, Perception, & Psychophysics}, abstract = {Gaze and arrow cues cause covert attention shifts even when they are uninformative. Nonetheless, it is unclear to what extent oculomotor behavior influences manual responses to social and nonsocial stimuli. In two experiments, we tracked the gaze of participants during the cueing task with nonpredictive gaze and arrow cues. In Experiment 1, the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements observers were overall slower to respond to the arrow cue compared with the gaze cue. Cue direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, we found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by the type of cue, both before and after the target onset, saccade landing positions were not. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In the presence of overt selection, saccade latency related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to different cues.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Gaze and arrow cues cause covert attention shifts even when they are uninformative. Nonetheless, it is unclear to what extent oculomotor behavior influences manual responses to social and nonsocial stimuli. In two experiments, we tracked the gaze of participants during the cueing task with nonpredictive gaze and arrow cues. In Experiment 1, the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements observers were overall slower to respond to the arrow cue compared with the gaze cue. Cue direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, we found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by the type of cue, both before and after the target onset, saccade landing positions were not. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In the presence of overt selection, saccade latency related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to different cues. |
Yoram S Bonneh; Tobias H Donner; Dov Sagi; Moshe Fried; Alexander Cooperman; Amos Arieli Motion-induced blindness and microsaccades: Cause and effect Journal Article Journal of Vision, 10 (14), pp. 1–15, 2010. @article{Bonneh2010, title = {Motion-induced blindness and microsaccades: Cause and effect}, author = {Yoram S Bonneh and Tobias H Donner and Dov Sagi and Moshe Fried and Alexander Cooperman and Amos Arieli}, doi = {10.1167/10.14.22.Introduction}, year = {2010}, date = {2010-01-01}, journal = {Journal of Vision}, volume = {10}, number = {14}, pages = {1--15}, abstract = {It has been suggested that subjective disappearance of visual stimuli results from a spontaneous reduction of microsaccade rate causing image stabilization, enhanced adaptation, and a consequent fading. In motion-induced blindness (MIB), salient visual targets disappear intermittently when surrounded by a moving pattern. We investigated whether changes in microsaccade rate can account for MIB. We first determined that the moving mask does not affect microsaccade metrics (rate, magnitude, and temporal distribution). We then compared the dynamics of microsaccades during reported illusory disappearance (MIB) and physical disappearance (Replay) of a salient peripheral target. We found large modulations of microsaccade rate following perceptual transitions, whether illusory (MIB) or real (Replay). For MIB, the rate also decreased prior to disappearance and increased prior to reappearance. Importantly, MIB persisted in the presence of microsaccades although sustained microsaccade rate was lower during invisible than visible periods. These results suggest that the microsaccade system reacts to changes in visibility, but microsaccades also modulate MIB. The latter modulation is well described by a Poisson model of the perceptual transitions assuming that the probability for reappearance and disappearance is modulated following a microsaccade. Our results show that microsaccades counteract disappearance but are neither necessary nor sufficient to account for MIB.}, keywords = {}, pubstate = {published}, tppubtype = {article} } It has been suggested that subjective disappearance of visual stimuli results from a spontaneous reduction of microsaccade rate causing image stabilization, enhanced adaptation, and a consequent fading. In motion-induced blindness (MIB), salient visual targets disappear intermittently when surrounded by a moving pattern. We investigated whether changes in microsaccade rate can account for MIB. We first determined that the moving mask does not affect microsaccade metrics (rate, magnitude, and temporal distribution). We then compared the dynamics of microsaccades during reported illusory disappearance (MIB) and physical disappearance (Replay) of a salient peripheral target. We found large modulations of microsaccade rate following perceptual transitions, whether illusory (MIB) or real (Replay). For MIB, the rate also decreased prior to disappearance and increased prior to reappearance. Importantly, MIB persisted in the presence of microsaccades although sustained microsaccade rate was lower during invisible than visible periods. These results suggest that the microsaccade system reacts to changes in visibility, but microsaccades also modulate MIB. The latter modulation is well described by a Poisson model of the perceptual transitions assuming that the probability for reappearance and disappearance is modulated following a microsaccade. Our results show that microsaccades counteract disappearance but are neither necessary nor sufficient to account for MIB. |
Yoram Bonneh; Yael Adini; Uri Polat Contrast sensitivity revealed by microsaccades Journal Article Journal of vision, 15 (9), pp. 1–12, 2015. @article{Bonneh2015, title = {Contrast sensitivity revealed by microsaccades}, author = {Yoram Bonneh and Yael Adini and Uri Polat}, doi = {10.1167/15.9.11}, year = {2015}, date = {2015-01-01}, journal = {Journal of vision}, volume = {15}, number = {9}, pages = {1--12}, abstract = {Microsaccades are small rapid and involuntary eye movements that occur during fixation in an apparently stochastic manner. They are known to be inhibited in response to sensory transients, with a time course that depends on the stimulus parameters and attention. However, the temporal precision of their onsets and the degree to which they can be used to assess the response of the visual system to basic stimulus parameters is currently unknown. Here we studied microsaccade response properties as a function of the contrast and spatial frequency of visual onsets. Observers (n¼ 18) viewed and silently counted 2-min sequences of Gabor patches presented briefly (100 ms) at 1 Hz. Contrast and spatial frequency were randomized in different experiments. We found that the microsaccade response time, as measured by the latency of the first microsaccade relative to stimulus onset following its release from inhibition, was sensitive to the contrast and spatial frequency of the stimulus and could be used to extract a contrast response function without the observers' response. We also found that contrast detection thresholds, measured behaviorally for different spatial frequencies, were highly and positively correlated (R = 0.87) with the microsaccade response time measured at high contrast (.4 times the threshold). These results show that different measures of microsaccade inhibition, especially the microsaccade response time, can provide accurate and involuntary measures of low-level visual properties such as contrast response and sensitivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microsaccades are small rapid and involuntary eye movements that occur during fixation in an apparently stochastic manner. They are known to be inhibited in response to sensory transients, with a time course that depends on the stimulus parameters and attention. However, the temporal precision of their onsets and the degree to which they can be used to assess the response of the visual system to basic stimulus parameters is currently unknown. Here we studied microsaccade response properties as a function of the contrast and spatial frequency of visual onsets. Observers (n¼ 18) viewed and silently counted 2-min sequences of Gabor patches presented briefly (100 ms) at 1 Hz. Contrast and spatial frequency were randomized in different experiments. We found that the microsaccade response time, as measured by the latency of the first microsaccade relative to stimulus onset following its release from inhibition, was sensitive to the contrast and spatial frequency of the stimulus and could be used to extract a contrast response function without the observers' response. We also found that contrast detection thresholds, measured behaviorally for different spatial frequencies, were highly and positively correlated (R = 0.87) with the microsaccade response time measured at high contrast (.4 times the threshold). These results show that different measures of microsaccade inhibition, especially the microsaccade response time, can provide accurate and involuntary measures of low-level visual properties such as contrast response and sensitivity. |
Yoram S Bonneh; Yael Adini; Uri Polat Contrast sensitivity revealed by spontaneous eyeblinks: Evidence for a common mechanism of oculomotor inhibition Journal Article Journal of Vision, 16 (7), pp. 1–15, 2016. @article{Bonneh2016, title = {Contrast sensitivity revealed by spontaneous eyeblinks: Evidence for a common mechanism of oculomotor inhibition}, author = {Yoram S Bonneh and Yael Adini and Uri Polat}, doi = {10.1167/16.7.1}, year = {2016}, date = {2016-01-01}, journal = {Journal of Vision}, volume = {16}, number = {7}, pages = {1--15}, abstract = {Spontaneous eyeblinks are known to serve important physiological functions, and recent evidence shows that they are also linked to cognitive processes. It is yet unclear whether this link reflects a crude rate modulation or, alternatively, an automatic and precise process, tightly linked to the low-level properties of sensory stimuli. We have recently reported (Y. S. Bonneh, Adini, & Polat, 2015) that, for microsaccades, the onset and release from inhibition in response to transient stimuli depend systematically on the low-level stimulus parameters. Here we reanalyzed our previous data for both microsaccades and eyeblinks for observers with sufficient blinking (.10% of trials, 18 of 23 observers tested) who watched and silently counted sequences of Gabor patches at 1 Hz with varied contrast and spatial frequency. We found that spontaneous eyeblinks, although less frequent, were similar to microsaccades in their modulation pattern in response to transient stimuli, demonstrating inhibition and rebound, which were dependent on the contrast and spatial frequency of the stimuli. The average blink response time, measured as the latency of the first blink following its release from inhibition, was longer for lower contrast and higher spatial frequency. Importantly, it was highly correlated with a similar measure for microsaccades as well as with psychophysical measures of contrast sensitivity. These results suggest that both eyeblinks and microsaccades are linked to the same inhibitory mechanism that presumably turns off oculomotor events while processing previous events and generates a rebound effect upon its release. The onset of both eyeblinks and microsaccades may thus reflect the time course of this mechanism and the associated cognitive process.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spontaneous eyeblinks are known to serve important physiological functions, and recent evidence shows that they are also linked to cognitive processes. It is yet unclear whether this link reflects a crude rate modulation or, alternatively, an automatic and precise process, tightly linked to the low-level properties of sensory stimuli. We have recently reported (Y. S. Bonneh, Adini, & Polat, 2015) that, for microsaccades, the onset and release from inhibition in response to transient stimuli depend systematically on the low-level stimulus parameters. Here we reanalyzed our previous data for both microsaccades and eyeblinks for observers with sufficient blinking (.10% of trials, 18 of 23 observers tested) who watched and silently counted sequences of Gabor patches at 1 Hz with varied contrast and spatial frequency. We found that spontaneous eyeblinks, although less frequent, were similar to microsaccades in their modulation pattern in response to transient stimuli, demonstrating inhibition and rebound, which were dependent on the contrast and spatial frequency of the stimuli. The average blink response time, measured as the latency of the first blink following its release from inhibition, was longer for lower contrast and higher spatial frequency. Importantly, it was highly correlated with a similar measure for microsaccades as well as with psychophysical measures of contrast sensitivity. These results suggest that both eyeblinks and microsaccades are linked to the same inhibitory mechanism that presumably turns off oculomotor events while processing previous events and generates a rebound effect upon its release. The onset of both eyeblinks and microsaccades may thus reflect the time course of this mechanism and the associated cognitive process. |
François Bonnetblanc; Pierre Baraduc Saccadic adaptation without retinal postsaccadic error Journal Article NeuroReport, 18 (13), pp. 1399–1402, 2007. @article{Bonnetblanc2007, title = {Saccadic adaptation without retinal postsaccadic error}, author = {Fran{ç}ois Bonnetblanc and Pierre Baraduc}, doi = {10.1097/WNR.0b013e3282c48cc1}, year = {2007}, date = {2007-01-01}, journal = {NeuroReport}, volume = {18}, number = {13}, pages = {1399--1402}, abstract = {Primary saccades undershoot their target. Corrective saccades are then triggered by retinal postsaccadic information. We tested whether primary saccades still undershoot when no postsaccadic visual information is available. Participants saccaded to five targets (10-34 degrees) that were either constantly illuminated (ON) or extinguished at saccade onset (OFF(Onset)). In OFF(Onset), few corrective saccades were observed. The saccadic gain increased over trials for the furthest (34 degrees) target. Terminal eye position after glissades or microsaccades progressively converged to the values observed in ON (targets over 16 degrees). Target extinction during the saccade only did not elicit any change. The results show that (i) postsaccadic retinal signals stabilize the saccadic gain and (ii) adaptive changes that reduce terminal error can take place without visual information.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Primary saccades undershoot their target. Corrective saccades are then triggered by retinal postsaccadic information. We tested whether primary saccades still undershoot when no postsaccadic visual information is available. Participants saccaded to five targets (10-34 degrees) that were either constantly illuminated (ON) or extinguished at saccade onset (OFF(Onset)). In OFF(Onset), few corrective saccades were observed. The saccadic gain increased over trials for the furthest (34 degrees) target. Terminal eye position after glissades or microsaccades progressively converged to the values observed in ON (targets over 16 degrees). Target extinction during the saccade only did not elicit any change. The results show that (i) postsaccadic retinal signals stabilize the saccadic gain and (ii) adaptive changes that reduce terminal error can take place without visual information. |
Paul J Boon; Jan Theeuwes; Artem V Belopolsky Updating visual-spatial working memory during object movement Journal Article Vision Research, 94 , pp. 51–57, 2014. @article{Boon2014, title = {Updating visual-spatial working memory during object movement}, author = {Paul J Boon and Jan Theeuwes and Artem V Belopolsky}, doi = {10.1016/j.visres.2013.11.002}, year = {2014}, date = {2014-01-01}, journal = {Vision Research}, volume = {94}, pages = {51--57}, publisher = {Elsevier Ltd}, abstract = {Working memory enables temporary maintenance and manipulation of information for immediate access by cognitive processes. The present study investigates how spatial information stored in working memory is updated during object movement. Participants had to remember a particular location on an object which, after a retention interval, started to move. The question was whether the memorized location was updated with the movement of the object or whether after object movement it remained represented in retinotopic coordinates. We used saccade trajectories to examine how memorized locations were represented. The results showed that immediately after the object stopped moving, there was both a retinotopic and an object-centered representation. However, 200. ms later, the activity at the retinotopic location decayed, making the memory representation fully object-centered. Our results suggest that memorized locations are updated from retinotopic to object-centered coordinates during, or shortly after object movement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Working memory enables temporary maintenance and manipulation of information for immediate access by cognitive processes. The present study investigates how spatial information stored in working memory is updated during object movement. Participants had to remember a particular location on an object which, after a retention interval, started to move. The question was whether the memorized location was updated with the movement of the object or whether after object movement it remained represented in retinotopic coordinates. We used saccade trajectories to examine how memorized locations were represented. The results showed that immediately after the object stopped moving, there was both a retinotopic and an object-centered representation. However, 200. ms later, the activity at the retinotopic location decayed, making the memory representation fully object-centered. Our results suggest that memorized locations are updated from retinotopic to object-centered coordinates during, or shortly after object movement. |
Paul J Boon; Artem V Belopolsky; Jan Theeuwes The role of the oculomotor system in updating visual-spatial working memory across saccades Journal Article PLoS ONE, 11 (9), pp. e0161829, 2016. @article{Boon2016, title = {The role of the oculomotor system in updating visual-spatial working memory across saccades}, author = {Paul J Boon and Artem V Belopolsky and Jan Theeuwes}, doi = {10.1371/journal.pone.0161829}, year = {2016}, date = {2016-01-01}, journal = {PLoS ONE}, volume = {11}, number = {9}, pages = {e0161829}, abstract = {Visual-spatial workingmemory (VSWM) helps us to maintain and manipulate visual infor- mation in the absence of sensory input. It has been proposed thatVSWMis an emergent property of the oculomotor system. In the present study we investigated the role of the ocu- lomotor system in updating of spatial working memory representations across saccades. Participants had to maintain a location in memory while making a saccade to a different location. During the saccade the target was displaced, which went unnoticed by the partici- pants. After executing the saccade, participants had to indicate the memorized location. If memory updating fully relies on cancellation driven by extraretinal oculomotor signals, the displacement should have no effect on the perceived location of thememorized stimulus. However, if postsaccadic retinal information about the location of the saccade target is used, the perceived location will be shifted according to the target displacement. As it has been suggested thatmaintenance of accurate spatial representations across saccades is especially important for action control, we used different ways of reporting the location held in memory; amatch-to-sample task, a mouse click or by making another saccade. The results showed a small systematic target displacement bias in all response modalities. Parametric manipulation of the distance between the to-be-memorized stimulus and sac- cade target revealed that target displacement bias increased over time and changed its spa- tial profile from being initially centered on locations around the saccade target to becoming spatially global. Taken together results suggest that we neither rely exclusively on extraret- inal nor on retinal information in updating working memory representations across sac- cades. The relative contribution of retinal signals is not fixed but depends on both the time available to integrate these signals as well as the distance between the saccade target and the remembered location.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual-spatial workingmemory (VSWM) helps us to maintain and manipulate visual infor- mation in the absence of sensory input. It has been proposed thatVSWMis an emergent property of the oculomotor system. In the present study we investigated the role of the ocu- lomotor system in updating of spatial working memory representations across saccades. Participants had to maintain a location in memory while making a saccade to a different location. During the saccade the target was displaced, which went unnoticed by the partici- pants. After executing the saccade, participants had to indicate the memorized location. If memory updating fully relies on cancellation driven by extraretinal oculomotor signals, the displacement should have no effect on the perceived location of thememorized stimulus. However, if postsaccadic retinal information about the location of the saccade target is used, the perceived location will be shifted according to the target displacement. As it has been suggested thatmaintenance of accurate spatial representations across saccades is especially important for action control, we used different ways of reporting the location held in memory; amatch-to-sample task, a mouse click or by making another saccade. The results showed a small systematic target displacement bias in all response modalities. Parametric manipulation of the distance between the to-be-memorized stimulus and sac- cade target revealed that target displacement bias increased over time and changed its spa- tial profile from being initially centered on locations around the saccade target to becoming spatially global. Taken together results suggest that we neither rely exclusively on extraret- inal nor on retinal information in updating working memory representations across sac- cades. The relative contribution of retinal signals is not fixed but depends on both the time available to integrate these signals as well as the distance between the saccade target and the remembered location. |
Paul J Boon; Artem V Belopolsky Eye abduction reduces but does not eliminate competition in the oculomotor system Journal Article Journal of Vision, 17 (5), pp. 1–10, 2017. @article{Boon2017, title = {Eye abduction reduces but does not eliminate competition in the oculomotor system}, author = {Paul J Boon and Artem V Belopolsky}, doi = {10.1167/17.5.15.doi}, year = {2017}, date = {2017-01-01}, journal = {Journal of Vision}, volume = {17}, number = {5}, pages = {1--10}, abstract = {Although it is well established that there is a tight coupling between covert attention and the eye movement system there is an ongoing controversy whether this relationship is functional. Previous studies demonstrated that disrupting the ability to execute an eye movement interferes with the allocation of covert attention. One technique that prevents the execution of an eye movement involves the abduction of the eye in the orbit while presenting the stimuli outside of the effective oculomotor range (Craighero, Nascimben, & Fadiga, 2004). Although eye abduction is supposed to disrupt activation of the oculomotor program responsible for the shift of covert attention, this crucial assumption has never been tested experimentally. In the present study we used saccadic curvature to examine whether eye abduction eliminates the target-distractor competition in the oculomotor system. We experimentally reduced the ability to execute saccades by abducting the eye by 308 (monocular vision). This way the peripheral part of the temporal hemifield was located outside the oculomotor range. Participants made a vertical eye movement while on some trials a distractor was shown either inside or outside of the oculomotor range. The curvature away from distractors located outside the oculomotor range was reduced, but not completely eliminated. This confirms that eye abduction influences the activation of the oculomotor program, but points to the fact that other forms of motor planning, such as head movements are also represented in the oculomotor system. The results are in line with the idea that covert attention is an emerging property of movement planning, but is not restricted to saccade planning.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although it is well established that there is a tight coupling between covert attention and the eye movement system there is an ongoing controversy whether this relationship is functional. Previous studies demonstrated that disrupting the ability to execute an eye movement interferes with the allocation of covert attention. One technique that prevents the execution of an eye movement involves the abduction of the eye in the orbit while presenting the stimuli outside of the effective oculomotor range (Craighero, Nascimben, & Fadiga, 2004). Although eye abduction is supposed to disrupt activation of the oculomotor program responsible for the shift of covert attention, this crucial assumption has never been tested experimentally. In the present study we used saccadic curvature to examine whether eye abduction eliminates the target-distractor competition in the oculomotor system. We experimentally reduced the ability to execute saccades by abducting the eye by 308 (monocular vision). This way the peripheral part of the temporal hemifield was located outside the oculomotor range. Participants made a vertical eye movement while on some trials a distractor was shown either inside or outside of the oculomotor range. The curvature away from distractors located outside the oculomotor range was reduced, but not completely eliminated. This confirms that eye abduction influences the activation of the oculomotor program, but points to the fact that other forms of motor planning, such as head movements are also represented in the oculomotor system. The results are in line with the idea that covert attention is an emerging property of movement planning, but is not restricted to saccade planning. |
Paul J Boon; Silvia Zeni; Jan Theeuwes; Artem V Belopolsky Rapid updating of spatial working memory across saccades Journal Article Scientific Reports, 8 , pp. 1072, 2018. @article{Boon2018, title = {Rapid updating of spatial working memory across saccades}, author = {Paul J Boon and Silvia Zeni and Jan Theeuwes and Artem V Belopolsky}, doi = {10.1038/s41598-017-18779-9}, year = {2018}, date = {2018-01-01}, journal = {Scientific Reports}, volume = {8}, pages = {1072}, publisher = {Springer US}, abstract = {Each time we make an eye movement, positions of objects on the retina change. In order to keep track of relevant objects their positions have to be updated. The situation becomes even more complex if the object is no longer present in the world and has to be held in memory. In the present study, we used saccadic curvature to investigate the time-course of updating a memorized location across saccades. Previous studies have shown that a memorized location competes with a saccade target for selection on the oculomotor map, which leads to saccades curving away from it. In our study participants performed a sequence of two saccades while keeping a location in memory. The trajectory of the second saccade was used to measure when the memorized location was updated after the first saccade. The results showed that the memorized location was rapidly updated with the eyes curving away from its spatial coordinates within 130 ms after the first eye movement. The time-course of updating was comparable to the updating of an exogenously attended location, and depended on how well the location was memorized.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Each time we make an eye movement, positions of objects on the retina change. In order to keep track of relevant objects their positions have to be updated. The situation becomes even more complex if the object is no longer present in the world and has to be held in memory. In the present study, we used saccadic curvature to investigate the time-course of updating a memorized location across saccades. Previous studies have shown that a memorized location competes with a saccade target for selection on the oculomotor map, which leads to saccades curving away from it. In our study participants performed a sequence of two saccades while keeping a location in memory. The trajectory of the second saccade was used to measure when the memorized location was updated after the first saccade. The results showed that the memorized location was rapidly updated with the eyes curving away from its spatial coordinates within 130 ms after the first eye movement. The time-course of updating was comparable to the updating of an exogenously attended location, and depended on how well the location was memorized. |
Tobias Bormann; Sascha A Wolfer; Wibke Hachmann; Claudia Neubauer; Lars Konieczny Fast word reading in pure alexia: “Fast, yet serial” Journal Article Neurocase, 21 (2), pp. 251–267, 2015. @article{Bormann2015, title = {Fast word reading in pure alexia: “Fast, yet serial”}, author = {Tobias Bormann and Sascha A Wolfer and Wibke Hachmann and Claudia Neubauer and Lars Konieczny}, doi = {10.1080/13554794.2014.890732}, year = {2015}, date = {2015-01-01}, journal = {Neurocase}, volume = {21}, number = {2}, pages = {251--267}, publisher = {Psychology Press}, abstract = {Pure alexia is a severe impairment of word reading in which individuals process letters serially with a pronounced length effect. Yet, there is considerable variation in the performance of alexic readers with generally very slow, but also occasionally fast responses, an observation addressed rarely in previous reports. It has been suggested that "fast" responses in pure alexia reflect residual parallel letter processing or that they may even be subserved by an independent reading system. Four experiments assessed fast and slow reading in a participant (DN) with pure alexia. Two behavioral experiments investigated frequency, neighborhood, and length effects in forced fast reading. Two further experiments measured eye movements when DN was forced to read quickly, or could respond faster because words were easier to process. Taken together, there was little support for the proposal that "qualitatively different" mechanisms or reading strategies underlie both types of responses in DN. Instead, fast responses are argued to be generated by the same serial-reading strategy.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pure alexia is a severe impairment of word reading in which individuals process letters serially with a pronounced length effect. Yet, there is considerable variation in the performance of alexic readers with generally very slow, but also occasionally fast responses, an observation addressed rarely in previous reports. It has been suggested that "fast" responses in pure alexia reflect residual parallel letter processing or that they may even be subserved by an independent reading system. Four experiments assessed fast and slow reading in a participant (DN) with pure alexia. Two behavioral experiments investigated frequency, neighborhood, and length effects in forced fast reading. Two further experiments measured eye movements when DN was forced to read quickly, or could respond faster because words were easier to process. Taken together, there was little support for the proposal that "qualitatively different" mechanisms or reading strategies underlie both types of responses in DN. Instead, fast responses are argued to be generated by the same serial-reading strategy. |
Sabine Born; Ulrich Ansorge; Dirk Kerzel Predictability of spatial and non-spatial target properties improves perception in the pre-saccadic interval Journal Article Vision Research, 91 , pp. 93–101, 2013. @article{Born2013, title = {Predictability of spatial and non-spatial target properties improves perception in the pre-saccadic interval}, author = {Sabine Born and Ulrich Ansorge and Dirk Kerzel}, doi = {10.1016/j.visres.2013.08.003}, year = {2013}, date = {2013-01-01}, journal = {Vision Research}, volume = {91}, pages = {93--101}, publisher = {Elsevier Ltd}, abstract = {In a dual-task paradigm with a perceptual discrimination task and a concurrent saccade task, we examined participants' ability to make use of prior knowledge of a critical property of the perceptual target to improve discrimination. Previous research suggests that during a short time window before a saccade, covert attention is imperatively directed towards the saccade target location. Consequently, discrimination of perceptual targets at the saccade target location is better than at other locations. We asked whether the obligatory pre-saccadic attention shift prevents perceptual benefits arising for perceptual target stimuli with predictable as opposed to non-predictable properties. We compared conditions in which the color or location of the perceptual target was constant to conditions in which those properties varied randomly across trials. In addition to the expected improvements of perception at the saccade target location, we found perception to be better with constant than with random properties of the perceptual target. Thus, color or location information about an upcoming perceptual target facilitates perception even while spatial attention is shifted to the saccade target. The improvement occurred irrespective of the saccade target location, which suggests that the underlying mechanism is independent of the pre-saccadic attention shift, but alternative interpretations are discussed as well.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In a dual-task paradigm with a perceptual discrimination task and a concurrent saccade task, we examined participants' ability to make use of prior knowledge of a critical property of the perceptual target to improve discrimination. Previous research suggests that during a short time window before a saccade, covert attention is imperatively directed towards the saccade target location. Consequently, discrimination of perceptual targets at the saccade target location is better than at other locations. We asked whether the obligatory pre-saccadic attention shift prevents perceptual benefits arising for perceptual target stimuli with predictable as opposed to non-predictable properties. We compared conditions in which the color or location of the perceptual target was constant to conditions in which those properties varied randomly across trials. In addition to the expected improvements of perception at the saccade target location, we found perception to be better with constant than with random properties of the perceptual target. Thus, color or location information about an upcoming perceptual target facilitates perception even while spatial attention is shifted to the saccade target. The improvement occurred irrespective of the saccade target location, which suggests that the underlying mechanism is independent of the pre-saccadic attention shift, but alternative interpretations are discussed as well. |
Sabine Born; Isaline Mottet; Dirk Kerzel Presaccadic perceptual facilitation effects depend on saccade execution: Evidence from the stop-signal paradigm Journal Article Journal of Vision, 14 (3), pp. 1–10, 2014. @article{Born2014, title = {Presaccadic perceptual facilitation effects depend on saccade execution: Evidence from the stop-signal paradigm}, author = {Sabine Born and Isaline Mottet and Dirk Kerzel}, doi = {10.1167/14.3.7}, year = {2014}, date = {2014-01-01}, journal = {Journal of Vision}, volume = {14}, number = {3}, pages = {1--10}, abstract = {Prior to the onset of a saccadic eye movement, perception is facilitated at the saccade target location. This has been attributed to a shift of attention. To test whether presaccadic attention shifts are strictly dependent on saccade execution, we examined whether they are found when observers are required to cancel the eye movement. We combined a dual task with the stop-signal paradigm: Subjects made saccades as quickly as possible to a cued location while discriminating a stimulus either at the saccade target or at the opposite location. A stop signal was presented on a subset of trials, asking subjects to cancel the eye movement. The delay of the stop signal was adjusted to yield successful inhibition of the saccade in 50% of trials. Results show similar perceptual facilitation at the saccade target for saccades with or without a stop signal, suggesting that presaccadic attention shifts are obligatory for all saccades. However, there was facilitation only when saccades were actually performed, not when observers successfully inhibited them. Thus, preparing an eye movement without subsequently executing it does not result in an attention shift. The results speak to a difference between saccade preparation and saccade programming. In light of the strong dependence on saccade execution, we discuss the functional role and causes of presaccadic attention shifts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Prior to the onset of a saccadic eye movement, perception is facilitated at the saccade target location. This has been attributed to a shift of attention. To test whether presaccadic attention shifts are strictly dependent on saccade execution, we examined whether they are found when observers are required to cancel the eye movement. We combined a dual task with the stop-signal paradigm: Subjects made saccades as quickly as possible to a cued location while discriminating a stimulus either at the saccade target or at the opposite location. A stop signal was presented on a subset of trials, asking subjects to cancel the eye movement. The delay of the stop signal was adjusted to yield successful inhibition of the saccade in 50% of trials. Results show similar perceptual facilitation at the saccade target for saccades with or without a stop signal, suggesting that presaccadic attention shifts are obligatory for all saccades. However, there was facilitation only when saccades were actually performed, not when observers successfully inhibited them. Thus, preparing an eye movement without subsequently executing it does not result in an attention shift. The results speak to a difference between saccade preparation and saccade programming. In light of the strong dependence on saccade execution, we discuss the functional role and causes of presaccadic attention shifts. |
Sabine Born; Hannah M Krüger; Eckart Zimmermann; Patrick Cavanagh Compression of space for low visibility probes Journal Article Frontiers in Systems Neuroscience, 10 , pp. 1–13, 2016. @article{Born2016, title = {Compression of space for low visibility probes}, author = {Sabine Born and Hannah M Krüger and Eckart Zimmermann and Patrick Cavanagh}, doi = {10.3389/fnsys.2016.00021}, year = {2016}, date = {2016-01-01}, journal = {Frontiers in Systems Neuroscience}, volume = {10}, pages = {1--13}, abstract = {Stimuli briefly flashed just before a saccade are perceived closer to the saccade target, a phenomenon known as perisaccadic compression of space (Ross, Morrone, & Burr, 1997). More recently, we have demonstrated that brief probes are attracted towards a visual reference when followed by a mask, even in the absence of saccades (Zimmermann, Born, Fink, & Cavanagh, 2014). Here, we ask whether spatial compression depends on the transient disruptions of the visual input stream caused by either a mask or a saccade. Both of these degrade the probe visibility but we show that low probe visibility alone causes compression in the absence of any disruption. In a first experiment, we varied the regions of the screen covered by a transient mask, including areas where no stimulus was presented and a condition without masking. In all conditions, we adjusted probe contrast to make the probe equally hard to detect. Compression effects were found in all conditions. To obtain compression without a mask, the probe had to be presented at much lower contrasts than with masking. Comparing mislocalizations at different probe detection rates across masking, saccades and low contrast conditions without mask or saccade, Experiment 2 confirmed this observation and showed a strong influence of probe contrast on compression. Finally, in Experiment 3, we found that compression decreased as probe duration increased both for masks and saccades although here we did find some evidence that factors other than simply visibility as we measured it contribute to compression. Our experiments suggest that compression reflects how the visual system localizes weak targets in the context of highly visible stimuli.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Stimuli briefly flashed just before a saccade are perceived closer to the saccade target, a phenomenon known as perisaccadic compression of space (Ross, Morrone, & Burr, 1997). More recently, we have demonstrated that brief probes are attracted towards a visual reference when followed by a mask, even in the absence of saccades (Zimmermann, Born, Fink, & Cavanagh, 2014). Here, we ask whether spatial compression depends on the transient disruptions of the visual input stream caused by either a mask or a saccade. Both of these degrade the probe visibility but we show that low probe visibility alone causes compression in the absence of any disruption. In a first experiment, we varied the regions of the screen covered by a transient mask, including areas where no stimulus was presented and a condition without masking. In all conditions, we adjusted probe contrast to make the probe equally hard to detect. Compression effects were found in all conditions. To obtain compression without a mask, the probe had to be presented at much lower contrasts than with masking. Comparing mislocalizations at different probe detection rates across masking, saccades and low contrast conditions without mask or saccade, Experiment 2 confirmed this observation and showed a strong influence of probe contrast on compression. Finally, in Experiment 3, we found that compression decreased as probe duration increased both for masks and saccades although here we did find some evidence that factors other than simply visibility as we measured it contribute to compression. Our experiments suggest that compression reflects how the visual system localizes weak targets in the context of highly visible stimuli. |