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2023 |
Jenny A. Nij Bijvank; Sam N. Hof; Stefanos E. Prouskas; Menno M. Schoonheim; Bernard M. J. Uitdehaag; Laurentius J. Rijn; Axel Petzold A novel eye-movement impairment in multiple sclerosis indicating widespread cortical damage Journal Article In: Brain, vol. 146, no. 6, pp. 2476–2488, 2023. @article{NijBijvank2023, In multiple sclerosis, remyelination trials have yet to deliver success like that achieved for relapse rates with disease course modifying treatment trials. The challenge is to have a clinical, functional outcome measure. Currently, there are none that have been validated, other than visual evoked potentials in optic neuritis. Like vision, quick eye movements (saccades) are heavily dependent on myelination. We proposed that it is possible to extrapolate from demyelination of the medial longitudinal fasciculus in the brainstem to quantitative assessment of cortical networks governing saccadic eye movements in multiple sclerosis. We have developed and validated a double-step saccadic test, which consists of a pair of eye movements towards two stimuli presented in quick succession (the demonstrate eye movement networks with saccades protocol). In this single-centre, cross-sectional cohort study we interrogated the structural and functional relationships of double-step saccades in multiple sclerosis. Data were collected for double-step saccades, cognitive function (extended Rao's Brief Repeatable Battery), disability (Expanded Disability Status Scale) and visual functioning in daily life (National Eye Institute Visual Function Questionnaire). MRI was used to quantify grey matter atrophy and multiple sclerosis lesion load. Multivariable linear regression models were used for analysis of the relationships between double-step saccades and clinical and MRI metrics. We included 209 individuals with multiple sclerosis (mean age 54.3 ± 10.5 years, 58% female, 63% relapsing-remitting multiple sclerosis) and 60 healthy control subjects (mean age 52.1 ± 9.2 years, 53% female). The proportion of correct double-step saccades was significantly reduced in multiple sclerosis (mean 0.29 ± 0.22) compared to controls (0.45 ± 0.22, P < 0.001). Consistent with this, there was a significantly larger double-step dysmetric saccadic error in multiple sclerosis (mean vertical error −1.18 ± 1.20°) compared to controls (−0.54 ± 0.86°, P < 0.001). Impaired double-step saccadic metrics were consistently associated with more severe global and local grey matter atrophy (correct responses—cortical grey matter: β = 0.42, P < 0.001), lesion load (vertical error: β = −0.28, P < 0.001), progressive phenotypes, more severe physical and cognitive impairment (correct responses—information processing: β = 0.46, P < 0.001) and visual functioning. In conclusion, double-step saccades represent a robust metric that revealed a novel eye-movement impairment in individuals with multiple sclerosis. Double-step saccades outperformed other saccadic tasks in their statistical relationship with clinical, cognitive and visual functioning, as well as global and local grey matter atrophy. Double-step saccades should be evaluated longitudinally and tested as a potential novel outcome measure for remyelination trials in multiple sclerosis. |
Andrey R. Nikolaev; Benedikt V. Ehinger; Radha Nila Meghanathan; Cees Leeuwen Planning to revisit: Neural activity in refixation precursors Journal Article In: Journal of Vision, vol. 23, no. 7, pp. 1–19, 2023. @article{Nikolaev2023, Eye tracking studies suggest that refixations—fixations to locations previously visited—serve to recover information lost or missed during earlier exploration of a visual scene. These studies have largely ignored the role of precursor fixations—previous fixations on locations the eyes return to later.We consider the possibility that preparations to return later are already made during precursor fixations. This process would mark precursor fixations as a special category of fixations, that is, distinct in neural activity from other fixation categories such as refixations and fixations to locations visited only once. To capture the neural signals associated with fixation categories, we analyzed electroencephalograms (EEGs) and eye movements recorded simultaneously in a free-viewing contour search task. We developed a methodological pipeline involving regression-based deconvolution modeling, allowing our analyses to account for overlapping EEG responses owing to the saccade sequence and other oculomotor covariates. We found that precursor fixations were preceded by the largest saccades among the fixation categories. Independent of the effect of saccade length, EEG amplitude was enhanced in precursor fixations compared with the other fixation categories 200 to 400 ms after fixation onsets, most noticeably over the occipital areas.We concluded that precursor fixations play a pivotal role in visual perception, marking the continuous occurrence of transitions between exploratory and exploitative modes of eye movement in natural viewing behavior. |
Sven Ohl; Lisa M. Kroell; Martin Rolfs In: Journal of Experimental Psychology: General, pp. 1–20, 2023. @article{Ohl2023, Visual working memory and actions are closely intertwined. Memory can guide our actions, but actions also impact what we remember. Even during memory maintenance, actions such as saccadic eye movements select content in visual working memory, resulting in better memory at locations that are congruent with the action goal as compared to incongruent locations. Here, we further substantiate the claim that saccadic eye movements are fundamentally linked to visual working memory by analyzing a large data set (.100k trials) of nine experiments (eight of them previously published). Using Bayesian hierarchical models, we demonstrate robust saccadic selection across the full range of probed saccade directions, manifesting as better memory performance at the saccade goal irrespective of its location in the visual field. By inspecting individual differences in saccadic selection, we show that saccadic selection was highly prevalent in the population. Moreover, both saccade metrics and visual working memory performance varied considerably across the visual field. Crucially, however, both idiosyncratic and systematic visual field anisotropies were not correlated between visual working memory and the oculomotor system, suggesting that they resulted from different sources (e.g., rely on separate spatial maps). In stark contrast, trial-by-trial variations in saccade metrics were strongly associated with memory performance: At any given location, shorter saccade latencies and more accurate saccades were associated with better memory performance, undergirding a robust link between action selection and visual memory. |
Kosuke Okazaki; Kenichiro Miura; Junya Matsumoto; Naomi Hasegawa; Michiko Fujimoto; Hidenaga Yamamori; Yuka Yasuda; Manabu Makinodan; Ryota Hashimoto Discrimination in the clinical diagnosis between patients with schizophrenia and healthy controls using eye movement and cognitive functions Journal Article In: Psychiatry and Clinical Neurosciences, vol. 77, no. 7, pp. 393–400, 2023. @article{Okazaki2023, Aim: Eye movements and cognitive functions are significantly impaired in patients with schizophrenia. The authors aimed to develop promising clinical diagnostic markers that fit practical digital health applications in psychiatry using eye movement and cognitive function data from 1254 healthy individuals and 336 patients with schizophrenia. Methods: Multivariate analyses using logistic regression were performed to confirm net performance of eye movements and cognitive functions scored using the Wechsler Adult Intelligence Scale, Third Edition, and Wechsler Memory Scale-Revised. The authors then examined the discrimination performance of pairs containing an eye movement and a cognitive function measure to search the pairs that would be effective in practical application for the discrimination according to the diagnostic criterion between the groups. Results: Multivariate analyses confirmed that eye movements and cognitive functions were effective modalities for discriminating between patients with schizophrenia and healthy controls. The discriminant analyses of the pairs demonstrated that seven eye movement measures and seven scores from cognitive function tests showed high discrimination performance when paired with one measure from the other modality. Moreover, seven pairs of digit-symbol coding or symbol-search and eye movement measures had high and robust discrimination performance. Conclusion: Seven pairs of an eye movement and a cognitive function measure were effective, robust, and less time-consuming in assisting with clinical diagnosis by categorizing healthy individuals or patients with schizophrenia. These findings may help develop an objective auxiliary diagnosis method working even on portable devices, which facilitates the consistency of diagnosis, earlier intervention, and shared decision-making. |
Henri Olkoniemi; Mikko Hurme; Henry Railo Neurologically healthy humans' ability to make saccades toward unseen targets Journal Article In: Neuroscience, vol. 513, pp. 111–125, 2023. @article{Olkoniemi2023a, Some patients with a visual field loss due to a lesion in the primary visual cortex (V1) can shift their gaze to stimuli presented in their blind visual field. The extent to which a similar “blindsight” capacity is present in neurologically healthy individuals remains unknown. Using retinotopically navigated transcranial magnetic stimulation (TMS) of V1 (Experiment 1) and metacontrast masking (Experiment 2) to suppress conscious vision, we examined neurologically healthy humans' ability to make saccadic eye movements toward visual targets that they reported not seeing. In the TMS experiment, the participants were more likely to initiate a saccade when a stimulus was presented, and they reported not seeing it, than in trials which no stimulus was presented. However, this happened only in a very small proportion (∼8%) of unseen trials, suggesting that saccadic reactions were largely based on conscious perception. In both experiments, saccade landing location was influenced by unconscious information: When the participants denied seeing the target but made a saccade, the saccade was made toward the correct location (TMS: 68%, metacontrast: 63%) more often than predicted by chance. Signal detection theoretic measures suggested that in the TMS experiment, saccades toward unseen targets may have been based on weak conscious experiences. In both experiments, reduced visibility of the target stimulus was associated with slower and less precise gaze shifts. These results suggest that saccades made by neurologically healthy humans may be influenced by unconscious information, although the initiation of saccades is largely based on conscious vision. |
John J. Orczyk; Annamaria Barczak; Monica N. O'Connell; Yoshinao Kajikawa Saccadic inhibition during free viewing in macaque monkeys Journal Article In: Journal of Neurophysiology, vol. 129, no. 2, pp. 356–367, 2023. @article{Orczyk2023, We investigated the time courses of saccade rate following visual stimuli during three conditions of free viewing in macaque monkeys. Under all conditions, saccade rate decreased transiently after the onset of visual stimuli. These results suggest that saccadic inhibition occurs during free viewing.Through the process of saccadic inhibition, visual events briefly suppress eye movements including microsaccades. In humans, saccadic inhibition has been shown to occur in response to the presentation of parafoveal or peripheral visual distractors during fixation and target-directed saccades and to physical changes of behaviorally relevant visual objects. In monkeys performing tasks that controlled eye movements, saccadic inhibition of microsaccades and target-directed saccades has been shown. Using eye data from three previously published studies, we investigated how saccade rate changed while monkeys were presented with visual stimuli under conditions with loose or no viewing demands. In two conditions, animals passively sat while an LED lamp flashed or screen-wide images appeared in front of them. In the third condition, images were repeated semiperiodically while animals had to maintain their gaze within a wide rectangular area and detect oddballs. Despite animals not being required to maintain fixation or make saccades to particular targets, the onset of visual events led to a temporary reduction of saccade rate across all conditions. Interestingly, saccadic inhibition was found at image offsets as well. These results show that saccadic inhibition occurs in monkeys during free viewing.NEW & NOTEWORTHY We investigated the time courses of saccade rate following visual stimuli during three conditions of free viewing in macaque monkeys. Under all conditions, saccade rate decreased transiently after the onset of visual stimuli. These results suggest that saccadic inhibition occurs during free viewing. |
Nicolas Orlando Dessaints; Laurent Goffart Tracking a moving visual target in the rhesus monkey: Influence of the occurrence frequency of the target path Journal Article In: Journal of Neurophysiology, vol. 130, no. 6, pp. 1425–1443, 2023. @article{OrlandoDessaints2023, Following previous studies documenting the ability to generate anticipatory responses, we tested whether the repeated motion of a visual target along the same path affected its oculomotor tracking. In six rhesus monkeys, we evaluated how the frequency of a target path influenced the onset, accuracy, and velocity of eye movements. Three hundred milliseconds after its extinction, a central target reappeared and immediately moved toward the periphery in four possible (oblique) directions and at a constant speed (20°/s or 40°/s). During each daily session, the frequency of one motion direction was either uncertain (25% of trials) or certain (100% of trials). Our results show no reduction of saccade latency between the two sessions. No express saccades were observed in either session. A slow eye movement started after target onset (presaccadic glissade) and its velocity was larger during the "certain" sessions only with the 40°/s target. No anticipatory eye movement was observed. Longer intersaccadic intervals were found during the "certain" sessions but the postsaccadic pursuit velocity exhibited no change. No correlation was found between the accuracy and precision of saccades (interceptive or catch-up) and the postsaccadic pursuit velocity. Repeatedly tracking a target that moves always along the same path does not favor the generation of anticipatory eye movements, saccadic or slow. Their occurrence is not spontaneous but seems to require preliminary training. Finally, for both sessions, the lack of correlation between the saccade-related and pursuit-related kinematic parameters is consistent with separate control of saccadic and slow eye movements.NEW & NOTEWORTHY Following previous studies documenting anticipatory movements, we investigated how the frequency of occurrence of a target path influenced the generation of tracking eye movements. When present, the effects were small. The limited performance that we found suggests that anticipatory responses require preliminary training, in which case, they should not be considered as a behavioral marker of the primates' ability to extrapolate but the outcome of learning and remembering past experience. |
Yongkai Li; Shuai Zhang; Gancheng Zhu; Zehao Huang; Rong Wang; Xiaoting Duan; Zhiguo Wang A CNN-based wearable system for driver drowsiness detection Journal Article In: Sensors, vol. 23, no. 7, 2023. @article{Li2023l, Drowsiness poses a serious challenge to road safety and various in-cabin sensing technologies have been experimented with to monitor driver alertness. Cameras offer a convenient means for contactless sensing, but they may violate user privacy and require complex algorithms to accommodate user (e.g., sunglasses) and environmental (e.g., lighting conditions) constraints. This paper presents a lightweight convolution neural network that measures eye closure based on eye images captured by a wearable glass prototype, which features a hot mirror-based design that allows the camera to be installed on the glass temples. The experimental results showed that the wearable glass prototype, with the neural network in its core, was highly effective in detecting eye blinks. The blink rate derived from the glass output was highly consistent with an industrial gold standard EyeLink eye-tracker. As eye blink characteristics are sensitive measures of driver drowsiness, the glass prototype and the lightweight neural network presented in this paper would provide a computationally efficient yet viable solution for real-world applications. |
Juan Linde-Domingo; Bernhard Spitzer Geometry of visuospatial working memory information in miniature gaze patterns Journal Article In: Nature Human Behaviour, pp. 1–16, 2023. @article{LindeDomingo2023, Stimulus-dependent eye movements have been recognized as a potential confound in decoding visual working memory information from neural signals. Here we combined eye-tracking with representational geometry analyses to uncover the information in miniature gaze patterns while participants (n = 41) were cued to maintain visual object orientations. Although participants were discouraged from breaking fixation by means of real-time feedback, small gaze shifts (<1°) robustly encoded the to-be-maintained stimulus orientation, with evidence for encoding two sequentially presented orientations at the same time. The orientation encoding on stimulus presentation was object-specific, but it changed to a more object-independent format during cued maintenance, particularly when attention had been temporarily withdrawn from the memorandum. Finally, categorical reporting biases increased after unattended storage, with indications of biased gaze geometries already emerging during the maintenance periods before behavioural reporting. These findings disclose a wealth of information in gaze patterns during visuospatial working memory and indicate systematic changes in representational format when memory contents have been unattended. |
Baiwei Liu; Anna C. Nobre; Freek Ede Microsaccades transiently lateralise EEG alpha activity Journal Article In: Progress in Neurobiology, vol. 224, pp. 1–9, 2023. @article{Liu2023, The lateralisation of 8–12 Hz alpha activity is a canonical signature of human spatial cognition that is typically studied under strict fixation requirements. Yet, even during attempted fixation, the brain produces small involuntary eye movements known as microsaccades. Here we report how spontaneous microsaccades – made in the absence of incentives to look elsewhere – can themselves drive transient lateralisation of EEG alpha power according to microsaccade direction. This transient lateralisation of posterior alpha power occurs similarly following start and return microsaccades and is, at least for start microsaccades, driven by increased alpha power ipsilateral to microsaccade direction. This reveals new links between spontaneous microsaccades and human electrophysiological brain activity. It highlights how microsaccades are an important factor to consider in studies relating alpha activity – including spontaneous fluctuations in alpha activity – to spatial cognition, such as studies on visual attention, anticipation, and working memory. |
Chi-Hung Liu; Chun-Wei Chang; June Hung; John J. H. Lin; Pi-Shan Sung; Li-Ang Lee; Cheng-Ting Hsiao; Yi-Ping Chao; Elaine Shinwei Huang; Shu-Ling Wang Brain computed tomography reading of stroke patients by resident doctors from different medical specialities: An eye-tracking study Journal Article In: Journal of Clinical Neuroscience, vol. 117, no. 88, pp. 173–180, 2023. @article{Liu2023a, Background: Using the eye-tracking technique, our work aimed to examine whether difference in clinical background may affect the training outcome of resident doctors' interpretation skills and reading behaviour related to brain computed tomography (CT). Methods: Twelve resident doctors in the neurology, radiology, and emergency departments were recruited. Each participant had to read CT images of the brain for two cases. We evaluated each participant's accuracy of lesion identification. We also used the eye-tracking technique to assess reading behaviour. We recorded dwell times, fixation counts, run counts, and first-run dwell times of target lesions to evaluate visual attention. Transition entropy was applied to assess the temporal relations and spatial dynamics of systematic image reading. Results: The eye-tracking results showed that the image reading sequence examined by transition entropy was comparable among resident doctors from different medical specialties (p = 0.82). However, the dwell time of the target lesions was shorter for the resident doctors from the neurology department (4828.63 ms |
Qing Liu; Xueyao Yang; Zekai Chen; Wenjuan Zhang Using synchronized eye movements to assess attentional engagement Journal Article In: Psychological Research, vol. 87, no. 7, pp. 2039–2047, 2023. @article{Liu2023d, The gradual emergence of online education in China in recent years requires new means of real-time monitoring and timely feedback to students. This research examines the effectiveness of synchronized eye movement assessment of attention engagement through two experiments. The first experiment used 24 university students in school as participants and made them watch the same video in high and low attentional engagement states (serial subtraction task) to compare the Inter-Subject Correlation (ISC) of participants' eye movements in different conditions. The results showed that the ISC of eye movements was significantly higher for participants in a high attentional engagement state than for participants in a low attentional engagement state. The second experiment had 26 university students in school as participants, as part of which they were made to watch video materials under the condition of having eye movement modeling examples. The results showed that the ISC of eye movements was significantly lower for participants in the group with eye movement modeling examples than those without eye movement modeling examples. However, overall test scores were significantly higher in the former than the latter. The first experiment showed that the eye movement trajectories of participants with high attentional engagement were more consistent than of those with low attentional engagement. Therefore, the ISC of participants' eye movements could be used as an objective indicator to assess and predict students' attentional conditions during online education. The second experiment showed that the eye movement modeling examples interfered with the participants' attention distribution to some extent; nevertheless, they positively affected the improvement in teaching effectiveness. Overall, the studies showed that the Inter-Subject Correlation is reliable to assess attentional engagement status in domestic online education. |
Yaohui Liu; Peida Zhan; Yanbin Fu; Qipeng Chen; Kaiwen Man; Yikun Luo In: Intelligence, vol. 100, pp. 1–14, 2023. @article{Liu2023h, Previous studies have found that participants use two cognitive strategies—constructive matching and response elimination—in responding to items in the Raven's Advanced Progressive Matrices (APM). This study proposed a multi-strategy psychometric model that builds on item responses and also incorporates eye-tracking measures, including but not limited to the proportional time on matrix area (PTM), the rate of toggling (ROT), and the rate of latency to first toggle (RLT). By jointly analyzing item responses and eye-tracking measures, this model can measure each participant's intelligence and identify the cognitive strategy used by each participant for each item in the APM. Several main findings were revealed from an eye-tracking-based APM study using the proposed model: (1) The effects of PTM and RLT on the constructive matching strategy selection probability were positive and higher for the former than the latter, while the effect of ROT was negligible. (2) The average intelligence of participants who used the constructive matching strategy was higher than that of participants who used the response elimination strategy, and participants with higher intelligence were more likely to use the constructive matching strategy. (3) High-intelligence participants increased their use of the constructive matching strategy as item difficulty increased, whereas low-intelligence participants decreased their use as item difficulty increased. (4) Participants took significantly less time using the constructive matching strategy than the response elimination strategy. Overall, the proposed model follows the theory-driven modeling logic and provides a new way of studying cognitive strategy in the APM by presenting quantitative results. |
Zoe Loh; Elizabeth H. Hall; Deborah Cronin; John M. Henderson Working memory control predicts fixation duration in scene-viewing Journal Article In: Psychological Research, vol. 87, no. 4, pp. 1143–1154, 2023. @article{Loh2023, When viewing scenes, observers differ in how long they linger at each fixation location and how far they move their eyes between fixations. What factors drive these differences in eye-movement behaviors? Previous work suggests individual differences in working memory capacity may influence fixation durations and saccade amplitudes. In the present study, participants (N = 98) performed two scene-viewing tasks, aesthetic judgment and memorization, while viewing 100 photographs of real-world scenes. Working memory capacity, working memory processing ability, and fluid intelligence were assessed with an operation span task, a memory updating task, and Raven's Advanced Progressive Matrices, respectively. Across participants, we found significant effects of task on both fixation durations and saccade amplitudes. At the level of each individual participant, we also found a significant relationship between memory updating task performance and participants' fixation duration distributions. However, we found no effect of fluid intelligence and no effect of working memory capacity on fixation duration or saccade amplitude distributions, inconsistent with previous findings. These results suggest that the ability to flexibly maintain and update working memory is strongly related to fixation duration behavior. |
Heather D. Lucas; Ana M. Daugherty; Edward Mcauley; Arthur F. Kramer; Neal J. Cohen Supplemental material for dynamic interactions between memory and viewing behaviors: Insights from dyadic modeling of eye movements Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 49, no. 6, pp. 786–801, 2023. @article{Lucas2023, Humans use eye movements to build visual memories. We investigated how the contributions of specific viewing behaviors to memory formation evolve over individual study epochs. We used dyadic modeling to explain performance on a spatial reconstruction task based on interactions among two gaze measures: (a) the entropy of the scanpath and (b) the frequency of item-to-item gaze transitions. To measure these interactions, our hypothesized model included causal pathways by which early-trial viewing behaviors impacted subsequent memory via downstream effects on later viewing. We found that lower scanpath entropy throughout the trial predicted better memory performance. By contrast, the effect of item-to- item transition frequency changed from negative to positive as the trial progressed. The model also revealed multiple pathways by which early-trial viewing dynamically altered late-trial viewing, thereby impacting memory indirectly. Finally, individual differences in scores on an independent measure of memory ability were found to predict viewing effectiveness, and viewing behaviors partially mediated the relation between memory ability and reconstruction accuracy. In a second experiment, the model showed a good fit for an independent dataset. These results highlight the dynamic nature of memory formation and suggest that the order in which eye movements occur can critically determine their effectiveness. |
Yingyi Luo; Dixiao Tan; Ming Yan Morphological structure influences saccade generation in Chinese reading Journal Article In: Reading and Writing, vol. 36, no. 5, pp. 1–17, 2023. @article{Luo2023d, Recent studies have demonstrated that saccadic programming in reading is not only determined by low-level visual factors. High-level morphological effects on saccade have been shown in two morphologically rich languages. In the present study, we examined the underlying mechanism of such morphological influences by comparing the processes of reading three-character Chinese compound words that differ in their structures in terms of morphological decomposition. Consistent with earlier reports, our results showed an effect of morphological structure on saccade. The readers' first-fixation location shifted further away from the beginning of the word, when the last two characters were more morphologically bounded and thus formed a [1 + 2] structure, than when the first two characters were more bounded (i.e., a [2 + 1] structure). The results are not accountable by a processing difficulty hypothesis, which proposes that saccade amplitude is determined by morphological complexity; rather, they suggest that Chinese readers parafoveally decompose a word and spontaneously target its longer stem, thus reflecting parafoveal access to words' stems. |
Anqi Lyu; Larry Abel; Allen M. Y. Cheong Effect of habitual reading direction on saccadic eye movements: A pilot study Journal Article In: PLoS ONE, vol. 18, pp. 1–16, 2023. @article{Lyu2023, Cognitive processes can influence the characteristics of saccadic eye movements. Reading habits, including habitual reading direction, also affect cognitive and visuospatial processes, favouring attention to the side where reading begins. Few studies have investigated the effect of habitual reading direction on saccade directionality of low-cognitive-demand stimuli (such as dots). The current study examined horizontal prosaccade, antisaccade, and self-paced saccade in subjects with two primary habitual reading directions. We hypothesised that saccades responding to the stimuli in subject's habitual reading direction would show a longer prosaccade latency and lower antisaccade error rate (errors being a reflexive glance to a suddenappearing target, rather than a saccade away from it). Sixteen young Chinese participants with primary habitual reading direction from left to right and sixteen young Arabic and Persian participants with primary habitual reading direction from right to left were recruited. All subjects spoke/read English as their second language. Subjects needed to look towards a 5°/10° target in the prosaccade task or look towards the mirror image location of the target in the antisaccade task and look between two 10° targets in the self-paced saccade task. Only Arabic and Persian participants showed a shorter and directional prosaccade latency towards 5° stimuli against their habitual reading direction. No significant effect of reading direction on antisaccade latency towards the correct directions was found. Chinese readers were found to generate significantly shorter prosaccade latencies and higher antisaccade directional errors compared with Arabic and Persian readers for stimuli appearing at their habitual reading side. The present pilot study provides insights into the effect of reading habits on saccadic eye movements of low-cognitive-demand stimuli and offers a platform for future studies to investigate the relationship between reading habits and eye movement behaviours. |
Hailong Lyu; David St Clair; Renrong Wu; Philip J. Benson; Wenbin Guo; Guodong Wang; Yi Liu; Shaohua Hu; Jingping Zhao Eye movement abnormalities can distinguish first-episode schizophrenia, chronic schizophrenia, and prodromal patients from healthy controls Journal Article In: Schizophrenia Bulletin Open, vol. 4, no. 1, pp. 1–11, 2023. @article{Lyu2023a, Background: This study attempts to replicate in a Chinese population an earlier UK report that eye movement abnormalities can accurately distinguish schizophrenia (SCZ) cases from healthy controls (HCs). It also seeks to determine whether first-episode SCZ differ from chronic SCZ and whether these eye movement abnormalities are enriched in psychosis risk syndrome (PRS). Methods: The training set included 104 Chinese HC and 60 Chinese patients with SCZ, and the testing set included 20 SCZ patients and 20 HC from a UK cohort. An additional 16 individuals with PRS were also enrolled. Eye movements of all participants were recorded during free-viewing, smooth pursuit, and fixation stability tasks. Group differences in 55 performance measures were compared and a gradient-boosted decision tree model was built for predictive analyses. Results: Extensive eye-movement abnormalities were observed in patients with SCZ on almost all eye-movement tests. On almost all individual variables, first-episode patients showed no statistically significant differences compared with chronic patients. The classification model was able to discriminate patients from controls with an area under the curve of 0.87; the model also classified 88% of PRS individuals as SCZ-like. Conclusions: Our findings replicate and extend the UK results. The overall accuracy of the Chinese study is virtually identical to the UK findings. We conclude that eye-movement abnormalities appear early in the natural history of the disorder and can be considered as potential trait markers for SCZ diathesis. |
Wenbo Ma; Mingsha Zhang Multiple step saccades are generated by internal real-time saccadic error correction Journal Article In: Frontiers in Neuroscience, vol. 17, pp. 1–9, 2023. @article{Ma2023a, Objectives: Multiple step saccades (MSSs) are an atypical form of saccade that consists of a series of small-amplitude saccades. It has been argued that the mechanism for generating MSS is due to the automatic saccadic plan. This argument was based on the observation that trials with MSS had shorter saccadic latency than trials without MSS in the reactive saccades. However, the validity of this argument has never been verified by other saccadic tasks. Alternatively, we and other researchers have speculated that the function of MSS is the same as that of the corrective saccade (CS), i.e., to correct saccadic errors. Thus, we propose that the function of the MSS is also to rectify saccadic errors and generated by forward internal models. The objective of the present study is to examine whether the automatic theory is universally applicable for the generation of MSSs in various saccadic tasks and to seek other possible mechanisms, such as error correction by forward internal models. Methods: Fifty young healthy subjects (YHSs) and fifty elderly healthy subjects (EHSs) were recruited in the present study. The task paradigms were prosaccade (PS), anti-saccade (AS) and memory-guided saccade (MGS) tasks. Results: Saccadic latency in trials with MSS was shorter than without MSS in the PS task but similar in the AS and MGS tasks. The intersaccadic intervals (ISI) were similar among the three tasks in both YHSs and EHSs. Conclusion: Our results indicate that the automatic theory is not a universal mechanism. Instead, the forward internal model for saccadic error correction might be an important mechanism. |
Samuel Madariaga; Cecilia Babul; José Ignacio Egaña; Iván Rubio-Venegas; Gamze Güney; Miguel Concha-Miranda; Pedro E. Maldonado; Christ Devia In: MethodsX, vol. 10, pp. 1–10, 2023. @article{Madariaga2023, In this work we present SaFiDe, a deterministic method to detect eye movements (saccades and fixations) from eye-trace data. We developed this method for human and nonhuman primate data from video- and coil-recorded eye traces and further applied the algorithm to eye traces computed from electrooculograms. All the data analyzed were from free-exploration paradigms, where the main challenge was to detect periods of saccades and fixations that were uncued by the task. The method uses velocity and acceleration thresholds, calculated from the eye trace, to detect saccade and fixation periods. We show that our fully deterministic method detects saccades and fixations from eye traces during free visual exploration. The algorithm was implemented in MATLAB, and the code is publicly available on a GitHub repository. • The algorithm presented is entirely deterministic, simplifying the comparison between subjects and tasks. • Thus far, the algorithm presented can operate over video-based eye tracker data, human electrooculogram records, or monkey scleral eye coil data. |
Federica Magnabosco; Olaf Hauk An eye on semantics: A study on the influence of concreteness and predictability on early fixation durations Journal Article In: Language, Cognition and Neuroscience, pp. 1–15, 2023. @article{Magnabosco2023, We used eye-tracking during natural reading to study how semantic control and representation mechanisms interact for the successful comprehension of sentences, by manipulating sentence context and single-word meaning. Specifically, we examined whether a word's semantic characteristic (concreteness) affects first fixation and gaze durations (FFDs and GDs) and whether it interacts with the predictability of a word. We used a linear mixed effects model including several possible psycholinguistic covariates. We found a small but reliable main effect of concreteness and replicated a predictability effect on FFDs, but we found no interaction between the two. The results parallel previous findings of additive effects of predictability (context) and frequency (lexical level) in fixation times. Our findings suggest that the semantics of a word and the context created by the preceding words additively influence early stages of word processing in natural sentence reading. |
Oliver Maith; Javier Baladron; Wolfgang Einhäuser; Fred H. Hamker Exploration behavior after reversals is predicted by STN-GPe synaptic plasticity in a basal ganglia model Journal Article In: iScience, vol. 26, no. 5, pp. 1–23, 2023. @article{Maith2023, Humans can quickly adapt their behavior to changes in the environment. Classical reversal learning tasks mainly measure how well participants can disengage from a previously successful behavior but not how alternative responses are explored. Here, we propose a novel 5-choice reversal learning task with alternating position-reward contingencies to study exploration behavior after a reversal. We compare human exploratory saccade behavior with a prediction obtained from a neuro-computational model of the basal ganglia. A new synaptic plasticity rule for learning the connectivity between the subthalamic nucleus (STN) and external globus pallidus (GPe) results in exploration biases to previously rewarded positions. The model simulations and human data both show that during experimental experience exploration becomes limited to only those positions that have been rewarded in the past. Our study demonstrates how quite complex behavior may result from a simple sub-circuit within the basal ganglia pathways. |
Silvia Makowski; Annika Bätz; Paul Prasse; Lena A. Jäger; Tobias Scheffer Detection of alcohol inebriation from eye movements Journal Article In: Procedia Computer Science, vol. 225, pp. 2086–2095, 2023. @article{Makowski2023, Today, the most convenient way of estimating an individual's blood-alcohol concentration requires a breathalyzer device and intense Today, the most convenient way of estimating an individual's blood-alcohol concentration requires a breathalyzer device and intense detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual user cooperation, which severely limits the scope of potential applications. We develop and study a machine-learning model that features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— user cooperation, which severely limits the scope of potential applications. We develop and study a machine-learning model that detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. |
Jun Maruta; Lisa A. Spielman; Jamshid Ghajar Visuomotor synchronization: Military normative performance Journal Article In: Military Medicine, vol. 188, no. 3-4, pp. E484–E491, 2023. @article{Maruta2023, Introduction: Cognitive processes such as perception and reasoning are preceded and dependent on attention. Because of the close overlap between neural circuits of attention and eye movement, attention may be objectively quantified with recording of eye movements during an attention-dependent task. Our previous work demonstrated that performance scores on a circular visual tracking task that requires dynamic synchronization of the gaze with the target motion can be impacted by concussion, sleep deprivation, and attention deficit/hyperactivity disorder. The current study examined the characteristics of performance on a standardized predictive visual tracking task in a large sample from a U.S. Military population to provide military normative data. Materials and Methods: The sample consisted of 1,594 active duty military service members of either sex aged 18-29 years old who were stationed at Fort Hood Army Base. The protocol was reviewed and approved by the U.S. Army Medical Research and Materiel Command Institutional Review Board. Demographic, medical, and military history data were collected using questionnaires, and performance-based data were collected using a circular visual tracking test and Trail Making Test. Differences in visual tracking performance by demographic characteristics were examined with a multivariate analysis of variance, as well as a Kolmogorov-Smirnov test and a rank-sum test. Associations with other measures were examined with a rank-sum test or Spearman correlations. Results: Robust sex differences in visual tracking performance were found across the various statistical models, as well as age differences in several isolated comparisons. Accordingly, norms of performance scores, described in terms of percentile standings, were developed adjusting for age and sex. The effects of other measures on visual tracking performance were small or statistically non-significant. An examination of the score distributions of various metrics suggested that strategies preferred by men and women may optimize different aspects of visual tracking performance. Conclusion: This large-scale quantification of attention, using dynamic visuomotor synchronization performance, provides rigorously characterized age- and sex-based military population norms. This study establishes analytics for assessing normal and impaired attention and detecting changes within individuals over time. Practical applications for combat readiness and surveillance of attention impairment from sleep insufficiency, concussion, medication, or attention disorders will be enhanced with portable, easily accessible, fast, and reliable dynamic eye-tracking technologies. |
Jana Masselink; Alexis Cheviet; Caroline Froment-Tilikete; Denis Pélisson; Markus Lappe A triple distinction of cerebellar function for oculomotor learning and fatigue compensation Journal Article In: PLoS Computational Biology, vol. 19, no. 8, pp. 1–37, 2023. @article{Masselink2023, The cerebellum implements error-based motor learning via synaptic gain adaptation of an inverse model, i.e. the mapping of a spatial movement goal onto a motor command. Recently, we modeled the motor and perceptual changes during learning of saccadic eye movements, showing that learning is actually a threefold process. Besides motor recalibration of (1) the inverse model, learning also comprises perceptual recalibration of (2) the visuospatial target map and (3) of a forward dynamics model that estimates the saccade size from corollary discharge. Yet, the site of perceptual recalibration remains unclear. Here we dissociate cerebellar contributions to the three stages of learning by modeling the learning data of eight cerebellar patients and eight healthy controls. Results showed that cerebellar pathology restrains short-term recalibration of the inverse model while the forward dynamics model is well informed about the reduced saccade change. Adaptation of the visuospatial target map trended in learning direction only in control subjects, yet without reaching significance. Moreover, some patients showed a tendency for uncompensated oculomotor fatigue caused by insufficient upregulation of saccade duration. According to our model, this could induce long-term perceptual compensation, consistent with the overestimation of target eccentricity found in the patients' baseline data. We conclude that the cerebellum mediates short-term adaptation of the inverse model, especially by control of saccade duration, while the forward dynamics model was not affected by cerebellar pathology. |
Siobhan M. McAteer; Anthony McGregor; Daniel T. Smith Oculomotor rehearsal in visuospatial working memory Journal Article In: Attention, Perception, and Psychophysics, vol. 85, pp. 261–275, 2023. @article{McAteer2023, The neural and cognitive mechanisms of spatial working memory are tightly coupled with the systems that control eye movements, but the precise nature of this coupling is not well understood. It has been argued that the oculomotor system is selectively involved in rehearsal of spatial but not visual material in visuospatial working memory. However, few studies have directly compared the effect of saccadic interference on visual and spatial memory, and there is little consensus on how the underlying working memory representation is affected by saccadic interference. In this study we aimed to examine how working memory for visual and spatial features is affected by overt and covert attentional interference across two experiments. Participants were shown a memory array, then asked to either maintain fixation or to overtly or covertly shift attention in a detection task during the delay period. Using the continuous report task we directly examined the precision of visual and spatial working memory representations and fit psychophysical functions to investigate the sources of recall error associated with different types of interference. These data were interpreted in terms of embodied theories of attention and memory and provide new insights into the nature of the interactions between cognitive and motor systems. |
Natalia Melnik; Stefan Pollmann Efficient versus inefficient visual search as training for saccadic re-referencing to an extrafoveal location Journal Article In: Journal of Vision, vol. 23, no. 10, pp. 1–13, 2023. @article{Melnik2023, Central vision loss is one of the leading causes of visual impairment in the elderly and its frequency is increasing. Without formal training, patients adopt an unaffected region of the retina as a new fixation location, a preferred retinal locus (PRL). However, learning to use the PRL as a reference location for saccades, that is, saccadic re-referencing, is protracted and time-consuming. Recent studies showed that training with visual search tasks can expedite this process. However, visual search can be driven by salient external features - leading to efficient search, or by internal goals, usually leading to inefficient, attention-demanding search. We compared saccadic re-referencing training in the presence of a simulated central scotoma with either an efficient or an inefficient visual search task. Participants had to respond by fixating the target with an experimenter-defined retinal location in the lower visual field. We observed that comparable relative training gains were obtained in both tasks for a number of behavioral parameters, with higher training gains for the trained task, compared to the untrained task. The transfer to the untrained task was only observed for some parameters. Our findings thus confirm and extend previous research showing comparable efficiency for exogenously and endogenously driven visual search tasks for saccadic re-referencing training. Our results also show that transfer of training gains to related tasks may be limited and needs to be tested for saccadic re-referencing-training paradigms to assess its suitability as a training tool for patients. |
Helena Palmieri; Antonio Fernández; Marisa Carrasco Microsaccades and temporal attention at different locations of the visual field Journal Article In: Journal of Vision, vol. 23, no. 5, pp. 1–17, 2023. @article{Palmieri2023, Temporal attention, the prioritization of information at specific points in time, improves performance in behavioral tasks but cannot ameliorate the perceptual asymmetries that exist across the visual field. That is, even after attentional deployment, performance is better along the horizontal than vertical meridian and worse at the upper than lower vertical meridian. Here we asked whether and how microsaccades—tiny fixational eye-movements—could mirror or alternatively attempt to compensate for these performance asymmetries by assessing temporal profiles and direction of microsaccades as a function of visual field location. Observers were asked to report the orientation of one of two targets presented at different time points, in one of three blocked locations (fovea, right horizontal meridian, upper vertical meridian).We found the following: (1) Microsaccade occurrence did not affect either task performance or the magnitude of the temporal attention effect. (2) Temporal attention modulated the microsaccade temporal profiles, and this modulation varied with polar angle location. At all locations, microsaccade rates were significantly more suppressed in anticipation of the target when temporally cued than in the neutral condition. Moreover, microsaccade rates were more suppressed during target presentation in the fovea than in the right horizontal meridian. (3) Across locations and attention conditions, there was a pronounced bias toward the upper hemifield. Overall, these results reveal that temporal attention benefits performance similarly around the visual field, microsaccade suppression is more pronounced for attention than expectation (neutral trials) across locations, and the directional bias toward the upper hemifield could reflect an attempt to compensate for typical poor performance at the upper vertical meridian. |
Xiaoyu Guo; Yifan Wang; Yuecui Kan; Meilin Wu; Linden J. Ball; Haijun Duan The HPA and SAM axis mediate the impairment of creativity under stress Journal Article In: Psychophysiology, pp. 1–18, 2023. @article{Guo2023, With the ever-changing social environment, individual creativity is facing a severe challenge induced by stress. However, little is known regarding the underlying mechanisms by which acute stress affects creative cognitive processing. The current research explored the impacts of the neuroendocrine response on creativity under stress and its underlying cognitive flexibility mechanisms. The enzyme-linked immuno sorbent assay was employed to assess salivary cortisol, which acted as a marker of stress-induced activation of the hypothalamic–pituitary–adrenal (HPA) axis. Eye blink rate (EBR) and pupil diameter were measured as respective indicators of dopamine and noradrenaline released by the activation of the sympathetic–adrenal–medullary (SAM) axis. The Wisconsin card task (WCST) measured cognitive flexibility, while the alternative uses task (AUT) and the remote association task (RAT) measured separately divergent and convergent thinking in creativity. Results showed higher cortisol increments following acute stress induction in the stress group than control group. Ocular results showed that the stress manipulation significantly increased EBR and pupil diameter compared to controls, reflecting increased SAM activity. Further analysis revealed that stress-released cortisol impaired the originality component of the AUT, reducing cognitive flexibility as measured by perseverative errors on the WCST task. Serial mediation analyses showed that both EBR and pupil diameter were also associated with increased perseverative errors leading to poor originality on the AUT. These findings confirm that physiological arousal under stress can impair divergent thinking through the regulation of different neuroendocrine pathways, in which the deterioration of flexible switching plays an important mediating role. |
Nicole X. Han; Miguel P. Eckstein Head and body cues guide eye movements and facilitate target search in real-world videos Journal Article In: Journal of Vision, vol. 23, no. 6, pp. 1–24, 2023. @article{Han2023, Static gaze cues presented in central vision result in observer shifts of covert attention and eye movements, and benefits in perceptual performance in the detection of simple targets. Less is known about how dynamic gazer behaviors with head and body motion influence search eye movements and performance in perceptual tasks in real-world scenes. Participants searched for a target person (yes/no task, 50% presence), whereas watching videos of one to three gazers looking at a designated person (50% valid gaze cue, looking at the target). To assess the contributions of different body parts, we digitally erase parts of the gazers in the videos to create three different body parts/whole conditions for gazers: floating heads (only head movements), headless bodies (only lower body movements), and the baseline condition with intact head and body.We show that valid dynamic gaze cues guided participants' eye movements (up to 3 fixations) closer to the target, speeded the time to foveate the target, reduced fixations to the gazers, and improved target detection. The effect of gaze cues in guiding eye movements to the search target was the smallest when the gazer's head was removed from the videos. To assess the inherent information about gaze goal location for each body parts/whole condition, we collected perceptual judgments estimating gaze goals by a separate group of observers with unlimited time. Observers' perceptual judgments showed larger estimate errors when the gazer's head was removed. This suggests that the reduced eye movement guidance from lower body cueing is related to observers' difficulty extracting gaze information without the presence of the head. Together, the study extends previous work by evaluating the impact of dynamic gazer behaviors on search with videos of real-world cluttered scenes. |
Nicole Xiao Han; Miguel Patricio Eckstein Inferential eye movement control while following dynamic gaze Journal Article In: eLife, vol. 12, pp. 1–26, 2023. @article{Han2023a, Attending to other people's gaze is evolutionary important to make inferences about intentions and actions. Gaze influences covert attention and triggers eye movements. However, we know little about how the brain controls the fine-grain dynamics of eye movements during gaze following. Observers followed people's gaze shifts in videos during search and we related the observer eye movement dynamics to the time course of gazer head movements extracted by a deep neural network. We show that the observers' brains use information in the visual periphery to execute predictive saccades that anticipate the information in the gazer's head direction by 190–350ms. The brain simultaneously monitors moment-to-moment changes in the gazer's head velocity to dynamically alter eye movements and re-fixate the gazer (reverse saccades) when the head accelerates before the initiation of the first forward gaze-following saccade. Using saccade-contingent manipulations of the videos, we experimentally show that the reverse saccades are planned concurrently with the first forward gaze-following saccade and have a functional role in reducing subsequent errors fixating on the gaze goal. Together, our findings characterize the inferential and functional nature of social attention's fine-grain eye movement dynamics. |
Frauke Heins; Jana Masselink; Joshua Nikodemus Scherer; Markus Lappe Adaptive changes to saccade amplitude and target localization do not require pre-saccadic target visibility Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–14, 2023. @article{Heins2023, The accuracy of saccadic eye movements is maintained by saccadic adaptation, a learning mechanism that is proposed to rely on visual prediction error, i.e., a mismatch between the pre-saccadically predicted and post-saccadically experienced position of the saccade target. However, recent research indicates that saccadic adaptation might be driven by postdictive motor error, i.e., a retrospective estimation of the pre-saccadic target position based on the post-saccadic image. We investigated whether oculomotor behavior can be adapted based on post-saccadic target information alone. We measured eye movements and localization judgements as participants aimed saccades at an initially invisible target, which was always shown only after the saccade. Each such trial was followed by either a pre- or a post-saccadic localization trial. The target position was fixed for the first 100 trials of the experiment and, during the following 200 trials, successively shifted inward or outward. Saccade amplitude and the pre- and post-saccadic localization judgements adjusted to the changing target position. Our results suggest that post-saccadic information is sufficient to induce error-reducing adaptive changes in saccade amplitude and target localization, possibly reflecting continuous updating of the estimated pre-saccadic target location driven by postdictive motor error. |
Beatriz Herrera; Amirsaman Sajad; Steven P. Errington; Jeffrey D. Schall; Jorge J. Riera Cortical origin of theta error signals Journal Article In: Cerebral Cortex, vol. 33, no. 23, pp. 11300–11319, 2023. @article{Herrera2023, A multi-scale approach elucidated the origin of the error-related-negativity (ERN), with its associated theta-rhythm, and the post-error-positivity (Pe) in macaque supplementary eye field (SEF). Using biophysical modeling, synaptic inputs to a subpopulation of layer-3 (L3) and layer-5 (L5) pyramidal cells (PCs) were optimized to reproduce error-related spiking modulation and inter-spike intervals. The intrinsic dynamics of dendrites in L5 but not L3 error PCs generate theta rhythmicity with random phases. Saccades synchronized the phases of the theta-rhythm, which was magnified on errors. Contributions from error PCs to the laminar current source density (CSD) observed in SEF were negligible and could not explain the observed association between error-related spiking modulation in L3 PCs and scalp-EEG. CSD from recorded laminar field potentials in SEF was comprised of multipolar components, with monopoles indicating strong electro-diffusion, dendritic/axonal electrotonic current leakage outside SEF, or violations of the model assumptions. Our results also demonstrate the involvement of secondary cortical regions, in addition to SEF, particularly for the later Pe component. The dipolar component from the observed CSD paralleled the ERN dynamics, while the quadrupolar component paralleled the Pe. These results provide the most advanced explanation to date of the cellular mechanisms generating the ERN. |
Jeff Huang; Donald Brien; Brian C. Coe; Giulia Longoni; Donald J. Mabbott; Douglas P. Munoz; E. Ann Yeh Delayed oculomotor response associates with optic neuritis in youth with demyelinating disorders Journal Article In: Multiple Sclerosis and Related Disorders, vol. 79, pp. 1–9, 2023. @article{Huang2023a, Introduction: Impairment in visual and cognitive functions occur in youth with demyelinating disorders such as multiple sclerosis, neuromyelitis optica spectrum disorder, and myelin oligodendrocyte glycoprotein antibody-associated disease. Quantitative behavioral assessment using eye-tracking and pupillometry can provide functional metrics for important prognostic and clinically relevant information at the bedside. Methods: Children and adolescents diagnosed with demyelinating disorders and healthy, age-matched controls completed an interleaved pro- and anti-saccade task using video-based eye-tracking and underwent spectral-domain optical coherence tomography examination for evaluation of retinal nerve fiber layer and ganglion cell inner plexiform layer thickness. Low-contrast visual acuity and Symbol Digit Modalities Test were performed for visual and cognitive functional assessments. We assessed saccade and pupil parameters including saccade reaction time, direction error rate, pupil response latency, peak constriction time, and peak constriction and dilation velocities. Generalized Estimating Equations were used to examine the association of eye-tracking parameters with optic neuritis history, structural metrics, and visual and cognitive scores. Results: The study included 36 demyelinating disorders patients, aged 8–18 yrs. (75% F; median = 15.22 yrs. |
Zehao Huang; Shuai Zhang; Zhiguo Wang Distractor-evoked deviation in saccade direction suggests an asymmetric representation of the upper and lower visual fields on oculomotor maps Journal Article In: Attention, Perception, & Psychophysics, vol. 85, no. 4, pp. 1150–1158, 2023. @article{Huang2023g, The programming of rapid eye movements or “saccades” involves a large collection of neural substrates. The subcortical oculomotor center – the superior colliculus (SC) – contains a topographical motor map that encodes saccade vectors. Using a visual distractor task, the present study examined a classic model of the SC motor map, which assumes a symmetrical representation of the upper visual field (UVF) and lower visual field (LVF). Visual distractors are known to attract or repel the saccade trajectory, depending on their angular distance from the target. In the present study, the distractor (if presented) was placed at a location that mirrored the target in the opposite visual field (upper or lower). The symmetrical SC model predicts equivalent directional deviations for saccades into the UVF and LVF. The results, however, showed that the directional deviations evoked by visual distractors were much stronger for saccades directed to the LVF. We argue that this observation is consistent with the recent neurophysiological finding that the LVF is relatively under-represented, as compared to the UVF, in the SC and possibly in other oculomotor centers. We conclude the paper with a suggested revision to the SC model. |
Christoph Huber-Huber; David Melcher Saccade execution increases the preview effect with faces: An EEG and eye-tracking coregistration study Journal Article In: Attention, Perception, & Psychophysics, pp. 1–17, 2023. @article{HuberHuber2023, Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision. |
Shao-Chin Hung; Antoine Barbot; Marisa Carrasco Visual perceptual learning modulates microsaccade rate and directionality Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–13, 2023. @article{Hung2023, Microsaccades, incessant “fixational eye movements” (< 1°), are an important window into cognitive functions. Yet, its role in visual perceptual learning (VPL)–improvements in visual discrimination due to practice–remains practically unexplored. Here we investigated whether and how microsaccades change in VPL. Human observers performed a Landolt acuity task for 5 consecutive days and were assigned to the Neutral or Attention group. On each trial, two peripheral Landolt squares were presented briefly along a diagonal. Observers reported the gap side of the target stimulus. Training improved acuity and modified the microsaccade rate; with training, the rate decreased during the fixation period but increased during the response cue. Furthermore, microsaccade direction during the response cue was biased toward the target location, and training enhanced and sped up this bias. Finally, the microsaccade rate during a task-free fixation period correlated with observers' initial acuity threshold, indicating that the fewer the microsaccades during fixation the better the individual visual acuity. All these results, which were similar for both the Neutral and Attention groups and at both trained and untrained locations, suggest that microsaccades could serve as a physiological marker reflecting functional dynamics in human perceptual learning. |
Shao-Chin Hung; Marisa Carrasco Microsaccades as a long-term oculomotor correlate in visual perceptual learning Journal Article In: Psychonomic Bulletin & Review, vol. 30, no. 1, pp. 235–249, 2023. @article{Hung2023a, Human perceptual learning, experience-induced gains in sensory discrimination, typically yields long-term performance improvements. Recent research revealed long-lasting transfer at the untrained location enabled by feature-based attention (FBA), reminiscent of its global effect (Hung & Carrasco, Scientific Reports,11(1), 13914, (2021)). Visual Perceptual Learning (VPL) is typically studied while observers maintain fixation, but the role of fixational eye movements is unknown. Microsaccades – the largest of fixational eye movements – provide a continuous, online, physiological measure from the oculomotor system that reveals dynamic processing, which is unavailable from behavioral measures alone. We investigated whether and how microsaccades change after training in an orientation discrimination task. For human observers trained with or without FBA, microsaccade rates were significantly reduced during the response window in both trained and untrained locations and orientations. Critically, consistent with long-term training benefits, this microsaccade-rate reduction persisted over a year. Furthermore, microsaccades were biased toward the target location prior to stimulus onset and were more suppressed for incorrect than correct trials after observers' responses. These findings reveal that fixational eye movements and VPL are tightly coupled and that learning-induced microsaccade changes are long lasting. Thus, microsaccades reflect functional dynamics of the oculomotor system during information encoding, maintenance and readout, and may serve as a reliable long-term physiological correlate in VPL. |
Satomi Inomata-Terada; Hideki Fukuda; Shin-ichi Tokushige; Shun-ichi Matsuda; Masashi Hamada; Yoshikazu Ugawa; Shoji Tsuji; Yasuo Terao Abnormal saccade profiles in hereditary spinocerebellar degeneration reveal cerebellar contribution to visually guided saccades Journal Article In: Clinical Neurophysiology, vol. 154, pp. 70–84, 2023. @article{InomataTerada2023, Objective: To study how the pathophysiology underlying hereditary spinocerebellar degeneration (spinocerebellar ataxia; SCA) with pure cerebellar manifestation evolves with disease progression using saccade recordings. Methods: We recorded visually- (VGS) and memory-guided saccade (MGS) task performance in a homogeneous population of 20 genetically proven SCA patients (12 SCA6 and eight SCA31 patients) and 19 normal controls. Results: For VGS but not MGS, saccade latency and amplitude were increased and more variable than those in normal subjects, which correlated with cerebellar symptom severity assessed using the International Cooperative Ataxia Rating Scale (ICARS). Parameters with significant correlations with cerebellar symptoms showed an aggravation after disease stage progression (ICARS > 50). The saccade velocity profile exhibited shortened acceleration and prolonged deceleration, which also correlated with disease progression. The main sequence relationship between saccade amplitude and peak velocity as well as saccade inhibitory control were preserved. Conclusions: The cerebellum may be involved in initiating VGS, which was aggravated acutely during disease stage progression. Dysfunction associated with disease progression occurs mainly in the cerebellum and brainstem interaction but may also eventually involve cortical saccade processing. Significance: Saccade recording can reveal cerebellar pathophysiology underlying SCA with disease progression. |
Patrick Jendritza; Frederike J. Klein; Pascal Fries Multi-area recordings and optogenetics in the awake, behaving marmoset Journal Article In: Nature Communications, vol. 14, no. 1, pp. 1–16, 2023. @article{Jendritza2023, The common marmoset has emerged as a key model in neuroscience. Marmosets are small in size, show great potential for genetic modification and exhibit complex behaviors. Thus, it is necessary to develop technology that enables monitoring and manipulation of the underlying neural circuits. Here, we describe a novel approach to record and optogenetically manipulate neural activity in awake, behaving marmosets. Our design utilizes a light-weight, 3D printed titanium chamber that can house several high-density silicon probes for semi-chronic recordings, while enabling simultaneous optogenetic stimulation. We demonstrate the application of our method in male marmosets by recording multi- and single-unit data from areas V1 and V6 with 192 channels simultaneously, and show that optogenetic activation of excitatory neurons in area V6 can influence behavior in a detection task. This method may enable future studies to investigate the neural basis of perception and behavior in the marmoset. |
Woojae Jeong; Seolmin Kim; JeongJun Park; Joonyeol Lee In: Communications Biology, vol. 6, no. 1, pp. 1–13, 2023. @article{Jeong2023, Humans integrate multiple sources of information for action-taking, using the reliability of each source to allocate weight to the data. This reliability-weighted information integration is a crucial property of Bayesian inference. In this study, participants were asked to perform a smooth pursuit eye movement task in which we independently manipulated the reliability of pursuit target motion and the direction-of-motion cue. Through an analysis of pursuit initiation and multivariate electroencephalography activity, we found neural and behavioral evidence of Bayesian information integration: more attraction toward the cue direction was generated when the target motion was weak and unreliable. Furthermore, using mathematical modeling, we found that the neural signature of Bayesian information integration had extra-retinal origins, although most of the multivariate electroencephalography activity patterns during pursuit were best correlated with the retinal velocity errors accumulated over time. Our results demonstrated neural implementation of Bayesian inference in human oculomotor behavior. |
Huibin Jin; Shouyi Chen Biometric recognition based on recurrence plot and inceptionv3 model using eye movements Journal Article In: IEEE Journal of Biomedical and Health Informatics, vol. 27, no. 11, pp. 5554–5563, 2023. @article{Jin2023, The ability to use eye movement signals as a feature in biometric recognition is a novel characteristic of biometric recognition technology. However, present technologies have not fully exploited the correlation features between eye movement signals. To address this, we propose an eye movement biometric recognition model that is based on recurrence plot encoding and the InceptionV3 model. We first encode the original eye movement signal using the recurrence plot to obtain a 2-D image that is then used as input for the InceptionV3 model to perform biometric recognition. Our experimental results using the GazeBaseV2.0 eye movement dataset demonstrate that our proposed model achieved a high biometric recognition accuracy of 96.58% ± 0.66% using the recurrence plot transformation of the horizontal gaze position signals and the InceptionV3 model, surpassing the accuracy achieved by other models. The use of horizontal gaze position eye movement signals for biometric recognition outperforms the use of vertical gaze position signals when using our proposed methods. Furthermore, the biometric recognition that is achieved through recurrent plot encoding is superior to that achieved using Markov transition fields and Gramian angular field transformations. |
Oren Kadosh; Yoram S. Bonneh Fixation-related visual mismatch negativity Journal Article In: Journal of Vision, vol. 23, no. 3, pp. 1–12, 2023. @article{Kadosh2023, Vision under natural conditions could be studied by combining electroencephalogram (EEG) and eye tracking as well as using saccades as triggers for the onset of the fixation-related potentials (FRPs) and for the oculomotor inhibition (OMI) that follows every saccade. The result of this analysis is thought to be equivalent to the event-related response following a peripheral preview. Previous studies that measured responses to visual deviants in a sequence of flashed stimuli found an increased negativity in the occipital N1 component (visual mismatch negativity [vMMN]), and prolonged saccadic inhibition for unexpected events. The aim of the current study was to develop an oddball paradigm in constrained natural-viewing and determine whether a similar mismatched FRP and prolonged OMI for deviance could be found. To this end, we developed a visual oddball paradigm on a static display to generate expectancy and surprise across successive saccades. Observers (n = 26) inspected, one after the other, seven small patterns of E and an inverted E arranged on the screen along a horizontal path, with one frequent (standard) and one rare (deviant), looking for a superimposed tiny dot target in each 5-second trial. Our results show a significantly larger FRP-N1 negativity for the deviant, compared with the standard and prolonged OMI of the following saccade, as previously found for transient oddballs. Our results show, for the first time, prolonged OMI and stronger fixation-related N1 to a task-irrelevant visual mismatch (vMMN) in natural, but task-guided viewing. These two signals combined could serve as markers of prediction error in free viewing. |
Pawel Kasprowski; Katarzyna Harezlak Upsampling eye movement signal using Convolutional Neural Networks Journal Article In: Procedia Computer Science, vol. 225, pp. 2595–2603, 2023. @article{Kasprowski2023, It is common in eye movement acquisition that data comes from different devices and exhibits different sampling rates. One of the It is common in eye movement acquisition that data comes from different devices and exhibits different sampling rates. One of the solutions to this problem is to recalculate the signal into another sampling rate. When upsampling is performed on a sequence of samples, it approximates the sequence that would have been obtained by sampling the signal at a higher rate. Many methods may be solutions to this problem is to recalculate the signal into another sampling rate. When upsampling is performed on a sequence of solutions to this problem is to recalculate the signal into another sampling rate. When upsampling is performed on a sequence of samples, it approximates the sequence that would have been obtained by sampling the signal at a higher rate. Many methods may be samples, it approximates the sequence that would have been obtained by sampling the signal at a higher rate. Many methods may be used for eye movement signal upsampling. Recently, Convolutional Neural Networks proved to be very efficient in upsampling (or used for eye movement signal upsampling. Recently, Convolutional Neural Networks proved to be very efficient in upsampling (or used for eye movement signal upsampling. Recently, Convolutional Neural Networks proved to be very efficient in upsampling (or supersampling) digital images. This paper attempts to utilize Convolutional Neural Networks using two architectures with different types of layers on the signal sampled with 125 Hz to obtain an eight-time increase in the sampling rate and produce the signal with supersampling) digital images. This paper attempts to utilize Convolutional Neural Networks using two architectures with different supersampling) digital images. This paper attempts to utilize Convolutional Neural Networks using two architectures with different types of layers on the signal sampled with 125 Hz to obtain an eight-time increase in the sampling rate and produce the signal with a 1000 Hz sampling rate. The experiments on the GazeBase dataset proved that this solution is feasible, and the Convolutional types of layers on the signal sampled with 125 Hz to obtain an eight-time increase in the sampling rate and produce the signal with a 1000 Hz sampling rate. The experiments on the GazeBase dataset proved that this solution is feasible, and the Convolutional Neural Network can learn the characteristic of the eye movement signal. a 1000 Hz sampling rate. The experiments on the GazeBase dataset proved that this solution is feasible, and the Convolutional Neural Network can learn the characteristic of the eye movement signal. |
Leor N. Katz; Gongchen Yu; James P. Herman; Richard J. Krauzlis Correlated variability in primate superior colliculus depends on functional class Journal Article In: Communications Biology, vol. 6, no. 1, pp. 1–13, 2023. @article{Katz2023, Correlated variability in neuronal activity (spike count correlations, rSC) can constrain how information is read out from populations of neurons. Traditionally, rSC is reported as a single value summarizing a brain area. However, single values, like summary statistics, stand to obscure underlying features of the constituent elements. We predict that in brain areas containing distinct neuronal subpopulations, different subpopulations will exhibit distinct levels of rSC that are not captured by the population rSC. We tested this idea in macaque superior colliculus (SC), a structure containing several functional classes (i.e., subpopulations) of neurons. We found that during saccade tasks, different functional classes exhibited differing degrees of rSC. “Delay class” neurons displayed the highest rSC, especially during saccades that relied on working memory. Such dependence of rSC on functional class and cognitive demand underscores the importance of taking functional subpopulations into account when attempting to model or infer population coding principles. |
Devin H. Kehoe; Lukas Schießer; Hassaan Malik; Mazyar Fallah Motion distractors perturb saccade programming later in time than static distractors Journal Article In: Current Research in Neurobiology, vol. 4, pp. 1–17, 2023. @article{Kehoe2023, The mechanism that reweights oculomotor vectors based on visual features is unclear. However, the latency of oculomotor visual activations gives insight into their antecedent featural processing. We compared the oculomotor processing time course of grayscale, task-irrelevant static and motion distractors during target selection by continuously measuring a battery of human saccadic behavioral metrics as a function of time after distractor onset. The motion direction was towards or away from the target and the motion speed was fast or slow. We compared static and motion distractors and observed that both distractors elicited curved saccades and shifted endpoints at short latencies (∼25 ms). After 50 ms, saccade trajectory biasing elicited by motion distractors lagged static distractor trajectory biasing by 10 ms. There were no such latency differences between distractor motion directions or motion speeds. This pattern suggests that additional processing of motion stimuli occurred prior to the propagation of visual information into the oculomotor system. We examined the interaction of distractor processing time (DPT) with two additional factors: saccadic reaction time (SRT) and saccadic amplitude. Shorter SRTs were associated with shorter DPT latencies of biased saccade trajectories. Both SRT and saccadic amplitude were associated with the magnitude of saccade trajectory biases. |
Krista R. Kelly; Kartik Kumar; Reed M. Jost; Christina S. Cheng-Patel; Lori M. Dao; Becky Luu; David Stager; Eileen E. Birch Objective assessment of control compared with clinical triple office control score in children with intermittent exotropia Journal Article In: Journal of AAPOS, vol. 27, no. 5, pp. 291–293, 2023. @article{Kelly2023, Poor control of intermittent exotropia may be used as an indication for surgery. However, control fluctuates during the day and from day to day. The standardized triple office control score (mean of three scores on a 6-point ordinal scale) is representative of repeated assessments throughout the day, but lacks validation against an objective measure of eye movements. We report the agreement between the triple office control score measured by the referring eyecare professional and lab-measured vergence instability using an EyeLink video eye tracker. Near and distance triple office control scores were moderately correlated with vergence instability. Near, but not distance, triple office control score was moderately correlated with the percentage of time intermittent exotropia was manifest during EyeLink recording. Larger triple office control scores for intermittent exotropia provide a meaningful description of larger vergence instability, supporting its use in clinical decisions and as a measure in clinical trials.[Formula presented] |
Anastasia Kerr-German; A. Caglar Tas; Aaron T. Buss A multi-method approach to addressing the toddler data desert in attention research Journal Article In: Cognitive Development, vol. 65, pp. 1–14, 2023. @article{KerrGerman2023, Visual attention skills undergo robust development change during infancy and continue to co-develop with other cognitive processes in early childhood. Despite this, this is a general disconnect between measures of the earliest foundations of attention during infancy and later development of attention in relation to executive functioning during the toddler years. To examine associations between these different measures of attention, the current study administered an oculomotor task (infant orienting with attention, IOWA) and a manual response (Flanker) task with a group of toddlers. We collected simultaneous neural recordings (using functional near-infrared spectroscopy), eye-tracking, and behavioral responses in 2.5- and 3.5-year-olds to examine the neural and behavioral associations between these skills. Results revealed that oculomotor facilitation in the IOWA task was negatively associated with accuracy on neutral trials in the Flanker task. Second, conflict scores between the two tasks were positively associated. At the neural level, however, the tasks showed distinct patterns of activation. Left frontal cortex was engaged during the Flanker task whereas right frontal and parietal cortex was engaged during the IOWA task. Activation during the IOWA task differed based on how well children could control oculomotor behavior during the task. Children with high levels of stimulus reactivity activated parietal cortex more strongly, but children with more controlled oculomotor behavior activated frontal cortex more strongly. |
Cynthia D. King; Stephanie N. Lovich; David L. K. Murphy; Rachel Landrum; David Kaylie; Christopher A. Shera; Jennifer M. Groh Individual similarities and differences in eye-movement-related eardrum oscillations (EMREOs) Journal Article In: Hearing Research, vol. 440, pp. 1–16, 2023. @article{King2023, We recently discovered a unique type of otoacoustic emission (OAE) time-locked to the onset (and offset) of saccadic eye movements and occurring in the absence of external sound (Gruters et al., 2018). How and why these eye-movement-related eardrum oscillations (EMREOs) are generated is unknown, with a role in visual-auditory integration being the likeliest candidate. Clues to both the drivers of EMREOs and their purpose can be gleaned by examining responses in normal hearing human subjects. Do EMREOs occur in all individuals with normal hearing? If so, what components of the response occur most consistently? Understanding which attributes of EMREOs are similar across participants and which show more variability will provide the groundwork for future comparisons with individuals with hearing abnormalities affecting the ear's various motor components. Here we report that in subjects with normal hearing thresholds and normal middle ear function, all ears show (a) measurable EMREOs (mean: 58.7 dB SPL; range 45–67 dB SPL for large contralateral saccades), (b) a phase reversal for contra- versus ipsilaterally-directed saccades, (c) a large peak in the signal occurring soon after saccade onset, (d) an additional large peak time-locked to saccade offset and (e) evidence that saccade duration is encoded in the signal. We interpret the attributes of EMREOs that are most consistent across subjects as the ones that are most likely to play an essential role in their function. The individual differences likely reflect normal variation in individuals' auditory system anatomy and physiology, much like traditional measures of auditory function such as auditory-evoked OAEs, tympanometry and auditory-evoked potentials. Future work will compare subjects with different types of auditory dysfunction to population data from normal hearing subjects. Overall, these findings provide important context for the widespread observations of visual- and eye-movement related signals found in cortical and subcortical auditory areas of the brain. |
Nathalie Klein Selle; Kristina Suchotzki; Yoni Pertzov; Matthias Gamer Orienting versus inhibition: The theory behind the ocular-based Concealed Information Test Journal Article In: Psychophysiology, vol. 60, no. 3, pp. 1–13, 2023. @article{KleinSelle2023, When trying to conceal one's knowledge, various ocular changes occur. However, which cognitive mechanisms drive these changes? Do orienting or inhibition—two processes previously associated with autonomic changes—play a role? To answer this question, we used a Concealed Information Test (CIT) in which participants were either motivated to conceal (orienting + inhibition) or reveal (orienting only) their knowledge. While pupil size increased in both motivational conditions, the fixation and blink CIT effects were confined to the conceal condition. These results were mirrored in autonomic changes, with skin conductance increasing in both conditions while heart rate decreased solely under motivation to conceal. Thus, different cognitive mechanisms seem to drive ocular responses. Pupil size appears to be linked to the orienting of attention (akin to skin conductance changes), while fixations and blinks rather seem to reflect arousal inhibition (comparable to heart rate changes). This knowledge strengthens CIT theory and illuminates the relationship between ocular and autonomic activity. |
Živa Korda; Sonja Walcher; Christof Körner; Mathias Benedek Effects of internally directed cognition on smooth pursuit eye movements: A systematic examination of perceptual decoupling Journal Article In: Attention, Perception, & Psychophysics, vol. 85, no. 4, pp. 1159–1178, 2023. @article{Korda2023, Eye behavior differs between internally and externally directed cognition and thus is indicative of an internal versus external attention focus. Recent work implicated perceptual decoupling (i.e., eye behavior becoming less determined by the sensory environment) as one of the key mechanisms involved in these attention-related eye movement differences. However, it is not yet understood how perceptual decoupling depends on the characteristics of the internal task. Therefore, we systematically examined effects of varying internal task demands on smooth pursuit eye movements. Specifically, we evaluated effects of the internal workload (control vs. low vs. high) and of internal task (arithmetic vs. visuospatial). The results of multilevel modelling showed that effects of perceptual decoupling were stronger for higher workload, and more pronounced for the visuospatial modality. Effects also followed a characteristic time-course relative to internal operations. The findings provide further support of the perceptual decoupling mechanism by showing that it is sensitive to the degree of interference between external and internal information. |
Sofia Krasovskaya; Árni Kristjánsson; W. Joseph MacInnes Microsaccade rate activity during the preparation of pro- and antisaccades Journal Article In: Attention, Perception, & Psychophysics, vol. 85, no. 7, pp. 2257–2276, 2023. @article{Krasovskaya2023, Microsaccades belong to the category of fixational micromovements and may be crucial for image stability on the retina. Eye movement paradigms typically require fixational control, but this does not eliminate all oculomotor activity. The antisaccade task requires a planned eye movement in the direction opposite of an onset, allowing separation of planning and execution. We build on previous studies of microsaccades in the antisaccade task using a combination of fixed and mixed pro- and antisaccade blocks. We hypothesized that microsaccade rates may be reduced prior to the execution of antisaccades as compared with regular saccades (prosaccades). In two experiments, we measured microsaccades in four conditions across three trial blocks: one block each of fixed prosaccade and antisaccade trials, and a mixed block where both saccade types were randomized. We anticipated that microsaccade rates would be higher prior to antisaccades than prosaccades due to the need to preemptively suppress reflexive saccades during antisaccade generation. In Experiment 1, with monocular eye tracking, there was an interaction between the effects of saccade and block type on microsaccade rates, suggesting lower rates on antisaccade trials, but only within mixed blocks. In Experiment 2, eye tracking was binocular, revealing suppressed microsaccade rates on antisaccade trials. A cluster permutation analysis of the microsaccade rate over the course of a trial did not reveal any particular critical time for this difference in microsaccade rates. Our findings suggest that microsaccade rates reflect the degree of suppression of the oculomotor system during the antisaccade task. |
Eswar Kurni; Manish Reddy Yedulla; PremNandhini Satgunam Microsaccadic eye movement orientations are equivocal in the presence of competing stimuli Journal Article In: Asian Journal of Physics, vol. 32, no. 3&4, pp. 159–166, 2023. @article{Kurni2023, Will someone reflexively look towards a primed target or to a non-primed target, when no instructions are given? Knowing this could help design visual function tests without the need for instructions. Simply, a target could be presented for a “priming phase” followed by two targets one of which is the primed target and the other is not. We asked the question to which target will an obsever look. We studied this on normally-sighted adults. Eye movements were tracked using EyeLink1000 Plus eye tracker and microsaccades were analyzed. The targets presented were from LEA symbols that are commonly used in children's visual acuity chart. Target size (15', 20' or 25') and presentation duration (200, 400 or 600 ms) were randomized. No instructions were given to the participants beyond asking them to look at the computer monitor in experiment I, and instructions were given to specifically look towards the primed target in experiment II. Overall we found that no preference (proportion of microsaccades <50%) was observed either to the primed or to the novel target in either of the experiments. The presence of two competing stimuli abolishes the microsaccde orientation to a target of interest, even with explicit verbal instructions. |
Jens Kürten; Tim Raettig; Julian Gutzeit; Lynn Huestegge Preparing for simultaneous action and inaction: Temporal dynamics and target levels of inhibitory control Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 49, no. 7, pp. 1068–1082, 2023. @article{Kuerten2023, When a single action is required, along with the simultaneous inhibition of another action, this typically results in frequent false-positive executions of the latter (inhibition failures). The absence of inhibitory demands in dual-action trials can render performance less error-prone (and sometimes faster) than in single-action trials. In the present study, we investigated the temporal dynamics of inhibitory control difficulties by varying the preparation time (for simultaneous action execution and inhibition). In two experiments, participants responded to a single peripheral visual target either with an eye movement toward it (Single Saccade), with a spatially corresponding button press (Single Manual), or with both responses simultaneously (Dual Action) as indicated by a color cue. Preparation time was manipulated via the cue-stimulus interval within blocks (Experiment 1) and between blocks (Experiment 2). Overall, responses were faster with longer (vs. shorter) preparation time. Crucially, however, our results reveal the exact dynamics of how inhibition failures (and thus dual-action benefits) in both response modalities substantially decrease with longer preparation, even though the cue did not contain information regarding the fully specified response that needed to be inhibited (i.e., its direction). These results highlight the role of sufficient preparation time not only for efficient action execution but also for concurrent inhibitory performance. The study contradicts the idea that inhibition can only be exerted globally or on the level of a fully specified response. Instead, it may also be directed at effector system representations or all associated responses, suggesting a highly flexible targeting of inhibitory control in cognition. |
Jens Kürten; Tim Raettig; Julian Gutzeit; Lynn Huestegge In: Psychological Research, vol. 87, no. 2, pp. 410–424, 2023. @article{Kuerten2023a, Previous research has shown that the simultaneous execution of two actions (instead of only one) is not necessarily more difficult but can actually be easier (less error-prone), in particular when executing one action requires the simultaneous inhibition of another action. Corresponding inhibitory demands are particularly challenging when the to-be-inhibited action is highly prepotent (i.e., characterized by a strong urge to be executed). Here, we study a range of important potential sources of such prepotency. Building on a previously established paradigm to elicit dual-action benefits, participants responded to stimuli with single actions (either manual button press or saccade) or dual actions (button press and saccade). Crucially, we compared blocks in which these response demands were randomly intermixed (mixed blocks) with pure blocks involving only one type of response demand. The results highlight the impact of global (action-inherent) sources of action prepotency, as reflected in more pronounced inhibitory failures in saccade vs. manual control, but also more local (transient) sources of influence, as reflected in a greater probability of inhibition failures following trials that required the to-be-inhibited type of action. In addition, sequential analyses revealed that inhibitory control (including its failure) is exerted at the level of response modality representations, not at the level of fully specified response representations. In sum, the study highlights important preconditions and mechanisms underlying the observation of dual-action benefits. |
Jan W. Kurzawski; Maria Pombo; Augustin Burchell; Nina M. Hanning; Simon Liao; Najib J. Majaj; Denis G. Pelli EasyEyes — A new method for accurate fixation in online vision testing Journal Article In: Frontiers in Human Neuroscience, vol. 17, pp. 1–12, 2023. @article{Kurzawski2023a, Online methods allow testing of larger, more diverse populations, with much less effort than in-lab testing. However, many psychophysical measurements, including visual crowding, require accurate eye fixation, which is classically achieved by testing only experienced observers who have learned to fixate reliably, or by using a gaze tracker to restrict testing to moments when fixation is accurate. Alas, both approaches are impractical online as online observers tend to be inexperienced, and online gaze tracking, using the built-in webcam, has a low precision (±4 deg). EasyEyes open-source software reliably measures peripheral thresholds online with accurate fixation achieved in a novel way, without gaze tracking. It tells observers to use the cursor to track a moving crosshair. At a random time during successful tracking, a brief target is presented in the periphery. The observer responds by identifying the target. To evaluate EasyEyes fixation accuracy and thresholds, we tested 12 naive observers in three ways in a counterbalanced order: first, in the laboratory, using gaze-contingent stimulus presentation; second, in the laboratory, using EasyEyes while independently monitoring gaze using EyeLink 1000; third, online at home, using EasyEyes. We find that crowding thresholds are consistent and individual differences are conserved. The small root mean square (RMS) fixation error (0.6 deg) during target presentation eliminates the need for gaze tracking. Thus, this method enables fixation-dependent measurements online, for easy testing of larger and more diverse populations. |
Elke B. Lange; Lauren K. Fink Eye blinking, musical processing, and subjective states—A methods account Journal Article In: Psychophysiology, vol. 60, no. 10, pp. 1–20, 2023. @article{Lange2023, Affective sciences often make use of self-reports to assess subjective states. Seeking a more implicit measure for states and emotions, our study explored spontaneous eye blinking during music listening. However, blinking is understudied in the context of research on subjective states. Therefore, a second goal was to explore different ways of analyzing blink activity recorded from infra-red eye trackers, using two additional data sets from earlier studies differing in blinking and viewing instructions. We first replicate the effect of increased blink rates during music listening in comparison with silence and show that the effect is not related to changes in self-reported valence, arousal, or to specific musical features. Interestingly, but in contrast, felt absorption reduced participants' blinking. The instruction to inhibit blinking did not change results. From a methodological perspective, we make suggestions about how to define blinks from data loss periods recorded by eye trackers and report a data-driven outlier rejection procedure and its efficiency for subject-mean analyses, as well as trial-based analyses. We ran a variety of mixed effects models that differed in how trials without blinking were treated. The main results largely converged across accounts. The broad consistency of results across different experiments, outlier treatments, and statistical models demonstrates the reliability of the reported effects. As recordings of data loss periods come for free when interested in eye movements or pupillometry, we encourage researchers to pay attention to blink activity and contribute to the further understanding of the relation between blinking, subjective states, and cognitive processing. |
Jochen Laubrock; Alexander Krutz; Jonathan Nübel; Sebastian Spethmann Gaze patterns reflect and predict expertise in dynamic echocardiographic imaging Journal Article In: Journal of Medical Imaging, vol. 10, no. S1, pp. 1–20, 2023. @article{Laubrock2023, Purpose: Echocardiography is the most important modality in cardiac imaging. Rapid valid visual assessment is a critical skill for image interpretation. However, it is unclear how skilled viewers assess echocardiographic images. Therefore, guidance and implicit advice are needed for learners to achieve valid image interpretation. Approach: Using a signal detection approach, we compared 15 certified experts with 15 medi- cal students in their diagnostic decision-making and viewing behavior. To quantify attention allocation, we recorded eye movements while viewing dynamic echocardiographic imaging loops of patients with reduced ejection fraction and healthy controls. Participants evaluated left ventricular ejection fraction and image quality (as diagnostic and visual control tasks, respectively). Results: Experts were much better at discriminating between patients and healthy controls (d0 of 2.58, versus 0.98 for novices). Eye tracking revealed that experts fixated diagnostically relevant areas earlier and more often, whereas novices were distracted by visually salient task-irrelevant stimuli. We show that expertise status can be almost perfectly classified either based on judg- ments or purely on eye movements and that an expertise score derived from viewing behavior predicts diagnostic quality. Conclusions: Judgments and eye tracking revealed significant differences between echocardi- ography experts and novices that can be used to derive numerical expertise scores. Experts have implicitly learned to ignore the salient motion cue presented by the mitral valve and to focus on the diagnostically more relevant left ventricle. These findings have implications for echocardi- ography training, objective characterization of echocardiographic expertise, and the design of user-friendly interfaces for echocardiography. |
Deming Li; Ankur A. Butala; Laureano Moro-Velazquez; Trevor Meyer; Esther S. Oh; Chelsey Motley; Jesús Villalba; Najim Dehak Automating analysis of eye movement and feature extraction for different neurodegenerative disorders Journal Article In: Computers in Biology and Medicine, vol. 170, pp. 1–16, 2023. @article{Li2023b, The clinical observation and assessment of extra-ocular movements is common practice in assessing neurode- generative disorders but remains observer-dependent. In the present study, we propose an algorithm that can automatically identify saccades, fixation, smooth pursuit, and blinks using a non-invasive eye tracker. Subsequently, response-to-stimuli-derived interpretable features were elicited that objectively and quantita- tively assess patient behaviors. The cohort analysis encompasses persons with mild cognitive impairment (MCI), Alzheimer's disease (AD), Parkinson's disease (PD), Parkinson's disease mimics (PDM), and controls (CTRL). Overall, results suggested that the AD/MCI and PD groups had significantly different saccade and pursuit characteristics compared to CTRL when the target moved faster or covered a larger visual angle during smooth pursuit. These two groups also displayed more omitted antisaccades and longer average antisaccade latency than CTRL. When reading a text passage silently, people with AD/MCI had more fixations. During visual exploration, people with PD demonstrated a more variable saccade duration than other groups. In the prosaccade task, the PD group showed a significantly smaller average hypometria gain and accuracy, with the most statistical significance and highest AUC scores of features studied. The minimum saccade gain was a PD- specific feature different from CTRL and PDM. These features, as oculographic biomarkers, can be potentially leveraged in distinguishing different types of NDs, yielding more objective and precise protocols to diagnose and monitor disease progression. |
Clara Grazia Chisari; Giorgia Sciacca; Ester Reggio; Claudio Terravecchia; Francesco Patti; Mario Zappia Subclinical involvement of eye movements detected by video-based eye tracking in myasthenia gravis Journal Article In: Neurological Sciences, vol. 44, no. 7, pp. 2555–2559, 2023. @article{Chisari2023, Background: Ocular abnormalities in myasthenia gravis (MG) are characterized by severely limited movements and rapid saccades. Data about eye motility of MG patients whose ocular movements are apparently normal are lacking. Our study assessed the eye movement parameters in MG patients without clinical eye motility dysfunctions and investigated the effects of neostigmine administration on the eye motility in these patients. Materials: In this longitudinal study, we screened all patients diagnosed with MG referring to the Neurologic Clinic of the University of Catania between October 1, 2019, and June 30, 2021. Ten age- and sex-matched healthy controls were enrolled. Patients underwent eye movement recording using the EyeLink1000 Plus® eye tracker at baseline and after 90 min from the intramuscular administration of neostigmine (0.5 mg). Results: A total of 14 MG patients with no clinical signs of ocular motor dysfunction (64.3% men, with a mean age of 50.4 ± 14.4 years) were enrolled. At baseline, saccades in MG patients showed slower velocities and longer latencies compared to controls. Moreover, the fatigue test induced a reduction in saccadic velocity and an increase in latencies. After neostigmine administration, the ocular motility analysis showed shorter saccadic latencies and a significant improvement of velocities. Conclusions: Eye motility is impaired even in MG patients with no clinical evidence of ocular movement disturbance. Video-based eye tracking may detect subclinical involvement of eye movements in patients with MG. |
Kahyun Choi; Sanghum Woo; Joonyeol Lee Motor-effector dependent modulation of sensory-motor processes identified by the multivariate pattern analysis of EEG activity Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–12, 2023. @article{Choi2023, Sensory information received through sensory organs is constantly modulated by numerous non-sensory factors. Recent studies have demonstrated that the state of action can modulate sensory representations in cortical areas. Similarly, sensory information can be modulated by the type of action used to report perception; however, systematic investigation of this issue is scarce. In this study, we examined whether sensorimotor processes represented in electroencephalography (EEG) activities vary depending on the type of effector behavior. Nineteen participants performed motion direction discrimination tasks in which visual inputs were the same, and only the effector behaviors for reporting perceived motion directions were different (smooth pursuit, saccadic eye movement, or button press). We used multivariate pattern analysis to compare the EEG activities for identical sensory inputs under different effector behaviors. The EEG activity patterns for the identical sensory stimulus before any motor action varied across the effector behavior conditions, and the choice of motor effectors modulated the neural direction discrimination differently. We suggest that the motor-effector dependent modulation of EEG direction discrimination might be caused by effector-specific motor planning or preparation signals because it did not have functional relevance to behavioral direction discriminability. |
Julien Claron; Matthieu Provansal; Quentin Salardaine; Pierre Tissier; Alexandre Dizeux; Thomas Deffieux; Serge Picaud; Mickael Tanter; Fabrice Arcizet; Pierre Pouget Co-variations of cerebral blood volume and single neurons discharge during resting state and visual cognitive tasks in non-human primates Journal Article In: Cell Reports, vol. 42, no. 4, pp. 1–16, 2023. @article{Claron2023, To better understand how the brain allows primates to perform various sets of tasks, the ability to simultaneously record neural activity at multiple spatiotemporal scales is challenging but necessary. However, the contribution of single-unit activities (SUAs) to neurovascular activity remains to be fully understood. Here, we combine functional ultrasound imaging of cerebral blood volume (CBV) and SUA recordings in visual and fronto-medial cortices of behaving macaques. We show that SUA provides a significant estimate of the neurovascular response below the typical fMRI spatial resolution of 2mm3. Furthermore, our results also show that SUAs and CBV activities are statistically uncorrelated during the resting state but correlate during tasks. These results have important implications for interpreting functional imaging findings while one constructs inferences of SUA during resting state or tasks. |
Claudia Contadini-Wright; Kaho Magami; Nishchay Mehta; Maria Chait In: Journal of Neuroscience, vol. 43, no. 26, pp. 4856–4866, 2023. @article{ContadiniWright2023, Listening in noisy environments requires effort - the active engagement of attention and other cognitive abilities - as well as increased arousal. The ability to separately quantify the contribution of these components is key to understanding the dynamics of effort and how it may change across listening situations and in certain populations. We concurrently measured two types of ocular data in young participants (both sexes): pupil dilation (PD; thought to index arousal aspects of effort) and microsaccades (MS; hypothesized to reflect automatic visual exploratory sampling), while they performed a speech-in-noise task under high- (HL) and low- (LL) listening load conditions. Sentences were manipulated so that the behaviorally relevant information (WABBLE) appeared at the end (Experiment 1) or beginning (Experiment 2) of the sentence, resulting in different temporal demands on focused attention. In line with previous reports, PD effects were associated with increased dilation under load. We observed a sustained difference between HL and LL conditions, consistent with increased phasic and tonic arousal. Importantly we show that MS rate was also modulated by listening load. This was manifested as a reduced MS rate in HL relative to LL. Critically, in contrast to the sustained difference seen for PD, MS effects were localized in time, specifically during periods when demands on auditory attention were greatest. These results demonstrate that auditory selective attention interfaces with the mechanisms controlling MS generation, establishing MS as an informative measure, complementary to PD, with which to quantify the temporal dynamics of auditory attentional processing under effortful listening conditions. |
Annabell Coors; Mohammed Aslam Imtiaz; Meta M. Boenniger; N. Ahmad Aziz; Monique M. B. Breteler; Ulrich Ettinger Polygenic risk scores for schizophrenia are associated with oculomotor endophenotypes Journal Article In: Psychological Medicine, vol. 53, no. 4, pp. 1611–1619, 2023. @article{Coors2023, Background Schizophrenia is a heterogeneous disorder with substantial heritability. The use of endophenotypes may help clarify its aetiology. Measures from the smooth pursuit and antisaccade eye movement tasks have been identified as endophenotypes for schizophrenia in twin and family studies. However, the genetic basis of the overlap between schizophrenia and these oculomotor markers is largely unknown. Here, we tested whether schizophrenia polygenic risk scores (PRS) were associated with oculomotor performance in the general population. Methods Analyses were based on the data of 2956 participants (aged 30-95) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Genotyping was performed on Omni-2.5 exome arrays. Using summary statistics from a recent meta-analysis based on the two largest schizophrenia genome-wide association studies to date, we quantified genetic risk for schizophrenia by creating PRS at different p value thresholds for genetic markers. We examined associations between PRS and oculomotor performance using multivariable regression models. Results Higher PRS were associated with higher antisaccade error rate and latency, and lower antisaccade amplitude gain. PRS showed inconsistent patterns of association with smooth pursuit velocity gain and were not associated with saccade rate during smooth pursuit or performance on a prosaccade control task. Conclusions There is an overlap between genetic determinants of schizophrenia and oculomotor endophenotypes. Our findings suggest that the mechanisms that underlie schizophrenia also affect oculomotor function in the general population. |
M. Eric Cui; Björn Herrmann Eye movements decrease during effortful speech listening Journal Article In: Journal of Neuroscience, vol. 43, no. 32, pp. 5856–5869, 2023. @article{Cui2023, Hearing impairment affects many older adults but is often diagnosed decades after speech comprehension in noisy situations has become effortful. Accurate assessment of listening effort may thus help diagnose hearing impairment earlier. However, pupillometry—the most used approach to assess listening effort—has limitations that hinder its use in practice. The current study explores a novel way to assess listening effort through eye movements. Building on cognitive and neurophysiological work, we examine the hypothesis that eye movements decrease when speech listening becomes challenging. In three experiments with human participants from both sexes, we demonstrate, consistent with this hypothesis, that fixation duration increases and spatial gaze dispersion decreases with increasing speech masking. Eye movements decreased during effortful speech listening for different visual scenes (free viewing, object tracking) and speech materials (simple sentences, naturalistic stories). In contrast, pupillometry was less sensitive to speech masking during story listening, suggesting pupillometric measures may not be as effective for the assessments of listening effort in naturalistic speech-listening paradigms. Our results reveal a critical link between eye movements and cognitive load, suggesting that neural activity in the brain regions that support the regulation of eye movements, such as frontal eye field and superior colliculus, are modulated when listening is effortful. |
Mario Dalmaso; Luigi Castelli; Chiara Bernardini; Giovanni Galfano Can masked gaze and arrow stimuli elicit overt orienting of attention? A registered report Journal Article In: Consciousness and Cognition, vol. 109, pp. 1–9, 2023. @article{Dalmaso2023, Viewing an averted gaze can elicit saccades towards the corresponding location. Here, the automaticity of this gaze-following behaviour phenomenon was further tested by exploring whether such an effect can be detected in response to briefly-presented masked averted gazes. Participants completed an oculomotor interference task consisting of making leftward/rightward saccades according to a symbolic instruction cue. Crucially, either a task-irrelevant averted-gaze face or an arrow (i.e., a non-social control stimulus) was also presented in different blocks of trials. Faces and arrows were presented for either 1000 ms, or 8 ms and then backward-masked, to reduce the likelihood of conscious processing. Worse oculomotor performance emerged when the saccade direction did not match (vs match) that suggested by the task-irrelevant gaze/arrow stimuli in the unmasked condition. However, in the masked condition, no oculomotor interference occurred for any task-irrelevant stimulus. Results enrich knowledge about boundary conditions for gaze/arrow-driven orienting using ecological attention measures. |
Alessio D'Aquino; Cornelia Frank; John Elvis Hagan; Thomas Schack Eye movements during motor imagery and execution reveal different visuomotor control strategies in manual interception Journal Article In: Psychophysiology, vol. 60, no. 12, pp. 1–16, 2023. @article{DAquino2023, Previous research has investigated the degree of congruency in gaze metrics between action execution (AE) and motor imagery (MI) for similar manual tasks. Although eye movement dynamics seem to be limited to relatively simple actions toward static objects, there is little evidence of how gaze parameters change during imagery as a function of more dynamic spatial and temporal task demands. This study examined the similarities and differences in eye movements during AE and MI for an interception task. Twenty-four students were asked to either mentally simulate or physically intercept a moving target on a computer display. Smooth pursuit, saccades, and response time were compared between the two conditions. The results show that MI was characterized by higher smooth pursuit gain and duration while no meaningful differences were found in the other parameters. The findings indicate that eye movements during imagery are not simply a duplicate of what happens during actual performance. Instead, eye movements appear to vary as a function of the interaction between visuomotor control strategies and task demands. |
Barry Dauphin; Harold H. Greene; Mindee Juve; Mellisa Boyle; Ellen Day-Suba Transforming psychological testing with saccadic responses: Internal consistency is high for Rorschach and facial expressions Journal Article In: Perceptual and Motor Skills, vol. 130, no. 5, pp. 1985–1999, 2023. @article{Dauphin2023, Psychologists have long been interested in the underlying visual perceptual processes associated with forming responses to certain psychological tests, including the Rorschach Ink Blot Test, which modern users conceptualize as a conceptual problem-solving task. Accordingly, we used eye tracking technology to assess the internal consistency of saccadic responses to both the Rorschach Ink Blot Test and a facial expression task. Internal consistency was highest for eye Fixation Duration (FD) and Saccade Amplitude (SA), and both FD and SA measures in the Rorschach were positively related to the same measures in the facial expression task. Given this high internal consistency of FD and SA for viewing Rorschach ink blots and viewing pictures from well-known collections of facial expressions, and given high correlations between these eye tracking measures across the two tasks, FD and SA may now be used in further studies of eye movements in visuo-attentive psychological/neuropsychological tests (e.g., the Thematic Apperception Test). Reliability of these eye movement measures across tasks enables their use for better understanding of underlying visual processes and improved interpretations of the meaning of behavioral responses to psychological/neuropsychological tests. |
Barry Dauphin; Harold H. Greene; Mindee Juve; Mellisa Boyle; Ellen Day-suba; Barry Dauphin; Harold H. Greene; Mindee Juve; Mellisa Boyle; Ellen Day-suba Seeing eye-to-eye: Internal consistencies of eye-tracking variables during Rorschach administration Journal Article In: Rorschachiana, pp. 1–26, 2023. @article{Dauphin2023a, Considering the continuing interest in the use of eye-tracking technology for study of the Rorschach response process, the present study examines the internal consistencies for several eye-tracking indices during Rorschach administration. Many experimental psychologists have recently maintained that researchers should be interested in and report the internal consistency statistics of performance measures, including eye tracking in order to improve effect size, the power of hypothesis testing, and the replicability of findings. In the current study, eye-tracking variables more relevant to understanding top–down (goal-driven) processes showed good-to-excellent internal consistencies, while variables largely affected by bottom–up (stimulus-driven) processes showed questionable or poor internal consistency. The current findings provide support for recent research strategies of utilizing protocol-level eye-tracking averages to link to Rorschach coding variables. In addition, the current study found differences across cards for the eye-tracking variables, showing medium-to-large effect sizes, which provides evidence for the stimulus pull of the cards for visual search strategies, including variables not previously used in Rorschach research. |
Cristina Malla; Alexander Goettker The effect of impaired velocity signals on goal-directed eye and hand movements Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–18, 2023. @article{Malla2023, Information about position and velocity is essential to predict where moving targets will be in the future, and to accurately move towards them. But how are the two signals combined over time to complete goal-directed movements? We show that when velocity information is impaired due to using second-order motion stimuli, saccades directed towards moving targets land at positions where targets were ~ 100 ms before saccade initiation, but hand movements are accurate. Importantly, the longer latencies of hand movements allow for additional time to process the sensory information available. When increasing the period of time one sees the moving target before making the saccade, saccades become accurate. In line with that, hand movements with short latencies show higher curvature, indicating corrections based on an update of incoming sensory information. These results suggest that movements are controlled by an independent and evolving combination of sensory information about the target's position and velocity. |
Eelke Vries; George Fejer; Freek Ede No obligatory trade-off between the use of space and time for working memory Journal Article In: Communications Psychology, vol. 1, no. 1, pp. 1–10, 2023. @article{Vries2023a, Space and time can each act as scaffolds for the individuation and selection of visual objects in working memory. Here we ask whether there is a trade-off between the use of space and time for visual working memory: whether observers will rely less on space, when memoranda can additionally be individuated through time. We tracked the use of space through directional biases in microsaccades after attention was directed to memory contents that had been encoded simultaneously or sequentially to the left and right of fixation. We found that spatial gaze biases were preserved when participants could (Experiment 1) and even when they had to (Experiment 2) additionally rely on time for object individuation. Thus, space remains a profound organizing medium for working memory even when other organizing sources are available and utilized, with no evidence for an obligatory trade-off between the use of space and time. |
Stefan Dowiasch; Marius Blanke; Jonas Knöll; Frank Bremmer Spatial localization during open-loop smooth pursuit Journal Article In: Frontiers in Neuroscience, vol. 17, pp. 1–11, 2023. @article{Dowiasch2023, Introduction: Numerous previous studies have shown that eye movements induce errors in the localization of briefly flashed stimuli. Remarkably, the error pattern is indicative of the underlying eye movement and the exact experimental condition. For smooth pursuit eye movements (SPEM) and the slow phase of the optokinetic nystagmus (OKN), perceived stimulus locations are shifted in the direction of the ongoing eye movement, with a hemifield asymmetry observed only during SPEM. During the slow phases of the optokinetic afternystagmus (OKAN), however, the error pattern can be described as a perceptual expansion of space. Different from SPEM and OKN, the OKAN is an open-loop eye movement. Methods: Visually guided smooth pursuit can be transformed into an open–loop eye movement by briefly blanking the pursuit target (gap). Here, we examined flash localization during open-loop pursuit and asked, whether localization is also prone to errors and whether these are similar to those found during SPEM or during OKAN. Human subjects tracked a pursuit target. In half of the trials, the target was extinguished for 300 ms (gap) during the steady–state, inducing open–loop pursuit. Flashes were presented during this gap or during steady–state (closed–loop) pursuit. Results: In both conditions, perceived flash locations were shifted in the direction of the eye movement. The overall error pattern was very similar with error size being slightly smaller in the gap condition. The differences between errors in the open- and closed-loop conditions were largest in the central visual field and smallest in the periphery. Discussion: We discuss the findings in light of the neural substrates driving the different forms of eye movements. |
Cody S. Dulaney; Jordan Murray; Fatema Ghasia Contrast sensitivity, optotype acuity and fixation eye movement abnormalities in amblyopia under binocular viewing Journal Article In: Journal of the Neurological Sciences, vol. 451, pp. 1–9, 2023. @article{Dulaney2023, Introduction: Visual function deficits are seen in amblyopic subjects during fellow and binocular viewing. The purpose of the study was to examine the relationship between Fixation Eye Movement (FEM) abnormalities and binocular contrast sensitivity and optotype acuity deficits in amblyopia. Methods: We recruited 10 controls and 25 amblyopic subjects [Anisometropic = 6 |
Matt J. Dunn; Perry Carter; Jay Self; Helena Lee; Fatima Shawkat Eyetracking-enhanced VEP for nystagmus Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–6, 2023. @article{Dunn2023, Visual evoked potentials (VEPs) are an important prognostic indicator of visual ability in patients with nystagmus. However, VEP testing requires stable fixation, which is impossible with nystagmus. Fixation instability reduces VEP amplitude, and VEP reliability is therefore low in this important patient group. We investigated whether VEP amplitude can be increased using an eye tracker by triggering acquisition only during slow periods of the waveform. Data were collected from 10 individuals with early-onset nystagmus. VEP was obtained under continuous (standard) acquisition, or triggered during periods of low eye velocity, as detected by an eye tracker. VEP amplitude was compared using Bonferroni corrected paired samples t-tests. VEP amplitude is significantly increased when triggered during low eye velocity (95% CI 1.42–6.83 µV, t(15) = 3.25 |
Merve Ekin; Koray Koçoğlu; Hatice Eraslan Boz; Müge Akkoyun; Işıl Yağmur Tüfekci; Berna Yalınçetin; Emre Bora; Gülden Akdal Spatial working memory in prodromal stage: An eye tracking study Journal Article In: Alzheimer's & Dementia, vol. 19, pp. 1–2, 2023. @article{Ekin2023, Abstract Background: Individuals at ultra-high risk for psychosis and bipolar disorder (UHR-P and UHR-BD) have shown cognitive abnormalities and sub-threshold clinical features (de Paula et al., 2015; Metzler et al., 2014). Assessing saccadic eyemovements is one of the useful methods for investigating high cognitive functions like spatial working memory and inhibition (Pierrot-Deseilligny et al., 2005; Winograd-Gurvich et al., 2008). Memory-guided saccade (MGS)may be described as short-term maintenance of attention bothwhen a peripheral target is presented, and a delay screen. The purpose of this study was to examine the differences between clinical risk groups and healthy controls (HCs) based on the memory-guided saccade. Method: The study was included 33 UHR-P (age: 21.61 ± 3.24), 28 UHR-BD (age: 21.64 ± 4.02), and 28 HCs (age: 22.11 ± 4.03). Participants were selected from cases of clinical-high-risk criteria in interviews made with The Structured Interview of Psychosis Risk Syndromes and Bipolar Prodrome Symptom Interview and Scale. The memory-guided saccade was measured with the number of the correct, incorrect, anticipatory and express saccades, also latency, peak velocity and amplitude for the correct saccades. Eye movement data were recorded from the right eye using an EyeLink 1000 Plus eye-tracker. All results were analyzed with SPSS software. Result: The anticipatory and express saccades in the cue screen, the anticipatory saccade in the delay screen and the total error response were significant between groups (p<0.05). There was a significant increase in UHR-BD compared to controls in the error responses (p = 0.018). The anticipatory saccades in UHR-BD were higher than in both UHR-P andHCon the cue screen (p =0.005 and p=0.014), and controls on the delay screen (p = 0.027). In addition, the express saccades in the cue screen showed statistical differences between the risk groups (p = 0.032). Conclusion: Memory-guided saccades are used to assess the top-down mechanism, including perceptual organization and goal-directed behaviors, and are related to frontal lobe functions like spatial working memory and inhibitory control (Ostendorf et al., 2004). The elevation of incorrect saccades and predictive parameters like anticipatory saccades have indicated that individuals at the prodromal stage may appear spatial problems in inhibitory and exhibitory functions. |
Merve Ekin; Koray Koçoğlu; Hatice Eraslan Boz; Müge Akkoyun; Işıl Yağmur Tüfekci; Ezgi Cesim; Berna Yalınçetin; Simge Uzman Özbek; Emre Bora; Gülden Akdal Antisaccade and memory-guided saccade in individuals at ultra-high-risk for bipolar disorder Journal Article In: Journal of Affective Disorders, vol. 339, pp. 965–972, 2023. @article{Ekin2023a, Background: Ultra-high-risk for bipolar disorder (UHR-BD) is an important paradigm to investigate the potential early-stage biomarkers of bipolar disorder, including eye-tracking abnormalities and cognitive functions. Antisaccade (AS) described as looking in the opposite direction of the target, and memory-guided saccade (MGS), identified as maintaining fixation, and remembering the location of the target, were used in this study. The aim of this study was to evaluate the differences in saccadic eye movements between UHR-BD and healthy controls (HCs) via AS-MGS. Methods: The study included 28 UHR-BD and 29 HCs. Participants were selected using a structured clinical interview for prodromal symptoms of BD. AS-MGS were measured with parameters like uncorrected errors, anticipatory saccades, and latency. Eye movements were recorded with the EyeLink 1000-Plus eye-tracker. Results: In the AS, the number of correct saccades was significantly decreased in UHR-BD (p = 0.020). Anticipatory (p = 0.009) and express saccades (p = 0.040) were increased in UHR-BD. In the MGS paradigm, the correct saccades were reduced in UHR-BD (p = 0.031). In addition, anticipatory (p = 0.004) and express saccades (p = 0.012) were significantly increased in cue-screen in UHR-BD. Conclusions: To our knowledge, this is the first study to evaluate cognitive functions with eye movements in individuals at UHR-BD. The current findings showed that eye movement functions, particularly in saccadic parameters related to inhibition and spatial perception, may be affected in the UHR-BD group. Therefore, assessment of oculomotor functions may provide observation of clinical and cognitive functions in the early-stage of bipolar disorder. However, further research is needed because the potential effects of medication may affect saccadic results. |
2022 |
Lisa Kunkel genannt Bode; Anna Sophie Schulte; Björn Hauptmann; Thomas F. Münte; Andreas Sprenger; Björn Machner Gaze-contingent display technology can help to reduce the ipsilesional attention bias in hemispatial neglect following stroke Journal Article In: Journal of NeuroEngineering and Rehabilitation, vol. 19, pp. 1–15, 2022. @article{KunkelgenanntBode2022, Background: Hemispatial neglect results from unilateral brain damage and represents a disabling unawareness for objects in the hemispace opposite the brain lesion (contralesional). The patients' attentional bias for ipsilesional hemispace represents a hallmark of neglect, which results from an imbalanced attentional priority map in the brain. The aim of this study was to investigate whether gaze-contingent display (GCD) technology, reducing the visual salience of objects in ipsilesional hemispace, is able to rebalance this map and increase awareness and exploration of objects in the neglected contralesional hemispace. Methods: Using remote eye-tracking, we recorded gaze positions in 19 patients with left hemispatial neglect following right-hemisphere stroke and 22 healthy control subjects, while they were watching static naturalistic scenes. There were two task conditions, free viewing (FV) or goal-directed visual search (VS), and four modification conditions including the unmodified original picture, a purely static modification and two differently strong modifications with an additional gaze-contingent mask (GC-LOW, GC-HIGH), that continuously reduced color saturation and contrast of objects in the right hemispace. Results: The patients' median gaze position (Center of Fixation) in the original pictures was markedly deviated to the right in both tasks (FV: 6.8° ± 0.8; VS: 5.5° ± 0.7), reflecting the neglect-typical ipsilesional attention bias. GC modification significantly reduced this bias in FV (GC-HIGH: d = − 3.2 ± 0.4°; p < 0.001). Furthermore, in FV and VS, GC modification increased the likelihood to start visual exploration in the (neglected) left hemifield by about 20%. This alleviation of the ipsilesional fixation bias was not associated with an improvement in detecting left-side targets, in contrast, the GC mask even decreased and slowed the detection of right-side targets. Subjectively, patients found the intervention pleasant and most of the patients did not notice any modification. Conclusions: GCD technology can be used to positively influence visual exploration patterns in patients with hemispatial neglect. Despite an alleviation of the neglect-related ipsilesional fixation bias, a concomitant functional benefit (improved detection of contralesional targets) was not achieved. Future studies may investigate individualized GCD-based modifications as augmented reality applications during the activities of daily living. |
Haiyan Wang; Matthew Walenski; Kaitlyn Litcofsky; Jennifer E. Mack; M. Marsel Mesulam; Cynthia K. Thompson Verb production and comprehension in primary progressive aphasia Journal Article In: Journal of Neurolinguistics, vol. 64, pp. 1–18, 2022. @article{Wang2022c, Studies of word class processing have found verb retrieval impairments in individuals with primary progressive aphasia (Bak et al., 2001; Cappa et al., 1998; Cotelli et al., 2006; Hillis, Heidler-Gary, et al., 2006; Hillis, Oh, & Ken, 2004; Marcotte et al., 2014; Rhee, Antiquena, & Grossman, 2001; Silveri & Ciccarelli, 2007; Thompson, Lukic, et al., 2012) associated primarily with the agrammatic variant. However, fewer studies have focused on verb comprehension, with inconsistent results. Because verbs are critical to both production and comprehension of clauses and sentences, we investigated verb processing across domains in agrammatic, logopenic, and semantic PPA and a group of age-matched healthy controls. Participants completed a confrontation naming task for verb production and an eye-tracking word-picture matching task for online verb comprehension. All PPA groups showed impaired verb production and comprehension relative to healthy controls. Most notably, the PPA-S group performed more poorly than the other two PPA variants in both domains. Overall, the results indicate that semantic deficits in the PPA-S extend beyond object knowledge to verbs as well, adding to our knowledge concerning the nature of the language deficits in the three variants of primary progressive aphasia. |
Mahboubeh Habibi; Wolfgang H. Oertel; Brian J. White; Donald C. Brien; Brian C. Coe; Heidi C. Riek; Julia Perkins; Rachel Yep; Laurent Itti; Lars Timmermann; Christoph Best; Elisabeth Sittig; Annette Janzen; Douglas P. Munoz Eye tracking identifies biomarkers in α-synucleinopathies versus progressive supranuclear palsy Journal Article In: Journal of Neurology, vol. 269, pp. 4920–4938, 2022. @article{Habibi2022, Objectives: This study (1) describes and compares saccade and pupil abnormalities in patients with manifest alpha-synucleinopathies (αSYN: Parkinson's disease (PD), Multiple System Atrophy (MSA)) and a tauopathy (progressive supranuclear palsy (PSP)); (2) determines whether patients with rapid-eye-movement sleep behaviour disorder (RBD), a prodromal stage of αSYN, already have abnormal responses that may indicate a risk for developing PD or MSA. Methods: Ninety (46 RBD, 27 PD, 17 MSA) patients with an αSYN, 10 PSP patients, and 132 healthy age-matched controls (CTRL) were examined with a 10-min video-based eye-tracking task (Free Viewing). Participants were free to look anywhere on the screen while saccade and pupil behaviours were measured. Results: PD, MSA, and PSP spent more time fixating the centre of the screen than CTRL. All patient groups made fewer macro-saccades (> 2◦ amplitude) with smaller amplitude than CTRL. Saccade frequency was greater in RBD than in other patients. Following clip change, saccades were temporarily suppressed, then rebounded at a slower pace than CTRL in all patient groups. RBD had distinct, although discrete saccade abnormalities that were more marked in PD, MSA, and even more in PSP. The vertical saccade rate was reduced in all patients and decreased most in PSP. Clip changes produced large increases or decreases in screen luminance requiring pupil constriction or dilation, respectively. PSP elicited smaller pupil constriction/dilation responses than CTRL, while MSA elicited the opposite. Conclusion: RBD patients already have discrete but less pronounced saccade abnormalities than PD and MSA patients. Vertical gaze palsy and altered pupil control differentiate PSP from αSYN. |
Christoph Helmchen; Philipp J. Koch; Gabriel Girard; Norbert Brüggemann; Björn Machner; Andreas Sprenger NPTX1-related oculomotor apraxia: An intra-hemispheric disconnection disorder Journal Article In: Journal of Neurology, vol. 269, no. 7, pp. 3931–3936, 2022. @article{Helmchen2022a, Oculomotor apraxia (OMA) is a rare and heavily disabling neurological disorder causing severe difficulties in the initia- tion and maintenance of voluntary eye movements when the head is stationary. If patients try to initiate saccades, they are grossly delayed and hypometric (stair-case). .. The aim of this study was to test competing pathophysiological hypotheses by functional and structural MRI, stating that OMA is related to either abnormal (i) inter-hemispheric or (ii) intra-hemispheric connectivity between the FEF and related oculomotor structures (oculomotor network) or (iii) both mechanisms. |
Leslie Guadron; A. John Opstal; Jeroen Goossens Speed-accuracy tradeoffs influence the main sequence of saccadic eye movements Journal Article In: Scientific Reports, vol. 12, pp. 1–14, 2022. @article{Guadron2022, Several studies have proposed that an optimal speed-accuracy tradeoff underlies the stereotyped relationship between amplitude, duration and peak velocity of saccades (main sequence). To test this theory, we asked 8 participants to make saccades to Gaussian-blurred spots and manipulated the task's accuracy constraints by varying target size (1, 3, and 5°). The largest targets indeed yielded more endpoint scatter (and lower gains) than the smallest targets, although this effect subsided with target eccentricity. The main sequence depended on several interacting factors: saccade latency, saccade gain and target size. Early saccades, which were faster than amplitude-matched late saccades, followed the target-size dependency one would expect from a speed-accuracy tradeoff process. They had higher peak velocities and shorter durations for larger targets than for smaller targets. For late saccades, however, the opposite was found. Deviations from the main sequence also covaried with saccade gain, in line with the idea that motor noise underlies part of the endpoint variability. Thus, our data provide partial evidence that the saccadic system weighs the detrimental effects of motor noise on saccade accuracy against movement duration and speed, but other factors also modulate the kinematics. We discuss the possible involvement of parallel saccade pathways to account for our findings. |
Mariana M. Gusso; Kate L. Christison-Lagay; David Zuckerman; Ganesh Chandrasekaran; Sharif I. Kronemer; Julia Z. Ding; Noah C. Freedman; Percy Nohama; Hal Blumenfeld More than a feeling: Scalp EEG and eye signals in conscious tactile perception Journal Article In: Consciousness and Cognition, vol. 105, pp. 1–14, 2022. @article{Gusso2022, Understanding the neural basis of consciousness is a fundamental goal of neuroscience, and sensory perception is often used as a proxy for consciousness in empirical studies. However, most studies rely on reported perception of visual stimuli. Here we present behavior, high density scalp EEG and eye metric recordings collected simultaneously during a novel tactile threshold perception task. We found significant N80, N140 and P300 event related potentials in perceived trials and in perceived versus not perceived trials. Significance was limited to a P100 and P300 in not perceived trials. We also found an increase in pupil diameter and blink rate and a decrease in microsaccade rate following perceived relative to not perceived tactile stimuli. These findings support the use of eye metrics as a measure of physiological arousal associated with conscious perception. Eye metrics may also represent a novel path toward the creation of tactile no-report tasks in the future. |
Nicole X. Han; Miguel P. Eckstein Gaze-cued shifts of attention and microsaccades are sustained for whole bodies but are transient for body parts Journal Article In: Psychonomic Bulletin & Review, vol. 29, pp. 1854–1878, 2022. @article{Han2022, Gaze direction is an evolutionarily important mechanism in daily social interactions. It reflects a person's internal cognitive state, spatial locus of interest, and predicts future actions. Studies have used static head images presented foveally and simple synthetic tasks to find that gaze orients attention and facilitates target detection at the cued location in a sustained manner. Little is known about how people's natural gaze behavior, including eyes, head, and body movements, jointly orient covert attention, microsaccades, and facilitate performance in more ecological dynamic scenes. Participants completed a target person detection task with videos of real scenes. The videos showed people looking toward (valid cue) or away from a target (invalid cue) location. We digitally manipulated the individuals in the videos directing gaze to create three conditions: whole-intact (head and body movements), floating heads (only head movements), and headless bodies (only body movements). We assessed their impact on participants' behavioral performance and microsaccades during the task. We show that, in isolation, an individual's head or body orienting toward the target-person direction led to facilitation in detection that is transient in time (200 ms). In contrast, only the whole-intact condition led to sustained facilitation (500 ms). Furthermore, observers executed microsaccades more frequently towards the cued direction for valid trials, but this bias was sustained in time only with the joint presence of head and body parts. Together, the results differ from previous findings with foveally presented static heads. In more real-world scenarios and tasks, sustained attention requires the presence of the whole-intact body of the individuals dynamically directing their gaze. |
Nina M. Hanning; Heiner Deubel The effect of spatial structure on presaccadic attention costs and benefits assessed with dynamic 1/f noise Journal Article In: Journal of Neurophysiology, vol. 127, pp. 1586–1592, 2022. @article{Hanning2022a, Already before the onset of a saccadic eye movement, we preferentially process visual information at the upcoming eye fixation. This “presaccadic shift of attention” is typically assessed via localized test items, which potentially bias the attention measurement. Here, we show how presaccadic attention shapes perception from saccade origin to target when no scene-structuring items are presented. Participants made saccades into a 1/f (“pink”) noise field, in which we embedded a brief orientation signal at various locations shortly before saccade onset. Local orientation discrimination performance served as a proxy for the allocation of attention. Results demonstrate that 1) the presaccadic attention shift is accompanied by considerable attentional costs at the presaccadic eye fixation and 2) saccades are preceded by shifts of attention to their goal location even if they are directed into an unstructured visual field, but the spread of attention, compared with target-directed saccades, is broad. We conclude that the absence or presence of saccade target objects markedly shapes the distribution of presaccadic attention and likely the underlying (space-based or object-based) cortical control mechanism. Our findings demonstrate the relevance of an item-free approach for measuring attentional dynamics across the visual field. |
Nina M. Hanning; Marc M. Himmelberg; Marisa Carrasco Presaccadic attention enhances contrast sensitivity, but not at the upper vertical meridian Journal Article In: iScience, vol. 25, no. 2, pp. 1–11, 2022. @article{Hanning2022, Visual performance has striking polar performance asymmetries: At a fixed eccentricity, it is better along the horizontal than vertical meridian and the lower than upper vertical meridian. These asymmetries are not alleviated by covert exogenous or endogenous attention, but have been studied exclusively during eye fixation. However, a major driver of everyday attentional orienting is saccade preparation, during which attention automatically shifts to the future eye fixation. This presaccadic attention shift is considered strong and compulsory, and relies on different neural computations and substrates than covert attention. Thus, we asked: Can presaccadic attention compensate for the ubiquitous performance asymmetries observed during eye fixation? Our data replicate polar performance asymmetries during fixation and document the same asymmetries during saccade preparation. Crucially, however, presaccadic attention enhanced contrast sensitivity at the horizontal and lower vertical meridian, but not at the upper vertical meridian. Thus, instead of attenuating performance asymmetries, presaccadic attention exacerbates them. |
Frauke Heins; Markus Lappe Flexible use of post-saccadic visual feedback in oculomotor learning Journal Article In: Journal of Vision, vol. 22, no. 1, pp. 1–16, 2022. @article{Heins2022, Saccadic eye movements bring objects of interest onto our fovea. These gaze shifts are essential for visual perception of our environment and the interaction with the objects within it. They precede our actions and are thus modulated by current goals. It is assumed that saccadic adaptation, a recalibration process that restores saccade accuracy in case of error, is mainly based on an implicit comparison of expected and actual post-saccadic position of the target on the retina. However, there is increasing evidence that task demands modulate saccade adaptation and that errors in task performance may be sufficient to induce changes to saccade amplitude. We investigated if human participants are able to flexibly use different information sources within the post-saccadic visual feedback in task-dependent fashion. Using intra-saccadic manipulation of the visual input, participants were either presented with congruent post-saccadic information, indicating the saccade target unambiguously, or incongruent post-saccadic information, creating conflict between two possible target objects. Using different task instructions, we found that participants were able to modify their saccade behavior such that they achieved the goal of the task. They succeeded in decreasing saccade gain or maintaining it, depending on what was necessary for the task, irrespective of whether the post-saccadic feedback was congruent or incongruent. It appears that action intentions prime task-relevant feature dimensions and thereby facilitated the selection of the relevant information within the post-saccadic image. Thus, participants use post-saccadic feedback flexibly, depending on their intentions and pending actions. |
Christoph Helmchen; Björn Machner; Andreas Sprenger; David S. Zee Monocular patching attenuates vertical nystagmus in Wernicke's Encephalopathy via release of activity in subcortical visual pathways Journal Article In: Movement Disorders Clinical Practice, vol. 9, no. 1, pp. 107–109, 2022. @article{Helmchen2022, Downbeat nystagmus (DBN) is common in ataxia syndromes and usually related to cerebellar flocculus dysfunction. Persistent and disabling DBN commonly occurs in B1 deficient Wernicke's encephalopathy (WE) causing a functional cerebellar disorder.1 Here we describe a new, unusual phenomenon in a WE patient who has had severe vertical oscillopsia for years due to an incapacitating DBN: oscillopsia and his nystagmus is markedly attenuated when he covers one eye and views monocularly. We propose this is a new clinical sign of emerging activity in subcortical visual pathways. |
Christoph Helmchen; Björn Machner; Janina Gablentz; Andreas Sprenger; David S. Zee Downbeat nystagmus is abolished by alcohol in nonalcoholic Wernicke encephalopathy Journal Article In: Neurology: Clinical Practice, vol. 12, no. 5, pp. E129–E132, 2022. @article{Helmchen2022b, Background and ObjectivesLesions of the cerebellar flocculus cause enduring downbeat nystagmus (DBN) with unrelenting oscillopsia. Unlike most patients with DBN, the flocculus is structurally spared in nonalcoholic Wernicke encephalopathy (nWE) with chronic DBN. The objective was to study the effects of alcohol in nWE.MethodsWe recorded eye movements of a unique patient with nWE under controlled alcohol consumption who said his oscillopsia disappeared with a few drinks of alcohol.ResultsHis DBN was markedly diminished by alcohol (by 77.4%), although he remained alert with normal saccades.DiscussionThis striking observation may be caused by the differential effect of alcohol on the perihypoglossal complex and the paramedian tract neurons, which control the level of activity in the flocculus, with opposite (inhibition and excitation, respectively) effects. The finding suggests new ideas about the treatment and pathophysiology of DBN with a structurally intact cerebellum. |
S. N. Hof; F. C. Loonstra; L. R. J. Ruiter; L. J. Rijn; A. Petzold; B. M. J. Uitdehaag; J. A. Nij Bijvank The prevalence of internuclear ophthalmoparesis in a population-based cohort of individuals with multiple sclerosis Journal Article In: Multiple Sclerosis and Related Disorders, vol. 63, pp. 1–7, 2022. @article{Hof2022, Background: Internuclear ophthalmoparesis (INO) occurs in 15–52% of individuals with multiple sclerosis (MS) and is reliably detected by infrared oculography. Methods for diagnosing INO with infrared oculography and the association between INO and MS characteristics need confirmation. We aimed to describe INO prevalence and the clinical characteristics of individuals with MS and INO in a population-based cohort of individuals with MS born in the year 1966 (Project Y). Methods: Previously described thresholds for the versional dysconjugacy index (VDI), assessed with standardized infrared oculography, were used to detect INO in participants of project Y. Clinical characteristics, visual functioning and complaints were compared between individuals with MS with INO and individuals with MS without INO. Results: Two-hundred-twenty individuals with MS and 110 healthy controls were included. VDI values exceeding the threshold for INO presented in 53 (24%) individuals with MS and 19 controls (13%). INO was associated with male sex, greater disability, worse cognition and worse arm function in individuals with MS. There was no association with disease duration, visual functioning or complaints. Conclusions: INO is prevalent among individuals with MS aged fifty-three and related to clinical characteristics of MS. INO was more frequently detected in healthy controls than previous studies, implying that oculography based diagnosis of INO requires further refinement. |
Alex J. Hoogerbrugge; Christoph Strauch; Zoril A. Oláh; Edwin S. Dalmaijer; Tanja C. W. Nijboer; Stefan Van der Stigchel Seeing the Forrest through the trees: Oculomotor metrics are linked to heart rate Journal Article In: PLoS ONE, vol. 17, no. 8, pp. 1–12, 2022. @article{Hoogerbrugge2022, Fluctuations in a person's arousal accompany mental states such as drowsiness, mental effort, or motivation, and have a profound effect on task performance. Here, we investigated the link between two central instances affected by arousal levels, heart rate and eye movements. In contrast to heart rate, eye movements can be inferred remotely and unobtrusively, and there is evidence that oculomotor metrics (i.e., fixations and saccades) are indicators for aspects of arousal going hand in hand with changes in mental effort, motivation, or task type. Gaze data and heart rate of 14 participants during film viewing were used in Random Forest models, the results of which show that blink rate and duration, and the movement aspect of oculomotor metrics (i.e., velocities and amplitudes) link to heart rate–more so than the amount or duration of fixations and saccades. We discuss that eye movements are not only linked to heart rate, but they may both be similarly influenced by the common underlying arousal system. These findings provide new pathways for the remote measurement of arousal, and its link to psychophysiological features. |
Lijuan Huang; Yunyu Zhou; Wencong Chen; Ping Lin; Yan Xie; Kaiwen He; Shasha Zhang; Yuyu Wu; Ningdong Li Correlations of FRMD7 gene mutations with ocular oscillations Journal Article In: Scientific Reports, vol. 12, no. 1, pp. 1–10, 2022. @article{Huang2022a, Mutations in the FERM domain containing 7 (FRMD7) gene have been proven to be responsible for infantile nystagmus (IN). The purpose of this study is to investigate FRMD7 gene mutations in patients with IN, and to evaluate the nystagmus intensity among patients with and without FRMD7 mutations. The affected males were subdivided into three groups according to whether or not having FRMD7 mutations and the types of mutations. Fifty-two mutations were detected in FRMD7 in 56 pedigrees and 34 sporadic patients with IN, including 28 novel and 24 previous reported mutations. The novel identified mutations further expand the spectrum of FRMD7 mutations. The parameters of nystagmus intensity and the patients' best corrected visual acuity were not statistically different among the patients with and without identified FRMD7 mutations, and also not different among patients with different mutant types. The FERM-C domain, whose amino acids are encoded by exons 7, 8 and 9, could be the harbor region for most mutations. Loss-of-function is suggested to be the common molecular mechanism for the X-linked infantile nystagmus. |
Todd E. Hudson; Jenna Conway; John-Ross Rizzo; John Martone; Liyung T. Chou; Laura J. Balcer; Steven L. Galetta; Janet C. Rucker In: Clinical and Translational Neuroscience, vol. 6, pp. 1–12, 2022. @article{Hudson2022, Number and picture rapid automatized naming (RAN) tests are useful sideline diagnostic tools. The main outcome measure of these RAN tests is the completion time, which is prolonged with a concussion, yet yields no information about eye movement behavior. We investigated eye movements during a digitized Mobile Universal Lexicon Evaluation System (MULES) test of rapid picture naming. A total of 23 participants with a history of concussion and 50 control participants performed MULES testing with simultaneous eye tracking. The test times were longer in participants with a concussion (32.4 s [95% CI 30.4, 35.8] vs. 26.9 s [95% CI 25.9, 28.0] |
Saad Idrees; Matthias Philipp Baumann; Maria M. Korympidou; Timm Schubert; Alexandra Kling; Katrin Franke; Ziad M. Hafed; Felix Franke; Thomas A. Münch Suppression without inhibition: How retinal computation contributes to saccadic suppression Journal Article In: Communications Biology, vol. 5, pp. 1–23, 2022. @article{Idrees2022, Visual perception remains stable across saccadic eye movements, despite the concurrent strongly disruptive visual flow. This stability is partially associated with a reduction in visual sensitivity, known as saccadic suppression, which already starts in the retina with reduced ganglion cell sensitivity. However, the retinal circuit mechanisms giving rise to such suppression remain unknown. Here, we describe these mechanisms using electrophysiology in mouse, pig, and macaque retina, 2-photon calcium imaging, computational modeling, and human psychophysics. We find that sequential stimuli, like those that naturally occur during saccades, trigger three independent suppressive mechanisms in the retina. The main mechanism is triggered by contrast-reversing sequential stimuli and originates within the receptive field center of ganglion cells. It does not involve inhibition or other known suppressive mechanisms like saturation or adaptation. Instead, it relies on temporal filtering of the inherently slow response of cone photoreceptors coupled with downstream nonlinearities. Two further mechanisms of suppression are present predominantly in ON ganglion cells and originate in the receptive field surround, highlighting another disparity between ON and OFF ganglion cells. The mechanisms uncovered here likely play a role in shaping the retinal output following eye movements and other natural viewing conditions where sequential stimulation is ubiquitous. |
Uday K. Jagadisan; Neeraj J. Gandhi Population temporal structure supplements the rate code during sensorimotor transformations Journal Article In: Current Biology, vol. 32, pp. 1010–1025, 2022. @article{Jagadisan2022, Sensorimotor transformations are mediated by premotor brain networks where individual neurons represent sensory, cognitive, and movement-related information. Such multiplexing poses a conundrum—how does a decoder know precisely when to initiate a movement if its inputs are active at times when a movement is not desired (e.g., in response to sensory stimulation)? Here, we propose a novel hypothesis: movement is triggered not only by an increase in firing rate but, critically, also by a reliable temporal pattern in the population response. Laminar recordings in the macaque superior colliculus (SC), a midbrain hub of orienting control, and pseudo-population analyses in SC and cortical frontal eye fields (FEFs) corroborated this hypothesis. Specifically, using a measure that captures the fidelity of the population code—here called temporal stability—we show that the temporal structure fluctuates during the visual response but becomes increasingly stable during the movement command. Importantly, we used spatiotemporally patterned microstimulation to causally test the contribution of population temporal stability in gating movement initiation and found that stable stimulation patterns were more likely to evoke a movement. Finally, a spiking neuron model was able to discriminate between stable and unstable input patterns, providing a putative biophysical mechanism for decoding temporal structure. These findings offer new insights into the long-standing debate on motor preparation and generation by situating the movement gating signal in temporal features of activity in shared neural substrates, and they highlight the importance of short-term population history in neuronal communication and behavior. |
Divya Jain; Kristy B. Arbogast; Catherine C. McDonald; Olivia E. Podolak; Susan S. Margulies; Kristina B. Metzger; David R. Howell; Mitchell M. Scheiman; Christina L. Master Eye tracking metrics differences among uninjured adolescents and those with acute or persistent post-concussion symptoms Journal Article In: Optometry and Vision Science, vol. 99, no. 8, pp. 616–625, 2022. @article{Jain2022, SIGNIFICANCE Eye tracking assessments that include pupil metrics can supplement current clinical assessments of vision and autonomic dysfunction in concussed adolescents. PURPOSE This study aimed to explore the utility of a 220-second eye tracking assessment in distinguishing eye position, saccadic movement, and pupillary dynamics among uninjured adolescents, those with acute post-concussion symptoms (≤28 days since concussion), or those with persistent post-concussion symptoms (>28 days since concussion). METHODS Two hundred fifty-six eye tracking metrics across a prospective observational cohort of 180 uninjured adolescents recruited from a private suburban high school and 224 concussed adolescents, with acute or persistent symptoms, recruited from a tertiary care subspecialty concussion care program, 13 to 17 years old, from August 2017 to June 2021 were compared. Kruskal-Wallis tests were used, and Bonferroni corrections were applied to account for multiple comparisons and constructed receiver operating characteristic curves. Principal components analysis and regression models were applied to determine whether eye tracking metrics can augment clinical and demographic information in differentiating uninjured controls from concussed adolescents. RESULTS Two metrics of eye position were worse in those with concussion than uninjured adolescents, and only one metric was significantly different between acute cases and persistent cases. Concussed adolescents had larger left and right mean, median, minimum, and maximum pupil size than uninjured controls. Concussed adolescents had greater differences in mean, median, and variance of left and right pupil size. Twelve metrics distinguished female concussed participants from uninjured; only four were associated with concussion status in males. A logistic regression model including clinical and demographics data and transformed eye tracking metrics performed better in predicting concussion status than clinical and demographics data alone. CONCLUSIONS Objective eye tracking technology is capable of quickly identifying vision and pupillary disturbances after concussion, augmenting traditional clinical concussion assessments. These metrics may add to existing clinical practice for monitoring recovery in a heterogeneous adolescent concussion population. |
Anupama Janardhanan; Vijaylakshmi Perumalswamy; Shashikant Shetty; Chitaranjan Mishra; Matt J. Dunn Acquired vertical pendular nystagmus in diffuse unilateral subacute neuroretinitis: A diagnostic dilemma Journal Article In: Indian Journal of Ophthalmology, vol. 2, pp. 503–505, 2022. @article{Janardhanan2022, A retinal infectious pathology, an acquired vertical nystagmus, and a suspicious neuroimaging result! Independently, these three entities are not uncommon. However, when they are consecutively observed in a young patient, it ramifies into an intriguing clinical scenario. A 17-year-old diagnosed case of diffuse unilateral subacute neuroretinitis presented to us with acute-onset vertical oscillations. On neuroimaging, she was found to have cerebellar dysgenesis. This case prompted us to revisit the pathogenesis of acquired vertical nystagmus and evaluate whether it resulted from disturbance of afferent (severe visual impairment) or efferent (cerebellar dysfunction) components of the neural integrator mechanism. |
Miranda J. Munoz; James L. Reilly; Gian D. Pal; Leo Verhagen Metman; Yessenia M. Rivera; Quentin H. Drane; Daniel M. Corcos; Fabian J. David; Lisa C. Goelz Medication adversely impacts visually-guided eye movements in Parkinson's disease Journal Article In: Clinical Neurophysiology, vol. 143, pp. 145–153, 2022. @article{Munoz2022, Objective: We examined whether previous inconsistent findings about the effect of anti-Parkinsonian medication on visually-guided saccades (VGS) were due to the use of different paradigms, which change the timing of fixation offset and target onset, or different target eccentricities. Methods: Thirty-three participants with Parkinson's disease (PD) completed the VGS tasks OFF and ON medication, along with 13 healthy controls. Performance on 3 paradigms (gap, step, and overlap) and 2 target eccentricities was recorded. We used mixed models to determine the effect of medication, paradigm, and target eccentricity on saccade latency, gain, and peak velocity. Results: First, we confirmed known paradigm effects on latency, and target eccentricity effects on gain and peak velocity in participants with PD. Second, latency was positively associated with OFF medication Movement Disorders Society – Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score in PD. Third, medication prolonged latency for the larger target eccentricity across the 3 paradigms, while decreasing gain and peak velocity in the step paradigm across target eccentricities. Conclusions: Medication adversely affected and was not therapeutically beneficial for VGS. Previous inconsistencies may have resulted from chosen target eccentricity. Significance: The negative medication effect on VGS may be clinically significant, as many activities in daily life require oculomotor control, inhibitory control, and visually-guided shifts of attention. |
Ryohei Nakayama; Jean Baptiste Bardin; Ai Koizumi; Isamu Motoyoshi; Kaoru Amano Building a decoder of perceptual decisions from microsaccades and pupil size Journal Article In: Frontiers in Psychology, vol. 13, pp. 1–14, 2022. @article{Nakayama2022, Many studies have reported neural correlates of visual awareness across several brain regions, including the sensory, parietal, and frontal areas. In most of these studies, participants were instructed to explicitly report their perceptual experience through a button press or verbal report. It is conceivable, however, that explicit reporting itself may trigger specific neural responses that can confound the direct examination of the neural correlates of visual awareness. This suggests the need to assess visual awareness without explicit reporting. One way to achieve this is to develop a technique to predict the visual awareness of participants based on their peripheral responses. Here, we used eye movements and pupil sizes to decode trial-by-trial changes in the awareness of a stimulus whose visibility was deteriorated due to adaptation-induced blindness (AIB). In the experiment, participants judged whether they perceived a target stimulus and rated the confidence they had in their perceptual judgment, while their eye movements and pupil sizes were recorded. We found that not only perceptual decision but also perceptual confidence can be separately decoded from the eye movement and pupil size. We discuss the potential of this technique with regard to assessing visual awareness in future neuroimaging experiments. |
Kien Trong Nguyen; Wei-Kuang Liang; Chi-Hung Juan; Chin-An Wang Time-frequency analysis of pupil size modulated by global luminance, arousal, and saccade preparation signals using Hilbert-Huang transform Journal Article In: International Journal of Psychophysiology, vol. 176, pp. 89–99, 2022. @article{Nguyen2022, Pupil size changes constantly and is mainly determined by global luminance signals. In addition, the pupil responds to various cognitive and arousal processes, with larger pupil dilation observed in higher levels of cognitive or arousal processing. Although these task-evoked pupillary responses are extensively used in the pupil research, pupil analysis focusing on the frequency domain, particularly in the context of arousal and cognitive modulations, is less established. Fourier Transform method (FFT) has been used to understand the modulation of task difficulty on pupil oscillations. However, physiological signals are often characterized as non-linear and non-stationary waves, and the conventional spectral analytical method with linearity presumption is less appropriate to reveal modulation dynamics between time and frequency. Here, we used Hilbert-Huang Transform (HHT) to examine the time-frequency modulations on pupil size regulated by arousal, cognitive, and global luminance signals. Consistent with previous research, using FFT, higher spectral densities were obtained with lower luminance background. Moreover, higher spectral densities were found in the high emotional arousal condition. With HHT, we further demonstrated temporal changes on amplitude spectrum and inter-trial phase coherence (ITPC) in each intrinsic mode function (IMF), with stronger amplitudes in higher IMFs (i.e., low frequencies). Moreover, although global luminance, arousal and saccade preparation modulated pupil oscillatory responses, the modulation pattern in different IMFs was different. Together, our results demonstrated dynamics between the time and frequency domain on pupil oscillatory responses, highlighting the importance of examining the time-frequency interactions in the context of various pupil modulations. |
James E. Niemeyer; Seth Akers-Campbell; Aaron Gregoire; Michael A. Paradiso Perceptual enhancement and suppression correlate with V1 neural activity during active sensing Journal Article In: Current Biology, vol. 32, pp. 2654–2667, 2022. @article{Niemeyer2022, Perception in multiple sensory modalities is an active process that involves exploratory behaviors. In humans and other primates, vision results from sensory sampling guided by saccadic eye movements. Saccades are known to modulate visual perception, and a corollary discharge signal associated with saccades appears to establish a sense of visual stability. Neural recordings have shown that saccades also modulate activity widely across the brain. To investigate the neural basis of saccadic effects on perception, simultaneous recordings from multiple neurons in area V1 were made as animals performed a contrast detection task. Perceptual and neural measures were compared when the animal made real saccades that brought a stimulus into V1 receptive fields and when simulated saccades were made (identical retinal stimulation but no eye movement). When real saccades were made and low spatial frequency stimuli were presented, we observed a reduction in both perceptual sensitivity and neural activity compared with simulated saccades; conversely, with higher spatial frequency stimuli, saccades increased visual sensitivity and neural activity. The performance of neural decoders, which used the activity of the population of simultaneously recorded neurons, showed saccade effects on sensitivity that mirrored the frequency-dependent perceptual changes, suggesting that the V1 population activity could support the perceptual effects. A minority of V1 neurons had significant choice probabilities, and the saccades decreased both average choice probability and pairwise noise correlations. Taken together, the findings suggest that a signal related to saccadic eye movements alters V1 spiking to increase the independence of spiking neurons and bias the system toward processing higher spatial frequencies, presumably to enhance object recognition. The effects of saccades on visual perception and noise correlations appear to parallel effects observed in other sensory modalities, suggesting a general principle of active sensory processing. |