EyeLink Cognitive Publications
All EyeLink cognitive and perception research publications up until 2023 (with some early 2024s) are listed below by year. You can search the publications using keywords such as Visual Search, Scene Perception, Face Processing, etc. You can also search for individual author names. If we missed any EyeLink cognitive or perception articles, please email us!
2023 |
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 |
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. |
Susanne M. Veen; Alexander Stamenkovic; James S. Thomas; Peter E. Pidcoe Skill-related adaptive modifications of gaze stabilization in elite and non-elite athletes Journal Article In: Frontiers in Sports and Active Living, vol. 4, pp. 1–7, 2022. @article{Veen2022, The vestibular ocular reflex (VOR) provides gaze stability during head movements by driving eye movements in a direction opposing head motion. Although vestibular-based rehabilitation strategies are available, it is still unclear whether VOR can be modulated by training. By examining adaptations in gaze stabilization mechanisms in a population with distinct visuomotor requirements for task success (i.e., gymnasts), this study was designed to determine whether experience level (as a proxy of training potential) was associated with gaze stabilization modifications during fixed target (VOR promoting) and fixed-to-head-movement target (VOR suppressing) tasks. Thirteen gymnasts of different skill levels participated in VOR and VOR suppression tasks. The gain between head and eye movements was calculated and compared between skill levels using an analysis of covariance. Across experience levels, there was a similar degradation in VOR gain away from −1 at higher movement speeds. However, during the suppression tasks, more experienced participants were able to maintain VOR gain closer to 0 across movement speeds, whereas novice participants showed greater variability in task execution regardless of movement speed. Changes in adaptive modifications to gaze stability associated with experience level suggest that the mechanisms impacting gaze stabilization can be manipulated through training. |
Elle Heusden; Wieske Zoest; Mieke Donk; Christian N. L. Olivers An attentional limbo: Saccades become momentarily non-selective in between saliency-driven and relevance-driven selection Journal Article In: Psychonomic Bulletin & Review, vol. 29, pp. 1327–1337, 2022. @article{Heusden2022, Human vision involves selectively directing the eyes to potential objects of interest. According to most prominent theories, selection is the quantal outcome of an ongoing competition between saliency-driven signals on the one hand, and relevance-driven signals on the other, with both types of signals continuously and concurrently projecting onto a common priority map. Here, we challenge this view. We asked participants to make a speeded eye movement towards a target orientation, which was presented together with a non-target of opposing tilt. In addition to the difference in relevance, the target and non-target also differed in saliency, with the target being either more or less salient than the non-target. We demonstrate that saliency- and relevance-driven eye movements have highly idiosyncratic temporal profiles, with saliency-driven eye movements occurring rapidly after display onset while relevance-driven eye movements occur only later. Remarkably, these types of eye movements can be fully separated in time: We find that around 250 ms after display onset, eye movements are no longer driven by saliency differences between potential targets, but also not yet driven by relevance information, resulting in a period of non-selectivity, which we refer to as the attentional limbo. Binomial modeling further confirmed that visual selection is not necessarily the outcome of a direct battle between saliency- and relevance-driven signals. Instead, selection reflects the dynamic changes in the underlying saliency- and relevance-driven processes themselves, and the time at which an action is initiated then determines which of the two will emerge as the driving force of behavior. |
Valentina Vencato; Mark Harwood; Laurent Madelain Saccadic initiation biased by fixational activity Journal Article In: Vision Research, vol. 201, pp. 1–15, 2022. @article{Vencato2022, Both the gap and overlap paradigm may reveal the interaction between fixating and moving the eyes, but the effects of the overlap paradigm have not been fully characterized yet. Here we present a series of experiments probing how an overlap paradigm, combined with the manipulation of stimuli durations, saliency and transient changes might modulate saccadic reaction time distributions. We recorded saccadic reaction time in four participants in six experiments in which a saccade-target appeared at a pseudo-random amplitude after a fixation period. First, we parametrically manipulated the duration of the overlap using a range of intervals (from 0 to 200 ms). In a second experiment we probed the interaction of various foreperiod intervals (i.e. the duration of the fixation period prior to saccade-target onset) and overlap using two overlap intervals (20 or 140 ms). In two additional experiments we manipulated either the stimuli sizes or their contrast ratio in overlap paradigms (20 or 140 ms). Lastly, we introduced a visual transient during the overlap interval via two manipulations (both with a range of SOA): either a distractor ring appeared around the fixation-target, or a dynamic random noise patch replaced the fixation-target. Results show reliable modifications in the latency distributions depending on the overlap interval as well as idiosyncratic differences. Additional experimental manipulations also affected the latency distributions revealing strong interacting inhibitory processes. We conclude that the effects of overlap intervals may combine with the influence of other stimuli properties affecting decision process. |
Jason E. Vice; Mandy K. Biles; Marcello Maniglia; Kristina M. Visscher Oculomotor changes following learned use of an eccentric retinal locus Journal Article In: Vision Research, vol. 201, pp. 1–9, 2022. @article{Vice2022, People with bilateral central vision loss sometimes develop a new point of oculomotor reference called a preferred retinal locus (PRL) that is used for fixating and planning saccadic eye movements. How individuals develop and learn to effectively use a PRL is still debated; in particular, the time course of learning to plan saccades using a PRL and learning to stabilize peripheral fixation at the desired location. Here we address knowledge limitations through research describing how eye movements change as a person learns to adopt an eccentric retinal locus. Using a gaze-contingent, eye tracking-guided paradigm to simulate central vision loss, 40 participants developed a PRL by engaging in an oculomotor and visual recognition task. After 12 training sessions, significant improvements were observed in six eye movement metrics addressing different aspects involved in learning to use a PRL: first saccade landing dispersion, saccadic re-referencing, saccadic precision, saccadic latency, percentage of useful trials, and fixation stability. Importantly, our analyses allowed separate examination of the stability of target fixation separately from the dispersion and precision of the landing location of saccades. These measures explained 50% of the across-subject variance in accuracy. Fixation stability and saccadic precision showed a strong, positive correlation. Although there was no statistically significant difference in rate of learning, individuals did tend to learn saccadic precision faster than fixation stability. Saccadic precision was also more associated with accuracy than fixation stability for the behavioral task. This suggests effective intervention strategies in low vision should address both fixation stability and saccadic precision. |
Manuel Vidal; Françoise Vitu In: PLoS ONE, vol. 17, no. 4, pp. 1–30, 2022. @article{Vidal2022, Throughout the day, humans react to multisensory events conveying both visual and auditory signals by rapidly reorienting their gaze. Several studies showed that sounds can impact the latency of visually guided saccades depending on when and where they are delivered. We found that unlocalized beeps delivered near the onset time of a visual target reduce latencies, more for early beeps and less for late beeps, however, this modulation is far weaker than for perceptual temporal judgments. Here we tested our previous assumption that beeps shift the perceived timing of target onset and result in two competing effects on saccade latencies: a multisensory modulation in line with the expected perceptual effect and an illusory gap/overlap effect, resulting from target appearance being perceived later/closer in time than fixation offset and shortening/lengthening saccade latencies. Gap/overlap effects involve an oculomotor component associated with neuronal activity in the superior colliculus (SC), a multisensory subcortical structure devoted to sensory-motor transformation. We therefore predicted that the interfering illusory gap/overlap effect would be weaker for manual responses, which involve distinct multisensory areas. In three experiments we manipulated the delay between target onset and an irrelevant auditory beep (stimulus onset asynchrony; SOA) and between target onset and fixation offset (real gap/overlap). Targets appeared left/right of fixation and participants were instructed to make quick saccades or button presses towards the targets. Adding a real overlap/gap (50% of SOA) compensated for the illusory gap/overlap by increasing the beep-related modulation of saccade latencies across the entire SOA range, whereas it barely affected manual responses. However, although auditory and gap/overlap effects modulated saccade latencies in similar ways, these were additive and could saturate, suggesting that they reflect independent mechanisms. Therefore, multisensory temporal binding affects perception and oculomotor control differently, likely due to the implication of the SC in saccade programming and multisensory integration. |
Cécile Vullings; Zachary Lively; Preeti Verghese Saccades during visual search in macular degeneration Journal Article In: Vision Research, vol. 201, pp. 1–14, 2022. @article{Vullings2022, Macular degeneration (MD) compromises both high-acuity vision and eye movements when the foveal regions of both eyes are affected. Individuals with MD adapt to central field loss by adopting a preferred retinal locus (PRL) for fixation. Here, we investigate how individuals with bilateral MD use eye movements to search for targets in a visual scene under realistic binocular viewing conditions. Five individuals with binocular scotomata, 3 individuals with monocular scotomata and 6 age-matched controls participated in our study. We first extensively mapped the binocular scotoma with an eyetracker, while fixation was carefully monitored (Vullings & Verghese, 2020). Participants then completed a visual search task where 0, 1, or 2 Gaussian blobs were distributed randomly across a natural scene. Participants were given 10 s to actively search the display and report the number of blobs. An analysis of saccade characteristics showed that individuals with binocular scotomata made more saccades in the direction of their scotoma than controls for the same directions. Saccades in the direction of the scotoma were typically of small amplitude, and did not fully uncover the region previously hidden by the scotoma. Rather than make more saccades to explore this hidden region, participants frequently made saccades back toward newly uncovered regions. Backward saccades likely serve a similar purpose to regressive saccades exhibited during reading in MD, by inspecting previously covered regions near the direction of gaze. Our analysis suggests that the higher prevalence of backward saccades in individuals with binocular scotomata might be related to the PRL being adjacent to the scotoma. |
Chin-an Wang; Brian White; Douglas P. Munoz Pupil-linked arousal signals in the midbrain superior colliculus Journal Article In: Journal of Cognitive Neuroscience, vol. 34, no. 8, pp. 1340–1354, 2022. @article{Wang2022b, The orienting response evoked by the appearance of a salient stimulus is modulated by arousal; however, neural under- pinnings for the interplay between orienting and arousal are not well understood. The superior colliculus (SC), causally involved in multiple components of the orienting response including gaze and attention shifts, receives not only multisensory and cognitive inputs but also arousal-regulated inputs from various cortical and subcortical structures. To investigate the impact of moment-by-moment fluctuations in arousal on orienting saccade responses, we used microstimulation of the monkey SC to trigger saccade responses, and we used pupil size and velocity to index the level ofarousal at stimulation onset because these measures correlate with changes in brain states and locus coeruleus activity. Saccades induced by SC microstimulation correlated with prestimulation pupil velocity, with higher pupil velocities on trials without evoked saccades than with evoked saccades. In contrast, prestimulation absolute pupil size did not correlate with saccade behavior. Moreover, pupil velocity correlated with evoked saccade latency and metrics. Together, our results demonstrated that small fluctuations in arousal, indexed by pupil velocity, can modulate the saccade response evoked by SC microstimulation in awake behaving monkeys. |
Ying Wang; Hai-Long Lyu; Xiao-Han Tian; Bing Lang; Xiao-Yi Wang; David St Clair; Renrong Wu; Jingping Zhao The similar eye movement dysfunction between major depressive disorder, bipolar depression and bipolar mania Journal Article In: The World Journal of Biological Psychiatry, vol. 23, no. 9, pp. 689–702, 2022. @article{Wang2022i, Objective: To find eye movement characteristics in patients with affective disorders. Method: The demographic and clinical evaluation data of patients with major depressive disorder (MDD), bipolar disorder (BPD), and healthy control (HC) were collected. EyeLink 1000 eye tracker was used to collect eye movement data. Chi-squared test and independent sample t-test were used for demographics and clinical characteristics. The Mann–Whitney U-test was used to compare the eye movement variables among four groups, and the FDR method was used for multiple comparison correction. Pearson correlation analysis was used to analyse the relationship between clinical symptoms and eye movement variables. Results: Patients with affective disorders showed smaller saccade amplitude under free-viewing task, more fixations and saccades, shorter fixation duration, longer saccade duration under fixation stability and smooth pursuit tasks (all, p < 0.05) when compared to HC, but there was no significant difference in all eye movement variables among patients in the three groups. Also, all eye movement variables under the three paradigms had no significant correlation with clinical scale scores. Conclusion: Patients with major depression, bipolar depression and bipolar mania share similar eye movement dysfunction under free-viewing, fixation stability and smooth pursuit tasks. |
Abigail L. M. Webb; Jordi M. Asher; Paul B. Hibbard Saccadic eye movements are deployed faster for salient facial stimuli, but are relatively indifferent to their emotional content Journal Article In: Vision Research, vol. 198, pp. 1–11, 2022. @article{Webb2022, The present study explores the threat bias for fearful facial expressions using saccadic latency, with a particular focus on the role of low-level facial information, including spatial frequency and contrast. In a simple localisation task, participants were presented with spatially-filtered versions of neutral, fearful, angry and happy faces. Together, our findings show that saccadic responses are not biased toward fearful expressions compared to neutral, angry or happy counterparts, regardless of their spatial frequency content. Saccadic response times are, however, significantly influenced by the spatial frequency and contrast of facial stimuli. We discuss the implications of these findings for the threat bias literature, and the extent to which image processing can be expected to influence behavioural responses to socially-relevant facial stimuli. |
Rebekka Schröder; Eliana Faiola; Maria Fernanda Urquijo; Katharina Bey; Inga Meyhöfer; Maria Steffens; Anna-Maria Kasparbauer; Anne Ruef; Hanna Högenauer; René Hurlemann; Joseph Kambeitz; Alexandra Philipsen; Michael Wagner; Nikolaos Koutsouleris; Ulrich Ettinger Neural correlates of smooth pursuit eye movements in schizotypy and recent onset psychosis: A multivariate pattern classification approach Journal Article In: Schizophrenia Bulletin Open, vol. 3, no. 1, pp. 1–13, 2022. @article{Schroeder2022, Schizotypy refers to a set of personality traits that bear resemblance, at subclinical level, to psychosis. Despite evidence of similarity at multiple levels of analysis, direct comparisons of schizotypy and clinical psychotic disorders are rare. Therefore, we used functional magnetic resonance imaging (fMRI) to examine the neural correlates and task-based functional connectivity (psychophysiological interactions; PPI) of smooth pursuit eye movements (SPEM) in patients with recent onset psychosis (ROP; n = 34), participants with high levels of negative (HNS; n = 46) or positive (HPS; n = 41) schizotypal traits, and low-schizotypy control participants (LS; n = 61) using machine-learning. Despite strong previous evidence that SPEM is a highly reliable marker of psychosis, patients and controls could not be significantly distinguished based on SPEM performance or blood oxygen level dependent (BOLD) signal during SPEM. Classification was, however, significant for the right frontal eye field (FEF) seed region in the PPI analyses but not for seed regions in other key areas of the SPEM network. Applying the right FEF classifier to the schizotypal samples yielded decision scores between the LS and ROP groups, suggesting similarities and dissimilarities of the HNS and HPS samples with the LS and ROP groups. The very small difference between groups is inconsistent with previous studies that showed significant differences between patients with ROP and controls in both SPEM performance and underlying neural mechanisms with large effect sizes. As the current study had sufficient power to detect such differences, other reasons are discussed. |
Rebekka Schröder; Martin Reuter; Kaja Faßbender; Thomas Plieger; Jessie Poulsen; Simon S. Y. Lui; Raymond C. K. Chan; Ulrich Ettinger The role of the SLC6A3 3' UTR VNTR in nicotine effects on cognitive, affective, and motor function Journal Article In: Psychopharmacology, vol. 239, no. 2, pp. 489–507, 2022. @article{Schroeder2022a, Rationale: Nicotine has been widely studied for its pro-dopaminergic effects. However, at the behavioural level, past investigations have yielded heterogeneous results concerning effects on cognitive, affective, and motor outcomes, possibly linked to individual differences at the level of genetics. A candidate polymorphism is the 40-base-pair variable number of tandem repeats polymorphism (rs28363170) in the SLC6A3 gene coding for the dopamine transporter (DAT). The polymorphism has been associated with striatal DAT availability (9R-carriers > 10R-homozygotes), and 9R-carriers have been shown to react more strongly to dopamine agonistic pharmacological challenges than 10R-homozygotes. Objectives: In this preregistered study, we hypothesized that 9R-carriers would be more responsive to nicotine due to genotype-related differences in DAT availability and resulting dopamine activity. Methods: N=194 non-smokers were grouped according to their genotype (9R-carriers, 10R-homozygotes) and received either 2-mg nicotine or placebo gum in a between-subject design. Spontaneous blink rate (SBR) was obtained as an indirect measure of striatal dopamine activity and smooth pursuit, stop signal, simple choice and affective processing tasks were carried out in randomized order. Results: Reaction times were decreased under nicotine compared to placebo in the simple choice and stop signal tasks, but nicotine and genotype had no effects on any of the other task outcomes. Conditional process analyses testing the mediating effect of SBR on performance and how this is affected by genotype yielded no significant results. Conclusions: Overall, we could not confirm our main hypothesis. Individual differences in nicotine response could not be explained by rs28363170 genotype. |
Ehsan Sedaghat-Nejad; Jay S. Pi; Paul Hage; Mohammad Amin Fakharian; Reza Shadmehr Synchronous spiking of cerebellar Purkinje cells during control of movements Journal Article In: PNAS, vol. 119, no. 14, pp. 1–11, 2022. @article{SedaghatNejad2022, The ability of the brain to accurately control a movement depends on the cerebellum. Yet, how the cerebellar neurons encode information relevant for this control remains poorly understood. The computations that are performed in the cerebellar cortex are transmitted to its nuclei via Purkinje cells (P cells), which are inhibitory neurons. How- ever, if the spiking activity within P cell populations were temporally synchronized, that inhibition would entrain nucleus neurons, making them fire. Do P cells transmit information by synchronously timing their spikes? We simultaneously recorded from multiple P cells while marmosets performed saccadic eye movements, and organized the neurons into populations that shared a complex spike response to error. Before move- ment onset, this population ofP cells increased their simple spike activity with a magni- tude that depended on the velocity of the upcoming saccade, and then sharply reduced their activity below baseline at saccade onset. During deceleration, the spikes became temporally aligned within the population. Thus, the P cells relied on disinhibition, combined with spike synchronization, to convey to the nucleus when to decelerate and potentially stop the movement. |
Natela M. Shanidze; Zachary Lively; Rachel Lee; Preeti Verghese Saccadic contributions to smooth pursuit in macular degeneration Journal Article In: Vision Research, vol. 200, pp. 1–13, 2022. @article{Shanidze2022, Saccades during smooth pursuit can help bring the fovea on target, particularly in cases of low pursuit gain. Individuals with macular degeneration often suffer damage to the central retina including the fovea, which impacts oculomotor function such as fixation, saccadic and smooth pursuit eye movements. We hypothesized that these oculomotor changes in macular degeneration (MD) would make saccades less appropriately directed (even if more numerous). To investigate saccades during pursuit in MD, we conducted a quantitative analysis of smooth pursuit eye movement data from a prior study, Vision Research 141 (2017) 181–190. Here we examined saccade frequency, magnitude, and direction across viewing conditions for MD and control participants during pursuit of a target moving in a modified step-ramp paradigm. Individuals with MD had more variability in saccade directions that included directions orthogonal to the target trajectory. PRL eccentricity significantly correlated with increases in saccades in non-target directions during smooth pursuit. These results suggest that a large number of saccades during pursuit in MD participants are unlikely to be catch-up saccades that serve to keep the eye on the target. |
Xiaoyu Tang; Mengying Yuan; Zhongyu Shi; Min Gao; Rongxia Ren; Wei Ming; Yulin Gao Multisensory integration attenuates visually induced oculomotor inhibition of return Journal Article In: Journal of Vision, vol. 22, no. 4, pp. 1–17, 2022. @article{Tang2022, Inhibition of return (IOR) is a mechanism of the attention system involving bias toward novel stimuli and delayed generation of responses to targets at previously attended locations. According to the two-component theory, IOR consists of a perceptual component and an oculomotor component (oculomotor IOR [O-IOR]) depending on whether the eye movement system is activated. Previous studies have shown that multisensory integration weakens IOR when paying attention to both visual and auditory modalities. However, it remains unclear whether the O-IOR effect attenuated by multisensory integration also occurs when the oculomotor system is activated. Here, using two eye movement experiments, we investigated the effect of multisensory integration on O-IOR using the exogenous spatial cueing paradigm. In Experiment 1, we found a greater visual O-IOR effect compared with audiovisual and auditory O-IOR in divided modality attention. The relative multisensory response enhancement (rMRE) and violations of Miller's bound showed a greater magnitude of multisensory integration in the cued location compared with the uncued location. In Experiment 2, the magnitude of the audiovisual O-IOR effect was significantly less than that of the visual O-IOR in single visual modality selective attention. Implications for the effect of multisensory integration on O-IOR were discussed under conditions of oculomotor system activation, shedding new light on the two-component theory of IOR. |
Elham Azizi; Joanne Fielding; Larry A. Abel Video game training in traumatic brain injury patients: an exploratory case report study using eye tracking Journal Article In: Journal of Eye Movement Research, vol. 15, no. 1, pp. 1–14, 2022. @article{Azizi2022, Remediation of attentional impairments is an essential component of cognitive rehabilitation after traumatic brain injury (TBI). Evidence from healthy participants has demonstrated attentional improvement following playing an action video game. This exploratory study investigated its application in TBI participants in a multiple baselines single case experimental design (SCED). Saccadic eye movements, recognized as the visible indicators of visual attention, were assessed to evaluate the effectiveness of the game training. Three severe TBI participants were trained in an action game for 10 hours. Saccadic eye movements during a self-paced saccade and an abstract visual search task were investigated during baseline, mid training and post-training. Using Percentage of Non-overlapping Data (PND), analysis showed consistent increase in the rate of the self-paced saccades in participants 1 (PND=80%) and 2 (PND=70%). In abstract search, fixation duration showed a minimally effective decrease for participant 2 (PND= 60%) and a moderately effective reduction in participant 3 (PND= 80%). Search time showed a highly effective reduction in participant 2 (PND = 100%) and moderately effective decrease in participant 3 (PND=70%). Overall, video game training might modify allocation of attention in eye movements. More evidence is required to validate the usefulness of this novel method of the cognitive training |
Daniela Balslev; Alexandra G. Mitchell; Patrick J. M. Faria; Lukasz Priba; Jennifer A. Macfarlane Proprioceptive contribution to oculomotor control in humans Journal Article In: Human Brain Mapping, vol. 43, no. 16, pp. 5081–5090, 2022. @article{Balslev2022, Stretch receptors in the extraocular muscles (EOMs) inform the central nervous system about the rotation of one's own eyes in the orbits. Whereas fine control of the skeletal muscles hinges critically on proprioceptive feedback, the role of proprioception in oculomotor control remains unclear. Human behavioural studies provide evidence for EOM proprioception in oculomotor control, however, behavioural and electrophysiological studies in the macaque do not. Unlike macaques, humans possess numerous muscle spindles in their EOMs. To find out whether the human oculomotor nuclei respond to proprioceptive feedback we used functional magnetic resonance imaging (fMRI). With their eyes closed, participants placed their right index finger on the eyelid at the outer corner of the right eye. When prompted by a sound, they pushed the eyeball gently and briefly towards the nose. Control conditions separated out motor and tactile task components. The stretch of the right lateral rectus muscle was associated with activation of the left oculomotor nucleus and subthreshold activation of the left abducens nucleus. Because these nuclei control the horizontal movements of the left eye, we hypothesized that proprioceptive stimulation of the right EOM triggered left eye movement. To test this, we followed up with an eye-tracking experiment in complete darkness using the same behavioural task as in the fMRI study. The left eye moved actively in the direction of the passive displacement of the right eye, albeit with a smaller amplitude. Eye tracking corroborated neuroimaging findings to suggest a proprioceptive contribution to ocular alignment. |
Sinem B. Beylergil; Camilla Kilbane; Aasef G. Shaikh; Fatema F. Ghasia Eye movements in Parkinson's disease during visual search Journal Article In: Journal of the Neurological Sciences, vol. 440, pp. 1–16, 2022. @article{Beylergil2022, Visual spatial dysfunction is not uncommon in Parkinson's disease. We hypothesized that visual search behavior is impaired in Parkinson's disease and the deficits correlate with changes in the amplitudes and frequency of fixational and non-fixational rapid eye movements. We measured eye movements, the horizontal and vertical angular position vectors of the right and left eye using high-resolution video oculography, in the Parkinsonian cohort who viewed a blank scene and pictures with real-life scene. Latter was associated with a task of searching an object hidden in a clutter, either at an expected or an unexpected location. Parkinsonian cohort took longer initial time to reach the region of interest. The ultimate response time was comparable in both Parkinson's disease and their healthy peers. The fixation duration was comparable in two cohorts but there was a trend wise decline for the ones located at unexpected locations. Parkinson's disease participants made more fixational saccades with significantly larger amplitude and less non-fixational saccades with significantly smaller amplitude during blank scene viewing. However, overall scanned area of the blank scene was not affected in Parkinson's disease. The Parkinson's disease participants made less non-fixational saccades with amplitudes comparable to healthy control during the visual search of a target object. Fixational saccades during visual search were larger in Parkinson's disease particularly when target was placed at an unexpected location, but the frequency was unchanged. |
Sinem Balta Beylergil; Jordan Murray; Angela M. Noecker; Palak Gupta; Camilla Kilbane; Cameron C. McIntyre; Fatema F. Ghasia; Aasef G. Shaikh Temporal patterns of spontaneous fixational eye movements: The influence of basal ganglia Journal Article In: Journal of Neuro-Ophthalmology, vol. 42, no. 1, pp. 45–55, 2022. @article{Beylergil2022a, Background:Spontaneity is a unique feature of the nervous system. One of the fundamentally critical and recognized forms of spontaneous motor activity is witnessed in the visuomotor system. Microsaccades, the miniature spontaneous eye movements, are critical for the visual perception. We hypothesized that microsaccades follow specific temporal patterns that are modulated by the basal ganglia output.Methods:We used high-resolution video-oculography to capture microsaccades in 48 subjects (31 healthy and 17 with Parkinson's disease) when subjects were asked to hold their gaze on a straight-ahead target projected on white background. We analyzed spontaneous discharge patterns of microsaccades.Results:The first analysis considering coefficient of variation in intersaccadic interval distribution demonstrated that microsaccades in Parkinson's disease are more dispersed than the control group. The second analysis scrutinized microsaccades' temporal variability and revealed 3 distinct occurrence patterns: regular rhythmic, clustered, and randomly occurring following a Poisson-like process. The regular pattern was relatively more common in Parkinson's disease. Subthalamic DBS modulated this temporal pattern. The amount of change in the temporal variability depended on the DBS-induced volume of tissue activation and its overlap with the subthalamic nucleus. The third analysis determined the autocorrelations of microsaccades within 2-second time windows. We found that Parkinson's disease altered local temporal organization in microsaccade generation, and DBS had a modulatory effect.Conclusion:The microsaccades occur in 3 temporal patterns. The basal ganglia are one of the modulators of the microsaccade spontaneity. |
Olivia G. Calancie; Donald C. Brien; Jeff Huang; Brian C. Coe; Linda Booij; Sarosh Khalid-Khan; Douglas P. Munoz Maturation of temporal saccade prediction from childhood to adulthood: Predictive saccades, reduced pupil size, and blink synchronization Journal Article In: Journal of Neuroscience, vol. 42, no. 1, pp. 69–80, 2022. @article{Calancie2022, When presented with a periodic stimulus, humans spontaneously adjust their movements from reacting to predicting the timing of its arrival, but little is known about how this sensorimotor adaptation changes across development. To investigate this, we analyzed saccade behavior in 114 healthy humans (ages 6–24 years) performing the visual metronome task, who were instructed to move their eyes in time with a visual target that alternated between two known locations at a fixed rate, and we compared their behavior to per- formance in a random task, where target onsets were randomized across five interstimulus intervals (ISIs) and thus the timing of appearance was unknown. Saccades initiated before registration of the visual target, thus in anticipation of its appearance, were la- beled predictive [saccade reaction time (SRT),90ms] and saccades that were made in reaction to its appearance were labeled reac- tive (SRT.90ms). Eye-tracking behavior including saccadic metrics (e.g., peak velocity, amplitude), pupil size following saccade to target, and blink behavior all varied as a function of predicting or reacting to periodic targets. Compared with reactive saccades, pre- dictive saccades had a lower peak velocity, a hypometric amplitude, smaller pupil size, and a reduced probability of blink occurrence before target appearance. The percentage of predictive and reactive saccades changed inversely from ages 8–16, at which they reached adult-levels of behavior. Differences in predictive saccades for fast and slow target rates are interpreted by differential maturation of cerebellar-thalamic-striatal pathways. |
Daniel Ernst; Jeremy M. Wolfe How fixation durations are affected by search difficulty manipulations Journal Article In: Visual Cognition, vol. 30, pp. 339–353, 2022. @article{Ernst2022, Many eye tracking studies of visual search have focused on the role of the number of fixations and the nature of scan paths. Less attention has been paid to fixation durations and to how those durations are affected by stimulus features. Previous studies have shown that fixation durations can be as important as the number of fixations in explaining search times with complex stimuli (e.g., in search for specific faces). In the present study, simple stimuli were used in a search experiment where participants searched for a closed ring among rings with a gap. We manipulated distractor heterogeneity (DH), target-distractor similarity (TDS), and stimulus density (SDY, set size within a constant search window), and estimated the contributions of these factors to gaze behaviour and trial search time. The results show that fixation durations contribute less to variation in overall search time with simple search stimuli as compared to previous studies with more complex stimuli. However, fixation durations still increased with DH, TDS, and SDY. These effects were mainly additive, and we did not find an interaction between DH and closer element spacing at high levels of SDY that might have been expected since both DH and SDY influence distractor grouping. |
Peter Essig; Jonas Müller; Siegfried Wahl Parameters of optokinetic nystagmus are influenced by the nature of a visual stimulus Journal Article In: Applied Sciences, vol. 12, pp. 1–13, 2022. @article{Essig2022, Studies on contrast sensitivity (CS) testing using optokinetic nystagmus (OKN) proposed adjusting the stimulus presentation duration based on its contrast, to increase the time efficiency of such measurement. Furthermore, stimulus-specific limits of the least OKN gain might reduce false negatives in OKN detection procedures. Therefore, we aimed to test the effects of various stimulus characteristics on OKN and to propose the stimulus-specific limits for the OKN gain and stimulus presentation duration. We tested the effect of contrast (C), spatial frequency ((Formula presented.)), and color on selected parameters of robust OKN response, namely its onset and offset time, amplitude, and gain. The right eyes of fifteen emmetropes were tracked with an infrared eye tracker during monocular observations of sinusoidal gratings moving over the horizontal plane with a velocity of ((Formula presented.)). The available contrast levels were C: 0.5%, 2.0%, 8.2%, 16.5%, 33.0%, and 55.5% presented in a random order for ten times in all measurements of (Formula presented.) : 0.12, 0.25, 0.5, and 1.00 cycles per degree and grating type: luminance, red-green, and blue-yellow. This study showed a significant effect of the stimulus characteristics on the OKN onset, offset and gain. The effect of (Formula presented.) was insignificant in OKN amplitude; however, it indicated significance for the C and grating type. Furthermore, the OKN gain and offset limits were proposed as functions of contrast for the luminance and chromatic gratings. This study concludes the characteristics of a visual stimulus have an effect on the OKN gain and onset and offset time, yet do not affect the eye-movement amplitude considerably. Moreover, the proposed limits are expected to improve the time efficiency and eye-movement detection in OKN-based contrast sensitivity measurements. |
Peter Essig; Yannick Sauer; Siegfried Wahl Reflexive saccades used for objective and automated measurements of contrast sensitivity in selected areas of visual field Journal Article In: Translational Vision Science & Technology, vol. 11, no. 5, pp. 1–12, 2022. @article{Essig2022a, Purpose: This study proposes a novel approach for objective and automated peripheral contrast sensitivity (CS) testing using reflexive saccades. Here the CS was examined in various areas the of visual field (VF) using a live analysis of gaze data. For validation of the new test, we examined CS with an established procedure of identifying the orientation of a contrast stimulus. Methods: To perform and validate the saccade-based testing, two separate measurement events were performed. In the first, participants were asked to execute a saccade toward a newly-appeared stimulus in their VF. After the saccade execution or stimulus expiry, reporting the target orientation was required in a four-alternatives forced choice (4AFC). Therefore the first measurement yields two outcomes (objective and subjec-tive). In the second measurement, only the identification of the stimulus orientation was requested, while fixating a central mark. Stimulus contrast was controlled by an adaptive psychometric procedure in both measurements. Results: The study found strong correlations (all r ≥ 0.79) of CS values for all three possible testing methods (saccade-based responding in saccadic measurements, keyboard-based responding in saccadic measurements, keyboard-based responding in non-saccadic measurements), showing the feasibility of employment of reflexive saccades in such testing. Second, this study shows a significant influence of eccentricity and direction of the stimulus on the CS function. Conclusions: CS measured with reflexive saccades is comparable to other testing methods over several areas of the participant's VF. Hence, we propose it as a novel and objective testing procedure for CS measurements. |
Marzieh Salehi Fadardi; Javad Salehi Fadardi; Monireh Mahjoob; Hassan Doosti Post-saccadic eye movement indices under cognitive load: A path analysis to determine visual performance Journal Article In: Journal of Ophthalmic and Vision Research, vol. 17, no. 3, pp. 397–404, 2022. @article{Fadardi2022, Purpose: The evidence on the linear relationship between cognitive load, saccade, fixation, and task performance was uncertain. We tested pathway models for degraded task performance resulting from changes in saccadic and post-saccadic fixation under cognitive load. Methods: Participants' (n = 38) eye movements were recorded using a post-saccadic discrimination task with and without arithmetic operations to impose cognitive load, validated through recording heart rate variability and subjective measurement. Results: Results showed that cognitive load led to longer latencies of saccade and fixation; more inaccurate responses and fewer secondary saccades (P < 0.001). Longer saccade latencies influenced task performance indirectly via increases in fixation latency, therefore, longer reaction times and higher response errors were observed due to limited fixation duration on desired target. Conclusion: We suggest that latency and duration of fixation indicate efficiency of information processing and can predict the speed and accuracy of task performance under cognitive load. |
Cecilia E. García Cena; David Gómez-Andrés; Irene Pulido-Valdeolivas; Victoria Galán Sánchez-Seco; Angela Domingo-Santos; Sara Moreno-García; Julián Benito-León Toward an automatic assessment of cognitive dysfunction in relapsing–remitting multiple sclerosis patients using eye movement analysis Journal Article In: Sensors, vol. 22, pp. 1–18, 2022. @article{GarciaCena2022, Despite the importance of cognitive function in multiple sclerosis, it is poorly represented in the Expanded Disability Status Scale (EDSS), the commonly used clinical measure to assess disability, suggesting that an analysis of eye movement, which is generated by an extensive and well-coordinated functional network that is engaged in cognitive function, could have the potential to extend and complement this more conventional measure. We aimed to measure the eye movement of a case series of MS patients with relapsing–remitting MS to assess their cognitive status using a conventional gaze tracker. A total of 41 relapsing–remitting MS patients and 43 age-matched healthy controls were recruited for this study. Overall, we could not find a clear common pattern in the eye motor abnormalities. Vertical eye movement was more impaired in MS patients than horizontal movement. Increased latencies were found in the prosaccades and reflexive saccades of antisaccade tests. The smooth pursuit was impaired with more corrections (backup and catchup movements, p<0.01). No correlation was found between eye movement variables and EDSS or disease duration. Despite significant alterations in the behavior of the eye movements in MS patients, which are compatible with altered cognitive status, there is no common pattern of these alterations. We interpret this as a consequence of the patchy, heterogeneous distribution of white matter involvement in MS that provokes multiple combinations of impairment at different points in the different networks involved in eye motor control. Further studies are therefore required. |
Nora Geiser; Brigitte Charlotte Kaufmann; Henrik Rühe; Noortje Maaijwee; Tobias Nef; Dario Cazzoli; Thomas Nyffeler Visual neglect after PICA stroke—A case study Journal Article In: Brain Sciences, vol. 12, pp. 1–10, 2022. @article{Geiser2022, After cerebellar stroke, cognition can be impaired, as described within the framework of the so-called Cerebellar Cognitive Affective Syndrome (CCAS). However, it remains unclear whether visual neglect can also be part of CCAS. We describe the case of a patient with a subacute cerebellar stroke after thrombosis of the left posterior inferior cerebellar artery (PICA), who showed a left-sided visual neglect, indicating that the cerebellum also has a modulatory function on visual attention. The neglect, however, was mild and only detectable when using the sensitive neuro-psychological Five-Point Test as well as video-oculography assessment, yet remained unnoticed when evaluated with common neglect-specific paper-pencil tests. Three weeks later, follow-up assessments revealed an amelioration of neglect symptoms. Therefore, these findings suggest that visual neglect may be a part of CCAS, but that the choice of neglect assessments and the time delay since stroke onset may be crucial. Although the exact underlying pathophysiological mechanisms remain unclear, we propose cerebellar–cerebral diaschisis as a possible explanation of why neglect can occur on the ipsilateral side. Further research applying sensitive assessment tools at different post-stroke stages is needed to investigate the incidence, lesion correlates, and pathophysiology of neglect after cerebellar lesions. |
Amirhossein Ghaderi; Matthias Niemeier; John Douglas Crawford Linear vector models of time perception account for saccade and stimulus novelty interactions Journal Article In: Heliyon, vol. 8, pp. 1–13, 2022. @article{Ghaderi2022, Various models (e.g., scalar, state-dependent network, and vector models) have been proposed to explain the global aspects of time perception, but they have not been tested against specific visual phenomena like perisaccadic time compression and novel stimulus time dilation. Here, in two separate experiments (N = 31), we tested how the perceived duration of a novel stimulus is influenced by 1) a simultaneous saccade, in combination with 2) a prior series of repeated stimuli in human participants. This yielded a novel behavioral interaction: pre-saccadic stimulus repetition neutralizes perisaccadic time compression. We then tested these results against simulations of the above models. Our data yielded low correlations against scalar model simulations, high but non-specific correlations for our feedforward neural network, and correlations that were both high and specific for a vector model based on identity of objective and subjective time. These results demonstrate the power of global time perception models in explaining disparate empirical phenomena and suggest that subjective time has a similar essence to time's physical vector. |
Alma Gharib; Barbara L. Thompson Analysis and novel methods for capture of normative eye-tracking data in 2.5-month old infants Journal Article In: PloS ONE, vol. 17, pp. 1–22, 2022. @article{Gharib2022, Development of attention systems is essential for both cognitive and social behavior maturation. Visual behavior has been used to assess development of these attention systems. Yet, given its importance, there is a notable lack of literature detailing successful methods and procedures for using eye-tracking in early infancy to assess oculomotor and attention dynamics. Here we show that eye-tracking technology can be used to automatically record and assess visual behavior in infants as young as 2.5 months, and present normative data describing fixation and saccade behavior at this age. Features of oculomotor dynamics were analyzed from 2.5-month old infants who viewed videos depicting live action, cartoons, geometric shapes, social and non-social scenes. Of the 54 infants enrolled, 50 infants successfully completed the eye-tracking task and high-quality data was collected for 32 of those infants. We demonstrate that modifications specifically tailored for the infant population allowed for consistent tracking of pupil and corneal reflection and minimal data loss. Additionally, we found consistent fixation and saccade behaviors across the entire six-minute duration of the videos, indicating that this is a feasible task for 2.5-month old infants. Moreover, normative oculomotor metrics for a free-viewing task in 2.5-month old infants are documented for the first time as a result of this high-quality data collection. |
Hanbin Go; James Danckert; Britt Anderson Saccadic eye movement metrics reflect surprise and mental model updating Journal Article In: Attention, Perception, and Psychophysics, vol. 84, no. 5, pp. 1553–1565, 2022. @article{Go2022, Two experiments investigated what eye movements can reveal about how we process surprising information and how we update mental models in dynamic and unstructured environments. Participants made saccades to visual targets presented one at a time, radially, around an invisible perimeter. Target locations were normally distributed and shifted at an unannounced point during the task. Trials following the shift were considered surprising and unexpected. These unexpected and surprising events prompted the need to update. Slower saccadic latencies were observed for surprising/unexpected events, perhaps indicative of the need to reorient attention to the unexpected target location. Longer dwell times were observed for events that signaled a change in the distribution. These data show that eye movement metrics provide a reliable indicator of mental model updating when contingencies change even in the absence of explicit change signals. |
Alexander Goettker; Emma E. M. Stewart Serial dependence for oculomotor control depends on early sensory signals Journal Article In: Current Biology, vol. 32, pp. 2956–2961, 2022. @article{Goettker2022, To create an accurate percept of the world, the visual system relies on past experience and prior assumptions.1 For example, although the retinal projection of an object moving in depth changes drastically, we still perceive the object at a constant size and velocity.2,3 Consequently, if we see the same object with a constant retinal size at two different depth levels, the perceived size differs (illustrated by the Ponzo illusion). Past experience also directly influences perceptual judgments, an effect known as serial dependence.4,5 Such sequential effects have also been reported for oculomotor behavior, even on the trial-by-trial level.6–10 An integration of past experiences seems like a smart and sophisticated mechanism to reduce uncertainty and improve behavior in a world full of statistical regularities. By leveraging the Ponzo illusion to dissociate perceived size and speed from retinal signals, we show that serial-dependence effects for oculomotor control are mediated by retinal error signals. These sequential effects likely take place in early sensory processing because they transfer to different visual stimuli. In contrast to recently reported history effects for perceptual decisions,11 sequential effects for oculomotor control deviate from perceptual mechanisms by not integrating spatial context and by ignoring size and velocity constancy. Although this dissociation might appear suboptimal, we argue that this effect reveals the different goals of the oculomotor and perceptual systems. The oculomotor system tries to reduce retinal error signals to bring and keep the target close to the fovea, whereas the visual system interprets retinal input to achieve an accurate representation of the world.12 |
A. Grillini; L. H. Koens; G. Lizaitiene; F. Lange; F. W. Cornelissen; M. A. J. Tijssen In: Clinical Parkinsonism and Related Disorders, vol. 7, pp. 1–6, 2022. @article{Grillini2022, Introduction: Vertical supranuclear gaze palsy is a key feature of Niemann-Pick type C (NP-C) and is commonly quantified using video-oculography (VOG). VOG requires sitting still for long times and performing specific tasks, thus it can be challenging or impossible for patients severely affected by movement disorders or cognitive impairment. To overcome this limitation, we measure saccades of NP-C patients using a fast eye tracking test based on continuous psychophysics and compare it to VOG. Methods: Saccades of six NP-C patients and six age-matched controls were assessed using VOG and Standardized Oculomotor and Neuro-ophthalmic Disorders Assessment (SONDA). In SONDA, participants continuously track a semi-randomly moving dot on a computer screen while their gaze is being tracked. For both assessments, sac- cades were quantified using four conventional measures: amplitude, gain, latency, and peak velocity. Further- more, SONDA's continuous measures were quantified with several novel spatio-temporal properties. Results: In the NP-C patients, both methods revealed reduced amplitude, gain, peak velocity, and increased la- tency of vertical saccades compared to horizontal saccades and compared to healthy controls. Effect sizes ob- tained with SONDA were overall larger than those for VOG. SONDA's spatio-temporal properties showed similar trends. Conclusion: SONDA reveals a deterioration of vertical saccades in NP-C patients that is consistent with VOG. SONDA's measures based on continuous psychophysics are consistent with traditional saccadic parameters and can potentially provide complementary information. SONDA shows larger effect sizes than VOG, suggesting that it provides robust and clinically relevant outcomes with a more intuitive task and shorter testing time. |
Scott N. Grossman; Rachel Calix; Todd Hudson; John Ross Rizzo; Ivan Selesnick; Steven Frucht; Steven L. Galetta; Laura J. Balcer; Janet C. Rucker Accuracy of clinical versus oculographic detection of pathological saccadic slowing Journal Article In: Journal of the Neurological Sciences, vol. 442, pp. 1–8, 2022. @article{Grossman2022, Saccadic slowing as a component of supranuclear saccadic gaze palsy is an important diagnostic sign in multiple neurologic conditions, including degenerative, inflammatory, genetic, or ischemic lesions affecting brainstem structures responsible for saccadic generation. Little attention has been given to the accuracy with which clinicians correctly identify saccadic slowing. We compared clinician (n = 19) judgements of horizontal and vertical saccade speed on video recordings of saccades (from 9 patients with slow saccades, 3 healthy controls) to objective saccade peak velocity measurements from infrared oculographic recordings. Clinician groups included neurology residents, general neurologists, and fellowship-trained neuro-ophthalmologists. Saccades with normal peak velocities on infrared recordings were correctly identified as normal in 57% (91/171; 171 = 9 videos × 19 clinicians) of clinician decisions; saccades determined to be slow on infrared recordings were correctly identified as slow in 84% (224/266; 266 = 14 videos × 19 clinicians) of clinician decisions. Vertical saccades were correctly identified as slow more often than horizontal saccades (94% versus 74% of decisions). No significant differences were identified between clinician training levels. Reliable differentiation between normal and slow saccades is clinically challenging; clinical performance is most accurate for detection of vertical saccade slowing. Quantitative analysis of saccade peak velocities enhances accurate detection and is likely to be especially useful for detection of mild saccadic slowing. |
Marcel Linka; Maximilian Davide Broda; Tamara Alsheimer; Benjamin Haas; Meike Ramon Characteristic fixation biases in Super-Recognizers Journal Article In: Journal of Vision, vol. 22, no. 8, pp. 1–15, 2022. @article{Linka2022, Neurotypical observers show large and reliable individual differences in gaze behavior along several semantic object dimensions. Individual gaze behavior toward faces has been linked to face identity processing, including that of neurotypical observers. Here, we investigated potential gaze biases in Super-Recognizers (SRs), individuals with exceptional face identity processing skills. Ten SRs, identified with a novel conservative diagnostic framework, and 43 controls freely viewed 700 complex scenes depicting more than 5000 objects. First, we tested whether SRs and controls differ in fixation biases along four semantic dimensions: faces, text, objects being touched, and bodies. Second, we tested potential group differences in fixation biases toward eyes and mouths. Finally, we tested whether SRs fixate closer to the theoretical optimal fixation point for face identification. SRs showed a stronger gaze bias toward faces and away from text and touched objects, starting from the first fixation onward. Further, SRs spent a significantly smaller proportion of first fixations and dwell time toward faces on mouths but did not differ in dwell time or first fixations devoted to eyes. Face fixation of SRs also fell significantly closer to the theoretical optimal fixation point for identification, just below the eyes. Our findings suggest that reliable superiority for face identity processing is accompanied by early fixation biases toward faces and preferred saccadic landing positions close to the theoretical optimum for face identification.We discuss future directions to investigate the functional basis of individual fixation behavior and face identity processing ability. |
Matteo Lisi; Michael J. Morgan; Joshua A. Solomon Perceptual decisions and oculomotor responses rely on temporally distinct streams of evidence Journal Article In: Communications Biology, vol. 5, pp. 1–8, 2022. @article{Lisi2022, Perceptual decisions often require the integration of noisy sensory evidence over time. This process is formalized with sequential sampling models, where evidence is accumulated up to a decision threshold before a choice is made. Although intuition suggests that decision formation must precede the preparation of a motor response (i.e., the action used to communicate the choice), neurophysiological findings have suggested that these two processes might be one and the same. To test this idea, we developed a reverse-correlation protocol in which the visual stimuli that influence decisions can be distinguished from those guiding motor responses. In three experiments, we found that the temporal weighting function of oculomotor responses did not overlap with the relatively early weighting function of stimulus properties having an impact on decision formation. These results support a timeline in which perceptual decisions are formed, at least in part, prior to the preparation of a motor response. |
Baiwei Liu; Anna C. Nobre; Freek Ede Functional but not obligatory link between microsaccades and neural modulation by covert spatial attention Journal Article In: Nature Communications, vol. 13, pp. 1–10, 2022. @article{Liu2022, Covert spatial attention is associated with spatial modulation of neural activity as well as with directional biases in fixational eye movements known as microsaccades. We studied how these two ‘fingerprints' of attention are interrelated in humans. We investigated spatial modulation of 8-12 Hz EEG alpha activity and microsaccades when attention is directed internally within the spatial layout of visual working memory. Consistent with a common origin, spatial modulations of alpha activity and microsaccades co-vary: alpha lateralisation is stronger in trials with microsaccades toward versus away from the memorised location of the to-be-attended item and occurs earlier in trials with earlier microsaccades toward this item. Critically, however, trials without attention-driven microsaccades nevertheless show clear spatial modulation of alpha activity – comparable to trials with attention-driven microsaccades. Thus, directional biases in microsaccades correlate with neural signatures of spatial attention, but they are not necessary for neural modulation by spatial attention to be manifest. |