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!
2024 |
Hong Zhou; Luhua Wei; Yanyan Jiang; Xia Wang; Yunchuang Sun; Fan Li; Jing Chen; Wei Sun; Lin Zhang; Guiping Zhao; Zhaoxia Wang Abnormal Ocular Movement in the Early Stage of Multiple-System Atrophy With Predominant Parkinsonism Distinct From Parkinson's Disease Journal Article In: Journal of Clinical Neurology, vol. 20, no. 1, pp. 37–45, 2024. @article{Zhou2024, Background and Purpose The eye-movement examination can be applied as a noninvasive method to identify multiple-system atrophy (MSA). Few studies have investigated eye movements during the early stage of MSA with predominant parkinsonism (MSA-P). We aimed to determine the characteristic oculomotor changes in the early stage of MSA-P. Methods We retrospectively selected 17 patients with MSA-P and 40 with Parkinson's disease (PD) with disease durations of less than 2 years, and 40 age-matched healthy controls (HCs). Oculomotor performance in the horizontal direction was measured in detail using videonystagmography. Results We found that the proportions of patients with MSA-P and PD exhibiting abnormal eye movements were 82.4% and 77.5%, respectively, which were significantly higher than that in the HCs (47.5%, p<0.05). Compared with HCs, patients with MSA-P presented significantly higher abnormal proportions of fixation and gaze-holding (17.6% vs. 0%), without-fixation (47.1% vs. 0%), prolonged latency in reflexive saccades (29.4% vs. 5.0%), memory-guided saccades (93.3% vs. 10.0%), and catch-up saccades in smooth-pursuit movement (SPM, 41.2% vs. 0) (all p<0.05). Compared with those with PD, patients with MSA-P presented a signifi- cantly higher proportion of catch-up saccades in SPM (41.2% vs. 2.5%, p<0.001). Conclusions MSA-P presented the characteristic of catch-up saccades in SPM in the early stage, which may provide some value in differentiating MSA-P from PD. |
Inbal Ziv; Inbar Avni; Ilan Dinstein; Gal Meiri; Yoram S. Bonneh Oculomotor randomness is higher in autistic children and increases with the severity of symptoms Journal Article In: Autism Research, pp. 1–17, 2024. @article{Ziv2024, A variety of studies have suggested that at least some children with autism spectrum disorder (ASD) view the world differently. Differences in gaze patterns as measured by eye tracking have been demonstrated during visual exploration of images and natural viewing of movies with social content. Here we analyzed the temporal randomness of saccades and blinks during natural viewing of movies, inspired by a recent measure of “randomness” applied to micro-movements of the hand and head in ASD (Torres et al., 2013; Torres & Denisova, 2016). We analyzed a large eye-tracking dataset of 189 ASD and 41 typically developing (TD) children (1–11 years old) who watched three movie clips with social content, each repeated twice. We found that oculomotor measures of randomness, obtained from gamma parameters of inter-saccade intervals (ISI) and blink duration distributions, were significantly higher in the ASD group compared with the TD group and were correlated with the ADOS comparison score, reflecting increased “randomness” in more severe cases. Moreover, these measures of randomness decreased with age, as well as with higher cognitive scores in both groups and were consistent across repeated viewing of each movie clip. Highly “random” eye movements in ASD children could be associated with high “neural variability” or noise, poor sensory-motor control, or weak engagement with the movies. These findings could contribute to the future development of oculomotor biomarkers as part of an integrative diagnostic tool for ASD. |
Xu Liu; Yu Li; Lihua Xu; Tianhong Zhang; Huiru Cui; Yanyan Wei; Mengqing Xia; Wenjun Su; Yingying Tang; Xiaochen Tang; Dan Zhang; Lothar Spillmann; Ian Max Andolina; Niall McLoughlin; Wei Wang; Jijun Wang Spatial and temporal abnormalities of spontaneous fixational saccades and their correlates with positive and cognitive symptoms in schizophrenia Journal Article In: Schizophrenia Bulletin, vol. 50, no. 1, pp. 78–88, 2024. @article{Liu2024, BACKGROUND AND HYPOTHESIS: Visual fixation is a dynamic process, with the spontaneous occurrence of microsaccades and macrosaccades. These fixational saccades are sensitive to the structural and functional alterations of the cortical-subcortical-cerebellar circuit. Given that dysfunctional cortical-subcortical-cerebellar circuit contributes to cognitive and behavioral impairments in schizophrenia, we hypothesized that patients with schizophrenia would exhibit abnormal fixational saccades and these abnormalities would be associated with the clinical manifestations. STUDY DESIGN: Saccades were recorded from 140 drug-naïve patients with first-episode schizophrenia and 160 age-matched healthy controls during ten separate trials of 6-second steady fixations. Positive and negative symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Cognition was assessed using the Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB). STUDY RESULTS: Patients with schizophrenia exhibited fixational saccades more vertically than controls, which was reflected in more vertical saccades with angles around 90° and a greater vertical shift of horizontal saccades with angles around 0° in patients. The fixational saccades, especially horizontal saccades, showed longer durations, faster peak velocities, and larger amplitudes in patients. Furthermore, the greater vertical shift of horizontal saccades was associated with higher PANSS total and positive symptom scores in patients, and the longer duration of horizontal saccades was associated with lower MCCB neurocognitive composite, attention/vigilance, and speed of processing scores. Finally, based solely on these fixational eye movements, a K-nearest neighbors model classified patients with an accuracy of 85%. Conclusions: Our results reveal spatial and temporal abnormalities of fixational saccades and suggest fixational saccades as a promising biomarker for cognitive and positive symptoms and for diagnosis of schizophrenia. |
Natalia Melnik; Stefan Pollmann Saccadic re-referencing training with gaze-contingent FRL-'fixation': Effects of scotoma type and size adaptation Journal Article In: Vision Research, vol. 214, no. 214, pp. 1–11, 2024. @article{Melnik2024, Foveal vision loss makes the fovea as saccadic reference point maladaptive. Training programs have been proposed that shift the saccadic reference point from the fovea to an extrafoveal location, just outside the area of vision loss. We used a visual search task to train normal-sighted participants to fixate target items with a predetermined 'forced retinal location' (FRL) adjacent to a simulated central scotoma. We found that training was comparatively successful for scotomata that had either a sharp or blurry demarcation from the background. Completing the task with sharp-edged scotoma resulted in overall higher training gains. Training with blurry-edged scotoma, however, yielded overall better results when scotoma size was increased after training and participants needed to adapt to a more eccentric FRL, as may be necessary in patients with progressive degenerative eye diseases. |
Kateryna Melnyk; Lee Friedman; Oleg V. Komogortsev What can entropy metrics tell us about the characteristics of ocular fixation trajectories? Journal Article In: PloS ONE, vol. 19, no. 1, pp. 1–45, 2024. @article{Melnyk2024, In this study, we provide a detailed analysis of entropy measures calculated for fixation eye movement trajectories from the three different datasets. We employed six key metrics (Fuzzy, Increment, Sample, Gridded Distribution, Phase, and Spectral Entropies). We calculate these six metrics on three sets of fixations: (1) fixations from the GazeCom dataset, (2) fixations from what we refer to as the "Lund" dataset, and (3) fixations from our own research laboratory ("OK Lab" dataset). For each entropy measure, for each dataset, we closely examined the 36 fixations with the highest entropy and the 36 fixations with the lowest entropy. From this, it was clear that the nature of the information from our entropy metrics depended on which dataset was evaluated. These entropy metrics found various types of misclassified fixations in the GazeCom dataset. Two entropy metrics also detected fixation with substantial linear drift. For the Lund dataset, the only finding was that low spectral entropy was associated with what we call "bumpy" fixations. These are fixations with low-frequency oscillations. For the OK Lab dataset, three entropies found fixations with high-frequency noise which probably represent ocular microtremor. In this dataset, one entropy found fixations with linear drift. The between-dataset results are discussed in terms of the number of fixations in each dataset, the different eye movement stimuli employed, and the method of eye movement classification. |
Nora Geiser; Brigitte Charlotte Kaufmann; Samuel Elia Johannes Knobel; Dario Cazzoli; Tobias Nef; Thomas Nyffeler Comparison of uni- and multimodal motion stimulation on visual neglect: A proof-of-concept study Journal Article In: Cortex, vol. 171, pp. 194–203, 2024. @article{Geiser2024, Spatial neglect is characterized by the failure to attend stimuli presented in the contralesional space. Typically, the visual modality is more severely impaired than the auditory one. This dissociation offers the possibility of cross-modal interactions, whereby auditory stimuli may have beneficial effects on the visual modality. A new auditory motion stimulation method with music dynamically moving from the right to the left hemispace has recently been shown to improve visual neglect. The aim of the present study was twofold: a) to compare the effects of unimodal auditory against visual motion stimulation, i.e., smooth pursuit training, which is an established therapeutical approach in neglect therapy and b) to explore whether a combination of auditory + visual motion stimulation, i.e., multimodal motion stimulation, would be more effective than unimodal auditory or visual motion stimulation. 28 patients with left-sided neglect due to a first-ever, right-hemispheric subacute stroke were included. Patients either received auditory, visual, or multimodal motion stimulation. The between-group effect of each motion stimulation condition as well as a control group without motion stimulation was investigated by means of a one-way ANOVA with the patient's visual exploration behaviour as an outcome variable. Our results showed that unimodal auditory motion stimulation is equally effective as unimodal visual motion stimulation: both interventions significantly improved neglect compared to the control group. Multimodal motion stimulation also significantly improved neglect, however, did not show greater improvement than unimodal auditory or visual motion stimulation alone. Besides the established visual motion stimulation, this proof-of-concept study suggests that auditory motion stimulation seems to be an alternative promising therapeutic approach to improve visual attention in neglect patients. Multimodal motion stimulation does not lead to any additional therapeutic gain. In neurorehabilitation, the implementation of either auditory or visual motion stimulation seems therefore reasonable. |
Vaibhav A. Diwadkar; Deborah Kashy; Jacqueline Bao; Katharine N. Thakkar Abnormal oculomotor corollary discharge signaling as a trans-diagnostic mechanism of psychosis Journal Article In: Schizophrenia Bulletin, pp. 1–11, 2024. @article{Diwadkar2024, Background and Hypothesis: Corollary discharge (CD) signals are “copies” of motor signals sent to sensory areas to predict the corresponding input. They are a posited mechanism enabling one to distinguish actions generated by oneself vs external forces. Consequently, altered CD is a hypothesized mechanism for agency disturbances in psychosis. Previous studies have shown a decreased influence of CD signals on visual perception in individuals with schizophrenia—particularly in those with more severe positive symptoms. We therefore hypothesized that altered CD may be a trans-diagnostic mechanism of psychosis. Study Design: We examined oculomotor CD (using the blanking task) in 49 participants with schizophrenia or schizoaffective disorder (SZ), 36 bipolar participants with psychosis (BPP), and 40 healthy controls (HC). Participants made a saccade to a visual target. Upon saccade initiation, the target disappeared and reappeared at a horizontally displaced position. Participants indicated the direction of displacement. With intact CD, participants can make accurate perceptual judgements. Otherwise, participants may use saccade landing site as a proxy of pre-saccadic target to inform perception. Thus, multi-level modeling was used to examine the influence of target displacement and saccade landing site on displacement judgements. Study Results: SZ and BPP were equally less sensitive to target displacement than HC. Moreover, regardless of diagnosis, SZ and BPP with more severe positive symptoms were more likely to rely on saccade landing site. Conclusions: These results suggest that altered CD may be a trans-diagnostic mechanism of psychosis. |
Palpolage Don Shehan Hiroshan Gunawardane; Raymond Robert MacNeil; Leo Zhao; James Theodore Enns; Clarence Wilfred Silva; Mu Chiao A fusion algorithm based on a constant velocity model for improving the measurement of saccade parameters with electrooculography Journal Article In: Sensors, vol. 24, no. 540, pp. 1–19, 2024. @article{Gunawardane2024, Abstract: Electrooculography (EOG) serves as a widely employed technique for tracking saccadic eye movements in a diverse array of applications. These encompass the identification of various medical conditions and the development of interfaces facilitating human–computer interaction. Nonetheless, EOG signals are often met with skepticism due to the presence of multiple sources of noise interference. These sources include electroencephalography, electromyography linked to facial and extraocular muscle activity, electrical noise, signal artifacts, skin-electrode drifts, impedance fluctuations over time, and a host of associated challenges. Traditional methods of addressing these issues, such as bandpass filtering, have been frequently utilized to overcome these challenges but have the associated drawback of altering the inherent characteristics of EOG signals, encompassing their shape, magnitude, peak velocity, and duration, all of which are pivotal parameters in research studies. In prior work, several model-based adaptive denoising strategies have been introduced, incorporating mechanical and electrical model-based state estimators. However, these approaches are really complex and rely on brain and neural control models that have difficulty processing EOG signals in real time. In this present investigation, we introduce a real-time denoising method grounded in a constant velocity model, adopting a physics-based model-oriented approach. This approach is underpinned by the assumption that there exists a consistent rate of change in the cornea-retinal potential during saccadic movements. Empirical findings reveal that this approach remarkably preserves EOG saccade signals, resulting in a substantial enhancement of up to 29% in signal preservation during the denoising process when compared to alternative techniques, such as bandpass filters, constant acceleration models, and model-based fusion methods. WABBLE: |
Reza Azadi; Alex O. Holcombe; Jay A. Edelman Hypometria of saccadic eye movements to targets in rapid circular motion Journal Article In: Journal of Vision, vol. 24, no. 1, pp. 1–19, 2024. @article{Azadi2024, Saccades to objects moving on a straight trajectory take the velocity of the object into account. However, it is not known whether saccades can compensate for curved trajectories, nor is it known how they are affected by high target speeds. In Experiment 1, participants made a saccade in a delayed saccade task to a target moving in a circular trajectory. Surprisingly, saccades to high-speed moving targets were severely hypometric, with gains of only ∼55% for trajectories of the largest angular speed (2 revolutions per second) and eccentricity (12°). They also had unusually low peak velocities. In Experiment 2, the target jumped along a circular path around a central fixation point. Hypometria was still severe, except for very large jumps. Experiment 3 was like Experiment 1, except that a landmark was positioned on the trajectory of the target, and participants were instructed to make a saccade to the landmark or to its memorized location. This ameliorated hypometria considerably. Given the delayed nature of the tasks of Experiments 1 and 2, participants had considerable time to program a voluntary saccade to a location on the trajectory, if not to the rapidly moving target itself. Nevertheless, the abnormal saccade properties indicate that motor programming was compromised. These results indicate that motor output can be inextricably bound to sensory input to its detriment, even during a highly voluntary motor act; that apparent motion can produce this behavior; and that such abnormal saccades can be "rescued" by the presence of a stable visual goal. |
2023 |
Eve C. Ayar; Michelle R. Heusser; Clara Bourrelly; Neeraj J. Gandhi Distinct context- and content- dependent population codes in superior colliculus during sensation and action Journal Article In: Proceedings of the National Academy of Sciences, vol. 120, no. 40, pp. 1–12, 2023. @article{Ayar2023, Sensorimotor transformation is the process of first sensing an object in the environment and then producing a movement in response to that stimulus. For visually guided saccades, neurons in the superior colliculus (SC) emit a burst of spikes to register the appearance of stimulus, and many of the same neurons discharge another burst to initiate the eye movement. We investigated whether the neural signatures of sensation and action in SC depend on context. Spiking activity along the dorsoventral axis was recorded with a laminar probe as Rhesus monkeys generated saccades to the same stimulus location in tasks that require either executive control to delay saccade onset until permission is granted or the production of an immediate response to a target whose onset is predictable. Using dimensionality reduction and discriminability methods, we show that the subspaces occupied during the visual and motor epochs were both distinct within each task and differentiable across tasks. Single-unit analyses, in contrast, show that the movement-related activity of SC neurons was not different between tasks. These results demonstrate that statistical features in neural activity of simultaneously recorded ensembles provide more insight than single neurons. They also indicate that cognitive processes associated with task requirements are multiplexed in SC population activity during both sensation and action and that downstream structures could use this activity to extract context. Additionally, the entire manifolds associated with sensory and motor responses, respectively, may be larger than the subspaces explored within a certain set of experiments. |
Louise Catheryne Barne; Jonathan Giordano Decoding trans-saccadic prediction error Journal Article In: Journal of Neuroscience, vol. 43, no. 11, pp. 1933–1939, 2023. @article{Barne2023, We are constantly sampling our environment by moving our eyes, but our subjective experience of the world is stable and constant. Stimulus displacement during or shortly after a saccade often goes unnoticed, a phenomenon called the saccadic suppression of displacement. Although we fail to notice such displacements, our oculomotor system computes the prediction errors and adequately adjusts the gaze and future saccadic execution, a phenomenon known as saccadic adaptation. In the present study, we aimed to find a brain signature of the trans-saccadic prediction error that informs the motor system but not explicit perception. We asked participants (either sex) to report whether a visual target was displaced during a saccade while recording electroencephalography (EEG). Using multivariate pattern analysis, we were able to differentiate displace- ments from no displacements, even when participants failed to report the displacement. In other words, we found that trans- saccadic prediction error is represented in the EEG signal 100 ms after the displacement presentation, mainly in occipital and parieto-occipital channels, even in the absence of explicit perception of the displacement. |
Cesar Barquero; Jui-Tai Chen; Douglas P. Munoz; Chin-An Wang In: Neuropsychologia, vol. 187, pp. 1–9, 2023. @article{Barquero2023, Microsaccades that occur during periods of fixation are modulated by various cognitive processes and have an impact on visual processing. A network of brain areas is involved in microsaccade generation, including the superior colliculus and frontal eye field (FEF) which are involved in modulating microsaccade rate and direction after the appearance of a visual cue (referred to as microsaccade cueing modulation). Although the neural mechanisms underlying microsaccade cueing modulations have been demonstrated in monkeys, limited research has investigated a causal role of these areas in humans. By applying continuous theta-burst transcranial magnetic stimulation (cTBS) over the right FEF and vertex, we investigated the role of human FEF in modulating microsaccade responses after the appearance of a visual target in a visual- and memory-delay saccade task. After target appearance, microsaccade rate was initially suppressed but then increased in both cTBS conditions. More importantly, in the visual-delay task, microsaccades after target appearance were directed to the ipsilateral side more often with FEF, compared to vertex stimulation. Moreover, microsaccades were directed towards the target location, then to the opposite location of the target in both tasks, with larger effects in the visual-, compared to, memory-delay task. This microsaccade direction modulation was delayed after FEF stimulation in the memory-delay task. Overall, some microsaccade cueing modulations were moderately disrupted after FEF cTBS, suggesting a causal role for involvement of the human FEF in microsaccade generation after presentation of salient stimuli. |
Mehdi Bejani; Elisa Luque-Buzo; Arsen Burlaka-Petrash; Jorge A. Gomez-Garcia; Julian D. Arias-Londono; F. Grandas-Perez; Jesus Grajal; Juan Ignacio Godino-Llorente Baseline wander removal applied to smooth pursuit eye movements from parkinsonian patients Journal Article In: IEEE Access, vol. 11, pp. 32119–32133, 2023. @article{Bejani2023, Prior studies aiming to parametrize the sequences obtained from the Smooth Pursuit Eye Movements (SPEM) of patients with Parkinson's disease are based on the manual extraction of cues of interest. This is because methods to automatically extract the relevant information are complex to implement and are constrained, in part, by the appearance of a baseline wander (BW). Thus, new methods are required for preprocessing the SPEM sequences to make the potential parameterisation procedures much more robust, removing the aforementioned BW. In this respect, the present study compares different BW removal methods applied to SPEM sequences based on several objective evaluation metrics. At the same time, it proposes a set of guidelines to estimate the ground truth that is required for comparison purposes. Data were collected using a high-speed video-based eye-tracking device. 52 patients and 60 controls and 12 young participants were enrolled in the study. The ground truth required to compare the different BW removal techniques was manually delineated according to a predefined protocol. Seven methods were developed to remove the BW, and four objective metrics were used to evaluate the results. According to the results, a method based on the Empirical Wavelet Transform provided the best performance removing the BW. Furthermore, the objective and subjective results show that potential asymmetries between left and right eye movements are solved by removing the BW. Regardless of the techniques used, BW removal is revealed to be a crucial step for any autonomous SPEM processing tool. |
Sanne Böing; Jasper H. Fabius; Marjoleine Hakkenberg; Tanja C. W. Nijboer; Stefan Van der Stigchel More (corrective) consecutive saccades after a lesion to the posterior parietal cortex Journal Article In: European Journal of Neuroscience, vol. 58, no. 7, pp. 3650–3670, 2023. @article{Boeing2023, To reach a target, primary saccades (S1s) are often followed by (corrective) consecutive saccades (S2, and potentially S3, S4, S5), which are based on retinal and extraretinal feedback. Processing these extraretinal signals was found to be significantly impaired by lesions to the posterior parietal cortex (PPC). Recent studies, however, added a more nuanced view to the role of the PPC, where patients with PPC lesions still used extraretinal signals for S2s and perceptual judgements (Fabius et al., 2020; Rath-Wilson & Guitton, 2015). Hence, it seems that a PPC lesion is not disrupting extraretinal processing per se. Yet, a lesion might still result in less reliable processing of extraretinal signals. Here, we investigated whether this lower reliability manifests as decreased or delayed S2 initiation. Patients with PPC lesions (n = 7) and controls (n = 26) performed a prosaccade task where the target either remained visible or was removed after S1 onset. When S1 is removed, accurate S2s (corrections of S1 error) rely solely on extraretinal signals. We analysed S2 quantity and timing using linear mixed-effects modelling and additive hazards analyses. Patients demonstrated slower S1 execution and lower S1 amplitudes than controls, but their S2s still compensated the S1 undershoot, also when they only relied on extraretinal information. Surprisingly, patients showed an increased amount of S2s. This deviation from control behaviour can be seen as suboptimal, but given the decreased accuracy of the primary saccade, it could be optimal for patients to employ more (corrective) consecutive saccades to overcome this inaccuracy. |
Clara Bourrelly; Corentin Massot; Neeraj J. Gandhi Rapid input-output transformation between local field potential and spiking activity during sensation but not action in the superior colliculus Journal Article In: Journal of Neuroscience, vol. 43, no. 22, pp. 4047–4061, 2023. @article{Bourrelly2023, Sensorimotor transformation is the sequential process of registering a sensory signal in the environment and then responding with the relevant movement at an appropriate time. For visually guided eye movements, neural signatures in the form of spiking activity of neurons have been extensively studied along the dorsoventral axis of the superior colliculus (SC). In contrast, the local field potential (LFP), which represents the putative input to a region, remains largely unexplored in the SC. We therefore compared amplitude levels and onset times of both spike bursts and LFP modulations recorded simultaneously with a laminar probe along the dorsoventral axis of SC in 3 male monkeys performing the visually guided delayed saccade task. Both signals displayed a gradual transition from sensory activity in the superficial layers to a predominantly motor response in the deeper layers, although the transition from principally sensory to mostly motor response occurred;500 lm deeper for the LFP. For the sensory response, LFP modulation preceded spike burst onset by,5 ms in the superficial and intermediate layers and only when data were analyzed on a trial-by-trial basis. The motor burst in the spiking activity led LFP modulation by.25 ms in the deeper layers. The results reveal a fast and efficient input-output transformation between LFP modulation and spike burst in the visually responsive layers activity during sensation but not during action. The spiking pattern observed during the movement phase is likely dominated by intracollicular processing that is not captured in the LFP. |
Maximilian Davide Broda; Theresa Haddad; Benjamin Haas Quick, eyes! Isolated upper face regions but not artificial features elicit rapid saccades Journal Article In: Journal of Vision, vol. 23, no. 2, pp. 1–9, 2023. @article{Broda2023, Human faces elicit faster saccades than objects or animals, resonating with the great importance of faces for our species. The underlying mechanisms are largely unclear. Here, we test two hypotheses based on previous findings. First, ultra-rapid saccades toward faces may not depend on the presence of the whole face, but the upper face region containing the eye region. Second, ultra-rapid saccades toward faces (and possibly face parts) may emerge from our extensive experience with this stimulus and thus extend to glasses and masks – artificial features frequently encountered as part of a face. To test these hypotheses, we asked 43 participants to complete a saccadic choice task, which contrasted images of whole, upper and lower faces, face masks, and glasses with car images. The resulting data confirmed ultra-rapid saccades for isolated upper face regions, but not for artificial facial features. |
Serena Castellotti; Martin Szinte; Maria Michela Del Viva; Anna Montagnini Saccadic trajectories deviate toward or away from optimally informative visual features Journal Article In: iScience, vol. 26, no. 8, pp. 1–17, 2023. @article{Castellotti2023, The saccades' path is influenced by visual distractors, making their trajectory curve away or toward them. Previous research suggested that the more salient the distractor, the more pronounced is the curvature. We investigate the saliency of spatial visual features, predicted by a constrained maximum entropy model to be optimal or non-optimal information carriers in fast vision, by using them as distractors in a saccadic task. Their effect was compared to that of luminance-based control distractors. Optimal features evoke a larger saccadic curvature compared to non-optimal features, and the magnitude and direction of deviation change as a function of the delay between distractor and saccade onset. Effects were similar to those found with high-luminance versus low-luminance distractors. Therefore, model-predicted information optimal features interfere with target-oriented saccades, following a dynamic attraction–repulsion pattern. This suggests that the visuo-oculomotor system rapidly and automatically processes optimally informative features while programming visually guided eye movements. |
Hatice Eraslan Boz; Koray Koçoğlu; Müge Akkoyun; Işıl Yağmur Tüfekci; Merve Ekin; Pınar Özçelik; Gülden Akdal In: Aging, Neuropsychology, and Cognition, pp. 1–22, 2023. @article{EraslanBoz2023b, Alzheimer's disease (AD) dementia is a degenerative illness that is characterized by a gradual decline in cognitive abilities. Amnestic mild cognitive impairment (aMCI) is seen as a precursor to AD. The changes in antisaccade performance that can be seen in MCI may provide important clues in the early detection of AD. Therefore, the antisaccade deficits in AD and aMCI remain a research question. This study aimed to examine antisaccade responses and the relationship between antisaccade and cognitive function in AD, aMCI, and healthy controls (HC). This study included 30 patients with early-stage AD, 34 with aMCI, and 32 HC. Patients with AD showed higher rates of uncorrected error, anticipatory saccades and corrected errors, as well as decreased correct saccade rates, and shortened saccade latency compared to aMCI and HC in this study. Patients with aMCI exhibited increased rates of express saccades relative to HC. The antisaccade task and cognitive domains were found to be significantly related. Our study showed that the rate of correct saccades has the capacity to distinguish AD from HC with 87% sensitivity and 86% specificity (AUC = 0.93, p < 0.001). In addition, the rate of uncorrected errors was found to be capable of distinguishing AD from HC with 84% sensitivity and 83% specificity (AUC = 0.91, p < 0.001). This study presented promising findings that these parameters can be used clinically to differentiate AD and aMCI from healthy older individuals. |
Jasper H. Fabius; Alessio Fracasso; Michele Deodato; David Melcher; Stefan Van der Stigchel Bilateral increase in MEG planar gradients prior to saccade onset Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–10, 2023. @article{Fabius2023, Every time we move our eyes, the retinal locations of objects change. To distinguish the changes caused by eye movements from actual external motion of the objects, the visual system is thought to anticipate the consequences of eye movements (saccades). Single neuron recordings have indeed demonstrated changes in receptive fields before saccade onset. Although some EEG studies with human participants have also demonstrated a pre-saccadic increased potential over the hemisphere that will process a stimulus after a saccade, results have been mixed. Here, we used magnetoencephalography to investigate the timing and lateralization of visually evoked planar gradients before saccade onset. We modelled the gradients from trials with both a saccade and a stimulus as the linear combination of the gradients from two conditions with either only a saccade or only a stimulus. We reasoned that any residual gradients in the condition with both a saccade and a stimulus must be uniquely linked to visually-evoked neural activity before a saccade. We observed a widespread increase in residual planar gradients. Interestingly, this increase was bilateral, showing activity both contralateral and ipsilateral to the stimulus, i.e. over the hemisphere that would process the stimulus after saccade offset. This pattern of results is consistent with predictive pre-saccadic changes involving both the current and the future receptive fields involved in processing an attended object, well before the start of the eye movement. The active, sensorimotor coupling of vision and the oculomotor system may underlie the seamless subjective experience of stable and continuous perception. |
Yunwei Fan; Li Li; Ping Chu; Qian Wu; Yuan Wang; Wen Hong Cao; Ningdong Li Clinical analysis of eye movement-based data in the medical diagnosis of amblyopia Journal Article In: Methods, vol. 213, pp. 26–32, 2023. @article{Fan2023a, Amblyopia is an abnormal visual processing-induced developmental disorder of the central nervous system that affects static and dynamic vision, as well as binocular visual function. Currently, changes in static vision in one eye are the gold standard for amblyopia diagnosis. However, there have been few comprehensive analyses of changes in dynamic vision, especially eye movement, among children with amblyopia. Here, we proposed an optimization scheme involving a video eye tracker combined with an “artificial eye” for comprehensive examination of eye movement in children with amblyopia; we sought to improve the diagnostic criteria for amblyopia and provide theoretical support for practical treatment. The resulting eye movement data were used to construct a deep learning approach for diagnostic and predictive applications. Through efforts to manage the uncooperativeness of children with strabismus who could not complete the eye movement assessment, this study quantitatively and objectively assessed the clinical implications of eye movement characteristics in children with amblyopia. Our results indicated that an amblyopic eye is always in a state of adjustment, and thus is not “lazy.” Additionally, we found that the eye movement parameters of amblyopic eyes and eyes with normal vision are significantly different. Finally, we identified eye movement parameters that can be used to supplement and optimize the diagnostic criteria for amblyopia, providing a diagnostic basis for evaluation of binocular visual function. |
Xinhui Fei; Yanqin Zhang; Deyi Kong; Qitang Huang; Minhua Wang; Jianwen Dong Quantitative model study of the psychological recovery benefit of landscape environment based on eye movement tracking technology Journal Article In: Sustainability, vol. 15, no. 14, pp. 1–19, 2023. @article{Fei2023, From the perspective of landscape and human health, we use the Self-Rating Restoration Scale (SRRS) as a tool to explore the mental health restoration benefits brought by a landscape environment to individuals and explore the characteristics of individual movement behavior when viewing the landscape through the eye movement tracking technology. We selected average blink duration, average gaze length, average saccade amplitude, blink number, number of fixation points, saccade number, and average pupil diameter as experimental indicators for data monitoring. Based on the eye movement heat map obtained by data visualization processing and the results of correlation analysis, we summarized the eye movement behavior characteristics of individuals when viewing the restorative landscape. We try to construct a quantitative evaluation model of the landscape mental recovery benefit with the objective eye movement index as the independent variable through the method of curve estimation. The study results show that individual eye movement behavior is related to the landscape type and the level of psychological recovery is also different. (1)The more singular that the constituent elements are, the more widespread and concentrated the regional distribution of individual attention areas, and the relative psychological recovery benefit is relatively weak. The more complex that the constituent elements are, the more scattered and smaller the individual interest area, and the psychological recovery benefit is better. Brightly colored, dynamic landscapes are easier to form areas of interest to improve the psychological response to the human body. (2) The psychological recovery benefit of the landscape is directly proportional to the changing trend of the average blink duration, number of fixation points, and number of saccades and is inversely proportional to the changing trend of the average gaze length. (3) The objective eye movement index of average blink duration can quantitatively predict the psychological recovery benefit value of the landscape environment. The number of fixation points, the number of saccades, and the average fixation length could predict the psychological recovery benefits of the landscape, while the other indicators had no prediction effect. |
Maria Feldmann; Jessica Borer; Walter Knirsch; Moritz M. Daum; Stephanie Wermelinger; Beatrice Latal Atypical gaze-following behaviour in infants with congenital heart disease Journal Article In: Early Human Development, vol. 181, pp. 1–7, 2023. @article{Feldmann2023a, Background: Neurodevelopmental impairments are the most prevalent non-cardiac long-term sequelae in children with complex congenital heart disease (CHD). Deficits include the social-emotional and social-cognitive domains. Little is known about the predecessors of social-cognitive development in infants with CHD during the first year of life. Gaze-following behaviour can be used to measure early social-cognitive abilities. Aims: To assess gaze-following development in infants with CHD compared to healthy controls. Study design: Prospective cohort study. Participants: Twenty-three infants who underwent neonatal correction for CHD and 84 healthy controls. Outcome measures: Gaze-following behaviour was assessed by eye tracking at 6 and 12 months. Difference scores for first fixation, fixation frequency and fixation duration towards the gaze-cued object were calculated across 6 trials and compared between groups at both testing time points while adjusting for known confounders. Linear mixed models were calculated to assess the longitudinal trajectory of gaze-following development while accounting for the nested and dependent data structure. Results: At 6 months, no difference in gaze-following behaviour between CHD and healthy controls was found. At 12 months, fixation frequency towards the gaze-cued was lower and looking duration was shorter in CHD compared to controls (p = 0.0077; p = 0.0068). Infants with CHD showed less increase with age in the fixation frequency towards the congruent object (p = 0.041) compared to controls. Conclusion: During the first year of life, gaze-following development diverges in infants with CHD compared to healthy controls. Further research is needed to investigate the clinical relevance of these findings and the association with later social-cognitive development. |
Heather Fielding-Gebhardt; Shannon E. Kelly; Kathryn E. Unruh; Lauren M. Schmitt; Stormi L. Pulver; Pravin Khemani; Matthew W. Mosconi Sensorimotor and inhibitory control in aging FMR1 premutation carriers Journal Article In: Frontiers in Human Neuroscience, vol. 17, pp. 1–10, 2023. @article{FieldingGebhardt2023, Aging FMR1 premutation carriers are at risk of developing neurodegenerative disorders, including fragile X-associated tremor/ataxia syndrome (FXTAS), and there is a need to identify biomarkers that can aid in identification and treatment of these disorders. While FXTAS is more common in males than females, females can develop the disease, and some evidence suggests that patterns of impairment may differ across sexes. Few studies include females with symptoms of FXTAS, and as a result, little information is available on key phenotypes for tracking disease risk and progression in female premutation carriers. Our aim was to examine quantitative motor and cognitive traits in aging premutation carriers. We administered oculomotor tests of visually guided/reactive saccades (motor) and antisaccades (cognitive control) in 22 premutation carriers (73% female) and 32 age- and sex-matched healthy controls. Neither reactive saccade latency nor accuracy differed between groups. FMR1 premutation carriers showed increased antisaccade latencies relative to controls, both when considering males and females together and when analyzing females separately. Reduced saccade accuracy and increased antisaccade latency each were associated with more severe clinically rated neuromotor impairments. Findings indicate that together male and female premutation carriers show a reduced ability to rapidly exert volitional control over prepotent responses and that quantitative differences in oculomotor behavior, including control of visually guided and antisaccades, may track with FXTAS – related degeneration in male and female premutation carriers. |
Nick Fogt; Andrew J. Toole; Xiangrui Li; Emmanuel Owusu; Steven T. T. Manning; Marjean T. Kulp Functional magnetic resonance imaging activation for different vergence eye movement subtypes Journal Article In: Ophthalmic and Physiological Optics, vol. 43, no. 1, pp. 93–104, 2023. @article{Fogt2023, Introduction: Maddox suggested that there were four convergence subtypes, each driven by a different stimulus. The purpose of this study was to assess the neural correlates for accommodative convergence, proximal convergence (convergence stimulus provided), disparity convergence and voluntary convergence (no specific convergence stimulus provided) using functional magnetic resonance imaging (fMRI). Methods: Ten subjects (mean age = 24.4 years) with normal binocular vision participated. The blood oxygenation level- dependent (BOLD) signals of the brain from fMRI scans were measured when subjects made vergence eye movements while: (1) alternately viewing letters monocularly where one eye viewed through a −2.00 D lens, (2) alternately viewing Difference of Gaussian targets monocularly at distance and near, (3) viewing random dot stereograms with increasing disparity and (4) voluntarily converging the eyes with binocular viewing. Results: The accommodative convergence paradigm resulted in activation on the right side in the right fusiform cortex and the right middle occipital cortex. The proximal convergence stimulus mainly activated areas in the right occipital lobe. The disparity stimulus activated areas in the left occipital cortex and the left frontal cortex. Finally, the voluntary convergence paradigm resulted in activation primarily in the occipital lobe and mostly bilaterally. Conclusion: The accommodative, proximal, disparity and voluntary convergence paradigms resulted in activation in unique areas in the brain with functional MRI. Activation was found in more areas in the proximal and voluntary conditions compared with the accommodative and disparity conditions. |
Alessio Fracasso; Antimo Buonocore; Ziad M. Hafed Peri-saccadic orientation identification performance and visual neural sensitivity are higher in the upper visual field Journal Article In: Journal of Neuroscience, vol. 43, no. 41, pp. 6884–6897, 2023. @article{Fracasso2023, Visual neural processing is distributed among a multitude of sensory and sensory-motor brain areas exhibiting varying degrees of functional specializations and spatial representational anisotropies. Such diversity raises the question of how perceptual performance is determined, at any one moment in time, during natural active visual behavior. Here, exploiting a known dichotomy between the primary visual cortex and superior colliculus in representing either the upper or lower visual fields, we asked whether peri-saccadic orientation identification performance is dominated by one or the other spatial anisotropy. Humans (48 participants, 29 females) reported the orientation of peri-saccadic upper visual field stimuli significantly better than lower visual field stimuli, unlike their performance during steady-state gaze fixation, and contrary to expected perceptual superiority in the lower visual field in the absence of saccades. Consistent with this, peri-saccadic superior colliculus visual neural responses in two male rhesus macaque monkeys were also significantly stronger in the upper visual field than in the lower visual field. Thus, peri-saccadic orientation identification performance is more in line with oculomotor, rather than visual, map spatial anisotropies. |
Sharavanan Ganesan; Natalia Melnik; Elena Azanon; Stefan Pollmann A gaze-contingent saccadic re-referencing training with simulated central vision loss Journal Article In: Journal of Vision, vol. 23, no. 1, pp. 1–25, 2023. @article{Ganesan2023, Patients with central vision loss (CVL) adopt an eccentric retinal location for fixation, a preferred retinal location (PRL), to compensate for vision loss at the fovea. Although most patients with CVL are able to rapidly use a PRL instead of the fovea, saccadic re-referencing to a PRL develops slowly.Without re-referencing, saccades land the saccade target in the scotoma. This results in corrective saccades and leads to inefficient visual exploration. Here, we tested a new method to train saccadic re-referencing. Healthy participants performed gaze-contingent visual search tasks with simulated central scotoma in which participants had to fixate targets with an experimenter-defined forced retinal location (FRL). In experiment 1, we compared single-target search and foraging search tasks in the course of five training sessions. Results showed that both tasks improved the efficiency of gaze sequences and led to saccadic re-referencing to the FRL. In experiment 2, we trained participants extensively for 25 sessions, both with and without a gaze-contingent FRL-marker visible during training. After extensive training, observers' performance approached that of foveal vision. Thus, gaze-contingent FRL-fixation may become an efficient tool for saccadic re-referencing training in patients with central vision loss. |
Caroline Giuricich; Robert J. Green; Heather Jordan; Mazyar Fallah Target–distractor competition modulates saccade trajectories in space and object space Journal Article In: eNeuro, vol. 10, no. 6, pp. 1–20, 2023. @article{Giuricich2023, Saccade planning and execution can be affected by a multitude of factors present in a target selection task. Recent studies have shown that the similarity between a target and nearby distractors affects the curvature of saccade trajectories, because of target–distractor competition. To further understand the nature of this competition, we varied the distance between and the similarity of complex target and distractor objects in a delayed match-to-sample task to examine their effects on human saccade trajectories and better understand the underlying neural circuitry. For trials with short saccadic reaction times (SRTs) when target–distractor competition is still active, the distractor is attractive and saccade trajectories are deviated toward the distractor. We found a robust effect of distance consistent with saccade vector averaging, whereas the effect of similarity suggested the existence of an object-based suppressive surround. At longer SRTs, there was sufficient time for competition between the objects to complete and the distractor to be repulsive, which resulted in saccade trajectory deviations away from the distractor exhibiting the effects of a spatial suppressive surround. In terms of similarity, as the target–distractor similarity decreased, the initial saccade angle shifted toward the target, reflecting stronger distractor inhibition. There were no interactions between distance and similarity at any point in the time course of target–distractor competition. Together, saccade trajectories reflect target–distractor competition that is affected independently by both spatial and object space suppressive surrounds. The differences in saccade trajectories at short and long SRTs distinguish between active and completed decision-making processes. |
Alexander Goettker; Nils Borgerding; Linus Leeske; Karl R. Gegenfurtner Cues for predictive eye movements in naturalistic scenes Journal Article In: Journal of Vision, vol. 23, no. 10, pp. 1–20, 2023. @article{Goettker2023, We previously compared following of the same trajectories with eye movements, but either as an isolated targets or embedded in a naturalistic scene-in this case, the movement of a puck in an ice hockey game. We observed that the oculomotor system was able to leverage the contextual cues available in the naturalistic scene to produce predictive eye movements. In this study, we wanted to assess which factors are critical for achieving this predictive advantage by manipulating four factors: the expertise of the viewers, the amount of available peripheral information, and positional and kinematic cues. The more peripheral information became available (by manipulating the area of the video that was visible), the better the predictions of all observers. However, expert ice hockey fans were consistently better at predicting than novices and used peripheral information more effectively for predictive saccades. Artificial cues about player positions did not lead to a predictive advantage, whereas impairing the causal structure of kinematic cues by playing the video in reverse led to a severe impairment. When videos were flipped vertically to introduce more difficult kinematic cues, predictive behavior was comparable to watching the original videos. Together, these results demonstrate that, when contextual information is available in naturalistic scenes, the oculomotor system is successfully integrating them and is not relying only on low-level information about the target trajectory. Critical factors for successful prediction seem to be the amount of available information, experience with the stimuli, and the availability of intact kinematic cues for player movements. |
Harold H. Greene; Vaibhav A. Diwadkar; James M. Brown Regularities in vertical saccadic metrics: New insights, and future perspectives Journal Article In: Frontiers in Psychology, vol. 14, pp. 1–10, 2023. @article{Greene2023, Introduction: Asymmetries in processing by the healthy brain demonstrate regularities that facilitate the modeling of brain operations. The goal of the present study was to determine asymmetries in saccadic metrics during visual exploration, devoid of confounding clutter in the visual field. Methods: Twenty healthy adults searched for a small, low-contrast gaze-contingent target on a blank computer screen. The target was visible, only if eye fixation was within a 5 deg. by 5 deg. area of the target's location. Results: Replicating previously-reported asymmetries, repeated measures contrast analyses indicated that up-directed saccades were executed earlier, were smaller in amplitude, and had greater probability than down-directed saccades. Given that saccade velocities are confounded by saccade amplitudes, it was also useful to investigate saccade kinematics of visual exploration, as a function of vertical saccade direction. Saccade kinematics were modeled for each participant, as a square root relationship between average saccade velocity (i.e., average velocity between launching and landing of a saccade) and corresponding saccade amplitude (Velocity = S*[Saccade Amplitude]0.5). A comparison of the vertical scaling parameter (S) for up- and down-directed saccades showed that up-directed saccades tended to be slower than down-directed ones. Discussion: To motivate future research, an ecological theory of asymmetric pre-saccadic inhibition was presented to explain the collection of vertical saccadic regularities. For example, given that the theory proposes strong inhibition for the releasing of reflexive down-directed prosaccades (cued by an attracting peripheral target below eye fixation), and weak inhibition for the releasing of up-directed prosaccades (cued by an attracting peripheral target above eye fixation), a prediction for future studies is longer reaction times for vertical anti-saccade cues above eye fixation. Finally, the present study with healthy individuals demonstrates a rationale for further study of vertical saccades in psychiatric disorders, as bio-markers for brain pathology. |
Leslie Guadron; Samuel A. Titchener; Carla J. Abbott; Lauren N. Ayton; John Opstal; Matthew A. Petoe; Jeroen Goossens The saccade main sequence in patients with retinitis pigmentosa and advanced age-related macular degeneration Journal Article In: Investigative Ophthalmology & Visual Science, vol. 64, no. 3, pp. 1–18, 2023. @article{Guadron2023, PURPOSE. Most eye-movement studies in patients with visual field defects have examined the strategies that patients use while exploring a visual scene, but they have not investigated saccade kinematics. In healthy vision, saccade trajectories follow the remarkably stereotyped “main sequence”: saccade duration increases linearly with saccade amplitude; peak velocity also increases linearly for small amplitudes, but approaches a saturation limit for large amplitudes. Recent theories propose that these relationships reflect the brain's attempt to optimize vision when planning eye movements. Therefore, in patients with bilateral retinal damage, saccadic behavior might differ to optimize vision under the constraints imposed by the visual field defects. METHODS. We compared saccadic behavior of patients with central vision loss, due to age-related macular degeneration (AMD), and patients with peripheral vision loss, due to retinitis pigmentosa (RP), to that of controls with normal vision (NV) using a horizontal saccade task. RESULTS. Both patient groups demonstrated deficits in saccade reaction times and target localization behavior, as well as altered saccade kinematics. Saccades were generally slower and the shape of the velocity profiles were often atypical, especially in the patients with RP. In the patients with AMD, the changes were far less dramatic. For both groups, saccade kinematics were affected most when the target was in the subjects' blind field. CONCLUSIONS. We conclude that defects of the central and peripheral retina have distinct effects on the saccade main sequence, and that visual inputs play an important role in planning the kinematics of a saccade. |
Rebekka Schröder; Kristof Keidel; Peter Trautner; Alexander Radbruch; Ulrich Ettinger Neural mechanisms of background and velocity effects in smooth pursuit eye movements Journal Article In: Human Brain Mapping, vol. 44, no. 3, pp. 1–17, 2023. @article{Schroeder2023a, Smooth pursuit eye movements (SPEM) are essential to guide behaviour in complex visual environments. SPEM accuracy is known to be degraded by the presence of a structured visual background and at higher target velocities. The aim of this preregistered study was to investigate the neural mechanisms of these robust behavioural effects. N = 33 participants performed a SPEM task with two background conditions (present and absent) at two target velocities (0.4 and 0.6 Hz). Eye movement and BOLD data were collected simultaneously. Both the presence of a structured background and faster target velocity decreased pursuit gain and increased catch-up saccade rate. Faster targets additionally increased position error. Higher BOLD response with background was found in extensive clusters in visual, parietal, and frontal areas (including the medial frontal eye fields; FEF) partially overlapping with the known SPEM network. Faster targets were associated with higher BOLD response in visual cortex and left lateral FEF. Task-based functional connectivity analyses (psychophysiological interactions; PPI) largely replicated previous results in the basic SPEM network but did not yield additional information regarding the neural underpinnings of the background and velocity effects. The results show that the presentation of visual background stimuli during SPEM induces activity in a widespread visuo-parieto-frontal network including areas contributing to cognitive aspects of oculomotor control such as medial FEF, whereas the response to higher target velocity involves visual and motor areas such as lateral FEF. Therefore, we were able to propose for the first time different functions of the medial and lateral FEF during SPEM. |
Werner Seitz; Artyom Zinchenko; Hermann J. Müller; Thomas Geyer Contextual cueing of visual search reflects the acquisition of an optimal, one-for-all oculomotor scanning strategy Journal Article In: Communications Psychology, vol. 1, no. 1, pp. 1–12, 2023. @article{Seitz2023, Visual search improves when a target is encountered repeatedly at a fixed location within a stable distractor arrangement (spatial context), compared to non-repeated contexts. The standard account attributes this contextual-cueing effect to the acquisition of display-specific long-term memories, which, when activated by the current display, cue attention to the target location. Here we present an alternative, procedural-optimization account, according to which contextual facilitation arises from the acquisition of generic oculomotor scanning strategies, optimized with respect to the entire set of displays, with frequently searched displays accruing greater weight in the optimization process. To decide between these alternatives, we examined measures of the similarity, across time-on-task, of the spatio-temporal sequences of fixations through repeated and non-repeated displays. We found scanpath similarity to increase generally with learning, but more for repeated versus non-repeated displays. This pattern contradicts display-specific guidance, but supports one-for-all scanpath optimization. |
Anaïs Servais; Noémie Préa; Christophe Hurter; Emmanuel J. Barbeau In: Acta Psychologica, vol. 240, pp. 1–13, 2023. @article{Servais2023, It is common to look away while trying to remember specific information, for example during autobiographical memory retrieval, a behavior referred to as gaze aversion. Given the competition between internal and external attention, gaze aversion is assumed to play a role in visual decoupling, i.e., suppressing environmental distractors during internal tasks. This suggests a link between gaze aversion and the attentional switch from the outside world to a temporary internal mental space that takes place during the initial stage of memory retrieval, but this assumption has never been verified so far. We designed a protocol where 33 participants answered 48 autobiographical questions while their eye movements were recorded with an eye-tracker and a camcorder. Results indicated that gaze aversion occurred early (median 1.09 s) and predominantly during the access phase of memory retrieval—i.e., the moment when the attentional switch is assumed to take place. In addition, gaze aversion lasted a relatively long time (on average 6 s), and was notably decoupled from concurrent head movements. These results support a role of gaze aversion in perceptual decoupling. Gaze aversion was also related to higher retrieval effort and was rare during memories which came spontaneously to mind. This suggests that gaze aversion might be required only when cognitive effort is required to switch the attention toward the internal world to help retrieving hard-to-access memories. Compared to eye vergence, another visual decoupling strategy, the association with the attentional switch seemed specific to gaze aversion. Our results provide for the first time several arguments supporting the hypothesis that gaze aversion is related to the attentional switch from the outside world to memory. |
Yijing Shan; Jay A. Edelman The reduction of saccadic inhibition by distractor repetition Journal Article In: Journal of Neurophysiology, vol. 130, no. 3, pp. 619–627, 2023. @article{Shan2023, When visual distractors are presented far from the goal of an impending voluntary saccadic eye movement, saccade execution will occur less frequently about 90 ms after distractor appearance, a phenomenon known as saccadic inhibition. However, it is also known that neural responses in visual and visuomotor areas of the brain will be attenuated if a visual stimulus appears several times in the same location in rapid succession. In particular, such visual adaptation can affect neurons in the mammalian superior colliculus (SC). As the SC is known to be intimately involved in the production of saccadic eye movements, and thus perhaps in saccadic inhibition, we used a memory-guided saccade task to test whether saccadic inhibition in humans would diminish if a distractor appeared several times in quick succession. We found that distractor repetition reduced saccadic inhibition considerably when distractors appeared opposite in space to the goal of the impending saccade. In addition, when three distractors appeared in quick succession but in different, spatially disparate locations, with only the final distractor appearing opposite the saccade goal, saccadic inhibition was reduced by an intermediate level, suggesting that its reduction due to distractor inhibition spatially generalizes. This suggests that distractor suppression can help reduce the impact that suddenly appearing visual stimuli have on purposive eye movement behavior.NEW & NOTEWORTHY This work combines approaches studying saccadic inhibition and visual adaptation to demonstrate that saccadic inhibition is largely eliminated with stimulus repetition. This is likely to be the largest demonstrated effect of visual stimulus context on saccadic inhibition. It also provides evidence for the existence of a mechanism that acts to suppress the effect of frequently appearing visual stimuli on purposive eye movement behavior in dynamic visual environments. |
Tarkeshwar Singh; John-Ross Rizzo; Cédrick Bonnet; Jennifer A. Semrau; Troy M. Herter Enhanced cognitive interference during visuomotor tasks may cause eye–hand dyscoordination Journal Article In: Experimental Brain Research, vol. 241, no. 2, pp. 547–558, 2023. @article{Singh2023, In complex visuomotor tasks, such as cooking, people make many saccades to continuously search for items before and during reaching movements. These tasks require cognitive resources, such as short-term memory and task-switching. Cognitive load may impact limb motor performance by increasing demands on mental processes, but mechanisms remain unclear. The Trail-Making Tests, in which participants sequentially search for and make reaching movements to 25 targets, consist of a simple numeric variant (Trails-A) and a cognitively challenging variant that requires alphanumeric switching (Trails-B). We have previously shown that stroke survivors and age-matched controls make many more saccades in Trails-B, and those increases in saccades are associated with decreases in speed and smoothness of reaching movements. However, it remains unclear how patients with neurological injuries, e.g., stroke, manage progressive increases in cognitive load during visuomotor tasks, such as the Trail-Making Tests. As Trails-B trial progresses, switching between numbers and letters leads to progressive increases in cognitive load. Here, we show that stroke survivors with damage to frontoparietal areas and age-matched controls made more saccades and had longer fixations as they progressed through the 25 alphanumeric targets in Trails-B. Furthermore, when stroke survivors made saccades during reaching movements in Trails-B, their movement speed slowed down significantly. Thus, damage to frontoparietal areas serving cognitive motor functions may cause interference between oculomotor, visual, and limb motor functions, which could lead to significant disruptions in activities of daily living. These findings augment our understanding of the mechanisms that underpin cognitive-motor interference during complex visuomotor tasks. |
Maverick E. Smith; Lester C. Loschky; Heather R. Bailey Eye movements and event segmentation: Eye movements reveal age-related differences in event model updating Journal Article In: Psychology and Aging, pp. 1–8, 2023. @article{Smith2023, People spontaneously segment continuous ongoing actions into sequences of events. Prior research found that gaze similarity and pupil dilation increase at event boundaries and that older adults segmentmore idiosyncratically than do young adults.We used eye tracking to explore age-related differences in gaze similarity (i.e., the extent to which individuals look at the same places at the same time as others) and pupil dilation at event boundaries. Older and young adults watched naturalistic videos of actors performing everyday activities while we tracked their eye movements. Afterward, they segmented the videos into subevents. Replicating prior work, we found that pupil size and gaze similarity increased at event boundaries. Thus, there were fewer individual differences in eye position at boundaries.We also found that young adults had higher gaze similarity than older adults throughout an entire video and at event boundaries. This study is the first to show that age-related differences in how people parse continuous everyday activities into events may be partially explained by individual differences in gaze patterns. Those who segment less normatively may do so because they fixate less normative regions. Results have implications for future interventions designed to improve encoding in older adults. |
Emma J. Solly; Meaghan Clough; Allison M. McKendrick; Owen B. White; Joanne Fielding Eye movement characteristics are not significantly influenced by psychiatric comorbidities in people with visual snow syndrome Journal Article In: Brain Research, vol. 1804, pp. 1–5, 2023. @article{Solly2023, Visual snow syndrome (VSS) is a neurological disorder primarily affecting the processing of visual information. Using ocular motor (OM) tasks, we previously demonstrated that participants with VSS exhibit altered saccade profiles consistent with visual attention impairments. We subsequently proposed that OM assessments may provide an objective measure of dysfunction in these individuals. However, VSS participants also frequently report significant psychiatric symptoms. Given that that these symptoms have been shown previously to influence performance on OM tasks, the objective of this study was to investigate whether psychiatric symptoms (specifically: depression, anxiety, fatigue, sleep difficulties, and depersonalization) influence the OM metrics found to differ in VSS. Sixty-one VSS participants completed a battery of four OM tasks and a series of online questionnaires assessing psychiatric symptomology. We revealed no significant relationship between psychiatric symptoms and OM metrics on any of the tasks, demonstrating that in participants with VSS, differences in OM behaviour are a feature of the disorder. This supports the utility of OM assessment in characterising deficit in VSS, whether supporting a diagnosis or monitoring future treatment efficacy. |
Sangkyu Son; Joonsik Moon; Yee-Joon Kim; Min-Suk Kang; Joonyeol Lee Frontal-to-visual information flow explains predictive motion tracking Journal Article In: NeuroImage, vol. 269, pp. 1–11, 2023. @article{Son2023, Predictive tracking demonstrates our ability to maintain a line of vision on moving objects even when they temporarily disappear. Models of smooth pursuit eye movements posit that our brain achieves this ability by directly streamlining motor programming from continuously updated sensory motion information. To test this hypothesis, we obtained sensory motion representation from multivariate electroencephalogram activity while human participants covertly tracked a temporarily occluded moving stimulus with their eyes remaining stationary at the fixation point. The sensory motion representation of the occluded target evolves to its maximum strength at the expected timing of reappearance, suggesting a timely modulation of the internal model of the visual target. We further characterize the spatiotemporal dynamics of the task-relevant motion information by computing the phase gradients of slow oscillations. We discovered a predominant posterior-to-anterior phase gradient immediately after stimulus occlusion; however, at the expected timing of reappearance, the axis reverses the gradient, becoming anterior-to-posterior. The behavioral bias of smooth pursuit eye movements, which is a signature of the predictive process of the pursuit, was correlated with the posterior division of the gradient. These results suggest that the sensory motion area modulated by the prediction signal is involved in updating motor programming. |
David Souto; Jennifer Sudkamp; Kyle Nacilla; Mateusz Bocian Tuning in to a hip-hop beat: Pursuit eye movements reveal processing of biological motion Journal Article In: Human Movement Science, vol. 91, pp. 1–12, 2023. @article{Souto2023, Smooth pursuit eye movements are mainly driven by motion signals to achieve their goal of reducing retinal motion blur. However, they can also show anticipation of predictable movement patterns. Oculomotor predictions may rely on an internal model of the target kinematics. Most investigations on the nature of those predictions have concentrated on simple stimuli, such as a decontextualized dot. However, biological motion is one of the most important visual stimuli in regulating human interaction and its perception involves integration of form and motion across time and space. Therefore, we asked whether there is a specific contribution of an internal model of biological motion in driving pursuit eye movements. Unlike previous contributions, we exploited the cyclical nature of walking to measure eye movement's ability to track the velocity oscillations of the hip of point-light walkers. We quantified the quality of tracking by cross-correlating pursuit and hip velocity oscillations. We found a robust correlation between signals, even along the horizontal dimension, where changes in velocity during the stepping cycle are very subtle. The inversion of the walker and the presentation of the hip-dot without context incurred the same additional phase lag along the horizontal dimension. These findings support the view that information beyond the hip-dot contributes to the prediction of hip kinematics that controls pursuit. We also found a smaller phase lag in inverted walkers for pursuit along the vertical dimension compared to upright walkers, indicating that inversion does not simply reduce prediction. We suggest that pursuit eye movements reflect the visual processing of biological motion and as such could provide an implicit measure of higher-level visual function. |
Maximilian Stefani; Marian Sauter Relative contributions of oculomotor capture and disengagement to distractor-related dwell times in visual search Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–10, 2023. @article{Stefani2023, In visual search, attention is reliably captured by salient distractors and must be actively disengaged from them to reach the target. In such attentional capture paradigms, dwell time is measured on distractors that appear in the periphery (e.g., on a random location on a circle). Distractor-related dwell time is typically thought to be largely due to stimulus-driven processes related to oculomotor capture dynamics. However, the extent to which oculomotor capture and oculomotor disengagement contribute to distractor dwell time has not been known because standard attentional capture paradigms cannot decouple these processes. In the present study, we used a novel paradigm combining classical attentional capture trials and delayed disengagement trials. We measured eye movements to dissociate the capture and disengagement mechanisms underlying distractor dwell time. We found that only two-thirds of distractor dwell time (~ 52 ms) can be explained by oculomotor capture, while one-third is explained by oculomotor disengagement (~ 18 ms), which has been neglected or underestimated in previous studies. Thus, oculomotor disengagement (goal-directed) processes play a more significant role in distractor dwell times than previously thought. |
Moritz Stolte; Leon Kraus; Ulrich Ansorge Visual attentional guidance during smooth pursuit eye movements: Distractor interference is independent of distractor-target similarity Journal Article In: Psychophysiology, vol. 60, no. 12, pp. 1–11, 2023. @article{Stolte2023, In the current study, we used abrupt-onset distractors similar and dissimilar in luminance to the target of a smooth pursuit eye-movement to test if abrupt-onset distractors capture attention in a top-down or bottom-up fashion while the eyes track a moving object. Abrupt onset distractors were presented at different positions relative to the current position of a pursuit target during the closed-loop phase of smooth pursuit. Across experiments, we varied the duration of the distractors, their motion direction, and task-relevance. We found that abrupt-onset distractors decreased the gain of horizontally directed smooth-pursuit eye-movements. This effect, however, was independent of the similarity in luminance between distractor and target. In addition, distracting effects on horizontal gain were the same, regardless of the exact duration and position of the distractors, suggesting that capture was relatively unspecific and short-lived (Experiments 1 and 2). This was different with distractors moving in a vertical direction, perpendicular to the horizontally moving target. In line with past findings, these distractors caused suppression of vertical gain (Experiment 3). Finally, making distractors task-relevant by asking observers to report distractor positions increased the pursuit gain effect of the distractors. This effect was also independent of target-distractor similarity (Experiment 4). In conclusion, the results suggest that a strong location signal exerted by the pursuit targets led to very brief and largely location-unspecific interference through the abrupt onsets and that this interference was bottom-up, implying that the control of smooth pursuit was independent of other target features besides its motion signal. |
Georgia F. Symons; William T. O'Brien; Larry Abel; Zhibin Chen; Daniel M. Costello; Terence J. O'Brien; Scott Kolbe; Joanne Fielding; Sandy R. Shultz; Meaghan Clough; William T. O'Brien; Larry Abel; Zhibin Chen; Daniel M. Costello; Terence J. O'brien; Scott Kolbe; Joanne Fielding; Sandy R. Shultz; Meaghan Clough Monitoring the acute and subacute recovery of cognitive ocular motor changes after a sports-related concussion Journal Article In: Cerebral Cortex, vol. 33, no. 9, pp. 5276–5288, 2023. @article{Symons2023, Identifying when recovery from a sports-related concussion (SRC) has occurred remains a challenge in clinical practice. This study investigated the utility of ocular motor (OM) assessment to monitor recovery post-SRC between sexes and compared to common clinical measures. From 139 preseason baseline assessments (i.e. before they sustained an SRC), 18 (12 males, 6 females) consequent SRCs were sustained and the longitudinal follow-ups were collected at 2, 6, and 13 days post-SRC. Participants completed visually guided, antisaccade (AS), and memory-guided saccade tasks requiring a saccade toward, away from, and to a remembered target, respectively. Changes in latency (processing speed), visual-spatial accuracy, and errors were measured. Clinical measures included The Sports Concussion Assessment Tool, King-Devick test, Stroop task, and Digit span. AS latency was significantly longer at 2 days and returned to baseline by 13-days post-SRC in females only (P < 0.001). Symptom numbers recovered from 2 to 6 days and 13 days (P < 0.05). Persistently poorer AS visual-spatial accuracy was identified at 2, 6 and 13 days post-SRC (P < 0.05) in both males and females but with differing trajectories. Clinical measures demonstrated consistent improvement reminiscent of practice effects. OM saccade assessment may have improved utility in tracking recovery compared to conventional measures and between sexes. |
Noam Tal-Perry; Shlomit Yuval-Greenberg Sequential effect and temporal orienting in prestimulus oculomotor inhibition Journal Article In: Journal of Vision, vol. 23, no. 14, pp. 1–13, 2023. @article{TalPerry2023, When faced with unfamiliar circumstances, we often turn to our past experiences with similar situations to shape our expectations. This results in the well-established sequential effect, in which previous trials influence the expectations of the current trial. Studies have revealed that, in addition to the classical behavioral metrics, the inhibition of eye movement could be used as a biomarker to study temporal expectations. This prestimulus oculomotor inhibition is found a few hundred milliseconds prior to predictable events, with a stronger inhibition for predictable than unpredictable events. The phenomenon has been found to occur in various temporal structures, such as rhythms, cue-association, and conditional probability, yet it is still unknown whether it reflects local sequential information of the previous trial. To explore this, we examined the relationship between the sequential effect and the prestimulus oculomotor inhibition. Our results (N = 40) revealed that inhibition was weaker when the previous trial was longer than the current trial, in line with findings of behavioral metrics. These findings indicate that the prestimulus oculomotor inhibition covaries with expectation based on local sequential information, demonstrating the tight connection between this phenomenon and expectation and providing a novel measurement for studying sequential effects in temporal expectation. |
Pin Kwang Tan; Cheng Tang; Roger Herikstad; Arunika Pillay; Camilo Libedinsky Distinct lateral prefrontal regions are organized in an anterior-posterior functional gradient Journal Article In: Journal of Neuroscience, vol. 43, no. 38, pp. 6564–6572, 2023. @article{Tan2023a, The dorsolateral prefrontal cortex (dlPFC) is composed of multiple anatomically-defined regions involved in higher-order cognitive processes, including working memory and selective attention. It is organized in an anterior-posterior global gradient where posterior regions track changes in the environment while anterior regions support abstract neural representations. However, it remains unknown if such a global gradient results from a smooth gradient that spans regions, or an emergent property arising from functionally distinct regions, i.e. an areal gradient. Here, we recorded single-neurons in the dlPFC of non-human primates trained to perform a memory-guided saccade task with an interfering distractor, and analyzed their physiological properties along the anterior-posterior axis. We found that these physiological properties were best described by an areal gradient. Further, population analyses revealed that there is a distributed representation of spatial information across the dlPFC. Our results validate the functional boundaries between anatomically-defined dlPFC regions and highlight the distributed nature of computations underlying working memory across the dlPFC. Significance Statement Activity of frontal lobe regions is known to possess an anterior-posterior functional gradient. However, it is not known whether this gradient is the result of individual brain regions organized in a gradient (like a staircase), or a smooth gradient that spans regions (like a slide). Analysis of physiological properties of individual neurons in the primate frontal regions suggest that individual regions are organized as a gradient, rather than a smooth gradient. At the population level, working memory was more prominent in posterior regions, even though it was also present in anterior regions. This is consistent with the functional segregation of brain regions that is also observed in other systems (i.e. the visual system). |
Diane C. Mézière; Lili Yu; Genevieve McArthur; Erik D. Reichle; Titus Malsburg Scanpath regularity as an index of reading comprehension Journal Article In: Scientific Studies of Reading, vol. 28, no. 1, pp. 79–100, 2023. @article{Meziere2023, Purpose: Recent research on the potential of using eye-tracking to measure reading comprehension ability suggests that the relationship between standard eye-tracking measures and reading comprehension is influenced by differences in task demands between comprehension assessments. We compared standard eye-tracking measures and scanpath regularity as predictors of reading comprehension scores. Method: We used a dataset in which 79 participants (mean age: 22 years, 82% females, 76% monolingual English speakers) were administered three widely-used reading comprehension assessments with varying task demands while their eye movements were monitored: the York Assessment of Reading for Comprehension; (YARC), the Gray Oral Reading Test; (GORT-5), and the sentence comprehension subtest of the Wide Range Achievement Test; (WRAT-4). Results: Results showed that scanpath regularity measures, similarly to standard eye-tracking measures, were influenced by differences in task demands between the three tests. Nevertheless, both types of eye-tracking measures made unique contributions as predictors of comprehension and the best set of predictors included both standard eye-tracking measures and at least one scanpath measure across tests. Conclusion: The results provide evidence that scanpaths capture differences in eye-movement patterns missed by standard eye-tracking measures. Overall, the results highlight the effect of task demands on eye-movement behavior and suggest that reading goals and task demands need to be considered when interpreting eye-tracking data. |
Diane C. Mézière; Lili Yu; Erik D. Reichle; Titus Malsburg; Genevieve McArthur Using eye-tracking measures to predict reading comprehension Journal Article In: Reading Research Quarterly, vol. 58, no. 3, pp. 425–449, 2023. @article{Meziere2023a, This study examined the potential of eye-tracking as a tool for assessing reading comprehension. We administered three widely used reading comprehension tests with varying task demands to 79 typical adult readers while monitoring their eye movements. In the York Assessment of Reading for Comprehension (YARC), participants were given passages of text to read silently, followed by comprehension questions. In the Gray Oral Reading Test (GORT-5), participants were given passages of text to read aloud, followed by comprehension questions. In the sentence comprehension subtest of the Wide Range Achievement Test (WRAT-4), participants were asked to provide a missing word in sentences that they read silently (i.e., a cloze task). Linear models predicting comprehension scores from eye-tracking measures yielded different results for the three tests. Eye-tracking measures explained significantly more variance than reading-speed data for the YARC (four times better), GORT (three times better), and the WRAT (1.3 time better). Importantly, there was no common strong predictor for all three tests. These results support growing recognition that reading comprehension tests do not measure the same cognitive processes, and that participants adapt their reading strategies to the tests' varying task demands. This study also suggests that eye-tracking may provide a useful alternative for measuring reading comprehension. |
Jenny A. Nij Bijvank; Sam N. Hof; Stefanos E. Prouskas; Menno M. Schoonheim; Bernard M. J. Uitdehaag; Laurentius J. Rijn; Axel Petzold A novel eye-movement impairment in multiple sclerosis indicating widespread cortical damage Journal Article In: Brain, vol. 146, no. 6, pp. 2476–2488, 2023. @article{NijBijvank2023, In multiple sclerosis, remyelination trials have yet to deliver success like that achieved for relapse rates with disease course modifying treatment trials. The challenge is to have a clinical, functional outcome measure. Currently, there are none that have been validated, other than visual evoked potentials in optic neuritis. Like vision, quick eye movements (saccades) are heavily dependent on myelination. We proposed that it is possible to extrapolate from demyelination of the medial longitudinal fasciculus in the brainstem to quantitative assessment of cortical networks governing saccadic eye movements in multiple sclerosis. We have developed and validated a double-step saccadic test, which consists of a pair of eye movements towards two stimuli presented in quick succession (the demonstrate eye movement networks with saccades protocol). In this single-centre, cross-sectional cohort study we interrogated the structural and functional relationships of double-step saccades in multiple sclerosis. Data were collected for double-step saccades, cognitive function (extended Rao's Brief Repeatable Battery), disability (Expanded Disability Status Scale) and visual functioning in daily life (National Eye Institute Visual Function Questionnaire). MRI was used to quantify grey matter atrophy and multiple sclerosis lesion load. Multivariable linear regression models were used for analysis of the relationships between double-step saccades and clinical and MRI metrics. We included 209 individuals with multiple sclerosis (mean age 54.3 ± 10.5 years, 58% female, 63% relapsing-remitting multiple sclerosis) and 60 healthy control subjects (mean age 52.1 ± 9.2 years, 53% female). The proportion of correct double-step saccades was significantly reduced in multiple sclerosis (mean 0.29 ± 0.22) compared to controls (0.45 ± 0.22, P < 0.001). Consistent with this, there was a significantly larger double-step dysmetric saccadic error in multiple sclerosis (mean vertical error −1.18 ± 1.20°) compared to controls (−0.54 ± 0.86°, P < 0.001). Impaired double-step saccadic metrics were consistently associated with more severe global and local grey matter atrophy (correct responses—cortical grey matter: β = 0.42, P < 0.001), lesion load (vertical error: β = −0.28, P < 0.001), progressive phenotypes, more severe physical and cognitive impairment (correct responses—information processing: β = 0.46, P < 0.001) and visual functioning. In conclusion, double-step saccades represent a robust metric that revealed a novel eye-movement impairment in individuals with multiple sclerosis. Double-step saccades outperformed other saccadic tasks in their statistical relationship with clinical, cognitive and visual functioning, as well as global and local grey matter atrophy. Double-step saccades should be evaluated longitudinally and tested as a potential novel outcome measure for remyelination trials in multiple sclerosis. |
Andrey R. Nikolaev; Benedikt V. Ehinger; Radha Nila Meghanathan; Cees Leeuwen Planning to revisit: Neural activity in refixation precursors Journal Article In: Journal of Vision, vol. 23, no. 7, pp. 1–19, 2023. @article{Nikolaev2023, Eye tracking studies suggest that refixations—fixations to locations previously visited—serve to recover information lost or missed during earlier exploration of a visual scene. These studies have largely ignored the role of precursor fixations—previous fixations on locations the eyes return to later.We consider the possibility that preparations to return later are already made during precursor fixations. This process would mark precursor fixations as a special category of fixations, that is, distinct in neural activity from other fixation categories such as refixations and fixations to locations visited only once. To capture the neural signals associated with fixation categories, we analyzed electroencephalograms (EEGs) and eye movements recorded simultaneously in a free-viewing contour search task. We developed a methodological pipeline involving regression-based deconvolution modeling, allowing our analyses to account for overlapping EEG responses owing to the saccade sequence and other oculomotor covariates. We found that precursor fixations were preceded by the largest saccades among the fixation categories. Independent of the effect of saccade length, EEG amplitude was enhanced in precursor fixations compared with the other fixation categories 200 to 400 ms after fixation onsets, most noticeably over the occipital areas.We concluded that precursor fixations play a pivotal role in visual perception, marking the continuous occurrence of transitions between exploratory and exploitative modes of eye movement in natural viewing behavior. |
Sven Ohl; Lisa M. Kroell; Martin Rolfs In: Journal of Experimental Psychology: General, pp. 1–20, 2023. @article{Ohl2023, Visual working memory and actions are closely intertwined. Memory can guide our actions, but actions also impact what we remember. Even during memory maintenance, actions such as saccadic eye movements select content in visual working memory, resulting in better memory at locations that are congruent with the action goal as compared to incongruent locations. Here, we further substantiate the claim that saccadic eye movements are fundamentally linked to visual working memory by analyzing a large data set (.100k trials) of nine experiments (eight of them previously published). Using Bayesian hierarchical models, we demonstrate robust saccadic selection across the full range of probed saccade directions, manifesting as better memory performance at the saccade goal irrespective of its location in the visual field. By inspecting individual differences in saccadic selection, we show that saccadic selection was highly prevalent in the population. Moreover, both saccade metrics and visual working memory performance varied considerably across the visual field. Crucially, however, both idiosyncratic and systematic visual field anisotropies were not correlated between visual working memory and the oculomotor system, suggesting that they resulted from different sources (e.g., rely on separate spatial maps). In stark contrast, trial-by-trial variations in saccade metrics were strongly associated with memory performance: At any given location, shorter saccade latencies and more accurate saccades were associated with better memory performance, undergirding a robust link between action selection and visual memory. |
Kosuke Okazaki; Kenichiro Miura; Junya Matsumoto; Naomi Hasegawa; Michiko Fujimoto; Hidenaga Yamamori; Yuka Yasuda; Manabu Makinodan; Ryota Hashimoto Discrimination in the clinical diagnosis between patients with schizophrenia and healthy controls using eye movement and cognitive functions Journal Article In: Psychiatry and Clinical Neurosciences, vol. 77, no. 7, pp. 393–400, 2023. @article{Okazaki2023, Aim: Eye movements and cognitive functions are significantly impaired in patients with schizophrenia. The authors aimed to develop promising clinical diagnostic markers that fit practical digital health applications in psychiatry using eye movement and cognitive function data from 1254 healthy individuals and 336 patients with schizophrenia. Methods: Multivariate analyses using logistic regression were performed to confirm net performance of eye movements and cognitive functions scored using the Wechsler Adult Intelligence Scale, Third Edition, and Wechsler Memory Scale-Revised. The authors then examined the discrimination performance of pairs containing an eye movement and a cognitive function measure to search the pairs that would be effective in practical application for the discrimination according to the diagnostic criterion between the groups. Results: Multivariate analyses confirmed that eye movements and cognitive functions were effective modalities for discriminating between patients with schizophrenia and healthy controls. The discriminant analyses of the pairs demonstrated that seven eye movement measures and seven scores from cognitive function tests showed high discrimination performance when paired with one measure from the other modality. Moreover, seven pairs of digit-symbol coding or symbol-search and eye movement measures had high and robust discrimination performance. Conclusion: Seven pairs of an eye movement and a cognitive function measure were effective, robust, and less time-consuming in assisting with clinical diagnosis by categorizing healthy individuals or patients with schizophrenia. These findings may help develop an objective auxiliary diagnosis method working even on portable devices, which facilitates the consistency of diagnosis, earlier intervention, and shared decision-making. |
Henri Olkoniemi; Mikko Hurme; Henry Railo Neurologically healthy humans' ability to make saccades toward unseen targets Journal Article In: Neuroscience, vol. 513, pp. 111–125, 2023. @article{Olkoniemi2023a, Some patients with a visual field loss due to a lesion in the primary visual cortex (V1) can shift their gaze to stimuli presented in their blind visual field. The extent to which a similar “blindsight” capacity is present in neurologically healthy individuals remains unknown. Using retinotopically navigated transcranial magnetic stimulation (TMS) of V1 (Experiment 1) and metacontrast masking (Experiment 2) to suppress conscious vision, we examined neurologically healthy humans' ability to make saccadic eye movements toward visual targets that they reported not seeing. In the TMS experiment, the participants were more likely to initiate a saccade when a stimulus was presented, and they reported not seeing it, than in trials which no stimulus was presented. However, this happened only in a very small proportion (∼8%) of unseen trials, suggesting that saccadic reactions were largely based on conscious perception. In both experiments, saccade landing location was influenced by unconscious information: When the participants denied seeing the target but made a saccade, the saccade was made toward the correct location (TMS: 68%, metacontrast: 63%) more often than predicted by chance. Signal detection theoretic measures suggested that in the TMS experiment, saccades toward unseen targets may have been based on weak conscious experiences. In both experiments, reduced visibility of the target stimulus was associated with slower and less precise gaze shifts. These results suggest that saccades made by neurologically healthy humans may be influenced by unconscious information, although the initiation of saccades is largely based on conscious vision. |
John J. Orczyk; Annamaria Barczak; Monica N. O'Connell; Yoshinao Kajikawa Saccadic inhibition during free viewing in macaque monkeys Journal Article In: Journal of Neurophysiology, vol. 129, no. 2, pp. 356–367, 2023. @article{Orczyk2023, We investigated the time courses of saccade rate following visual stimuli during three conditions of free viewing in macaque monkeys. Under all conditions, saccade rate decreased transiently after the onset of visual stimuli. These results suggest that saccadic inhibition occurs during free viewing.Through the process of saccadic inhibition, visual events briefly suppress eye movements including microsaccades. In humans, saccadic inhibition has been shown to occur in response to the presentation of parafoveal or peripheral visual distractors during fixation and target-directed saccades and to physical changes of behaviorally relevant visual objects. In monkeys performing tasks that controlled eye movements, saccadic inhibition of microsaccades and target-directed saccades has been shown. Using eye data from three previously published studies, we investigated how saccade rate changed while monkeys were presented with visual stimuli under conditions with loose or no viewing demands. In two conditions, animals passively sat while an LED lamp flashed or screen-wide images appeared in front of them. In the third condition, images were repeated semiperiodically while animals had to maintain their gaze within a wide rectangular area and detect oddballs. Despite animals not being required to maintain fixation or make saccades to particular targets, the onset of visual events led to a temporary reduction of saccade rate across all conditions. Interestingly, saccadic inhibition was found at image offsets as well. These results show that saccadic inhibition occurs in monkeys during free viewing.NEW & NOTEWORTHY We investigated the time courses of saccade rate following visual stimuli during three conditions of free viewing in macaque monkeys. Under all conditions, saccade rate decreased transiently after the onset of visual stimuli. These results suggest that saccadic inhibition occurs during free viewing. |
Nicolas Orlando Dessaints; Laurent Goffart Tracking a moving visual target in the rhesus monkey: Influence of the occurrence frequency of the target path Journal Article In: Journal of Neurophysiology, vol. 130, no. 6, pp. 1425–1443, 2023. @article{OrlandoDessaints2023, Following previous studies documenting the ability to generate anticipatory responses, we tested whether the repeated motion of a visual target along the same path affected its oculomotor tracking. In six rhesus monkeys, we evaluated how the frequency of a target path influenced the onset, accuracy, and velocity of eye movements. Three hundred milliseconds after its extinction, a central target reappeared and immediately moved toward the periphery in four possible (oblique) directions and at a constant speed (20°/s or 40°/s). During each daily session, the frequency of one motion direction was either uncertain (25% of trials) or certain (100% of trials). Our results show no reduction of saccade latency between the two sessions. No express saccades were observed in either session. A slow eye movement started after target onset (presaccadic glissade) and its velocity was larger during the "certain" sessions only with the 40°/s target. No anticipatory eye movement was observed. Longer intersaccadic intervals were found during the "certain" sessions but the postsaccadic pursuit velocity exhibited no change. No correlation was found between the accuracy and precision of saccades (interceptive or catch-up) and the postsaccadic pursuit velocity. Repeatedly tracking a target that moves always along the same path does not favor the generation of anticipatory eye movements, saccadic or slow. Their occurrence is not spontaneous but seems to require preliminary training. Finally, for both sessions, the lack of correlation between the saccade-related and pursuit-related kinematic parameters is consistent with separate control of saccadic and slow eye movements.NEW & NOTEWORTHY Following previous studies documenting anticipatory movements, we investigated how the frequency of occurrence of a target path influenced the generation of tracking eye movements. When present, the effects were small. The limited performance that we found suggests that anticipatory responses require preliminary training, in which case, they should not be considered as a behavioral marker of the primates' ability to extrapolate but the outcome of learning and remembering past experience. |
JeongJun Park; Seolmin Kim; Hyung Goo R. Kim; Joonyeol Lee Prior expectation enhances sensorimotor behavior by modulating population tuning and subspace activity in sensory cortex Journal Article In: Science Advances, vol. 9, no. 27, pp. 1–20, 2023. @article{Park2023, Prior knowledge facilitates our perception and goal-directed behaviors, particularly when sensory input is lacking or noisy. However, the neural mechanisms underlying the improvement in sensorimotor behavior by prior expectations remain unknown. In this study, we examine the neural activity in the middle temporal (MT) area of visual cortex while monkeys perform a smooth pursuit eye movement task with prior expectation of the visual target's motion direction. Prior expectations discriminately reduce the MT neural responses depending on their preferred directions, when the sensory evidence is weak. This response reduction effectively sharpens neural population direction tuning. Simulations with a realistic MT population demonstrate that sharpening the tuning can explain the biases and variabilities in smooth pursuit, suggesting that neural computations in the sensory area alone can underpin the integration of prior knowledge and sensory evidence. State-space analysis further supports this by revealing neural signals of prior expectations in the MT population activity that correlate with behavioral changes. |
Soon Young Park; Kenneth Holmqvist; Diederick C. Niehorster; Ludwig Huber; Zsófia Virányi How to improve data quality in dog eye tracking Journal Article In: Behavior Research Methods, vol. 55, no. 4, pp. 1513–1536, 2023. @article{Park2023a, Pupil–corneal reflection (P–CR) eye tracking has gained a prominent role in studying dog visual cognition, despite methodological challenges that often lead to lower-quality data than when recording from humans. In the current study, we investigated if and how the morphology of dogs might interfere with tracking of P–CR systems, and to what extent such interference, possibly in combination with dog-unique eye-movement characteristics, may undermine data quality and affect eye-movement classification when processed through algorithms. For this aim, we have conducted an eye-tracking experiment with dogs and humans, and investigated incidences of tracking interference, compared how they blinked, and examined how differential quality of dog and human data affected the detection and classification of eye-movement events. Our results show that the morphology of dogs' face and eye can interfere with tracking methods of the systems, and dogs blink less often but their blinks are longer. Importantly, the lower quality of dog data lead to larger differences in how two different event detection algorithms classified fixations, indicating that the results of key dependent variables are more susceptible to choice of algorithm in dog than human data. Further, two measures of the Nyström & Holmqvist (Behavior Research Methods, 42(4), 188–204, 2010) algorithm showed that dog fixations are less stable and dog data have more trials with extreme levels of noise. Our findings call for analyses better adjusted to the characteristics of dog eye-tracking data, and our recommendations help future dog eye-tracking studies acquire quality data to enable robust comparisons of visual cognition between dogs and humans. |
Christina U. Pfeuffer; Andrea Kiesel; Lynn Huestegge Similar proactive effect monitoring in free and forced choice action modes Journal Article In: Psychological Research, vol. 87, no. 1, pp. 226–241, 2023. @article{Pfeuffer2023, When our actions yield predictable consequences in the environment, our eyes often already saccade towards the locations we expect these consequences to appear at. Such spontaneous anticipatory saccades occur based on bi-directional associations between action and effect formed by prior experience. That is, our eye movements are guided by expectations derived from prior learning history. Anticipatory saccades presumably reflect a proactive effect monitoring process that prepares a later comparison of expected and actual effect. Here, we examined whether anticipatory saccades emerged under forced choice conditions when only actions but not target stimuli were predictive of future effects and whether action mode (forced choice vs. free choice, i.e., stimulus-based vs. stimulus-independent choice) affected proactive effect monitoring. Participants produced predictable visual effects on the left/right side via forced choice and free choice left/right key presses. Action and visual effect were spatially compatible in one half of the experiment and spatially incompatible in the other half. Irrespective of whether effects were predicted by target stimuli in addition to participants' actions, in both action modes, we observed anticipatory saccades towards the location of future effects. Importantly, neither the frequency, nor latency or amplitude of these anticipatory saccades significantly differed between forced choice and free choice action modes. Overall, our findings suggest that proactive effect monitoring of future action consequences, as reflected in anticipatory saccades, is comparable between forced choice and free choice action modes. |
Anastasia Pilat; Rebecca J. McLean; Anna Vanina; Robert A. Dineen; Irene Gottlob Clinical features and imaging characteristics in achiasmia Journal Article In: Brain Communications, vol. 5, no. 4, pp. 1–11, 2023. @article{Pilat2023, Achiasmia is a rare visual pathway maldevelopment with reduced decussation of the axons in the optic chiasm. Our aim was to investigate clinical characteristics, macular, optic nerve and brain morphology in achiasmia. A prospective, cross-sectional, observational study of 12 participants with achiasmia [8 males and 4 females; 29.6 ± 18.4 years (mean ± standard deviation)] and 24 gender-, age-, ethnicity- and refraction-matched healthy controls was done. Full ophthalmology assessment, eye movement recording, a high-resolution spectral-domain optical coherence tomography of the macular and optic disc, five-channel visual-evoked responses, eye movement recordings and MRI scans of the brain and orbits were acquired. Achiasmia was confirmed in all 12 clinical participants by visual-evoked responses. Visual acuity in this group was 0.63 ± 0.19 and 0.53 ± 0.19 for the right and left eyes, respectively; most participants had mild refractive errors. All participants with achiasmia had see-saw nystagmus and no measurable stereo vision. Strabismus and abnormal head position were noted in 58% of participants. Optical coherence tomography showed optic nerve hypoplasia with associated foveal hypoplasia in four participants. In the remaining achiasmia participants, macular changes with significantly thinner paracentral inner segment (P = 0.002), wider pit (P = 0.04) and visual flattening of the ellipsoid line were found. MRI demonstrated chiasmatic aplasia in 3/12 (25%), chiasmatic hypoplasia in 7/12 (58%) and a subjectively normal chiasm in 2/12 (17%). Septo-optic dysplasia and severe bilateral optic nerve hypoplasia were found in three patients with chiasmic aplasia/hypoplasia on MRI. In this largest series of achiasmia patients to date, we found for the first time that neuronal abnormalities occur already at the retinal level. Foveal changes, optic nerve hypoplasia and the midline brain anomaly suggest that these abnormalities could be part of the same spectrum, with different manifestations of events during foetal development occurring with varying severity. |
Megan Polden; Trevor J. Crawford Eye movement latency coefficient of variation as a predictor of cognitive impairment: An eye tracking study of cognitive impairment Journal Article In: Vision, vol. 7, no. 2, pp. 1–12, 2023. @article{Polden2023, Studies demonstrated impairment in the control of saccadic eye movements in Alzheimer's disease (AD) and people with mild cognitive impairment (MCI) when conducting the pro-saccade and antisaccade tasks. Research showed that changes in the pro and antisaccade latencies may be particularly sensitive to dementia and general executive functioning. These tasks show potential for diagnostic use, as they provide a rich set of potential eye tracking markers. One such marker, the coefficient of variation (CV), is so far overlooked. For biological markers to be reliable, they must be able to detect abnormalities in preclinical stages. MCI is often viewed as a predecessor to AD, with certain classifications of MCI more likely than others to progress to AD. The current study examined the potential of CV scores on pro and antisaccade tasks to distinguish participants with AD, amnestic MCI (aMCI), non-amnesiac MCI (naMCI), and older controls. The analyses revealed no significant differences in CV scores across the groups using the pro or antisaccade task. Antisaccade mean latencies were able to distinguish participants with AD and the MCI subgroups. Future research is needed on CV measures and attentional fluctuations in AD and MCI individuals to fully assess this measure's potential to robustly distinguish clinical groups with high sensitivity and specificity. |
Antonella Pomè; Sandra Tyralla; Eckart Zimmermann Altered oculomotor flexibility is linked to high autistic traits Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–12, 2023. @article{Pome2023, Autism is a multifaced disorder comprising sensory abnormalities and a general inflexibility in the motor domain. The sensorimotor system is continuously challenged to answer whether motion-contingent errors result from own movements or whether they are due to external motion. Disturbances in this decision could lead to the perception of motion when there is none and to an inflexibility with regard to motor learning. Here, we test the hypothesis that altered processing of gaze-contingent sensations are responsible for both the motor inflexibility and the sensory overload in autism. We measured motor flexibility by testing how strong participants adapted in a classical saccade adaptation task. We asked healthy participants, scored for autistic traits, to make saccades to a target that was displaced either in inward or in outward direction during saccade execution. The amount of saccade adaptation, that requires to shift the internal target representation, varied with the autistic symptom severity. The higher participants scored for autistic traits, the less they adapted. In order to test for visual stability, we asked participants to localize the position of the saccade target after they completed their saccade. We found the often-reported saccade-induced mislocalization in low Autistic Quotient (AQ) participants. However, we also found mislocalization in high AQ participants despite the absence of saccade adaptation. Our data suggest that high autistic traits are associated with an oculomotor inflexibility that might produce altered processing of trans-saccadic vision which might increase the perceptual overstimulation that is experienced in autism spectrum disorders (ASD). |
Jan Ole Radecke; Andreas Sprenger; Hannah Stöckler; Lisa Espeter; Mandy Josephine Reichhardt; Lara S. Thomann; Tim Erdbrügger; Yvonne Buschermöhle; Stefan Borgwardt; Till R. Schneider; Joachim Gross; Carsten H. Wolters; Rebekka Lencer Normative tDCS over V5 and FEF reveals practice-induced modulation of extraretinal smooth pursuit mechanisms, but no specific stimulation effect Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–15, 2023. @article{Radecke2023, The neural networks subserving smooth pursuit eye movements (SPEM) provide an ideal model for investigating the interaction of sensory processing and motor control during ongoing movements. To better understand core plasticity aspects of sensorimotor processing for SPEM, normative sham, anodal or cathodal transcranial direct current stimulation (tDCS) was applied over visual area V5 and frontal eye fields (FEF) in sixty healthy participants. The identical within-subject paradigm was used to assess SPEM modulations by practice. While no specific tDCS effects were revealed, within- and between-session practice effects indicate plasticity of top-down extraretinal mechanisms that mainly affect SPEM in the absence of visual input and during SPEM initiation. To explore the potential of tDCS effects, individual electric field simulations were computed based on calibrated finite element head models and individual functional localization of V5 and FEF location (using functional MRI) and orientation (using combined EEG/MEG) was conducted. Simulations revealed only limited electric field target intensities induced by the applied normative tDCS montages but indicate the potential efficacy of personalized tDCS for the modulation of SPEM. In sum, results indicate the potential susceptibility of extraretinal SPEM control to targeted external neuromodulation (e.g., personalized tDCS) and intrinsic learning protocols. |
Ralph S. Redden; Matthew D. Hilchey; Sinan Aslam; Jason Ivanoff; Raymond M. Klein Using speed and accuracy and the Simon Effect to explore the output form of inhibition of return Journal Article In: Vision, vol. 7, no. 1, pp. 1–13, 2023. @article{Redden2023, Inhibition of return (IOR) refers to slower responses to targets presented at previously cued locations. Contrasting target discrimination performance over various eye movement conditions has shown the level of activation of the reflexive oculomotor system determines the nature of the effect. Notably, an inhibitory effect of a cue nearer to the input end of the processing continuum is observed when the reflexive oculomotor system is actively suppressed, and an inhibitory effect nearer the output end of the processing continuum is observed when the reflexive oculomotor system is actively engaged. Furthermore, these two forms of IOR interact differently with the Simon effect. Drift diffusion modeling has suggested that two parameters can theoretically account for the speed-accuracy tradeoff rendered by the output-based form of IOR: increased threshold and decreased trial noise. In Experiment 1, we demonstrate that the threshold parameter best accounts for the output-based form of IOR by measuring it with intermixed discrimination and localization targets. Experiment 2 employed the response-signal methodology and showed that the output-based form has no effect on the accrual of information about the target's identity. These results converge with the response bias account for the output form of IOR. |
Peter Reddingius; Daniel S. Asfaw; Vera M. Mönter; Nicholas D. Smith; Pete R. Jones; David P. Crabb Data on eye movements of glaucoma patients with asymmetrical visual field loss during free viewing Journal Article In: Data in Brief, vol. 48, pp. 1–7, 2023. @article{Reddingius2023, This paper describes data from Asfaw at al. [1], which examined the eye movements of glaucoma patients (n=15) with pronounced asymmetrical vision loss (visual field loss worse in one eye). This allows for within-subject comparisons between the better and worse eye, thereby controlling for the effects of individual differences between patients. All patients had a clinical diagnosis of open angle glaucoma (OAG). Participants were asked to look at images of nature monocularly (free viewing; fellow eye patched) while gaze was recorded at 1000 Hz using a remote eye tracker (EyeLink 1000). Raw and processed eye tracking data are provided. In addition, clinical (visual acuity, contrast sensitivity and visual field) and demographic information (age, sex) are provided. |
Scott Roberts; Peter R. Kufahl; Rebecca J. Ryznar; Taylor Norris; Sagar Patel; K. Dean Gubler; Dean Paz; Greg Schwimer; Richard Besserman; Anthony J. LaPorta Start-of-day oculomotor screening demonstrates the effects of fatigue and rest during a total immersion training program Journal Article In: Surgery, vol. 174, no. 5, pp. 1193–1200, 2023. @article{Roberts2023, Background: Investigating changes in sleep and fatigue metrics during intensive surgical and trauma skills training, this study explored the dynamic association between oculomotor metrics and fatigue. Specifically, alterations in these relations over extended stress exposure, the influence of time of day, and the impact of fatigue exposure on sleep metrics were examined. Methods: Thirty-nine military medical students participated in 6 days of immersion, hyper-realistic, and high-stress experiential casualty training. Participants completed surveys assessing the state of sleepiness with oculomotor tests performed each morning and evening, analyzing eye movement and pupillary change to characterize fatigue. Participants wore Fitbit TM devices to measure overall time asleep and time in each sleep stage during the training. Results: Fitbit data showed increased average minutes in rapid eye movement, deep sleep, and less time in light sleep from day 1 to day 4. The microsaccade peak velocity-to-displacement ratio exhibited a morning decrease but not in afternoon sessions, indicating repeated but temporary effects of accumulated fatigue. There were no findings regarding pupil reactivity to illumination changes. Conclusion: This study describes characteristics of fatigue measured by rapid and individually calibrated oculomotor tests. It demonstrates oculomotor relationships to fatigue in start-of-day testing, providing a direction for timing for optimal fatigue testing. These data suggest that improved sleep could signal resilience to fatigue during afternoon testing. Further investigation with more participants and longer duration is warranted. A deeper understanding of the interrelationships between training, sleep, and fatigue could improve surgical and military fitness. |
Cristina Rovira-Gay; Clara Mestre; Marc Argiles; Valldeflors Vinuela-Navarro; Jaume Pujol Feasibility of measuring fusional vergence amplitudes objectively Journal Article In: PLoS ONE, vol. 18, pp. 1–14, 2023. @article{RoviraGay2023, Two tests to measure fusional vergence amplitudes objectively were developed and validated against the two conventional clinical tests. Forty-nine adults participated in the study. Participants' negative (BI, base in) and positive (BO, base out) fusional vergence amplitudes at near were measured objectively in an haploscopic set-up by recording eye movements with an EyeLink 1000 Plus (SR Research). Stimulus disparity changed in steps or smoothly mimicking a prim bar and a Risley prism, respectively. Break and recovery points were determined offline using a custom Matlab algorithm for the analysis of eye movements. Fusional vergence amplitudes were also measured with two clinical tests using a Risley prism and a prism bar. A better agreement between tests was found for the measurement of BI than for BO fusional vergence amplitudes. The means ± SD of the differences between the BI break and recovery points measured with the two objective tests were -1.74 ± 3.35 PD and -1.97 ± 2.60 PD, respectively, which were comparable to those obtained for the subjective tests. For the BO break and recovery points, although the means of the differences between the two objective tests were small, high variability between subjects was found (0.31 ± 6.44 PD and -2.84 ± 7.01 PD, respectively). This study showed the feasibility to measure fusional vergence amplitudes objectively and overcome limitations of the conventional subjective tests. However, these tests cannot be used interchangeably due to their poor agreement. |
Shreshth Saxena; Lauren K. Fink; Elke B. Lange Deep learning models for webcam eye tracking in online experiments Journal Article In: Behavior Research Methods, pp. 1–17, 2023. @article{Saxena2023a, Eye tracking is prevalent in scientific and commercial applications. Recent computer vision and deep learning methods enable eye tracking with off-the-shelf webcams and reduce dependence on expensive, restrictive hardware. However, such deep learning methods have not yet been applied and evaluated for remote, online psychological experiments. In this study, we tackle critical challenges faced in remote eye tracking setups and systematically evaluate appearance-based deep learning methods of gaze tracking and blink detection. From their own homes and laptops, 65 participants performed a battery of eye tracking tasks including (i) fixation, (ii) zone classification, (iii) free viewing, (iv) smooth pursuit, and (v) blink detection. Webcam recordings of the participants performing these tasks were processed offline through appearance-based models of gaze and blink detection. The task battery required different eye movements that characterized gaze and blink prediction accuracy over a comprehensive list of measures. We find the best gaze accuracy to be 2.4° and precision of 0.47°, which outperforms previous online eye tracking studies and reduces the gap between laboratory-based and online eye tracking performance. We release the experiment template, recorded data, and analysis code with the motivation to escalate affordable, accessible, and scalable eye tracking that has the potential to accelerate research in the fields of psychological science, cognitive neuroscience, user experience design, and human–computer interfaces. |
Yongkai Li; Shuai Zhang; Gancheng Zhu; Zehao Huang; Rong Wang; Xiaoting Duan; Zhiguo Wang A CNN-based wearable system for driver drowsiness detection Journal Article In: Sensors, vol. 23, no. 7, 2023. @article{Li2023l, Drowsiness poses a serious challenge to road safety and various in-cabin sensing technologies have been experimented with to monitor driver alertness. Cameras offer a convenient means for contactless sensing, but they may violate user privacy and require complex algorithms to accommodate user (e.g., sunglasses) and environmental (e.g., lighting conditions) constraints. This paper presents a lightweight convolution neural network that measures eye closure based on eye images captured by a wearable glass prototype, which features a hot mirror-based design that allows the camera to be installed on the glass temples. The experimental results showed that the wearable glass prototype, with the neural network in its core, was highly effective in detecting eye blinks. The blink rate derived from the glass output was highly consistent with an industrial gold standard EyeLink eye-tracker. As eye blink characteristics are sensitive measures of driver drowsiness, the glass prototype and the lightweight neural network presented in this paper would provide a computationally efficient yet viable solution for real-world applications. |
Juan Linde-Domingo; Bernhard Spitzer Geometry of visuospatial working memory information in miniature gaze patterns Journal Article In: Nature Human Behaviour, pp. 1–16, 2023. @article{LindeDomingo2023, Stimulus-dependent eye movements have been recognized as a potential confound in decoding visual working memory information from neural signals. Here we combined eye-tracking with representational geometry analyses to uncover the information in miniature gaze patterns while participants (n = 41) were cued to maintain visual object orientations. Although participants were discouraged from breaking fixation by means of real-time feedback, small gaze shifts (<1°) robustly encoded the to-be-maintained stimulus orientation, with evidence for encoding two sequentially presented orientations at the same time. The orientation encoding on stimulus presentation was object-specific, but it changed to a more object-independent format during cued maintenance, particularly when attention had been temporarily withdrawn from the memorandum. Finally, categorical reporting biases increased after unattended storage, with indications of biased gaze geometries already emerging during the maintenance periods before behavioural reporting. These findings disclose a wealth of information in gaze patterns during visuospatial working memory and indicate systematic changes in representational format when memory contents have been unattended. |
Baiwei Liu; Anna C. Nobre; Freek Ede Microsaccades transiently lateralise EEG alpha activity Journal Article In: Progress in Neurobiology, vol. 224, pp. 1–9, 2023. @article{Liu2023, The lateralisation of 8–12 Hz alpha activity is a canonical signature of human spatial cognition that is typically studied under strict fixation requirements. Yet, even during attempted fixation, the brain produces small involuntary eye movements known as microsaccades. Here we report how spontaneous microsaccades – made in the absence of incentives to look elsewhere – can themselves drive transient lateralisation of EEG alpha power according to microsaccade direction. This transient lateralisation of posterior alpha power occurs similarly following start and return microsaccades and is, at least for start microsaccades, driven by increased alpha power ipsilateral to microsaccade direction. This reveals new links between spontaneous microsaccades and human electrophysiological brain activity. It highlights how microsaccades are an important factor to consider in studies relating alpha activity – including spontaneous fluctuations in alpha activity – to spatial cognition, such as studies on visual attention, anticipation, and working memory. |
Chi-Hung Liu; Chun-Wei Chang; June Hung; John J. H. Lin; Pi-Shan Sung; Li-Ang Lee; Cheng-Ting Hsiao; Yi-Ping Chao; Elaine Shinwei Huang; Shu-Ling Wang Brain computed tomography reading of stroke patients by resident doctors from different medical specialities: An eye-tracking study Journal Article In: Journal of Clinical Neuroscience, vol. 117, no. 88, pp. 173–180, 2023. @article{Liu2023a, Background: Using the eye-tracking technique, our work aimed to examine whether difference in clinical background may affect the training outcome of resident doctors' interpretation skills and reading behaviour related to brain computed tomography (CT). Methods: Twelve resident doctors in the neurology, radiology, and emergency departments were recruited. Each participant had to read CT images of the brain for two cases. We evaluated each participant's accuracy of lesion identification. We also used the eye-tracking technique to assess reading behaviour. We recorded dwell times, fixation counts, run counts, and first-run dwell times of target lesions to evaluate visual attention. Transition entropy was applied to assess the temporal relations and spatial dynamics of systematic image reading. Results: The eye-tracking results showed that the image reading sequence examined by transition entropy was comparable among resident doctors from different medical specialties (p = 0.82). However, the dwell time of the target lesions was shorter for the resident doctors from the neurology department (4828.63 ms |
Qing Liu; Xueyao Yang; Zekai Chen; Wenjuan Zhang Using synchronized eye movements to assess attentional engagement Journal Article In: Psychological Research, vol. 87, no. 7, pp. 2039–2047, 2023. @article{Liu2023d, The gradual emergence of online education in China in recent years requires new means of real-time monitoring and timely feedback to students. This research examines the effectiveness of synchronized eye movement assessment of attention engagement through two experiments. The first experiment used 24 university students in school as participants and made them watch the same video in high and low attentional engagement states (serial subtraction task) to compare the Inter-Subject Correlation (ISC) of participants' eye movements in different conditions. The results showed that the ISC of eye movements was significantly higher for participants in a high attentional engagement state than for participants in a low attentional engagement state. The second experiment had 26 university students in school as participants, as part of which they were made to watch video materials under the condition of having eye movement modeling examples. The results showed that the ISC of eye movements was significantly lower for participants in the group with eye movement modeling examples than those without eye movement modeling examples. However, overall test scores were significantly higher in the former than the latter. The first experiment showed that the eye movement trajectories of participants with high attentional engagement were more consistent than of those with low attentional engagement. Therefore, the ISC of participants' eye movements could be used as an objective indicator to assess and predict students' attentional conditions during online education. The second experiment showed that the eye movement modeling examples interfered with the participants' attention distribution to some extent; nevertheless, they positively affected the improvement in teaching effectiveness. Overall, the studies showed that the Inter-Subject Correlation is reliable to assess attentional engagement status in domestic online education. |
Yaohui Liu; Peida Zhan; Yanbin Fu; Qipeng Chen; Kaiwen Man; Yikun Luo In: Intelligence, vol. 100, pp. 1–14, 2023. @article{Liu2023h, Previous studies have found that participants use two cognitive strategies—constructive matching and response elimination—in responding to items in the Raven's Advanced Progressive Matrices (APM). This study proposed a multi-strategy psychometric model that builds on item responses and also incorporates eye-tracking measures, including but not limited to the proportional time on matrix area (PTM), the rate of toggling (ROT), and the rate of latency to first toggle (RLT). By jointly analyzing item responses and eye-tracking measures, this model can measure each participant's intelligence and identify the cognitive strategy used by each participant for each item in the APM. Several main findings were revealed from an eye-tracking-based APM study using the proposed model: (1) The effects of PTM and RLT on the constructive matching strategy selection probability were positive and higher for the former than the latter, while the effect of ROT was negligible. (2) The average intelligence of participants who used the constructive matching strategy was higher than that of participants who used the response elimination strategy, and participants with higher intelligence were more likely to use the constructive matching strategy. (3) High-intelligence participants increased their use of the constructive matching strategy as item difficulty increased, whereas low-intelligence participants decreased their use as item difficulty increased. (4) Participants took significantly less time using the constructive matching strategy than the response elimination strategy. Overall, the proposed model follows the theory-driven modeling logic and provides a new way of studying cognitive strategy in the APM by presenting quantitative results. |
Zoe Loh; Elizabeth H. Hall; Deborah Cronin; John M. Henderson Working memory control predicts fixation duration in scene-viewing Journal Article In: Psychological Research, vol. 87, no. 4, pp. 1143–1154, 2023. @article{Loh2023, When viewing scenes, observers differ in how long they linger at each fixation location and how far they move their eyes between fixations. What factors drive these differences in eye-movement behaviors? Previous work suggests individual differences in working memory capacity may influence fixation durations and saccade amplitudes. In the present study, participants (N = 98) performed two scene-viewing tasks, aesthetic judgment and memorization, while viewing 100 photographs of real-world scenes. Working memory capacity, working memory processing ability, and fluid intelligence were assessed with an operation span task, a memory updating task, and Raven's Advanced Progressive Matrices, respectively. Across participants, we found significant effects of task on both fixation durations and saccade amplitudes. At the level of each individual participant, we also found a significant relationship between memory updating task performance and participants' fixation duration distributions. However, we found no effect of fluid intelligence and no effect of working memory capacity on fixation duration or saccade amplitude distributions, inconsistent with previous findings. These results suggest that the ability to flexibly maintain and update working memory is strongly related to fixation duration behavior. |
Heather D. Lucas; Ana M. Daugherty; Edward Mcauley; Arthur F. Kramer; Neal J. Cohen Supplemental material for dynamic interactions between memory and viewing behaviors: Insights from dyadic modeling of eye movements Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 49, no. 6, pp. 786–801, 2023. @article{Lucas2023, Humans use eye movements to build visual memories. We investigated how the contributions of specific viewing behaviors to memory formation evolve over individual study epochs. We used dyadic modeling to explain performance on a spatial reconstruction task based on interactions among two gaze measures: (a) the entropy of the scanpath and (b) the frequency of item-to-item gaze transitions. To measure these interactions, our hypothesized model included causal pathways by which early-trial viewing behaviors impacted subsequent memory via downstream effects on later viewing. We found that lower scanpath entropy throughout the trial predicted better memory performance. By contrast, the effect of item-to- item transition frequency changed from negative to positive as the trial progressed. The model also revealed multiple pathways by which early-trial viewing dynamically altered late-trial viewing, thereby impacting memory indirectly. Finally, individual differences in scores on an independent measure of memory ability were found to predict viewing effectiveness, and viewing behaviors partially mediated the relation between memory ability and reconstruction accuracy. In a second experiment, the model showed a good fit for an independent dataset. These results highlight the dynamic nature of memory formation and suggest that the order in which eye movements occur can critically determine their effectiveness. |
Yingyi Luo; Dixiao Tan; Ming Yan Morphological structure influences saccade generation in Chinese reading Journal Article In: Reading and Writing, vol. 36, no. 5, pp. 1–17, 2023. @article{Luo2023d, Recent studies have demonstrated that saccadic programming in reading is not only determined by low-level visual factors. High-level morphological effects on saccade have been shown in two morphologically rich languages. In the present study, we examined the underlying mechanism of such morphological influences by comparing the processes of reading three-character Chinese compound words that differ in their structures in terms of morphological decomposition. Consistent with earlier reports, our results showed an effect of morphological structure on saccade. The readers' first-fixation location shifted further away from the beginning of the word, when the last two characters were more morphologically bounded and thus formed a [1 + 2] structure, than when the first two characters were more bounded (i.e., a [2 + 1] structure). The results are not accountable by a processing difficulty hypothesis, which proposes that saccade amplitude is determined by morphological complexity; rather, they suggest that Chinese readers parafoveally decompose a word and spontaneously target its longer stem, thus reflecting parafoveal access to words' stems. |
Anqi Lyu; Larry Abel; Allen M. Y. Cheong Effect of habitual reading direction on saccadic eye movements: A pilot study Journal Article In: PLoS ONE, vol. 18, pp. 1–16, 2023. @article{Lyu2023, Cognitive processes can influence the characteristics of saccadic eye movements. Reading habits, including habitual reading direction, also affect cognitive and visuospatial processes, favouring attention to the side where reading begins. Few studies have investigated the effect of habitual reading direction on saccade directionality of low-cognitive-demand stimuli (such as dots). The current study examined horizontal prosaccade, antisaccade, and self-paced saccade in subjects with two primary habitual reading directions. We hypothesised that saccades responding to the stimuli in subject's habitual reading direction would show a longer prosaccade latency and lower antisaccade error rate (errors being a reflexive glance to a suddenappearing target, rather than a saccade away from it). Sixteen young Chinese participants with primary habitual reading direction from left to right and sixteen young Arabic and Persian participants with primary habitual reading direction from right to left were recruited. All subjects spoke/read English as their second language. Subjects needed to look towards a 5°/10° target in the prosaccade task or look towards the mirror image location of the target in the antisaccade task and look between two 10° targets in the self-paced saccade task. Only Arabic and Persian participants showed a shorter and directional prosaccade latency towards 5° stimuli against their habitual reading direction. No significant effect of reading direction on antisaccade latency towards the correct directions was found. Chinese readers were found to generate significantly shorter prosaccade latencies and higher antisaccade directional errors compared with Arabic and Persian readers for stimuli appearing at their habitual reading side. The present pilot study provides insights into the effect of reading habits on saccadic eye movements of low-cognitive-demand stimuli and offers a platform for future studies to investigate the relationship between reading habits and eye movement behaviours. |
Hailong Lyu; David St Clair; Renrong Wu; Philip J. Benson; Wenbin Guo; Guodong Wang; Yi Liu; Shaohua Hu; Jingping Zhao Eye movement abnormalities can distinguish first-episode schizophrenia, chronic schizophrenia, and prodromal patients from healthy controls Journal Article In: Schizophrenia Bulletin Open, vol. 4, no. 1, pp. 1–11, 2023. @article{Lyu2023a, Background: This study attempts to replicate in a Chinese population an earlier UK report that eye movement abnormalities can accurately distinguish schizophrenia (SCZ) cases from healthy controls (HCs). It also seeks to determine whether first-episode SCZ differ from chronic SCZ and whether these eye movement abnormalities are enriched in psychosis risk syndrome (PRS). Methods: The training set included 104 Chinese HC and 60 Chinese patients with SCZ, and the testing set included 20 SCZ patients and 20 HC from a UK cohort. An additional 16 individuals with PRS were also enrolled. Eye movements of all participants were recorded during free-viewing, smooth pursuit, and fixation stability tasks. Group differences in 55 performance measures were compared and a gradient-boosted decision tree model was built for predictive analyses. Results: Extensive eye-movement abnormalities were observed in patients with SCZ on almost all eye-movement tests. On almost all individual variables, first-episode patients showed no statistically significant differences compared with chronic patients. The classification model was able to discriminate patients from controls with an area under the curve of 0.87; the model also classified 88% of PRS individuals as SCZ-like. Conclusions: Our findings replicate and extend the UK results. The overall accuracy of the Chinese study is virtually identical to the UK findings. We conclude that eye-movement abnormalities appear early in the natural history of the disorder and can be considered as potential trait markers for SCZ diathesis. |
Wenbo Ma; Mingsha Zhang Multiple step saccades are generated by internal real-time saccadic error correction Journal Article In: Frontiers in Neuroscience, vol. 17, pp. 1–9, 2023. @article{Ma2023a, Objectives: Multiple step saccades (MSSs) are an atypical form of saccade that consists of a series of small-amplitude saccades. It has been argued that the mechanism for generating MSS is due to the automatic saccadic plan. This argument was based on the observation that trials with MSS had shorter saccadic latency than trials without MSS in the reactive saccades. However, the validity of this argument has never been verified by other saccadic tasks. Alternatively, we and other researchers have speculated that the function of MSS is the same as that of the corrective saccade (CS), i.e., to correct saccadic errors. Thus, we propose that the function of the MSS is also to rectify saccadic errors and generated by forward internal models. The objective of the present study is to examine whether the automatic theory is universally applicable for the generation of MSSs in various saccadic tasks and to seek other possible mechanisms, such as error correction by forward internal models. Methods: Fifty young healthy subjects (YHSs) and fifty elderly healthy subjects (EHSs) were recruited in the present study. The task paradigms were prosaccade (PS), anti-saccade (AS) and memory-guided saccade (MGS) tasks. Results: Saccadic latency in trials with MSS was shorter than without MSS in the PS task but similar in the AS and MGS tasks. The intersaccadic intervals (ISI) were similar among the three tasks in both YHSs and EHSs. Conclusion: Our results indicate that the automatic theory is not a universal mechanism. Instead, the forward internal model for saccadic error correction might be an important mechanism. |
Samuel Madariaga; Cecilia Babul; José Ignacio Egaña; Iván Rubio-Venegas; Gamze Güney; Miguel Concha-Miranda; Pedro E. Maldonado; Christ Devia In: MethodsX, vol. 10, pp. 1–10, 2023. @article{Madariaga2023, In this work we present SaFiDe, a deterministic method to detect eye movements (saccades and fixations) from eye-trace data. We developed this method for human and nonhuman primate data from video- and coil-recorded eye traces and further applied the algorithm to eye traces computed from electrooculograms. All the data analyzed were from free-exploration paradigms, where the main challenge was to detect periods of saccades and fixations that were uncued by the task. The method uses velocity and acceleration thresholds, calculated from the eye trace, to detect saccade and fixation periods. We show that our fully deterministic method detects saccades and fixations from eye traces during free visual exploration. The algorithm was implemented in MATLAB, and the code is publicly available on a GitHub repository. • The algorithm presented is entirely deterministic, simplifying the comparison between subjects and tasks. • Thus far, the algorithm presented can operate over video-based eye tracker data, human electrooculogram records, or monkey scleral eye coil data. |
Federica Magnabosco; Olaf Hauk An eye on semantics: A study on the influence of concreteness and predictability on early fixation durations Journal Article In: Language, Cognition and Neuroscience, pp. 1–15, 2023. @article{Magnabosco2023, We used eye-tracking during natural reading to study how semantic control and representation mechanisms interact for the successful comprehension of sentences, by manipulating sentence context and single-word meaning. Specifically, we examined whether a word's semantic characteristic (concreteness) affects first fixation and gaze durations (FFDs and GDs) and whether it interacts with the predictability of a word. We used a linear mixed effects model including several possible psycholinguistic covariates. We found a small but reliable main effect of concreteness and replicated a predictability effect on FFDs, but we found no interaction between the two. The results parallel previous findings of additive effects of predictability (context) and frequency (lexical level) in fixation times. Our findings suggest that the semantics of a word and the context created by the preceding words additively influence early stages of word processing in natural sentence reading. |
Oliver Maith; Javier Baladron; Wolfgang Einhäuser; Fred H. Hamker Exploration behavior after reversals is predicted by STN-GPe synaptic plasticity in a basal ganglia model Journal Article In: iScience, vol. 26, no. 5, pp. 1–23, 2023. @article{Maith2023, Humans can quickly adapt their behavior to changes in the environment. Classical reversal learning tasks mainly measure how well participants can disengage from a previously successful behavior but not how alternative responses are explored. Here, we propose a novel 5-choice reversal learning task with alternating position-reward contingencies to study exploration behavior after a reversal. We compare human exploratory saccade behavior with a prediction obtained from a neuro-computational model of the basal ganglia. A new synaptic plasticity rule for learning the connectivity between the subthalamic nucleus (STN) and external globus pallidus (GPe) results in exploration biases to previously rewarded positions. The model simulations and human data both show that during experimental experience exploration becomes limited to only those positions that have been rewarded in the past. Our study demonstrates how quite complex behavior may result from a simple sub-circuit within the basal ganglia pathways. |
Silvia Makowski; Annika Bätz; Paul Prasse; Lena A. Jäger; Tobias Scheffer Detection of alcohol inebriation from eye movements Journal Article In: Procedia Computer Science, vol. 225, pp. 2086–2095, 2023. @article{Makowski2023, Today, the most convenient way of estimating an individual's blood-alcohol concentration requires a breathalyzer device and intense Today, the most convenient way of estimating an individual's blood-alcohol concentration requires a breathalyzer device and intense detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual user cooperation, which severely limits the scope of potential applications. We develop and study a machine-learning model that features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— user cooperation, which severely limits the scope of potential applications. We develop and study a machine-learning model that detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual detects alcohol inebriation based on a person's eye gaze and eye closure. We investigate the relative contribution of individual and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The features derived from eye gaze and eye closure to the model. In order to train and experimentally evaluate the model, we collect— and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the and share—a new data set with participants in baseline and alcohol-intoxicated states. We find that the model can in fact detect the most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be consumption of a moderate amount of alcohol; the accuracy grows significantly with increasing blood alcohol concentration. The collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- most relevant features turn out to relate to the velocity and acceleration profiles during fixations and saccades. From our proof-of- concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. concept study, we can conclude that contactless inebriation detection based on eye gaze is in fact possible, albeit data need to be collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include collected on an industrial scale to reach practical applicability. Potential applications of contactless inebriation detection include the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. the detection of impaired drivers or operators of other hazardous machinery as well as health-monitoring applications. |
Jun Maruta; Lisa A. Spielman; Jamshid Ghajar Visuomotor synchronization: Military normative performance Journal Article In: Military Medicine, vol. 188, no. 3-4, pp. E484–E491, 2023. @article{Maruta2023, Introduction: Cognitive processes such as perception and reasoning are preceded and dependent on attention. Because of the close overlap between neural circuits of attention and eye movement, attention may be objectively quantified with recording of eye movements during an attention-dependent task. Our previous work demonstrated that performance scores on a circular visual tracking task that requires dynamic synchronization of the gaze with the target motion can be impacted by concussion, sleep deprivation, and attention deficit/hyperactivity disorder. The current study examined the characteristics of performance on a standardized predictive visual tracking task in a large sample from a U.S. Military population to provide military normative data. Materials and Methods: The sample consisted of 1,594 active duty military service members of either sex aged 18-29 years old who were stationed at Fort Hood Army Base. The protocol was reviewed and approved by the U.S. Army Medical Research and Materiel Command Institutional Review Board. Demographic, medical, and military history data were collected using questionnaires, and performance-based data were collected using a circular visual tracking test and Trail Making Test. Differences in visual tracking performance by demographic characteristics were examined with a multivariate analysis of variance, as well as a Kolmogorov-Smirnov test and a rank-sum test. Associations with other measures were examined with a rank-sum test or Spearman correlations. Results: Robust sex differences in visual tracking performance were found across the various statistical models, as well as age differences in several isolated comparisons. Accordingly, norms of performance scores, described in terms of percentile standings, were developed adjusting for age and sex. The effects of other measures on visual tracking performance were small or statistically non-significant. An examination of the score distributions of various metrics suggested that strategies preferred by men and women may optimize different aspects of visual tracking performance. Conclusion: This large-scale quantification of attention, using dynamic visuomotor synchronization performance, provides rigorously characterized age- and sex-based military population norms. This study establishes analytics for assessing normal and impaired attention and detecting changes within individuals over time. Practical applications for combat readiness and surveillance of attention impairment from sleep insufficiency, concussion, medication, or attention disorders will be enhanced with portable, easily accessible, fast, and reliable dynamic eye-tracking technologies. |
Jana Masselink; Alexis Cheviet; Caroline Froment-Tilikete; Denis Pélisson; Markus Lappe A triple distinction of cerebellar function for oculomotor learning and fatigue compensation Journal Article In: PLoS Computational Biology, vol. 19, no. 8, pp. 1–37, 2023. @article{Masselink2023, The cerebellum implements error-based motor learning via synaptic gain adaptation of an inverse model, i.e. the mapping of a spatial movement goal onto a motor command. Recently, we modeled the motor and perceptual changes during learning of saccadic eye movements, showing that learning is actually a threefold process. Besides motor recalibration of (1) the inverse model, learning also comprises perceptual recalibration of (2) the visuospatial target map and (3) of a forward dynamics model that estimates the saccade size from corollary discharge. Yet, the site of perceptual recalibration remains unclear. Here we dissociate cerebellar contributions to the three stages of learning by modeling the learning data of eight cerebellar patients and eight healthy controls. Results showed that cerebellar pathology restrains short-term recalibration of the inverse model while the forward dynamics model is well informed about the reduced saccade change. Adaptation of the visuospatial target map trended in learning direction only in control subjects, yet without reaching significance. Moreover, some patients showed a tendency for uncompensated oculomotor fatigue caused by insufficient upregulation of saccade duration. According to our model, this could induce long-term perceptual compensation, consistent with the overestimation of target eccentricity found in the patients' baseline data. We conclude that the cerebellum mediates short-term adaptation of the inverse model, especially by control of saccade duration, while the forward dynamics model was not affected by cerebellar pathology. |
Siobhan M. McAteer; Anthony McGregor; Daniel T. Smith Oculomotor rehearsal in visuospatial working memory Journal Article In: Attention, Perception, and Psychophysics, vol. 85, pp. 261–275, 2023. @article{McAteer2023, The neural and cognitive mechanisms of spatial working memory are tightly coupled with the systems that control eye movements, but the precise nature of this coupling is not well understood. It has been argued that the oculomotor system is selectively involved in rehearsal of spatial but not visual material in visuospatial working memory. However, few studies have directly compared the effect of saccadic interference on visual and spatial memory, and there is little consensus on how the underlying working memory representation is affected by saccadic interference. In this study we aimed to examine how working memory for visual and spatial features is affected by overt and covert attentional interference across two experiments. Participants were shown a memory array, then asked to either maintain fixation or to overtly or covertly shift attention in a detection task during the delay period. Using the continuous report task we directly examined the precision of visual and spatial working memory representations and fit psychophysical functions to investigate the sources of recall error associated with different types of interference. These data were interpreted in terms of embodied theories of attention and memory and provide new insights into the nature of the interactions between cognitive and motor systems. |
Natalia Melnik; Stefan Pollmann Efficient versus inefficient visual search as training for saccadic re-referencing to an extrafoveal location Journal Article In: Journal of Vision, vol. 23, no. 10, pp. 1–13, 2023. @article{Melnik2023, Central vision loss is one of the leading causes of visual impairment in the elderly and its frequency is increasing. Without formal training, patients adopt an unaffected region of the retina as a new fixation location, a preferred retinal locus (PRL). However, learning to use the PRL as a reference location for saccades, that is, saccadic re-referencing, is protracted and time-consuming. Recent studies showed that training with visual search tasks can expedite this process. However, visual search can be driven by salient external features - leading to efficient search, or by internal goals, usually leading to inefficient, attention-demanding search. We compared saccadic re-referencing training in the presence of a simulated central scotoma with either an efficient or an inefficient visual search task. Participants had to respond by fixating the target with an experimenter-defined retinal location in the lower visual field. We observed that comparable relative training gains were obtained in both tasks for a number of behavioral parameters, with higher training gains for the trained task, compared to the untrained task. The transfer to the untrained task was only observed for some parameters. Our findings thus confirm and extend previous research showing comparable efficiency for exogenously and endogenously driven visual search tasks for saccadic re-referencing training. Our results also show that transfer of training gains to related tasks may be limited and needs to be tested for saccadic re-referencing-training paradigms to assess its suitability as a training tool for patients. |
Helena Palmieri; Antonio Fernández; Marisa Carrasco Microsaccades and temporal attention at different locations of the visual field Journal Article In: Journal of Vision, vol. 23, no. 5, pp. 1–17, 2023. @article{Palmieri2023, Temporal attention, the prioritization of information at specific points in time, improves performance in behavioral tasks but cannot ameliorate the perceptual asymmetries that exist across the visual field. That is, even after attentional deployment, performance is better along the horizontal than vertical meridian and worse at the upper than lower vertical meridian. Here we asked whether and how microsaccades—tiny fixational eye-movements—could mirror or alternatively attempt to compensate for these performance asymmetries by assessing temporal profiles and direction of microsaccades as a function of visual field location. Observers were asked to report the orientation of one of two targets presented at different time points, in one of three blocked locations (fovea, right horizontal meridian, upper vertical meridian).We found the following: (1) Microsaccade occurrence did not affect either task performance or the magnitude of the temporal attention effect. (2) Temporal attention modulated the microsaccade temporal profiles, and this modulation varied with polar angle location. At all locations, microsaccade rates were significantly more suppressed in anticipation of the target when temporally cued than in the neutral condition. Moreover, microsaccade rates were more suppressed during target presentation in the fovea than in the right horizontal meridian. (3) Across locations and attention conditions, there was a pronounced bias toward the upper hemifield. Overall, these results reveal that temporal attention benefits performance similarly around the visual field, microsaccade suppression is more pronounced for attention than expectation (neutral trials) across locations, and the directional bias toward the upper hemifield could reflect an attempt to compensate for typical poor performance at the upper vertical meridian. |
Yasuo Terao; Yoshiko Nomura; Hideki Fukuda; Okihide Hikosaka; Kazue Kimura; Shun-ichi Matsuda; Akihiro Yugeta; Francesco Fisicaro; Kyoko Hoshino; Yoshikazu Ugawa The pathophysiology of Gilles de la Tourette Syndrome: Changes in saccade performance by low-dose L-Dopa and dopamine receptor blockers Journal Article In: Brain Sciences, vol. 13, no. 12, pp. 1–23, 2023. @article{Terao2023, Aim: To elucidate the pathophysiology of Gilles de la Tourette syndrome (GTS), which is associated with prior use of dopamine receptor antagonists (blockers) and treatment by L-Dopa, through saccade performance. Method: In 226 male GTS patients (5–14 years), we followed vocal and motor tics and obsessive–compulsive disorder (OCD) after discontinuing blockers at the first visit starting with low-dose L-Dopa. We recorded visual- (VGS) and memory-guided saccades (MGS) in 110 patients and 26 normal participants. Results: At the first visit, prior blocker users exhibited more severe vocal tics and OCD, but not motor tics, which persisted during follow-up. Patients treated with L-Dopa showed greater improvement of motor tics, but not vocal tics and OCD. Patients with and without blocker use showed similarly impaired MGS performance, while patients with blocker use showed more prominently impaired inhibitory control of saccades, associated with vocal tics and OCD. Discussion: Impaired MGS performance suggested a mild hypodopaminergic state causing reduced direct pathway activity in the (oculo-)motor loops of the basal ganglia–thalamocortical circuit. Blocker use may aggravate vocal tics and OCD due to disinhibition within the associative and limbic loops. The findings provide a rationale for discouraging blocker use and using low-dose L-Dopa in GTS. |
Lonneke Teunissen; Luc P. J. Selen; W. Pieter Medendorp Abrupt, but not gradual, motor adaptation biases saccadic target selection Journal Article In: Journal of Neurophysiology, vol. 129, no. 3, pp. 733–748, 2023. @article{Teunissen2023, Decisions between potential motor actions are influenced by their costs, but costs change when movements are adapted. Using a saccadic target selection task, we show that target preference shifts after abrupt, but not after gradual adaptation. We suggest that this difference emerges because abrupt adaptation results in target remapping, and thus directly influences cost calculations, whereas gradual adaptation is mainly driven by corrections to a forward model that is not involved in cost calculations.Motor costs influence movement selection. These costs could change when movements are adapted in response to errors. When the motor system attributes the encountered errors to an external cause, appropriate movement selection requires an update of the movement goal, which prompts the selection of a different control policy. However, when errors are attributed to an internal cause, the initially selected control policy could remain unchanged, but the internal forward model of the body needs to be updated, resulting in an online correction of the movement. We hypothesized that external attribution of errors leads to the selection of a different control policy, and thus to a change in the expected cost of movements. This should also affect subsequent motor decisions. Conversely, internal attribution of errors may (initially) only evoke online corrections, and thus is expected to leave the motor decision process unchanged. We tested this hypothesis using a saccadic adaptation paradigm, designed to change the relative motor cost of two targets. Motor decisions were measured using a target selection task between the two saccadic targets before and after adaptation. Adaptation was induced by either abrupt or gradual perturbation schedules, which are thought to induce more external or internal attribution of errors, respectively. By taking individual variability into account, our results show that saccadic decisions shift toward the least costly target after adaptation, but only when the perturbation is abruptly, and not gradually, introduced. We suggest that credit assignment of errors not only influences motor adaptation but also subsequent motor decisions.NEW & NOTEWORTHY Decisions between potential motor actions are influenced by their costs, but costs change when movements are adapted. Using a saccadic target selection task, we show that target preference shifts after abrupt, but not after gradual adaptation. We suggest that this difference emerges because abrupt adaptation results in target remapping, and thus directly influences cost calculations, whereas gradual adaptation is mainly driven by corrections to a forward model that is not involved in cost calculations. |
Sandra Tyralla; Antonella Pomè; Eckart Zimmermann Motor recalibration of visual and saccadic maps Journal Article In: Proceedings of the Royal Society B: Biological Sciences, vol. 290, no. 1994, pp. 1–10, 2023. @article{Tyralla2023, How does the brain maintain an accurate visual representation of external space? Movement errors following saccade execution provide sufficient information to recalibrate motor and visual space. Here, we asked whether spatial information for vision and saccades is processed in shared or in separate resources. We used saccade adaptation to modify both, saccade amplitudes and visual mislocalization. After saccade adaptation was induced, we compared participants' saccadic and perceptual localization before and after we inserted 'no error' trials. In these trials, we clamped the post-saccadic error online to the predicted endpoints of saccades. In separate experiments, we either annulled the retinal or the prediction error. We also varied the number of 'no error' trials across conditions. In all conditions, we found that saccade adaptation remained undisturbed by the insertion of 'no error' trials. However, mislocalization decreased as a function of the number of trials in which zero retinal error was displayed. When the prediction error was clamped to zero, no mislocalization was observed at all. The results demonstrate the post-saccadic error is used separately to recalibrate visual and saccadic space. |
Elle Heusden; Christian N. L. Olivers; Mieke Donk The eyes prefer targets nearby fixation: Quantifying eccentricity-dependent attentional biases in oculomotor selection Journal Article In: Vision Research, vol. 205, pp. 1–11, 2023. @article{Heusden2023, An important function of peripheral vision is to provide the target of the next eye movement. Here we investigate the extent to which the eyes are biased to select a target closer to fixation over one further away. Participants were presented with displays containing two identical singleton targets and were asked to move their eyes to either one of them. The targets could be presented at three different eccentricities relative to central fixation. In one condition both singletons were presented at the same eccentricity, providing an estimate of the speed of selection at each of the eccentricities. The saccadic latency distributions from this same-eccentricity condition were then used to predict the selection bias when both targets were presented at different eccentricities. The results show that when targets are presented at different eccentricities, participants are biased to select the item closest to fixation. This eccentricity-based bias was considerably stronger than predicted on the basis of saccadic latency distributions in the same-eccentricity condition. This rules out speed of processing per se as a sole explanation for such a bias. Instead, the results are consistent with attentional competition being weighted in favour of items close to fixation. |
Valldeflors Vinuela-Navarro; Joan Goset; Mikel Aldaba; Clara Mestre; Cristina Rovira-Gay; Neus Cano; Mar Ariza; Bàrbara Delàs; Maite Garolera; Meritxell Vilaseca Eye movements in patients with post-COVID condition Journal Article In: Biomedical Optics Express, vol. 14, no. 8, pp. 1–14, 2023. @article{VinuelaNavarro2023, Eye movement control is impaired in some neurological conditions, but the impact of COVID-19 on eye movements remains unknown. This study aims to investigate differences in oculomotor function and pupil response in individuals who suffer post-COVID-19 condition (PCC) with cognitive deficits. Saccades, smooth pursuit, fixation, vergence and pupillary response were recorded using an eye tracker. Eye movements and pupil response parameters were computed. Data from 16 controls, 38 COVID mild (home recovery) and 19 COVID severe (hospital admission) participants were analyzed. Saccadic latencies were shorter in controls (183 ± 54 ms) than in COVID mild (236 ± 83 ms) and COVID severe (227 ± 42 ms) participants (p = 0.017). Fixation stability was poorer in COVID mild participants (Bivariate Contour Ellipse Area of 0.80 ± 1.61° 2 vs 0.36 ± 0.65 ° 2 for controls |
A. C. L. Vrijling; M. J. Boer; R. J. Renken; J. B. C. Marsman; A. Grillini; C. E. Petrillo; J. Heutink; N. M. Jansonius; F. W. Cornelissen Stimulus contrast, pursuit mode, and age strongly influence tracking performance on a continuous visual tracking task Journal Article In: Vision Research, vol. 205, pp. 1–11, 2023. @article{Vrijling2023, Human observers tend to naturally track moving stimuli. This tendency may be exploited towards an intuitive means of screening visual function as an impairment induced reduction in stimulus visibility will decrease tracking performance. Yet, to be able to detect subtle impairments, stimulus contrast is critical. If too high, the decrease in performance may remain undetected. Therefore, for this approach to become reliable and sensitive, we need a detailed understanding of how age, stimulus contrast, and the type of stimulus movement affect continuous tracking performance. To do so, we evaluated how well twenty younger and twenty older participants tracked a semi-randomly moving stimulus (Goldmann size III, 0.43 degrees of visual angle), presented at five contrast levels (5%-10%-20%-40%-80%). The stimulus could move smoothly only (smooth pursuit mode) or in alternation with displacements (saccadic pursuit mode). Additionally, we assessed static foveal and peripheral contrast thresholds. For all participants, tracking performance improved with increasing contrast in both pursuit modes. To reach threshold performance levels, older participants required about twice as much contrast (20% vs. 10% and 40% vs. 20% in smooth and saccadic modes respectively). Saccadic pursuit detection thresholds correlated significantly with static peripheral contrast thresholds (rho = 0.64). Smooth pursuit detection thresholds were uncorrelated with static foveal contrast thresholds (rho = 0.29). We conclude that continuous visual stimulus tracking is strongly affected by stimulus contrast, pursuit mode, and age. This provides essential insights that can be applied towards new and intuitive approaches of screening visual function. |
Ilja Wagner; Alexander C. Sch€utz Interaction of dynamic error signals in saccade adaptation Journal Article In: Journal of Neurophysiology, vol. 129, no. 3, pp. 717–732, 2023. @article{Wagner2023, Motor adaptation maintains movement accuracy. To evaluate movement accuracy, motor adaptation relies on an error signal, generated by the movement target, while suppressing error signals from irrelevant objects in the vicinity. Previous work used static testing environments, where all information required to evaluate movement accuracy was available simultaneously. Using saccadic eye movements as a model for motor adaptation, we tested how movement accuracy is maintained in dynamic environments, where the availability of conflicting error signals varied over time. Participants made a vertical saccade toward a target (either a small square or a large ring). Upon saccade detection, two candidate stimuli were shown left and right of the target, and participants were instructed to discriminate a feature on one of the candidates. Critically, candidate stimuli were presented sequentially, and saccade adaptation, thus, had to resolve a conflict between a task-relevant and a task-irrelevant error signal that were separated in space and time. We found that the saccade target influenced several aspects of oculomotor learning. In presence of a small target, saccade adaptation evaluated movement accuracy based on the first available error signal after the saccade, irrespective of its task relevance. However, a large target not only allowed for greater flexibility when evaluating movement accuracy, but it also promoted a stronger contribution of strategic behavior when compensating inaccurate saccades. Our results demonstrate how motor adaptation maintains movement accuracy in dynamic environments, and how properties of the visual environment modulate the relative contribution of different learning processes. |
Sonja Walcher; Živa Korda; Christof Körner; Mathias Benedek The effects of type and workload of internal tasks on voluntary saccades in a targetdistractor saccade task Journal Article In: PLoS ONE, vol. 18, pp. 1–27, 2023. @article{Walcher2023, When we engage in internally directed cognition, like doing mental arithmetic or mind wandering, fewer cognitive resources are assigned for other activities like reacting to perceptual input-an effect termed perceptual decoupling. However, the exact conditions under which perceptual decoupling occurs and its underlying cognitive mechanisms are still unclear. Hence, the present study systematically manipulated the task type (arithmetic, visuospatial) and workload (control, low, high) of the internal task in a within-subject design and tested its effects on voluntary saccades in a target-distractor saccade task. As expected, engagement in internal tasks delayed saccades to the target. This effect was moderated by time, task, and workload: The delay was largest right after internal task onset and then decreased, potentially reflecting the intensity of internal task demands. Saccades were also more delayed for the high compared to the low workload condition in the arithmetic task, whereas workload conditions had similarly high effects in the visuospatial task. Findings suggests that perceptual decoupling of eye behavior gradually increases with internal demands on general resources and that perceptual decoupling is specifically sensitive to internal demands on visuospatial resources. The latter may be mediated by interference due to eye behavior elicited by the internal task itself. Internal tasks did not affect the saccade latencydeviation trade-off, indicating that while the internal tasks delayed the execution of the saccade, the perception of the saccade stimuli and spatial planning of the saccade continued unaffected in parallel to the internal tasks. Together, these findings shed further light on the specific mechanisms underlying perceptual decoupling by suggesting that perceptual decoupling of eye behavior increases as internal demands on cognitive resources overlap more strongly with demands of the external task. |
Josefine Waldthaler; Lena Stock; Charlotte Krüger-Zechlin; Zain Deeb; Lars Timmermann Cluster analysis reveals distinct patterns of saccade impairment and their relation to cognitive profiles in Parkinson's disease Journal Article In: Journal of Neuropsychology, vol. 17, no. 2, pp. 251–263, 2023. @article{Waldthaler2023b, Saccade performance has been reported to be altered in Parkinson's disease (PD), however, with a large variability between studies as both motor and cognitive impairment interfere with oculomotor control. The aim of this study was to identify different patterns in saccade alterations in PD using a data-driven approach and to explore their relationship with cognitive phenotypes. Sixty-one participants with PD and 25 controls performed eye-tracking (horizontal and vertical prosaccades, antisaccades) and neuropsychological testing. Hierarchical cluster analysis was applied to the eye-tracking data to subsequently compare the clusters based on demographical, clinical and cognitive characteristics. The three identified clusters of saccade alterations differed in cognitive profiles from healthy controls, but not in PD-related motor symptoms or demographics. The rate of directive errors in the antisaccade task was increased in clusters 1 and 2. Further, cluster 1 was defined by a general disinhibition of reflexive saccades and executive dysfunction in the neuropsychological evaluation. In cluster 2, prolonged saccade latencies and hypometria were accompanied by multidomain cognitive impairment. The cluster 3 showed increased antisaccade latency and vertical hypometria despite lack of evidence for cognitive impairment. Our results suggest that there may be at least two opposing patterns of saccade alterations associated with cognitive impairment in PD, which may explain some of the contradictory results of previous studies. |
Chin-An Wang; Neil G. Muggleton; Yi-Hsuan Chang; Cesar Barquero; Ying-Chun Kuo Time-on-task effects on human pupillary and saccadic metrics after theta burst transcranial magnetic stimulation over the frontal eye field Journal Article In: IBRO Neuroscience Reports, vol. 15, pp. 364–375, 2023. @article{Wang2023c, Pupil size undergoes constant changes primarily influenced by ambient luminance. These changes are referred to as the pupillary light reflex (PLR), where the pupil transiently constricts in response to light. PLR kinematics provides valuable insights into autonomic nervous system function and have significant clinical applications. Recent research indicates that attention plays a role in modulating the PLR, and the circuit involving the frontal eye field (FEF) and superior colliculus is causally involved in controlling this pupillary modulation. However, there is limited research exploring the role of the human FEF in these pupillary responses, and its impact on PLR metrics remains unexplored. Additionally, although the protocol of continuous theta-burst stimulation (cTBS) is well-established, the period of disruption after cTBS is yet to be examined in pupillary responses. Our study aimed to investigate the effects of FEF cTBS on pupillary and saccadic metrics in relation to time spent performing a task (referred to as time-on-task). We presented a bright stimulus to induce the PLR in visual- and memory-delay saccade tasks following cTBS over the right FEF or vertex. FEF cTBS, compared to vertex cTBS, resulted in decreased baseline pupil size, peak constriction velocities, and amplitude. Furthermore, the time-on-task effects on baseline pupil size, peak amplitude, and peak time differed between the two stimulation conditions. In contrast, the time-on-task effects on saccadic metrics were less pronounced between the two conditions. In summary, our study provides the first evidence that FEF cTBS affects human PLR metrics and that these effects are modulated by time-on-task. |
Scott N. J. Watamaniuk; Jeremy B. Badler; Stephen J. Heinen Peripheral targets attenuate miniature eye movements during fixation Journal Article In: Scientific Reports, vol. 13, no. 1, pp. 1–9, 2023. @article{Watamaniuk2023, Fixating a small dot is a universal technique for stabilizing gaze in vision and eye movement research, and for clinical imaging of normal and diseased retinae. During fixation, microsaccades and drifts occur that presumably benefit vision, yet microsaccades compromise image stability and usurp task attention. Previous work suggested that microsaccades and smooth pursuit catch-up saccades are controlled by similar mechanisms. This, and other previous work showing fewer catch-up saccades during smooth pursuit of peripheral targets suggested that a peripheral target might similarly mitigate microsaccades. Here, human observers fixated one of three stimuli: a small central dot, the center of a peripheral, circular array of small dots, or a central/peripheral stimulus created by combining the two. The microsaccade rate was significantly lower with the peripheral array than with the dot. However, inserting the dot into the array increased the microsaccade rate to single-dot levels. Drift speed also decreased with the peripheral array, both with and without the central dot. Eye position variability was higher with the array than with the composite stimulus. The results suggest that analogous to the foveal pursuit, foveating a stationary target engages the saccadic system likely compromising retinal-image stability. In contrast, fixating a peripheral stimulus improves stability, thereby affording better retinal imaging and releasing attention for experimental tasks. |
Junru Wu; Min Li; Wenbo Ma; Zhihao Zhang; Mingsha Zhang; Xuemei Li In: Gerontology, vol. 69, no. 3, pp. 321–335, 2023. @article{Wu2023d, Background: Among the elderly, dementia is a common and disabling disorder with primary manifestations of cognitive impairments. Diagnosis and intervention in its early stages is the key to effective treatment. Nowadays, the test of cognitive function relies mainly on neuropsychological tests, such as the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). However, they have noticeable shortcomings, e.g., the biases of subjective judgments from physicians and the cost of the labor of these well-trained physicians. Thus, advanced and objective methods are urgently needed to evaluate cognitive functions. Methods: We developed a cognitive assessment system through measuring the saccadic eye movements in three tasks. The cognitive functions were evaluated by both our system and the neuropsychological tests in 310 subjects, and the evaluating results were directly compared. Results: In general, most saccadic parameters correlate well with the MMSE and MoCA scores. Moreover, some subjects with high MMSE and MoCA scores have high error rates in performing these three saccadic tasks due to various errors. The primary error types vary among tasks, indicating that different tasks assess certain specific brain functions preferentially. Thus, to improve the accuracy of evaluation through saccadic tasks, we built a weighted model to combine the saccadic parameters of the three saccadic tasks, and our model showed a good diagnosis performance in detecting patients with cognitive impairment. Conclusion: The comprehensive analysis of saccadic parameters in multiple tasks could be a reliable, objective, and sensitive method to evaluate cognitive function and thus to help diagnose cognitive impairments. |
Dan Zhang; Lihua Xu; Yuou Xie; Xiaochen Tang; Yegang Hu; Xu Liu; Guisen Wu; Zhenying Qian; Yingying Tang; Zhi Liu; Tao Chen; HaiChun Liu; Tianhong Zhang; Jijun Wang Eye movement indices as predictors of conversion to psychosis in individuals at clinical high risk Journal Article In: European Archives of Psychiatry and Clinical Neuroscience, vol. 273, no. 3, pp. 553–563, 2023. @article{Zhang2023i, Eye movement abnormalities have been established as an “endophenotype” of schizophrenia. However, less is known about the possibility of these abnormalities as biomarkers for psychosis conversion among clinical high risk (CHR) populations. In the present study, 108 CHR individuals and 70 healthy controls (HC) underwent clinical assessments and eye-tracking tests, comprising fixation stability and free-viewing tasks. According to three-year follow-up outcomes, CHR participants were further stratified into CHR-converter (CHR-C; n = 21) and CHR-nonconverter (CHR-NC; n = 87) subgroups. Prediction models were constructed using Cox regression and logistic regression. The CHR-C group showed more saccades of the fixation stability test (no distractor) and a reduced saccade amplitude of the free-viewing test than HC. Moreover, the CHR-NC group exhibited excessive saccades and an increased saccade amplitude of the fixation stability test (no distractor; with distractor) compared with HC. Furthermore, two indices could effectively discriminate CHR-C from CHR-NC with an area under the receiver-operating characteristic (ROC) curve of 0.80, including the saccade number of the fixation stability test (no distractor) and the saccade amplitude of the free-viewing test. Combined with negative symptom scores of the Scale of Prodromal Symptoms, the area was 0.81. These findings support that eye movement alterations might emerge before the onset of clinically overt psychosis and could assist in predicting psychosis transition among CHR populations. |
Ji Su Yeon; Ha Na Jung; Jae-Young Kim; Kyong In Jung; Hae Young Lopilly Park; Chan Kee Park; Hyo Won Kim; Man Soo Kim; Yong Chan Kim Deviated saccadic trajectory as a biometric signature of glaucoma Journal Article In: Translational Vision Science & Technology, vol. 12, no. 7, pp. 1–12, 2023. @article{Yeon2023, Purpose: To investigate whether the trajectories of saccadic eye movements (SEMs) significantly differ between glaucoma patients and controls. Methods: SEMs were recorded by video-based infrared oculography in 53 patients with glaucoma and 41 age-matched controls. Participants were asked to bilaterally view 24°-horizontal, 14°-vertical, and 20°-diagonal eccentric Goldmann III-sized stimuli. SEMs were evaluated with respect to the saccadic reaction time (SRT), the mean velocity, amplitude, and two novel measures: departure angle (DA) and arrival angle (AA). These parameters were compared between the groups and the associations of SEM parameters with glaucoma parameters and integrated visual field defects were investigated. Results: Glaucoma patients exhibited increased mean SRT, DA, and AA values compared with controls for 14°-vertical visual targets (P = 0.05, P < 0.01, and P < 0.01, respectively). The SRT, DA, and AA were significantly associated with the mean and pattern standard deviations of perimetry and with the mean RNFL thickness by OCT (all P < 0.001). Glaucoma was associated with the AA (P = 0.05) and both the SRT (P = 0.01) and DA (P = 0.04) were associated with integrated visual field defects. Conclusions: The saccadic trajectories of glaucoma patients depart in an erroneous path and compensate the disparity by deviating the trajectory at arrival. Translational Relevance: The initial deviation that we observed (despite continuous exposure to the stimulus) suggests the disoriented spatial perception of glaucoma patients which may be relevant to difficulties encountered daily. |