Saccades Research Articles

Saccade execution increases the preview effect with faces: An EEG and eye-tracking coregistration study.

Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision.

Functional relation between postural sway and saccadic eye movements is strong and not altered by moving visual environment and concomitant memory task

We investigated whether the adaptation of postural control to perform saccadic tasks is still maintained in challenging situations such as when the posture is challenged with a large movement of the moving room and with the addition of a second perturbation as a visual task of memorization. Thirty young adults (20.0 ± 1.3 years) were randomly assigned to the control and experimental groups. Participants stood upright on a force plate inside a moving room wearing eye-tracking. The room moved back and forth (anterior–posterior direction), at low (.6 cm—first and third trials) and high (3.5 cm—second trial) amplitude, and frequency of .2 Hz. In each trial, participants performed left-right horizontal saccades on a target (1.1 Hz). The experimental group also performed a concomitant number memorization task. There were no differences between groups in the coupling between center of pressure (CoP) displacements and visual stimulus in any condition. There was also no difference in the performance of the saccadic task. In the memorization task, CoP displacements in response to the visual stimulus frequency (room motion) were not affected. The performance in the memorization task was similar between room conditions. Overall, increasing cognitive involvement by adding a working memory task does not deteriorate the postural stabilization of young adults to accomplish accurate gaze shifts. Also, it does not interfere with adaptive visual reweighting due to changes in the moving room amplitude. In conclusion, young adults are flexible in optimizing their postural control to succeed in multiple tasks even under perturbation.

1 Neurocognitive Correlates of Oculomotor Performance among U.S. Military Personnel with Mild Traumatic Brain Injury

Objective:To examine neurocognitive correlates of oculomotor performance among U.S. military personnel with history of mild traumatic brain injury (mTBI).Participants and Methods:A series of studies (total n=356) were conducted to examine saccadic eye movements and manual button presses collected in response to attention stimuli, and to compare these findings to the results of standardized neuropsychological tests. Study 1 included n=27 with remote mTBI and n=54 controls who completed the Bethesda Eye and Attention Measure (BEAM), an eye tracking task that was designed to measure visual attention and executive function. In Study 2, n=51 with chronic mTBI and n=33 controls completed the Fusion n-Back task, an eye tracking task that was designed to assess the impact of working memory load on visual attention performance. Study 3 examined psychometric characteristics of BEAM among n=191 military personnel with remote mTBI. In all studies, participants completed eye tracking tasks, a structured TBI diagnostic interview, and a brief battery of standardized neuropsychological tests.Results:In Study 1, BEAM saccadic and manual metrics demonstrated strong reliability and high sensitivity to multiple cognitive cues designed to elicit spatial orienting, temporal alerting, executive interference, perceptual release (gap) and inhibition (n2p=.76, p<.001). However, corresponding saccadic and manual measurements were weakly related to each other, and only manual (not saccadic) measurements were related to estimated verbal intelligence or years of education. Standardized neuropsychological measures did not differ between groups, but mTBI participants were more likely to be impaired on saccadic metrics than controls.In Study 2, Standardized cognitive measures and estimated premorbid intelligence were positively associated with all manual metrics from the Fusion n-Back test, but were not associated with mTBI history or with saccadic metrics. Fusion n-Back saccadic and manual metrics had strong reliability and complementary sensitivity to chronic mTBI, with combined predictive power of PPV=.78, NPV=.72, r2=.44 for classification of remote mild TBI vs. controls on the more cognitively-challenging 1-back task condition.In Study 3, BEAM metrics including manual RT latency and consistency, saccadic RT consistency, and saccadic inhibition errors showed consistent correlations with standardized measures of visual attention, processing speed, task switching, working memory, and executive functions. Hierarchical regressions showed that BEAM saccadic and manual metrics were independently predictive of cognitive test performance, above and beyond effects of demographic factors and clinical characteristics.Conclusions:Results demonstrated some surprising findings related to neurocognitive influences on oculomotor performance. While both saccadic and manual performance were strongly and similarly influenced by attention cues, these two modalities were only weakly correlated to one another. Additionally, manual metrics were more strongly and consistently related to standardized cognitive test performance and premorbid intelligence than saccadic metrics. However, saccadic metrics demonstrated superior sensitivity to remote/chronic mTBI relative to manual metrics and standardized neuropsychological measures. Overall, these results suggest that saccadic eye tracking measures may provide unique value in assessment of mTBI and neurocognitive functions that is complementary with more common forms of assessment relying upon somatomotor response modalities.

Abstract 102: Pseudo‐Internuclear Ophthalmoplegia in a Patient with an Acute Globus Pallidus Infarct: A Case Report

Introduction Internuclear ophthalmoplegia (INO) is an ocular movement disorder typically due to a lesion in the medial longitudinal fasciculus (MLF). Rarely, similar ocular movement abnormalities can be observed in the absence of an MLF lesion. This case report aims to highlight a potential association between acute globus pallidus (GP) infarct and an ocular movement abnormality resembling INO. Methods N/A Results Case Presentation: A 72‐year‐old male with a medical history significant for chronic myeloid leukemia, prostate cancer, type 2 diabetes mellitus, hypertension, prior stroke, and heart failure presented with dizziness. Examination revealed right INO, skew deviation with right hypertropia, left lower extremity weakness, left upper extremity dysmetria, right facial weakness (prior deficit), and ataxic gait. MRI of brain confirmed an acute lacunar infarct in the right globus pallidus with no apparent brainstem or cerebellar lesion. The patient was started on dual antiplatelet therapy and discharged with home rehabilitation services to improve his balance. Discussion: The patient presented with pseudo‐INO in the setting of an acute globus pallidus infarct. This case introduces the idea that ocular motor abnormalities resembling INO could occur due to a GP lesion, which was not previously reported. The basal ganglia control saccadic eye movements by means of their connection to the superior colliculus (SC). GP was shown to have a role in this connection which may provide a plausible explanation for this observation. Another possible explanation can be based on the concept of diaschisis, where a lesion in a specific area of the brain (GP in this case) can lead to deficits or impairments in various functions associated with that region (the SC and its pathway for controlling saccadic eye movement). Conclusion This case emphasizes that slow adducting saccades and associated nystagmus is not always INO.

Objective assessment of eye alignment and disparity-driven vergence in Parkinson's disease.

Self-reported diplopia is described in up to one-third of Parkinson's disease (PD) patients. The purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD. We used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance). We categorized PD subjects into three groups, considering their time-based control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent <80% but greater >5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (<5% of the time when the eyes were well-aligned). All three groups exhibited greater eye deviation under monocular viewing than controls. PD subjects exhibited fusion-initiating and fusion-maintaining vergence deficits (prolonged latencies, reduced vergence gain, increased variance of fusion-maintaining component) with a greater probability of saccadic movements than controls. Group 2 and Group 3 subjects were more likely to exhibit failure to initiate vergence (>20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson's Disease Rating Scale (UPDRS-a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05). The majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms.

Pre-occupancy evaluation of a virtual music school classroom: Influence of color and type of lighting on music performers

The built environment has the potential to influence human emotions, behaviors, and cognitive abilities. This study examined the influence of classroom architectural design variables on musicians’ emotional and cognitive experiences during solo performance. Specifically, the effects of color and type of lighting were explored. Using immersive virtual reality technology, musicians were immersed in a virtual representation of a real conservatory classroom. Study participants were exposed to variations in room design while playing their instruments. Questionnaires were used to assess the musicians’ level of immersion in the virtual environment and to determine how design variables affected their perception of the environment and emotional state. In addition, eye tracking was used to record eye behavior during performance and to identify involuntary eye movements indicative of emotional arousal. The results of this study support the feasibility of enhancing the musician experience and reducing performance anxiety during solo performances by manipulating environmental design variables. Our research showed that the combination of daylight and window views contributed significantly to a more positive evaluation of the environment, making it appear more pleasant, open, warm and light. In contrast, the absence of daylight and no outside views not only had a negative impact on environmental ratings, but also significantly increased saccadic eye movements, which are associated with higher levels of anxiety. In addition, rooms with reddish walls and floors were perceived as warmer than those with blue or gray tones.

Rawabogo Community's Attention in Developing of Tourism Village (Study Case: Rawabogo Village, Ciwidey District)

Rawabogo Village is one of the villages in Ciwidey District which is unique with its historical site of Mount Nagra Padang and indigenous peoples. In the development of the Rawabogo Tourism Village, there were problems concerning community participation and empowerment. Community participation is built through an understanding of the desires, interests, demands, and a sense of ownership of the to develop tourism village. However, the measurement process related to desires, interests, demands, and a sense of ownership is difficult to measure accurately and dynamically using questionnaires and interviews. So it is necessary to have other measurement methods that can support the results of the questionnaires and interviews. Thus, this study aims to identify the attention of the people of Rawabogo Village to the development of tourism villages. The type of research is mixed research and data collection method used in this research comprises the primary and secondary data, while the sampling method used is purposive sampling with 10 respondents. The analysis result shows that the Rawabogo communities have high attention in developing the Rawabogo Tourism Village, which is also supported by obtaining the Saccadic movement pattern and fixation on each respondent, as well as the number of blinks which as a whole represent the average number of blinks of adults. The application of this mixed method, the eye tracking method and the classical method (questionaries and interviews), is the first step to including the scientific measurement of public awareness in the planning or development process.&#x0D; Keywords: Attention, Community, Tourist Village

Visual feedback and declines in attention are associated with altered visual strategy during a force-steadiness task in older adults.

Greater heterogeneity exists in older adults relative to young adults when performing highly skilled manual tasks. The purpose of this study was to assess the influence of visual feedback and attentional demand on visual strategy during a submaximal force-steadiness task in young and older adults. Eye movements of 21 young (age 20-38 yr; 11 females, 10 males) and 21 older (age 65-90 yr; 11 females, 10 males) adults were recorded during a pinch force-steadiness task while viewing feedback with higher and lower gain and while performing a visuospatial task. For the visuospatial task, participants imagined a star moving around four boxes and reported the final location after a series of directions. Performance on standardized tests of attention was measured. All participants gazed near the target line and made left-to-right saccadic eye movements during the force-steadiness tasks without the visuospatial task. Older adults made fewer saccades than young adults (21.0 ± 2.9 and 23.6 ± 4.4 saccades, respectively) and with higher versus lower gain (20.9 ± 4.0 and 23.7 ± 3.5 saccades, respectively). Most participants used the same visual strategy when performing the visuospatial task though seven older adults used an altered strategy; gaze did not stay near the target line nor travel exclusively left to right. Performance on standardized measures of attention was impaired in this subset compared with older adults who did not use the altered visual strategy. Results indicate that visual feedback influences visual strategy and reveals unique eye movements in some older adults when allocating attention across tasks.NEW & NOTEWORTHY This study contributes novel findings of age-related changes in visual strategy and associations with attentional deficits during hand motor tasks. Older adults used fewer saccades than young adults and with higher versus lower gain visual feedback during a force-steadiness task. A subset of older adults used an altered visual strategy when allocating attention across multiple tasks. Given that this subset demonstrated attentional deficits, the altered visual strategy could serve to indicate motor and/or cognitive impairments.

Eyeball translations affect saccadic eye movements beyond brainstem control.

Vision requires that we rotate our eyes frequently to look at informative structures in the scene. Eye movements are planned by the brain but their execution depends on the mechanical properties of the oculomotor plant, that is, the arrangement of eyeball position, muscle insertions, and pulley locations. Therefore, the biomechanics of rotations is sensitive to eyeball translation because it changes muscle levers. Eyeball translations are little researched as they are difficult to measure with conventional techniques. Here, we investigated the effects of eyeball translation on the coordination of eyeball rotation by high-speed MRI recordings of saccadic eye movements during blinks, which are known to produce strong translations. We found that saccades during blinks massively overshoot their targets and that these overshoots occur in a transient fashion such that the gaze is back on target at the time the blink ends. These dynamic overshoots were tightly coupled to the eyeball translation, both in time and in size. Saccades made without blinks were also accompanied by small amounts of transient eyeball retraction, the size of which scaled with saccade amplitude. These findings demonstrate a complex combination of rotation and translation of the eye. The mechanical consequences of eyeball translation on oculomotor control should be considered along with the neural implementation in the brainstem to understand the generation of eye movements and their disorders.NEW & NOTEWORTHY We found that saccades during blinks can massively overshoot their target when the eyeball is retracted. Our data imply that the overshoots are not part of the saccade plan prepared in the brainstem, but instead a consequence of the altered biomechanics resulting from concurrent eyeball translation and rotation. To our best knowledge, this is the first direct observation of dynamic properties of the oculomotor plant altering the execution of rotational eye movements.

The Effect of Stimulus Contrast and Spatial Position on Saccadic Eye Movement Parameters.

(1) Background: Saccadic eye movements are rapid eye movements aimed to position the object image on the central retina, ensuring high-resolution data sampling across the visual field. Although saccadic eye movements are studied extensively, different experimental settings applied across different studies have left an open question of whether and how stimulus parameters can affect the saccadic performance. The current study aims to explore the effect of stimulus contrast and spatial position on saccadic eye movement latency, peak velocity and accuracy measurements. (2) Methods: Saccadic eye movement targets of different contrast levels were presented at four different spatial positions. The eye movements were recorded with a Tobii Pro Fusion video-oculograph (250 Hz). (3) Results: The results demonstrate a significant effect of stimulus spatial position on the latency and peak velocity measurements at a medium grey background, 30 cd/m2 (negative and positive stimulus polarity), light grey background, 90 cd/m2 (negative polarity), and black background, 3 cd/m2 (positive polarity). A significant effect of the stimulus spatial position was observed on the accuracy measurements when the saccadic eye movement stimuli were presented on a medium grey background (negative polarity) and on a black background. No significant effect of stimulus contrast was observed on the peak velocity measurements under all conditions. A significant stimulus contrast effect on latency and accuracy was observed only on a light grey background. (4) Conclusions: The best saccadic eye movement performance (lowest latency, highest peak velocity and accuracy measurements) can be observed when the saccades are oriented to the right and left from the central fixation point. Furthermore, when presenting the stimulus on a light grey background, a very low contrast stimuli should be considered carefully.

Dissociating the Contributions of Frontal Eye Field Activity to Spatial Working Memory and Motor Preparation.

Neurons within dorsolateral prefrontal cortex (PFC) of primates are characterized by robust persistent spiking activity exhibited during the delay period of working memory tasks. This includes the frontal eye field (FEF) where nearly half of the neurons are active when spatial locations are held in working memory. Past evidence has established the FEF's contribution to the planning and triggering of saccadic eye movements as well as to the control of visual spatial attention. However, it remains unclear whether persistent delay activity reflects a similar dual role in movement planning and visuospatial working memory. We trained male monkeys to alternate between different forms of a spatial working memory task which could dissociate remembered stimulus locations from planned eye movements. We tested the effects of inactivation of FEF sites on behavioral performance in the different tasks. Consistent with previous studies, FEF inactivation impaired the execution of memory-guided saccades (MGSs), and impaired performance when remembered locations matched the planned eye movement. In contrast, memory performance was largely unaffected when the remembered location was dissociated from the correct eye movement response. Overall, the inactivation effects demonstrated clear deficits in eye movements, regardless of task type, but little or no evidence of a deficit in spatial working memory. Thus, our results indicate that persistent delay activity in the FEF contributes primarily to the preparation of eye movements and not to spatial working memory.SIGNIFICANCE STATEMENT Many frontal eye field (FEF) neurons exhibit spatially tuned persistent spiking activity during the delay period of working memory tasks. However, the role of the FEF in spatial working memory remains unresolved. We tested the effects of inactivation of FEF sites on behavioral performance in different forms of a spatial working memory task, one of which dissociated the remembered stimulus locations from planned eye movements. We found that FEF inactivation produced clear deficits in eye movements, regardless of task type, but no deficit in spatial working memory when dissociated from those movements.

Diabetic older women without peripheral neuropathy amplify body sway but are capable of improving postural stability during a saccadic gaze task

BackgroundDiabetic older people tend to present deteriorated performance in balance and locomotion activities, even those without peripheral neuropathy. There is evidence that saccadic eye movements are used to reduce body sway in young and older healthy adults, but it has not been shown that diabetic older people preserve this visuomotor adaptation capacity. Research questionAre diabetic older women without peripheral neuropathy capable of improving postural stability during a saccadic gaze task? MethodsSeventeen type 2 diabetic older women (68.2 ± 10.7 years old) and seventeen healthy women, age-matched controls (66.0 ± 8.4 years old) voluntarily participated in the study. All participants were instructed to stand upright, barefoot, as stable as possible, for 30 s. Participants maintained their feet parallel to each other, at standard and narrow bases of support, while either fixating on a stationary target (fixation condition) or performing horizontal saccadic eye movements to follow a target (eccentricity of 11° of visual angle), which continuously disappeared and reappeared immediately on the opposite side (saccade 0.5 Hz and saccade 1.1 Hz conditions). ResultsResults indicated that the diabetic group clearly had deteriorated postural control, as shown by increased values of mean sway amplitude and mean sway velocity. However, diabetic and control groups were similarly capable of using saccadic eye movements to improve their postural stability, reducing their sway velocity compared to a gaze fixation condition. SignificanceDiabetes per se (without peripheral neuropathy) amplifies postural sway of older women as compared to their healthy age-matched controls. However, diabetic older women without peripheral neuropathy are capable of improving postural stability during a saccadic gaze task.

Complex spikes perturb movements and reveal the sensorimotor map of Purkinje cells

Computations that are performed by the cerebellar cortex are transmitted via simple spikes of Purkinje cells (P-cells) to downstream structures, but because P-cells are many synapses away from muscles, we do not know the relationship between modulation of simple spikes and control of behavior. Here, we recorded the spiking activities of hundreds of P-cells in the oculomotor vermis of marmosets during saccadic eye movements and found that following the presentation of a visual stimulus, the olivary input to a P-cell coarsely described the direction and amplitude of the visual stimulus as well as the upcoming movement. Occasionally, the complex spike occurred just before saccade onset, suppressing the P-cell's simple spikes and disrupting its output during that saccade. Remarkably, this brief suppression of simple spikes altered the saccade's trajectory by pulling the eyes toward the part of the visual space that was preferentially encoded by the olivary input to that P-cell. Thus, there is an alignment between the sensory space encoded by the complex spikes and the behavior conveyed by the simple spikes: a reduction in simple spikes is a signal to bias the ongoing movement toward the part of the sensory space preferentially encoded by the olivary input to that P-cell.

Concordant GRADE-3 Truncal Ataxia and Ocular Laterodeviation in Acute Medullary Stroke.

Background: Severe truncal ataxia associated with an inability to sit up without assistance (STA grade 3) is frequent in patients with central acute vestibular syndrome (AVS) involving the brainstem or cerebellum. When these patients have nystagmus, central HINTS excludes peripheral lesions; however, additional localization and lateralization signs are helpful, not only to resolve the peripheral versus central vestibular lesion dilemma, but to zero in on a precise lesion localization/lateralization to the lateral medulla, the most common ischemic lesion localization associated with an initially false-negative stroke MRI. Methods: This is a study of AVS patients with additional inclusion criteria: grades 2 or 3 ataxia with an eventual diagnosis of medullary stroke (MS), either involving the lateral medulla (LMS) or the medial medulla (MMS), and horizontal (h) gaze paralysis was the main exclusion criteria. All patients sat on the side of the bed or stretcher, with assistance if needed. A general neurologic examination followed in the sitting position, the testing protocol included the head impulse, spontaneous nystagmus, and skew deviation (HINTS) tests, followed by observation of the effect of brief 3-5 sec eyelid closure on ocular position, and saccade and pursuit eye movement tests. If they could sit, the protocol included the ability to stand with a wide base, then a narrow base, the Romberg test, and tandem gait. Radiographic lesion localization and horizontal gaze deviation concluded the protocol. Results: A total of 34 patients met the entry criteria, 34 MS (13 in the lateral medulla, 12 previously described, and 1 new patient), and 1 new MMS. Among them, n = 10/12 had grade 3 ataxia, and 3 (1 new patient) had grade 2 ataxia. In addition, overt ocular laterodeviation (OLD) was present in thirteen of them (35.3%). All OLD patients had gaze deviation and ipsilateral saccade and truncal lateropulsion, 1 medial medulla stroke patient had grade 3 truncal contrapulsion and contralateral hemiparesis without OLD, n = 20/21 patients with LMS without OLD had grade 3 truncal ataxia, and 1 had grade 2 truncal ataxia. Discussion: AVS patients with severe truncal ataxia (inability to sit without assistance) potentially have brainstem, cerebellum, or subcortical lesions. All patients had central HINTS; however, simultaneous direction-concordant STA 3 and OLD provided greater lateral medulla localization specificity, affecting the ipsilateral medulla. Future work to explore a practical posterior circulation stroke scale that includes HINTS, STA, and OLD will potentially select cases for thrombolysis even in the event of initially false-negative imaging.

Development of a Magnetoresistive-Based Wearable Eye-Tracking System for Oculomotor Assessment in Neurological and Otoneurological Research-Preliminary In Vivo Tests.

Over the past 20 years, several eye-tracking technologies have been developed. This article aims to present a new type of eye tracker capable of producing detailed information on eye and head movements using an array of magnetoresistive detectors fixed on the patient's head and a small magnet inserted into a contact lens, adapted to the curvature of the cornea of the subject. The software used for data analysis can combine or compare eye and head movements and can represent them as 2D or 3D images. Preliminary data involve an initial patient who was asked to perform several tasks to establish the accuracy, reliability, and tolerance of the magnetic eye tracker and software. The tasks included assessment of saccadic eye movements and pursuit, "drawing" alphabetic shapes or letters, and reading. Finally, a Head Impulse Test (HIT) was performed to estimate the VOR gain, comparing the standard deviation established via vHIT with that established via this magnetic eye tracker (mHIT). This prototypical device is minimally invasive, lightweight, relatively cheap, and tolerable, with a high degree of reliability and precision. All these characteristics could lead to the future use of the magnetic eye tracker in neurological and otoneurological fields.

Gaze-speech coordination during social interaction in Parkinson's disease.

Parkinson's disease (PD) can affect social interaction and communication as well as motor and cognitive processes. Speech is affected in PD, as is the control of voluntary eye movements which are thought to play an important role in 'turn taking' in conversation. This study aimed to measure eye movements during spoken conversation in PD to assess whether differences in patterns of eye gaze are linked to disrupted turn taking and impaired communication efficiency. Eleven participants with mild PD and 14 controls completed a two-player guessing game. During each 3 min game turn, one of the players had to guess the names of as many objects as possible based only on the other player's description. Eye movements were recorded simultaneously in both participants using mobile eye trackers along with speech onset and offset times. When people with PD played the role of describer, the other player guessed fewer objects compared to when controls described objects. When guessing objects, people with PD performed just as well as controls. Analysis of eye fixations showed that people with PD made longer periods of fixation on the other player's face relative to controls and a lower number of such 'gaze on face' periods. A combination of oculomotor, cognitive and speech abnormalities may disrupt communication in PD. Better public awareness of oculomotor, speech and other deficits in the condition could improve social connectedness in people with Parkinson's. What is already known on this subject? Parkinson's disease is known to affect the control of voluntary eye movements. Direction of eye gaze is important in spoken conversation as a cue to turn-taking, but no studies have examined whether eye movements are different during communication in people with Parkinson's. What this paper adds to existing knowledge? People with Parkinson's showed longer periods of eye fixation during conversations compared to controls. Delays and overlaps between speech turns were also affected in patients. What are the clinical implications of this work? Better knowledge of the effect of the disease on eye gaze control amongst clinicians may help improve communication and social connectedness for patients in the future.

B - 03 Inhibitory Control and Saccadic Eye Movement in Adults with Attention-Deficit Hyperactivity Disorder: an Eye-Tracking Analysis.

The objective of this study was to investigate oculomotor differences between adults with and without attention-deficit hyperactivity disorder (ADHD) during a computerized response inhibition task, utilizing eye-tracking technology. Twenty-nine adults with ADHD and 35 controls (ages 18-32) were recruited from Sona Systems and the Learning Center at a university. Participants completed 120 randomized trials of the flanker task while their eye movements were monitored. Saccadic eye movement was investigated, while reaction time and performance errors were recorded from the flanker task. Participants with ADHD were required to refrain from taking stimulant medication the day of the experiment. A linear mixed-effects regression model was fitted. Having ADHD resulted in significantly slower response times, t(57) = 2.73, p < 0.005, 95% CI [0.04, 0.27], but not significantly more errors than control participants on the flanker task. There were no significant differences in the number of saccades between groups. Further analysis demonstrated that adults with ADHD had a significantly higher number of saccades as the number of trials increased, t(7019) = 3.69, p < 0.001, 95% CI [0.00105, 0.00314]. Slower reaction time in adults with ADHD during the flanker task indicates slower processing, but this did not affect their accuracy. While no differences were found in the number of saccades between groups, higher saccades as trial number increased in adults with ADHD suggests possible fatigue contributing to oculomotor differences. Further research is necessary to investigate potential gaze differences during a task that necessitates increased saccadic eye movement.

A - 9 The Progressive Supranuclear Palsy Rating Scale Identifies Early Motor Symptoms in Primary Progressive Aphasia.

This study examined cross-sectional differences in Progressive Supranuclear Palsy Rating Scale (PSPRS) scores among participants with behavioral variant frontotemporal dementia (bvFTD) and primary progressive aphasia (PPA). We hypothesized that participants with nonfluent/agrammatic PPA (nfPPA) will show the highest (worst) PSPRS scores and greater gray matter atrophy in regions associated with progressive supranuclear palsy (PSP) pathology. Participants were enrolled in the ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration consortium (ALLFTD). Analyses were limited to first visit data. Ten anatomic regions of interest were pre-selected for analysis based on previously identified neuroanatomic correlates of PSPRS performance. Differences in participant characteristics and clinical outcomes were compared using pairwise comparison of means. Linear multivariable regression adjusting for age and total intracranial volume was used to examine associations between regional gray matter volumes and diagnosis. The analyses were stratified by disease severity. Participants with early-stage nfPPA had higher total PSPRS scores compared to those with bvFTD or semantic dementia (SD) and performed more poorly on domains of dysphagia, fine motor movements, falls, postural stability, dysarthria, saccadic eye movements, and motor rigidity. Participants with advanced-stage nfPPA showed greater atrophy in the left putamen, supplementary motor area, and precentral gyrus than those with bvFTD. Our study highlights the phenotypic complexity of PPA and the utility of the PSPRS in capturing early motor symptoms in nfPPA. These data suggest that the PSPRS may facilitate early intervention in identifying and facilitating treatment of early motor symptoms, decreasing disability and improving quality of life in PPA.

OCT-based dynamic mechanical analysis of vitreous humour

The vitreous humour plays an important role in shock absorption, i.e. the damping of the mechanical movement, to protect the delicate tissues within the eye. However, this damping is different for movements with different frequencies/velocities. While the collective low-frequency (below 100 Hz) damping behaviour of the vitreous humour associated with the saccadic and lens movements is well-studied, to the best of our knowledge, the high-frequency damping behaviour of the vitreous humour, which represents the response of the microstructural components, is not exhaustively documented. Here, we utilise a non-destructive testing method called Optical Coherence Tomography (OCT) to measure the high-frequency (100–350 Hz, waves able to probe approximately 500 µm distances) biomechanical behaviour of the vitreous humour. We parametrise this behaviour by calculating the shear storage modulus, shear loss modulus and phase angle. We compare these parameters to their low-frequency counterparts obtained with a rheometer, providing a comprehensive mechanical spectrum of the vitreous humour behaviour. The processing method developed in this study and the data collected help better understand the vitreous humour shock absorption properties. Consequently, they could allow a development of better vitreous humour substitutes. The local probing of the high-frequency regime and the non-invasive character of the OCT method provide new qualities in mapping the damping behaviour.

Cultural Influences on Saccadic Patterns in Facial Perception: A Comparative Study of American and Japanese Real and Animated Faces

This study investigated the influence of saccadic eye movements and emotions on real and animated faces to enhance a detailed perception of facial information. Considering the cross-cultural differences in facial features, animated faces also influence visual preferences due to their unique visual appeal. Since there are differences in facial features across cultures, animated faces can also impact visual preferences due to their unique visual appeal. This study involved 60 participants and utilized four stimulus conditions, including real and animated faces from America and Japan. A five-point Likert scale was employed to measure participants’ subjective emotional pleasure and arousal levels, while eye-tracking equipment was used to analyze participants’ saccadic eye movements. The results revealed that, in comparison to Japanese real faces (JT), American real faces (AT) exhibited significantly greater average saccadic distances (AT: 113.03 ± 46.26, JT: 110.78 ± 45.55, p &lt; 0.05). However, there was no statistically significant difference in the average saccadic distance between Japanese and American animated faces (109.88 ± 45.73 and 110.85 ± 45.31, respectively). Additionally, evaluating the mediating role of pleasure and arousal levels among these facial stimuli did not impact saccadic behavior. Our observations suggest that cultural factors wield a pronounced impact on saccadic behavior within real-life scenarios. However, these cultural nuances appear to attenuate in virtual and abstract animated environments. This study’s findings shed new light on the dynamic relationship between saccadic eye movements, emotions, and cultural dimensions, unraveling complexities in facial perception across diverse cultural landscapes. The implications of our research extend to animation, serving as a catalyst for further exploration in this burgeoning field.