Search Results (66)

Some estimates suggest that one in seven good readers and the majority of children with reading difficulties suffer from oculomotor dysfunction (OMD), an umbrella term for abnormalities in comfortable and accurate fixations, pursuits, and saccades. However, national vision evaluation programs worldwide are often limited to distance visual acuity (dVA), not testing for OMD despite its high prevalence and the ease of detecting it in brief optometric evaluations. We hypothesized that reading acquisition is dependent on good oculomotor functions, and therefore inadequate oculomotor control will be associated with reading difficulties. We retrospectively examined and compared oculomotor evaluations (using DEM and NSUCO) and reading assessments (using standardized national reading norms) of a normative class (28 first graders (6–7 yr. olds)) that were independently obtained while blind to the other assessment. Better oculomotor performance as estimated by DEM was associated with better reading performance, and almost a third (29.6%) of the children were categorized by DEM as having OMD-related difficulties. Control analysis revealed dVA was not positively associated with reading performance. Linear regression analyses further corroborated these findings. Since this study is based on a small cohort and since there are studies suggesting that DEM may actually reflect visual processing speed or cognitive factors rather than oculomotor function, replications are needed to substantiate the direct contribution of oculomotor functions to reading acquisition. Young children struggling with reading may benefit from a comprehensive visual evaluation, including oculomotor testing, to provide a more thorough assessment of their learning-related difficulties. Full article

Event detection is the most important element of eye movement analysis. Deep learning approaches have recently demonstrated superior performance across various fields, so researchers have also used them to identify eye movement events. In this study, a combination of two-dimensional convolutional neural networks (2D-CNN) and long short-term memory (LSTM) layers is proposed to simultaneously classify input data into fixations, saccades, post-saccadic oscillations (PSOs), and smooth pursuits (SPs). The first step involves calculating features (i.e., velocity, acceleration, jerk, and direction) from positional points. Various combinations of these features have been used as input to the networks. The performance of the proposed method was evaluated across all feature combinations and compared to state-of-the-art feature sets. Combining velocity and direction with acceleration and/or jerk demonstrated significant performance improvement compared to other feature combinations. The results show that the proposed method, using a combination of velocity and direction with acceleration and/or jerk, improves PSO identification performance, which has been difficult to distinguish from short saccades, fixations, and SPs using classic algorithms. Finally, heuristic event measures were applied, and performance was compared across different feature combinations. The results indicate that the model combining velocity, acceleration, jerk, and direction achieved the highest accuracy and most closely matched the ground truth. It correctly classified 82% of fixations, 90% of saccades, and 88% of smooth pursuits. However, the PSO detection rate was only 73%, highlighting the need for further research. Full article

Background: The impact of dance training on brainstem-mediated vestibular reflexes remains unclear. This study examined the vestibulo-ocular reflex (VOR) and its suppression during high-speed head movements, which may closely resemble the head-turning speeds used in dancers’ spotting techniques, using the video head impulse test. Methods: Eighteen female college students (mean age: 21 years) were divided into two groups—nine trained dancers (≥six years of dance training) and nine age-matched non-dancers—all without a history of hearing, vestibular, or neurological disorders. VOR function was assessed using the head impulse paradigm (HIMP) and the suppression head impulse paradigm (SHIMP) for right and left lateral stimulation, with minimum head velocities of 150°/s. Results: All participants exhibited VOR measures within normal limits and the VOR gain of dancers did not significantly differ from that of non-dancers. However, most dancers reported a preference for right-sided pirouettes and the right-side SHIMP gain negatively correlated with years of training, suggesting a link between preferred turning direction and VOR suppression ability. Furthermore, dancers with over 15 years of training exhibited earlier anti-compensatory saccade latencies (~75 ms) during SHIMP. Conclusions: Trained dancers maintain a healthy VOR and may develop enhanced voluntary control, enabling more effective VOR suppression. The earlier onset of anti-compensatory saccades suggests neural adaptations in eye–head coordination for high-velocity movements. Given the study’s small sample size and the inclusion of non-fulltime dancers, future research with larger samples of professional dancers is needed for enhanced generalizability. These findings provide preliminary evidence of dance-related neuroplasticity in brainstem-mediated vestibular reflexes and open new research avenues. Full article

Background and Objectives: Spinal muscular atrophy (SMA) is a progressive, autosomal recessive, rare neuromuscular disorder caused by a genetic defect in the SMN1 gene, where the SMN2 gene cannot sufficiently compensate. Patients experience progressive and predominantly proximal muscular weakness and atrophy. Oculomotor disorders are currently not regarded as a typical feature of SMA. The aim of this study was to determine whether oculomotor abnormalities are present in subjects with SMA and to assess a potential relationship between the oculomotor parameters and disease duration. Materials and Methods: An analysis of 15 patients with SMA type 2 and type 3 and 15 age-matched healthy controls was conducted. The oculomotor performance, including the analysis of smooth pursuit velocity gain and saccades parameters (latency, velocity, accuracy) in the horizontal and vertical directions, was compared between both groups. Results: The analysis of smooth pursuit gain in the participants revealed a marginally significant reduction between the SMA patients and the healthy controls in the horizontal direction at a frequency of 0.2 Hz (p = 0.051), but no significant differences were observed at any other frequency or direction. The vertical velocity of the saccade eye movements of the SMA patients was increased compared with the healthy subjects, which was statistically significant for the amplitude of ±10° (p = 0.030), but not for the amplitude of ±16.5° (p = 0.107). The horizontal saccade latency, saccade velocity and saccade accuracy did not differ significantly between the SMA patients and the controls. None of the oculomotor parameters were associated with disease duration. Conclusions: While certain oculomotor abnormalities, such as increased vertical saccade velocity, were observed in the SMA patients, these findings do not indicate a defining role of oculomotor impairment in SMA pathology or its clinical characteristics. Full article

The impact of ambient brightness surroundings on the peak velocities of visually guided saccades remains a topic of debate in the field of eye-tracking research. While some studies suggest that saccades in darkness are slower than in light, others question this finding, citing inconsistencies influenced by factors such as pupil deformation during saccades, gaze position, or the measurement technique itself. To investigate these, we developed RELAY (Robotic EyeLink AnalYsis), a low-cost, stepper motor-driven artificial eye capable of simulating human saccades with controlled pupil, gaze directions, and brightness. Using the EyeLink 1000, a widely employed eye tracker, we assessed accuracy and precision across three illumination settings. Our results confirm the reliability of the EyeLink 1000, demonstrating no artifacts in pupil-based eye tracking related to brightness variations. This suggests that previously observed changes in peak velocities with varying brightness are likely due to human factors, warranting further investigation. However, we observed systematic deviations in measured pupil size depending on gaze direction. These findings emphasize the importance of reporting illumination conditions and gaze parameters in eye-tracking experiments to ensure data consistency and comparability. Our novel artificial eye provides a robust and reproducible platform for evaluating eye tracking systems and deepening our understanding of the human visual system. Full article

Purpose: Accurate and precise navigation in space and postural stability rely on the central integration of multisensory input (vestibular, proprioceptive, visual), weighted according to its reliability, to continuously update the internal estimate of the direction of gravity. In this study, we examined both peripheral and central vestibular functions in a world-renowned 53-year-old male tightrope walker and investigated the extent to which his exceptional performance was reflected in our findings. Methods: Comprehensive assessments were conducted, including semicircular canal function tests (caloric irrigation, rotatory-chair testing, video head impulse testing of all six canals, dynamic visual acuity) and otolith function evaluations (subjective visual vertical, fundus photography, ocular/cervical vestibular-evoked myogenic potentials [oVEMPs/cVEMPs]). Additionally, static and dynamic posturography, as well as video-oculography (smooth-pursuit eye movements, saccades, nystagmus testing), were performed. The participant’s results were compared to established normative values. High-resolution diffusion tensor magnetic resonance imaging (DT-MRI) was utilized to assess motor tract integrity. Results: Semicircular canal testing revealed normal results except for a slightly reduced response to right-sided caloric irrigation (26% asymmetry ratio; cut-off = 25%). Otolith testing, however, showed marked asymmetry in oVEMP amplitudes, confirmed with two devices (37% and 53% weaker on the left side; cut-off = 30%). Bone-conducted cVEMP amplitudes were mildly reduced bilaterally. Posturography, video-oculography, and subjective visual vertical testing were all within normal ranges. Diffusion tensor MRI revealed no structural abnormalities correlating with the observed functional asymmetry. Conclusions: This professional tightrope walker’s exceptional balance skills contrast starkly with significant peripheral vestibular (otolithic) deficits, while MR imaging, including diffusion tensor imaging, remained normal. These findings highlight the critical role of central computational mechanisms in optimizing multisensory input signals and fully compensating for vestibular asymmetries in this unique case. Full article

Spatiotemporal models for the 3-D shape and motion of objects allowed large progress in the 1980s in visual perception of moving objects observed from a moving platform. Despite the successes demonstrated with several vehicles, the “4-D approach” has not been accepted generally. Its advantage is that only the last image of the sequence needs to be analyzed in detail to allow the full state vectors of moving objects, including their velocity components, to be reconstructed by the feedback of prediction errors. The vehicle carrying the cameras can, thus, together with conventional measurements, directly create a visualization of the situation encountered. In 1994, at the final demonstration of the project PROMETHEUS, two sedan vehicles using this approach were the only ones worldwide capable of driving autonomously in standard heavy traffic on three-lane Autoroutes near Paris at speeds up to 130 km/h (convoy driving, lane changes, passing). Up to ten vehicles nearby could be perceived. In this paper, the three-layer architecture of the perception system is reviewed. At the end of the 1990s, the system evolved from mere recognition of objects in motion, to understanding complex dynamic scenes by developing behavioral capabilities, like fast saccadic changes in the gaze direction for flexible concentration on objects of interest. By analyzing motion of objects over time, the situation for decision making was assessed. In the third-generation system “EMS-vision” behavioral capabilities of agents were represented on an abstract level for characterizing their potential behaviors. These maneuvers form an additional knowledge base. The system has proven capable of driving in networks of minor roads, including off-road sections, with avoidance of negative obstacles (ditches). Results are shown for road vehicle guidance. Potential transitions to a robot mind and to the now-favored CNN are touched on. Full article

Since game mechanics and their visual aspects have become more and more addictive, there is concern about the growing prevalence of Internet gaming disorder (IGD). In the current narrative review, we searched PubMed and Google Scholar databases for the keywords “igd biomarker gaming” and terms related to biomarker modalities. The biomarkers we found are grouped into several categories based on a measurement method and are discussed in the light of theoretical addiction models (tripartite neurocognitive model, I-PACE). Both theories point to gaming-related problems with salience and inhibition. The first dysfunction makes an individual more susceptible to game stimuli (raised reward seeking), and the second negatively impacts resistance to these stimuli (decreased cognitive control). The IGD patients’ hypersensitivity to reward manifests mostly in ventral striatum (VS) measurements. However, there is also empirical support for a ventral-to-dorsal striatal shift and transition from goal-directed to habitual behaviors. The deficits in executive control are demonstrated in parameters related to the prefrontal cortex (PFC), especially the dorsolateral prefrontal cortex (DLPFC). In general, the connection of PFC with reward under cortex nuclei seems to be dysregulated. Other biomarkers include reduced P3 amplitudes, high-frequency heart rate variability (HRV), and the number of eye blinks and saccadic eye movements during the non-resting state. A few studies propose a diagnostic (multimodal) model of IGD. The current review also comments on inconsistencies in findings in the nucleus accumbens (NAcc), anterior cingulate cortex (ACC), and precuneus and makes suggestions for future IGD studies. Full article

The tremendous increase in the use of video-based eye tracking has made it possible to collect eye tracking data from thousands of participants. The traditional procedures for the manual detection and classification of saccades and for trial categorization (e.g., correct vs. incorrect) are not viable for the large datasets being collected. Additionally, video-based eye trackers allow for the analysis of pupil responses and blink behaviors. Here, we present a detailed description of our pipeline for collecting, storing, and cleaning data, as well as for organizing participant codes, which are fairly lab-specific but nonetheless, are important precursory steps in establishing standardized pipelines. More importantly, we also include descriptions of the automated detection and classification of saccades, blinks, “blincades” (blinks occurring during saccades), and boomerang saccades (two nearly simultaneous saccades in opposite directions where speed-based algorithms fail to split them), This is almost entirely task-agnostic and can be used on a wide variety of data. We additionally describe novel findings regarding post-saccadic oscillations and provide a method to achieve more accurate estimates for saccade end points. Lastly, we describe the automated behavior classification for the interleaved pro/anti-saccade task (IPAST), a task that probes voluntary and inhibitory control. This pipeline was evaluated using data collected from 592 human participants between 5 and 93 years of age, making it robust enough to handle large clinical patient datasets. In summary, this pipeline has been optimized to consistently handle large datasets obtained from diverse study cohorts (i.e., developmental, aging, clinical) and collected across multiple laboratory sites. Full article

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. Full article

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. Full article

This study investigates the change in horizontal saccadic eye movement and smooth pursuit in patients with acquired comitant esotropia (ACE), before and after strabismus surgery. The horizontal saccades and pursuit in 11 patients with ACE were recorded using a video eye-tracker under binocular viewing before and after strabismus surgery. Participants were instructed to fixate on the new target as rapidly as possible when it randomly appeared at either 18.3° rightward or 18.3° leftward. For smooth pursuit, participants were asked to track, as accurately as possible, a step-ramp target moving at ±6.1°/s. The asymmetry of adduction-abduction and the binocular coordination in gains of saccade and pursuit were compared between the pre- and post-surgical data. The asymmetry of adduction-abduction saccade gain in each eye after surgery tended to be smaller than that before surgery. The binocular coordination of saccade showed significant improvement after surgery in only the non-dominant eye direction. Adduction-abduction asymmetry in the smooth pursuit gain in each eye after surgery tended to be smaller than before surgery. After surgery, the binocular coordination of pursuit was improved significantly in both directions. In patients with ACE, binocular coordination of saccade and smooth pursuit was poor. Binocular coordination of saccade and pursuit seems to be improved due to the improvement in ocular deviation angle and binocular visual function after surgery. Full article

The control of eye gaze is critical to the execution of many skills. The observation that task experts in many domains exhibit more efficient control of eye gaze than novices has led to the development of gaze training interventions that teach these behaviours. We aimed to extend this literature by i) examining the relative benefits of feed-forward (observing an expert’s eye movements) versus feed-back (observing your own eye movements) training, and ii) automating this training within virtual reality. Serving personnel from the British Army and Royal Navy were randomised to either feed-forward or feed-back training within a virtual reality simulation of a room search and clearance task. Eye movement metrics – including visual search, saccade direction, and entropy – were recorded to quantify the efficiency of visual search behaviours. Feed-forward and feed-back eye movement training produced distinct learning benefits, but both accelerated the development of efficient gaze behaviours. However, we found no evidence that these more efficient search behaviours transferred to better decision making in the room clearance task. Our results suggest integrating eye movement training principles within virtual reality training simulations may be effective, but further work is needed to understand the learning mechanisms. Full article

Smooth pursuit eye movements and saccadic eye movements are vital for precise vision. Therefore, tests for eye movement are important for assessing nervous or muscular diseases. However, objective measurements are not frequently performed due to the need for a polygraph system, electrodes, amplifier, and personal computer for data analysis. To address this, we developed an all-in-one eye-movement-measuring device that simultaneously presents visual stimuli, records eye positions, and examines its feasibility for evaluating eye movements. This device generates stimulus that induces eye movements and records those movements continuously. The horizontal or vertical eye movements of 16 participants were measured at various visual target speeds of 20–100 deg/s. The maximum cross-correlation coefficient (rho max) between the eye and visual target positions was used as an index of eye movement accuracy. A repeated-measures multi-way analysis of variance was performed, with the main effect being that rho max significantly decreased as the visual target speed increased. The average (±standard deviation) rho max values across all velocities were 0.995 ± 0.008 and 0.967 ± 0.062 in the horizontal and vertical directions, respectively, and were significantly higher for horizontal eye movements than for vertical eye movements. Moreover, rho max and saccadic frequency were significantly correlated for the slowest and fastest visual target motions. These suggest that our device enables accurate measurements of eye movements. We believe our new measurement device can be applied clinically for easily and objectively evaluating eye movements. Full article

Microsaccades are at the interface between basic oculomotor phenomena and complex processes of cognitive functioning, and they also have been a challenge for subtle experimentation and adequate statistical analysis. In the second part of the special thematic issue (for the first part see Martinez-Conde, Engbert, & Groner, 2020) the authors present a series of articles which demonstrate that microsaccades are still an interesting and rewarding area of scientific research the forefront of research in many areas of sensory, perceptual, and cognitive processes. In their article “Pupillary and microsaccadic responses to cognitive effort and emotional arousal during complex decision making” Krejtz, Żurawska, Duchowski, & Wichary (2020) investigate pupillary and microsaccadic responses to information processing during multi-attribute decision making under affective priming. The participants were randomly assigned into three affective priming conditions (neutral, aversive, and erotic) and instructed to make discriminative decisions. As hypothesized by the authors, the results showed microsaccadic rate inhibition and pupillary dilation, depending on cognitive effort prior to decision and moderated by affective priming. Aversive priming increased pupillary and microsaccadic responses to information processing effort. The results indicate that pupillary response is more influenced by affective priming than microsaccadic rate. The results are discussed in the light of neuropsychological mechanisms of pupillary and microsaccadic behavior. In the article “Microsaccadic rate signatures correlate under monocular and binocular stimulation conditions” Essig, Leube, Rifai, & Wahl (2020) investigate microsaccades with respect to their directional distribution and rate under monocular and binocular conditions. In both stimulation conditions participants fixated a Gabor patch presented randomly in orientation of 45° or 135° over a wide range of spatial frequencies. Microsaccades were mostly horizontally oriented regardless of the spatial frequency of the grating. This outcome was consistent between both stimulation conditions. This study found that the microsaccadic rate signature curve correlates between both stimulation conditions, therefore extending the use of microsaccades to clinical applications, since parameters as contrast sensitivity, have frequently been measured monocularly in the clinical studies. The study “Microsaccades during high speed continuous visual search” by Martin, Davis, Riesenhuber, & Thorpe (2020) provides an analysis of the microsaccades occurring during visual search, targeting to small faces pasted either into cluttered background photos or into a simple gray background. Participants were instructed to target singular 3-degree upright or inverted faces in changing scenes. As soon as the participant’s gaze reached the target face, a new face was displayed in a different random location. Regardless of the experimental context (e.g., background scene, no background scene), or target eccentricity (from 4 to 20 degrees of visual angle), The authors found that the microsaccade rate dropped to near zero levels within 12 ms. There were almost never any microsaccades after stimulus onset and before the first saccade to the face. In about 20% of the trials, there was a single microsaccade that occurred almost immediately after the preceding saccade’s offset. The authors argue that a single feedforward pass through the visual hierarchy of processing a stimulus is needed to effectuate prolonged continuous visual search and provide evidence that microsaccades can serve perceptual functions like correcting saccades or effectuating task-oriented goals during continuous visual search. While many studies have characterized the eye movements during visual fixation, including microsaccades, in most cases only horizontal and vertical components have been recorded and analyzed. Little is known about the torsional component of microsaccades. In the study “Torsional component of microsaccades during fixation and quick phases during optokinetic stimulation” Sadeghpour & Otero-Millan (2020) recorded eye movements around the three axes of rotation during fixation and torsional optokinetic stimulus. The authors found that the average amplitude of the torsional component of microsaccades during fixation was 0.34 ± 0.07 degrees with velocities following a main sequence with a slope comparable to the horizontal and vertical components. The size of the torsional displacement during microsaccades was correlated with the horizontal but not the vertical component. In the presence of an optokinetic stimulus a nystagmus was induced producing more frequent and larger torsional quick phases compared to microsaccades produced during fixation of a stationary stimulus. The torsional component and the vertical vergence component of quick phases increased with higher velocities. In previous research, microsaccades have been interpreted as psychophysiological indicators of task load. So far, it is still under debate how different types of task demands are influencing microsaccade rate. In their article “The interplay between task difficulty and microsaccade rate: Evidence for the critical role of visual load” Schneider et al. (1921) examined the relation between visual load, mental load and microsaccade rate. The participants carried out a continuous performance task (n-back) in which visual task load (letters vs. abstract figures) and mental task load (1-back to 4-back) were manipulated as within-subjects variables. Eye tracking data, performance data as well as subjective workload were recorded. Data analysis revealed an increased level of microsaccade rate for stimuli of high visual demand (i.e., abstract figures), while mental demand (n-back-level) did not modulate microsaccade rate. The authors concluded that microsaccade rate reflects visual load of a task rather than its mental load. This conclusion is in accordance with the proposition of Krueger et al. (2019) “Microsaccades distinguish looking from seeing”, linking sensory with cognitive phenomena. The present special thematic issue adds several new interesting facets to the research landscape around microsaccades. They still remain an attractive focus of interdisciplinary research and transdisciplinary applications. Thus, as already noted in the first part of this special thematic issue, research on microsaccades will not only endure, but keep evolving as the knowledge base expands. Full article