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Journal of Neurophysiology Aug 2018Saccades adapt to persistent natural or artificially imposed dysmetrias. The characteristics and circuitry of saccade adaptation have been revealed using a visually...
Saccades adapt to persistent natural or artificially imposed dysmetrias. The characteristics and circuitry of saccade adaptation have been revealed using a visually guided task (VGT) where the vectors of the target step and the intended saccade command are the same. However, in real life, another saccade occasionally intervenes before the saccade to the target occurs. This necessitates an updating of the intended saccade to account for the intervening saccadic displacement, which dissociates the visual target signal and the intended saccade command. We determined whether the adaptation process is similar for VGT and updated saccades by studying the transfer of adaptation between them. The ultimate visual target was dissociated from the intended saccade command with double-step saccade tasks (DSTs) in which two targets are flashed sequentially at different locations while the monkey maintains fixation. The resulting saccades toward the first and second targets occur in the dark. The transfer of visually guided saccade adaptation to the second saccades of a DST and vice versa depended on the eccentricity of the second visual target, and not the second saccade command. If a target with the same eccentricity as the adapted target appears briefly during the intersaccadic interval of a DST, more adaptation transfers. Because a brief appearance of the visual target either before the first saccade or during the intersaccadic interval influences how much adaptation transfer the second saccade will express, the processing of adaptation and DST updating may overlap. NEW & NOTEWORTHY Adaptation and the spatial updating of saccades are thought to be independent processes. When we dissociate the visual target and the intended saccade command, the transfer of visually guided saccade adaptation to the saccades of the double-step saccade tasks (DST) and vice versa is driven by a visual not motor error. The visual target has an effect until the second saccade of a DST occurs. Therefore, the processing of adaptation and the spatial updating of saccades may overlap.
Topics: Adaptation, Physiological; Animals; Eye Movement Measurements; Fixation, Ocular; Macaca mulatta; Photic Stimulation; Psychomotor Performance; Saccades; Spatial Processing
PubMed: 29694278
DOI: 10.1152/jn.00075.2018 -
Journal of Computational Neuroscience Aug 2021Voluntary rapid eye movements (saccades) redirect the fovea toward objects of visual interest. The saccadic system can be considered as a dual-mode system: in one mode... (Review)
Review
Voluntary rapid eye movements (saccades) redirect the fovea toward objects of visual interest. The saccadic system can be considered as a dual-mode system: in one mode the eye is fixating, in the other it is making a saccade. In this review, we consider two examples of dysfunctional saccades, interrupted saccades in late-onset Tay-Sachs disease and gaze-position dependent opsoclonus after concussion, which fail to properly shift between fixation and saccade modes. Insights and benefits gained from bi-directional collaborative exchange between clinical and basic scientists are emphasized. In the case of interrupted saccades, existing mathematical models were sufficiently detailed to provide support for the cause of interrupted saccades. In the case of gaze-position dependent opsoclonus, existing models could not explain the behavior, but further development provided a reasonable hypothesis for the mechanism underlying the behavior. Collaboration between clinical and basic science is a rich source of progress for developing biologically plausible models and understanding neurological disease. Approaching a clinical problem with a specific hypothesis (model) in mind often prompts new experimental tests and provides insights into basic mechanisms.
Topics: Models, Neurological; Saccades
PubMed: 33839988
DOI: 10.1007/s10827-021-00785-6 -
Journal of Neurophysiology Jul 2024Temporal intervals appear compressed at the time of saccades. Here, I asked if saccadic compression of time is related to motor planning or to saccade execution. To...
Temporal intervals appear compressed at the time of saccades. Here, I asked if saccadic compression of time is related to motor planning or to saccade execution. To dissociate saccade motor planning from its execution, I used the double-step paradigm, in which subjects have to perform two horizontal saccades successively. At various times around the saccade sequence, I presented two large horizontal bars, which marked an interval lasting 100 ms. After 700 ms, a second temporal interval was presented, varying in duration across trials. Subjects were required to judge which interval appeared shorter. I found that during the first saccades in the double-step paradigm, temporal intervals were compressed. Maximum temporal compression coincided with saccade onset. Around the time of the second saccade, I found temporal compression as well, however, the time of maximum compression preceded saccade onset by about 70 ms. I compared the magnitude and time of temporal compression between double-step saccades and amplitude-matched single saccades, which I measured separately. Although I found no difference in time compression magnitude, the time when maximum compression occurred differed significantly. I conclude that the temporal shift of time compression in double-step saccades demonstrates the influence of saccade motor planning on time perception. Visually defined temporal intervals appear compressed at the time of saccades. Here, I tested time perception during double-step saccades dissociating saccade planning from execution. Although around the time of the first saccade, peak compression was found at saccade onset, compression around the time of the second saccade peaked 70 ms before saccade onset. The results suggest that saccade motor planning influences time perception.
Topics: Saccades; Humans; Male; Adult; Female; Time Perception; Young Adult; Psychomotor Performance
PubMed: 38810256
DOI: 10.1152/jn.00117.2024 -
Journal of Vision Mar 2019Recent studies have demonstrated that saccadic reaction times (SRTs) are influenced by the temporal regularities of dynamic environments (Vullings & Madelain, 2018)....
Recent studies have demonstrated that saccadic reaction times (SRTs) are influenced by the temporal regularities of dynamic environments (Vullings & Madelain, 2018). Here, we ask whether discriminative control (i.e., the possibility to use external stimuli signaling the future state of the environment) of latencies in a search task might be established using reinforcement contingencies. Eight participants made saccades within 80-750 ms toward a target displayed among distractors. We constructed two latency classes, "short" and "long," using the first and last quartiles of the individual baseline distributions. We then used a latency-contingent display paradigm in which finding the visual target among other items was made contingent upon specific SRTs. For a first group, the postsaccadic target was displayed only following short latencies with leftward saccades, and following long latencies with rightward saccades. The opposite was true for a second group. When short- and long-latency saccades were reinforced (i.e., the target was displayed) depending on the saccade direction, median latencies differed by 74 ms on average (all outside the 98% null hypothesis confidence intervals). Posttraining, in the absence of reinforcement, we still observed strong differences in latency distributions, averaging 64 ms for leftward versus rightward saccades. Our results demonstrate the discriminative control of SRTs, further supporting the effects of reinforcement learning for saccade. This study reveals that saccade triggering is finely controlled by learned temporal and spatial properties of the environment using predictive mechanisms.
Topics: Adolescent; Adult; Female; Humans; Learning; Male; Photic Stimulation; Reaction Time; Reinforcement, Psychology; Saccades; Young Adult
PubMed: 30924844
DOI: 10.1167/19.3.16 -
Vision Research Feb 2018Previous research on the spatiotemporal dynamics of exogenous and endogenous attentional allocation during saccade preparation yielded conflicting results. We...
Previous research on the spatiotemporal dynamics of exogenous and endogenous attentional allocation during saccade preparation yielded conflicting results. We hypothesize that this can be explained by the cueing type used to orient attention in a perceptual task. We investigated the time-course of attentional allocation as a function of cueing type (central vs peripheral), spatial congruency of the cued perceptual and saccade task locations, and cue validity in a dual-task paradigm. Participants performed a visual discrimination task during saccade preparation. We found that central and peripheral cues differentially affected the time-course of attentional allocation depending on spatial congruency and cue validity. Peripheral cues quickly and transiently oriented attention to the cued location. In the congruent condition, attention was maintained by the pre-saccadic attention shift, but declined in the spatially incongruent condition. Central cues slowly oriented attention to the cued location. In the congruent condition, attention was boosted by the pre-saccadic attention shift compared to a slower increase in the spatially incongruent condition. The pre-saccadic attention shift - the automatic and obligatory shift of attention to the saccade target - observed in the invalid spatially incongruent condition was not differentially affected by the cueing type orienting attention away from it. Our results suggest that exogenous and endogenous attention is dynamically and flexibly allocated to cued locations during saccade preparation while pre-saccadic attentional resources are progressively shifted to the saccade target irrespective of the cueing type. We argue that attentional selection for perception represents a partially independent process in contrast to the pre-saccadic attention shift.
Topics: Adult; Analysis of Variance; Attention; Cues; Discrimination, Psychological; Female; Humans; Male; Photic Stimulation; Reaction Time; Saccades; Visual Fields; Visual Perception; Young Adult
PubMed: 29262304
DOI: 10.1016/j.visres.2017.12.002 -
Cerebral Cortex (New York, N.Y. : 1991) Aug 2018Primates frequently make saccades direct fovea on interesting objects to receive acute visual information. However, saccade displaces the images on retina and disrupts...
Primates frequently make saccades direct fovea on interesting objects to receive acute visual information. However, saccade displaces the images on retina and disrupts the visual constancy. One possible mechanism to retain visual constancy is by integrating the presaccadic and postsaccadic visual information right at the time of saccade, which makes the timing of saccade crucial. So far, the saccadic timing signals have been found only in the subcortical regions, for example, the cerebellum and superior colliculus, but not in the neocortex. Here we report 2 types of saccadic timing signals in macaque lateral intraparietal area (LIP). First, many presaccadic response neurons started to decline activity either right around the start (saccade-on-decay) or the end (saccade-off-decay) of saccades. Notably, the time difference between saccade-off-decay and saccade-on-decay was highly correlated with the mean duration of saccades but not with the individual ones, and both saccade-off-decay and saccade-on-decay were better aligned with saccade end than saccade start-reflecting prediction. Second, the peak activity plateau of a group of postsaccadic response neurons was highly correlated with the actual duration of saccade-reflecting reality. While the predicted timing signals might facilitate the integration of visual information across saccades in LIP, the actual duration signals might calibrate the prediction errors.
Topics: Action Potentials; Animals; Color; Cues; Macaca mulatta; Male; Neurons; Parietal Lobe; Patch-Clamp Techniques; Photic Stimulation; Saccades; Time Factors; Time Perception
PubMed: 28968649
DOI: 10.1093/cercor/bhx166 -
Investigative Ophthalmology & Visual... Mar 2023Most 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...
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.
Topics: Humans; Saccades; Retinitis Pigmentosa; Eye Movements; Retinal Diseases; Macular Degeneration; Scotoma
PubMed: 36857076
DOI: 10.1167/iovs.64.3.1 -
Vision Research Sep 2023Saccadic localisation of targets of various properties has been extensively studied, but rarely for texture-defined figures. In this paper, three experiments that...
Saccadic localisation of targets of various properties has been extensively studied, but rarely for texture-defined figures. In this paper, three experiments that investigate the way information from a texture target is processed in order to provide a signal for eye movement control are presented. Participants made saccades to target regions embedded in a background structure, and the saccade landing position and latency were measured. The textures comprised line elements, with orientations of the lines configured to form the figure and ground. Various orientation profile configurations (Block, Blur, and Cornsweet), were used in order to measure the role of edge profiles in driving eye movements and producing salience. We found that in all cases the visual system is in fact able to effectively segregate a texture figure from the ground in order to accurately plan a saccade to the target-figure. While saccadic latency was the highest for the Blur profile, the mean saccadic landing position was mostly unaffected by the various profiles (Experiment 1). More specifically, we showed that saccades were directed to the centre-of-gravity of the target (Experiment 2). We also found that figures with information of orientation contrast at both the edge and centre of figure (i.e. Block) produced the highest level of saliency in attracting eye movements (Experiment 3). Overall, the results show that saccades are planned on the representation of the whole target shape rather than a local salient region based on orientation contrast cues, and that the various texture profiles were important only to the extent that they affected the time to programme a saccade.
Topics: Humans; Eye Movements; Saccades; Reaction Time
PubMed: 37276684
DOI: 10.1016/j.visres.2023.108264 -
Journal of Vision Apr 2018Does visual processing start anew after each eye movement, or is information integrated across saccades? Here we test a strong prediction of the integration hypothesis:...
Does visual processing start anew after each eye movement, or is information integrated across saccades? Here we test a strong prediction of the integration hypothesis: that information acquired after a saccade interferes with the perception of images acquired before the saccade. We investigate perception of a basic visual feature, grating orientation, and we take advantage of a delayed interference phenomenon-in human participants, the reported orientation of a target grating, briefly presented at an eccentric location, is strongly biased toward the orientation of flanker gratings that are flashed shortly after the target. Crucially, we find that the effect is the same whether or not a saccade is made during the delay interval even though the eye movement produces a large retinotopic separation between target and flankers. However, the trans-saccadic effect nearly vanishes when flankers are displaced to a different screen location even when this location matches the retinotopic coordinates of the target. We conclude that information about grating orientation is integrated across saccades within a spatial region that is defined in external coordinates and thereby is stable in spite of the movement of the eyes.
Topics: Adult; Female; Humans; Male; Orientation; Saccades; Visual Perception; Young Adult
PubMed: 29621386
DOI: 10.1167/18.4.9 -
Journal of Neurophysiology Oct 2019Across saccades, humans can integrate the low-resolution presaccadic information of an upcoming saccade target with the high-resolution postsaccadic information. There...
Across saccades, humans can integrate the low-resolution presaccadic information of an upcoming saccade target with the high-resolution postsaccadic information. There is converging evidence to suggest that transsaccadic integration occurs at the saccade target. However, given divergent evidence on the spatial specificity of related mechanisms such as attention, visual working memory, and remapping, it is unclear whether integration is also possible at locations other than the saccade target. We tested the spatial profile of transsaccadic integration, by testing perceptual performance at six locations around the saccade target and between the saccade target and initial fixation. Results show that integration benefits do not differ between the saccade target and surrounding locations. Transsaccadic integration benefits are not specific to the saccade target and can occur at other locations when they are behaviorally relevant, although there is a trend for worse performance for the location above initial fixation compared with those in the direction of the saccade. This suggests that transsaccadic integration may be a more general mechanism used to reconcile task-relevant pre- and postsaccadic information at attended locations other than the saccade target. This study shows that integration of pre- and postsaccadic information across saccades is not restricted to the saccade target. We found performance benefits of transsaccadic integration at attended locations other than the saccade target, and these benefits did not differ from those found at the saccade target. This suggests that transsaccadic integration may be a more general mechanism used to reconcile pre- and postsaccadic information at task-relevant locations.
Topics: Adult; Female; Fixation, Ocular; Humans; Male; Psychomotor Performance; Saccades; Spatial Behavior
PubMed: 31365324
DOI: 10.1152/jn.00420.2019