scholarly journals Oculomotor Target Selection is Mediated by Complex Objects

2021 ◽  
Author(s):  
Devin Heinze Kehoe ◽  
Jennifer Lewis ◽  
Mazyar Fallah
Keyword(s):  
Time Course ◽  
Target Selection ◽  
Dorsal Stream ◽  
Oculomotor System ◽  
Task Demands ◽  
Frequency Error ◽  
Complex Objects ◽  
Vector Modulation ◽  
Featural Processing ◽  
Vector Representations

Oculomotor target selection often requires discriminating visual features, but it remains unclear how oculomotor substrates encoding saccade vectors functionally contribute to this process. One possibility is that oculomotor vector representations (observed directly as physiological activation or inferred from behavioral interference) of potential targets are continuously re-weighted by task-relevance computed elsewhere in specialized visual modules, while an alternative possibility is that oculomotor modules utilize local featural analyses to actively discriminate potential targets. Strengthening the former account, oculomotor vector representations have longer onset latencies for ventral- (i.e., color) than dorsal-stream features (i.e., luminance), suggesting that oculomotor vector representations originate from featurally-relevant specialized visual modules. Here, we extended this reasoning by behaviorally examining whether the onset latency of saccadic interference elicited by visually complex stimuli is greater than is commonly observed for simple stimuli. We measured human saccade metrics (saccade curvature, endpoint deviations, saccade frequency, error proportion) as a function of time after abrupt distractor onset. Distractors were novel, visually complex, and had to be discriminated from targets to guide saccades. The earliest saccadic interference latency was ~110 ms, considerably longer than previous experiments, suggesting that sensory representations projected into the oculomotor system are gated to allow for sufficient featural processing to satisfy task demands. Surprisingly, initial oculomotor vector representations encoded features, as we manipulated the visual similarity between targets and distractors and observed increased vector modulation response magnitude and duration when the distractor was highly similar to the target. Oculomotor vector modulation was gradually extinguished over the time course of the experiment.

scholarly journals Higher order, multifeatural object encoding by the oculomotor system

2018 ◽  
Vol 120 (6) ◽  
pp. 3042-3062 ◽  
Author(s):  
Devin H. Kehoe ◽  
Selvi Aybulut ◽  
Mazyar Fallah
Keyword(s):  
Visual Processing ◽  
Time Course ◽  
Target Selection ◽  
Oculomotor System ◽  
Higher Order ◽  
Movement Planning ◽  
Cognitive Information ◽  
Saccadic Target ◽  
Cortical Visual Processing ◽  
Vector Modulation

Previous behavioral and physiological research has demonstrated that as the behavioral relevance of potential saccade goals increases, they elicit more competition during target selection processing as evidenced by increased saccade curvature and neural activity. However, these effects have only been demonstrated for lower order feature singletons, and it remains unclear whether more complicated featural differences between higher order objects also elicit vector modulation. Therefore, we measured human saccades curvature elicited by distractors bilaterally flanking a target during a visual search saccade task and systematically varied subsets of features shared between the two distractors and the target, referred to as objective similarity (OS). Our results demonstrate that saccades deviated away from the distractor highest in OS to the target and that there was a linear relationship between the magnitude of saccade deviation and the number of feature differences between the most similar distractor and the target. Furthermore, an analysis of curvature over the time course of the saccade demonstrated that curvature only occurred in the first 20–30 ms of the movement. Given the multifeatural complexity of the novel stimuli, these results suggest that saccadic target selection processing involves dynamically reweighting vector representations for movement planning to several possible targets based on their behavioral relevance. NEW & NOTEWORTHY We demonstrate that small featural differences between unfamiliar, higher order object representations modulate vector weights during saccadic target selection processing. Such effects have previously only been demonstrated for familiar, simple feature singletons (e.g., color) in which features characterize entire objects. The complexity and novelty of our stimuli suggest that the oculomotor system dynamically receives visual/cognitive information processed in the higher order representational networks of the cortical visual processing hierarchy and integrates this information for saccadic movement planning.

scholarly journals Spatial attention during saccade decisions

2017 ◽  
Vol 118 (1) ◽  
pp. 149-160 ◽  
Author(s):  
Donatas Jonikaitis ◽  
Anna Klapetek ◽  
Heiner Deubel
Keyword(s):  
Decision Making ◽  
Spatial Attention ◽  
Time Course ◽  
Target Selection ◽  
Strong Association ◽  
Oculomotor System ◽  
Visual Sensitivity ◽  
Saccade Target ◽  
Selection History ◽  
Target Locations

Behavioral measures of decision making are usually limited to observations of decision outcomes. In the present study, we made use of the fact that oculomotor and sensory selection are closely linked to track oculomotor decision making before oculomotor responses are made. We asked participants to make a saccadic eye movement to one of two memorized target locations and observed that visual sensitivity increased at both the chosen and the nonchosen saccade target locations, with a clear bias toward the chosen target. The time course of changes in visual sensitivity was related to saccadic latency, with the competition between the chosen and nonchosen targets resolved faster before short-latency saccades. On error trials, we observed an increased competition between the chosen and nonchosen targets. Moreover, oculomotor selection and visual sensitivity were influenced by top-down and bottom-up factors as well as by selection history and predicted the direction of saccades. Our findings demonstrate that saccade decisions have direct visual consequences and show that decision making can be traced in the human oculomotor system well before choices are made. Our results also indicate a strong association between decision making, saccade target selection, and visual sensitivity. NEW & NOTEWORTHY We show that saccadic decisions can be tracked by measuring spatial attention. Spatial attention is allocated in parallel to the two competing saccade targets, and the time course of spatial attention differs for fast-slow and for correct-erroneous decisions. Saccade decisions take the form of a competition between potential saccade goals, which is associated with spatial attention allocation to those locations.

scholarly journals On the origin of event-related potentials indexing covert attentional selection during visual search: timing of selection by macaque frontal eye field and event-related potentials during pop-out search

2013 ◽  
Vol 109 (2) ◽  
pp. 557-569 ◽  
Author(s):  
Braden A. Purcell ◽  
Jeffrey D. Schall ◽  
Geoffrey F. Woodman
Keyword(s):  
Time Course ◽  
Target Selection ◽  
Event Related Potentials ◽  
Attentional Selection ◽  
Task Demands ◽  
Frontal Eye Field ◽  
Neural Basis ◽  
Set Size ◽  
Related Potentials ◽  
Eye Field

Event-related potentials (ERPs) have provided crucial data concerning the time course of psychological processes, but the neural mechanisms producing ERP components remain poorly understood. This study continues a program of research in which we investigated the neural basis of attention-related ERP components by simultaneously recording intracranially and extracranially from macaque monkeys. Here, we compare the timing of attentional selection by the macaque homologue of the human N2pc component (m-N2pc) with the timing of selection in the frontal eye field (FEF), an attentional-control structure believed to influence posterior visual areas thought to generate the N2pc. We recorded FEF single-unit spiking and local field potentials (LFPs) simultaneously with the m-N2pc in monkeys performing an efficient pop-out search task. We assessed how the timing of attentional selection depends on task demands by direct comparison with a previous study of inefficient search in the same monkeys (e.g., finding a T among Ls). Target selection by FEF spikes, LFPs, and the m-N2pc was earlier during efficient pop-out search rather than during inefficient search. The timing and magnitude of selection in all three signals varied with set size during inefficient but not efficient search. During pop-out search, attentional selection was evident in FEF spiking and LFP before the m-N2pc, following the same sequence observed during inefficient search. These observations are consistent with the hypothesis that feedback from FEF modulates neural activity in posterior regions that appear to generate the m-N2pc even when competition for attention among items in a visual scene is minimal.

scholarly journals Oculomotor Target Selection is Cortically Mediated by Complex Objects

2020 ◽  
Author(s):  
Devin H. Kehoe ◽  
Jennifer Lewis ◽  
Mazyar Fallah
Keyword(s):  
Target Selection ◽  
Oculomotor System ◽  
Visual Features ◽  
Frequency Error ◽  
Object Representations ◽  
Distractor Processing ◽  
Visual Cortices ◽  
Visual Onset ◽  
Onset Response ◽  
Onset Responses

AbstractSuccessful oculomotor target selection often requires discriminating visual features but it remains contentious whether oculomotor substrates encoding saccade vectors functionally contribute to this process. One possibility is that visual features are discriminated cortically and oculomotor modules select the object with the highest activation in the set of all preprocessed cortical object representations, while an alternative possibility is that oculomotor modules actively discriminate potential targets based on visual features. If the latter view is correct, these modules should not require input from specialized visual cortices encoding the task relevant features. We therefore examined whether the latency of visual onset responses elicited by abrupt distractor onsets is consistent with input from specialized visual cortices by non-invasively measuring human saccade metrics (saccade curvature, endpoint deviations, saccade frequency, error proportion) as a function of distractor processing time for novel, visually complex distractors that had to be discriminated from a target to guide saccades. Visual onset response latencies were ~110 ms, consistent with projections from anterior cortical sites specialized for object processing. Surprisingly, oculomotor visual onset responses encoded features, as we manipulated the visual similarity between targets and distractors and observed an increased visual onset response magnitude and duration when the distractor was highly similar to the target, which was not attributable to an inhibitory processing delay. Visual onset responses were dynamically modulated by executive function, as these responses were anticipatorily extinguished over the time course of the experiment. As expected, the latency of distractor-related inhibition was modulated by the behavioral relevance of the distractor.Significance StatementWe provide novel insights into the role of the oculomotor system in saccadic target selection by challenging the convention that neural substrates that encode oculomotor vectors functionally contribute to target discrimination. Our data show that the oculomotor system selects a winner from amongst the preprocessed object representations output from specialized visual cortices as supposed to discriminating visual features locally. We also challenge the convention that oculomotor visual onset responses are feature-invariant, as they encoded task-relevance.

Area MT Neurons Respond to Visual Motion Distant From Their Receptive Fields

2005 ◽  
Vol 94 (6) ◽  
pp. 4156-4167 ◽  
Author(s):  
Daniel Zaksas ◽  
Tatiana Pasternak
Keyword(s):  
Time Course ◽  
Visual Motion ◽  
Cognitive Task ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Task Demands ◽  
Visual Signals ◽  
Area Mt ◽  
Mt Neurons ◽  
Stimulus Offset

Neurons in cortical area MT have localized receptive fields (RF) representing the contralateral hemifield and play an important role in processing visual motion. We recorded the activity of these neurons during a behavioral task in which two monkeys were required to discriminate and remember visual motion presented in the ipsilateral hemifield. During the task, the monkeys viewed two stimuli, sample and test, separated by a brief delay and reported whether they contained motion in the same or in opposite directions. Fifty to 70% of MT neurons were activated by the motion stimuli presented in the ipsilateral hemifield at locations far removed from their classical receptive fields. These responses were in the form of excitation or suppression and were delayed relative to conventional MT responses. Both excitatory and suppressive responses were direction selective, but the nature and the time course of their directionality differed from the conventional excitatory responses recorded with stimuli in the RF. Direction selectivity of the excitatory remote response was transient and early, whereas the suppressive response developed later and persisted after stimulus offset. The presence or absence of these unusual responses on error trials, as well as their magnitude, was affected by the behavioral significance of stimuli used in the task. We hypothesize that these responses represent top-down signals from brain region(s) accessing information about stimuli in the entire visual field and about the behavioral state of the animal. The recruitment of neurons in the opposite hemisphere during processing of behaviorally relevant visual signals reveals a mechanism by which sensory processing can be affected by cognitive task demands.

scholarly journals Left-Hemispheric Asymmetry for Object-Based Attention: an ERP Study

2019 ◽  
Vol 9 (11) ◽  
pp. 315 ◽  
Author(s):  
Andrea Orlandi ◽  
Alice Mado Proverbio
Keyword(s):  
Visual Attention ◽  
Hemispheric Asymmetry ◽  
Time Course ◽  
Electrophysiological Study ◽  
Target Selection ◽  
Neural Correlates ◽  
Specific Stimulus ◽  
Object Categories ◽  
Object Based ◽  
Stimulus Features

It has been shown that selective attention enhances the activity in visual regions associated with stimulus processing. The left hemisphere seems to have a prominent role when non-spatial attention is directed towards specific stimulus features (e.g., color, spatial frequency). The present electrophysiological study investigated the time course and neural correlates of object-based attention, under the assumption of left-hemispheric asymmetry. Twenty-nine right-handed participants were presented with 3D graphic images representing the shapes of different object categories (wooden dummies, chairs, structures of cubes) which lacked detail. They were instructed to press a button in response to a target stimulus indicated at the beginning of each run. The perception of non-target stimuli elicited a larger anterior N2 component, which was likely associated with motor inhibition. Conversely, target selection resulted in an enhanced selection negativity (SN) response lateralized over the left occipito-temporal regions, followed by a larger centro-parietal P300 response. These potentials were interpreted as indexing attentional selection and categorization processes, respectively. The standardized weighted low-resolution electromagnetic tomography (swLORETA) source reconstruction showed the engagement of a fronto-temporo-limbic network underlying object-based visual attention. Overall, the SN scalp distribution and relative neural generators hinted at a left-hemispheric advantage for non-spatial object-based visual attention.

scholarly journals Time course of spatiotopic updating across saccades

2019 ◽  
Vol 116 (6) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jasper H. Fabius ◽  
Alessio Fracasso ◽  
Tanja C. W. Nijboer ◽  
Stefan Van der Stigchel
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Time Course ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Stimulus Onset ◽  
Oculomotor Behavior ◽  
Behavioral Studies ◽  
The Brain

Humans move their eyes several times per second, yet we perceive the outside world as continuous despite the sudden disruptions created by each eye movement. To date, the mechanism that the brain employs to achieve visual continuity across eye movements remains unclear. While it has been proposed that the oculomotor system quickly updates and informs the visual system about the upcoming eye movement, behavioral studies investigating the time course of this updating suggest the involvement of a slow mechanism, estimated to take more than 500 ms to operate effectively. This is a surprisingly slow estimate, because both the visual system and the oculomotor system process information faster. If spatiotopic updating is indeed this slow, it cannot contribute to perceptual continuity, because it is outside the temporal regime of typical oculomotor behavior. Here, we argue that the behavioral paradigms that have been used previously are suboptimal to measure the speed of spatiotopic updating. In this study, we used a fast gaze-contingent paradigm, using high phi as a continuous stimulus across eye movements. We observed fast spatiotopic updating within 150 ms after stimulus onset. The results suggest the involvement of a fast updating mechanism that predictively influences visual perception after an eye movement. The temporal characteristics of this mechanism are compatible with the rate at which saccadic eye movements are typically observed in natural viewing.

scholarly journals Goal-driven modulation as a function of time in saccadic target selection

2008 ◽  
Vol 61 (10) ◽  
pp. 1553-1572 ◽  
Author(s):  
Wieske Van Zoest ◽  
Mieke Donk
Keyword(s):  
Eye Movement ◽  
Response Latency ◽  
Time Course ◽  
Target Selection ◽  
Visual Selection ◽  
Full Time ◽  
Specific Target ◽  
Different Dimensions ◽  
Saccadic Target ◽  
Speed Accuracy

Four experiments were performed to investigate the contribution of goal-driven modulation in saccadic target selection as a function of time. Observers were required to make an eye movement to a prespecified target that was concurrently presented with multiple nontargets and possibly one distractor. Target and distractor were defined in different dimensions (orientation dimension and colour dimension in Experiment 1), or were both defined in the same dimension (i.e., both defined in the orientation dimension in Experiment 2, or both defined in the colour dimension in Experiments 3 and 4). The identities of target and distractor were switched over conditions. Speed–accuracy functions were computed to examine the full time course of selection in each condition. There were three major results. First, the ability to exert goal-driven control increased as a function of response latency. Second, this ability depended on the specific target–distractor combination, yet was not a function of whether target and distractor were defined within or across dimensions. Third, goal-driven control was available earlier when target and distractor were dissimilar than when they were similar. It was concluded that the influence of goal-driven control in visual selection is not all or none, but is of a continuous nature.

Asynchronies in the Development of Electrophysiological Responses to Motion and Color

2004 ◽  
Vol 16 (8) ◽  
pp. 1363-1374 ◽  
Author(s):  
Teresa V. Mitchell ◽  
Helen J. Neville
Keyword(s):  
Time Course ◽  
Behavioral Plasticity ◽  
Dorsal Stream ◽  
Event Related Potentials ◽  
Developmental Time ◽  
Ventral Stream ◽  
Visual Stream ◽  
Age Related ◽  
Electrophysiological Responses ◽  
Related Potentials

Recent reports have documented greater plasticity in the dorsal visual stream as compared with the ventral visual stream. This study sought to test the hypothesis that this greater plasticity may be related to a more protracted period of development in the dorsal as compared with the ventral stream. Age-related effects on event-related potentials (ERPs) elicited by motion and color stimuli, designed to activate the two visual streams, were assessed in healthy individuals aged 6 years through adulthood. Although significant developmental effects were observed in amplitudes of ERPs to both color and motion stimuli, marked latency effects were observed only in response to motion. These results provide support for the hypothesis that the dorsal stream displays a longer developmental time course across the early school years than the ventral stream. Implications for neural and behavioral plasticity are discussed.

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