scholarly journals Modulations of foveal vision associated with microsaccade preparation

2020 ◽  
Vol 117 (20) ◽  
pp. 11178-11183
Author(s):  
Natalya Shelchkova ◽  
Martina Poletti
Keyword(s):  
Eye Movements ◽  
Visual Discrimination ◽  
Target Location ◽  
Onset Time ◽  
Spatial Vision ◽  
Saccade Target ◽  
Foveal Vision ◽  
Movement Onset ◽  
High Acuity ◽  
Gaze Position

It is known that attention shifts prior to a saccade to start processing the saccade target before it lands in the foveola, the high-resolution region of the retina. Yet, once the target is foveated, microsaccades, tiny saccades maintaining the fixated object within the fovea, continue to occur. What is the link between these eye movements and attention? There is growing evidence that these eye movements are associated with covert shifts of attention in the visual periphery, when the attended stimuli are presented far from the center of gaze. Yet, microsaccades are primarily used to explore complex foveal stimuli and to optimize fine spatial vision in the foveola, suggesting that the influences of microsaccades on attention may predominantly impact vision at this scale. To address this question we tracked gaze position with high precision and briefly presented high-acuity stimuli at predefined foveal locations right before microsaccade execution. Our results show that visual discrimination changes prior to microsaccade onset. An enhancement occurs at the microsaccade target location. This modulation is highly selective and it is coupled with a drastic impairment at the opposite foveal location, just a few arcminutes away. This effect is strongest when stimuli are presented closer to the eye movement onset time. These findings reveal that the link between attention and microsaccades is deeper than previously thought, exerting its strongest effects within the foveola. As a result, during fixation, foveal vision is constantly being reshaped both in space and in time with the occurrence of microsaccades.

scholarly journals Vision as oculomotor reward: cognitive contributions to the dynamic control of saccadic eye movements

2021 ◽  
Author(s):  
Christian Wolf ◽  
Markus Lappe
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Visual System ◽  
Dynamic Control ◽  
Saccadic Eye Movements ◽  
Saccade Target ◽  
Cognitive Mechanisms ◽  
Foveal Vision ◽  
Subsequent Behavior ◽  
High Level

AbstractHumans and other primates are equipped with a foveated visual system. As a consequence, we reorient our fovea to objects and targets in the visual field that are conspicuous or that we consider relevant or worth looking at. These reorientations are achieved by means of saccadic eye movements. Where we saccade to depends on various low-level factors such as a targets’ luminance but also crucially on high-level factors like the expected reward or a targets’ relevance for perception and subsequent behavior. Here, we review recent findings how the control of saccadic eye movements is influenced by higher-level cognitive processes. We first describe the pathways by which cognitive contributions can influence the neural oculomotor circuit. Second, we summarize what saccade parameters reveal about cognitive mechanisms, particularly saccade latencies, saccade kinematics and changes in saccade gain. Finally, we review findings on what renders a saccade target valuable, as reflected in oculomotor behavior. We emphasize that foveal vision of the target after the saccade can constitute an internal reward for the visual system and that this is reflected in oculomotor dynamics that serve to quickly and accurately provide detailed foveal vision of relevant targets in the visual field.

scholarly journals Foveal vision at the time of microsaccades

2021 ◽  
Author(s):  
Naghmeh Mostofi ◽  
Janis Intoy ◽  
Michele Rucci
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Time Course ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Visual Exploration ◽  
Social Grooming ◽  
Foveal Vision ◽  
High Acuity ◽  
Display Control

AbstractHumans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primate’s social grooming, which—like most explorations of fine patterns—primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the peri-saccadic time-course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed new light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.

scholarly journals Foveal vision predictively sensitizes to defining features of eye movement targets

2022 ◽  
Author(s):  
Lisa M Kroell ◽  
Martin Rolfs
Keyword(s):  
Eye Movements ◽  
Human Vision ◽  
Saccade Target ◽  
Large Field ◽  
Visual Features ◽  
Foveal Vision ◽  
Seamless Transition ◽  
Field Noise ◽  
The Impact ◽  
Passive Fixation

Despite the fovea's singular importance for active human vision, the impact of large eye movements on foveal processing remains elusive. Building on findings from passive fixation tasks, we hypothesized that during the preparation of rapid eye movements (saccades), foveal processing anticipates soon-to-be fixated visual features. Using a dynamic large-field noise paradigm, we indeed demonstrate that sensitivity for defining features of a saccade target is enhanced in the pre-saccadic center of gaze. Enhancement manifested in higher Hit Rates for foveal probes with target-congruent orientation, and a sensitization to incidental, target-like orientation information in foveally presented noise. Enhancement was spatially confined to the center of gaze and its immediate vicinity. We suggest a crucial contribution of foveal processing to trans-saccadic visual continuity which has previously been overlooked: Foveal processing of saccade targets commences before the movement is executed and thereby enables a seamless transition once the center of gaze reaches the target.

scholarly journals Parietal Representation of Object-Based Saccades

2002 ◽  
Vol 88 (4) ◽  
pp. 1815-1829 ◽  
Author(s):  
Philip N. Sabes ◽  
Boris Breznen ◽  
Richard A. Andersen
Keyword(s):  
Eye Movements ◽  
Target Location ◽  
Saccadic Eye Movements ◽  
Object Orientation ◽  
Saccade Target ◽  
Spatial Variables ◽  
Preferred Direction ◽  
Orientation Effects ◽  
Object Based ◽  
Saccade Task

When monkeys make saccadic eye movements to simple visual targets, neurons in the lateral intraparietal area (LIP) display a retinotopic, or eye-centered, coding of the target location. However natural saccadic eye movements are often directed at objects or parts of objects in the visual scene. In this paper we investigate whether LIP represents saccadic eye movements differently when the target is specified as part of a visually displayed object. Monkeys were trained to perform an object-based saccade task that required them to make saccades to previously cued parts of an abstract object after the object reappeared in a new orientation. We recorded single neurons in area LIP of two macaque monkeys and analyzed their activity in the object-based saccade task, as well as two control tasks: a standard memory saccade task and a fixation task with passive object viewing. The majority of LIP neurons that were tuned in the memory saccade task were also tuned in the object-based saccade task. Using a hierarchical generalized linear model analysis, we compared the effects of three different spatial variables on the firing rate: the retinotopic location of the target, the object-fixed location of the target, and the orientation of the object in space. There was no evidence of an explicit object-fixed representation in the activity in LIP during either of the object-based tasks. In other words, no cells had receptive fields that rotated with the object. While some cells showed a modulation of activity due to the location of the target on the object, these variations were small compared to the retinotopic effects. For most cells, firing rates were best accounted for by either the retinotopic direction of the movement, the orientation of the object, or both spatial variables. The preferred direction of these retinotopic and object orientation effects were found to be invariant across tasks. On average, the object orientation effects were consistent with the retinotopic coding of potential target locations on the object. This interpretation is supported by the fact that the magnitude of these two effects were roughly equal in the early portions of the trial, but around the time of the motor response, the retinotopic effects dominated. We conclude that LIP uses the same retinotopic coding of saccade target whether the target is specified as an absolute point in space or as a location on a moving object.

The Main Sequence of Human Optokinetic Afternystagmus (OKAN)

2009 ◽  
Vol 101 (6) ◽  
pp. 2889-2897 ◽  
Author(s):  
Andre Kaminiarz ◽  
Kerstin Königs ◽  
Frank Bremmer
Keyword(s):  
Neural Networks ◽  
Eye Movements ◽  
Main Sequence ◽  
Critical Role ◽  
Saccade Target ◽  
Control Mechanisms ◽  
Visually Guided ◽  
Background Characteristics ◽  
Optokinetic Afternystagmus

Different types of fast eye movements, including saccades and fast phases of optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN), are coded by only partially overlapping neural networks. This is a likely cause for the differences that have been reported for the dynamic parameters of fast eye movements. The dependence of two of these parameters—peak velocity and duration—on saccadic amplitude has been termed “main sequence.” The main sequence of OKAN fast phases has not yet been analyzed. These eye movements are unique in that they are generated by purely subcortical control mechanisms and that they occur in complete darkness. In this study, we recorded fast phases of OKAN and OKN as well as visually guided and spontaneous saccades under identical background conditions because background characteristics have been reported to influence the main sequence of saccades. Our data clearly show that fast phases of OKAN and OKN differ with respect to their main sequence. OKAN fast phases were characterized by their lower peak velocities and longer durations compared with those of OKN fast phases. Furthermore we found that the main sequence of spontaneous saccades depends heavily on background characteristics, with saccades in darkness being slower and lasting longer. On the contrary, the main sequence of visually guided saccades depended on background characteristics only very slightly. This implies that the existence of a visual saccade target largely cancels out the effect of background luminance. Our data underline the critical role of environmental conditions (light vs. darkness), behavioral tasks (e.g., spontaneous vs. visually guided), and the underlying neural networks for the exact spatiotemporal characteristics of fast eye movements.

scholarly journals Saccades and smooth pursuit eye movements trigger equivalent gaze-cued orienting effects

2018 ◽  
Vol 71 (9) ◽  
pp. 1860-1872 ◽  
Author(s):  
Stephen RH Langton ◽  
Alex H McIntyre ◽  
Peter JB Hancock ◽  
Helmut Leder
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Target Location ◽  
Eye Gaze ◽  
Saccadic Eye Movements ◽  
Gaze Shift ◽  
The Gaze ◽  
Orienting Effect ◽  
Motion Speed ◽  
Uncued Target

Research has established that a perceived eye gaze produces a concomitant shift in a viewer’s spatial attention in the direction of that gaze. The two experiments reported here investigate the extent to which the nature of the eye movement made by the gazer contributes to this orienting effect. On each trial in these experiments, participants were asked to make a speeded response to a target that could appear in a location toward which a centrally presented face had just gazed (a cued target) or in a location that was not the recipient of a gaze (an uncued target). The gaze cues consisted of either fast saccadic eye movements or slower smooth pursuit movements. Cued targets were responded to faster than uncued targets, and this gaze-cued orienting effect was found to be equivalent for each type of gaze shift both when the gazes were un-predictive of target location (Experiment 1) and counterpredictive of target location (Experiment 2). The results offer no support for the hypothesis that motion speed modulates gaze-cued orienting. However, they do suggest that motion of the eyes per se, regardless of the type of movement, may be sufficient to trigger an orienting effect.

Functional properties of monkey caudate neurons. III. Activities related to expectation of target and reward

1989 ◽  
Vol 61 (4) ◽  
pp. 814-832 ◽  
Author(s):  
O. Hikosaka ◽  
M. Sakamoto ◽  
S. Usui
Keyword(s):  
Spatial Information ◽  
Target Location ◽  
Hand Movement ◽  
Visual Fixation ◽  
Saccade Target ◽  
Tonic Activity ◽  
Sustained Activity ◽  
Neural Activities ◽  
Reward Expectancy ◽  
Mouth Movement

1. The present paper reports complex neural activities in the monkey caudate nucleus that precede and anticipate visual stimuli and reward in learned visuomotor paradigms. These activities were revealed typically in the delayed saccade task in which memory and anticipation were required. We classified these activities according to their relationships to the task. 2. Activity related to expectation of a cue (n = 46) preceded the presentation of a spot of light (target cue) that signified the future location of saccade target. When the target cue was delayed, the activity was prolonged accordingly. The same spot of light was preceded by no activity if it acted as a distracting stimulus. 3. The sustained activity (n = 80) was a tonic discharge starting after the target cue as if holding the spatial information. 4. The activity related to expectation of target (n = 109) preceded the appearance of the target whose location was cued previously. It started with or after a saccade to the cued target location and ended with the appearance of the target. The activity was greater when the target was expected to appear in the contralateral visual field. 5. The activity related to expectation of reward (n = 57) preceded a task-specific reward. It started with the appearance of the final target and ended with the reward. In most cases, the activity was nonselective for how the monkey obtained the reward, i.e., by visual fixation only, by a saccade, or by a hand movement. The activity was dependent partly on visual fixation. 6. A few neurons showed tonic activity selectively before lever release and are thus considered to be related to the preparation of hand movements. 7. The activity related to breaking fixation (n = 33) occurred phasically if the monkey broke fixation, aborting the trial. 8. Activity related to reward (n = 104) was a phasic discharge that occurred before or after a reward of water was delivered. The activity was not simply related to a specific movement involved in the reward-obtaining behavior (eye, hand, or mouth movement). 9. Fixation-related activity (n = 72) was tonic activity continuing as long as the monkey attentively fixated a spot of light. It was dependent on reward expectancy in most cases. 10. The present results, together with those in the preceding papers, indicate that the activities of individual caudate neurons--sensory, motor, or cognitive--are dependent on specific contexts of learned behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

Recasting the Smooth Pursuit Eye Movement System

2004 ◽  
Vol 91 (2) ◽  
pp. 591-603 ◽  
Author(s):  
Richard J. Krauzlis
Keyword(s):  
Eye Movements ◽  
Brain Stem ◽  
Smooth Pursuit ◽  
Visual Motion ◽  
Saccadic Eye Movements ◽  
Extrastriate Cortex ◽  
High Acuity ◽  
Voluntary Eye Movements ◽  
New Perspective ◽  
The Brain

Primates use a combination of smooth pursuit and saccadic eye movements to stabilize the retinal image of selected objects within the high-acuity region near the fovea. Pursuit has traditionally been viewed as a relatively automatic behavior, driven by visual motion signals and mediated by pathways that connect visual areas in the cerebral cortex to motor regions in the cerebellum. However, recent findings indicate that this view needs to be reconsidered. Rather than being controlled primarily by areas in extrastriate cortex specialized for processing visual motion, pursuit involves an extended network of cortical areas, and, of these, the pursuit-related region in the frontal eye fields appears to exert the most direct influence. The traditional pathways through the cerebellum are important, but there are also newly identified routes involving structures previously associated with the control of saccades, including the basal ganglia, the superior colliculus, and nuclei in the brain stem reticular formation. These recent findings suggest that the pursuit system has a functional architecture very similar to that of the saccadic system. This viewpoint provides a new perspective on the processing steps that occur as descending control signals interact with circuits in the brain stem and cerebellum responsible for gating and executing voluntary eye movements. Although the traditional view describes pursuit and saccades as two distinct neural systems, it may be more accurate to consider the two movements as different outcomes from a shared cascade of sensory–motor functions.

A Neural Network Model of Flexible Spatial Updating

2004 ◽  
Vol 91 (4) ◽  
pp. 1608-1619 ◽  
Author(s):  
Robert L. White ◽  
Lawrence H. Snyder
Keyword(s):  
Neural Network ◽  
Reference Frame ◽  
Spatial Information ◽  
Target Location ◽  
Target Position ◽  
Spatial Location ◽  
Spatial Updating ◽  
Gaze Shift ◽  
Fixed Reference ◽  
Gaze Position

Neurons in many cortical areas involved in visuospatial processing represent remembered spatial information in retinotopic coordinates. During a gaze shift, the retinotopic representation of a target location that is fixed in the world (world-fixed reference frame) must be updated, whereas the representation of a target fixed relative to the center of gaze (gaze-fixed) must remain constant. To investigate how such computations might be performed, we trained a 3-layer recurrent neural network to store and update a spatial location based on a gaze perturbation signal, and to do so flexibly based on a contextual cue. The network produced an accurate readout of target position when cued to either reference frame, but was less precise when updating was performed. This output mimics the pattern of behavior seen in animals performing a similar task. We tested whether updating would preferentially use gaze position or gaze velocity signals, and found that the network strongly preferred velocity for updating world-fixed targets. Furthermore, we found that gaze position gain fields were not present when velocity signals were available for updating. These results have implications for how updating is performed in the brain.

Visual Discrimination Learning in Rats with Lesions of Superior Colliculus: Door-Push and Approach Errors in Modified Jumping Stand

1981 ◽  
Vol 33 (3b) ◽  
pp. 141-157 ◽  
Author(s):  
Paul Dean ◽  
Sian G. Pope
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Open Field ◽  
Discrimination Learning ◽  
Visual Discrimination ◽  
Visual Discrimination Learning ◽  
Central Platform ◽  
Area Centralis ◽  
Scanning Head ◽  
Discrimination Apparatus

It has been suggested that, for some species, lesions of the superior colliculus affect visual discrimination learning, but only in certain conditions: (a) when problems are first learnt only after operation, or (b) when discriminanda require detailed scanning, or (c) when “approach” responses to the discriminanda are measured, rather than the response of actually touching them. These suggestions were examined in rats learning visual discriminations in a modified jumping-stand apparatus, after sustaining large lesions of the superior colliculus (and in some cases also of the pretectum). The lesions produced open-field hyperactivity and reduced exploration, indicating effective tectal damage, but the rats learnt a series of difficult discriminations in a door-push task as fast as normal rats, and they did not make more approach errors. Their main abnormality in the discrimination apparatus was that they looked less often between the stimulus doors before stepping across to one of them from the central platform. It is suggested that in rats, as in other animals, lesions of the superior colliculus disrupt the control of scanning head and eye movements; in rats, however, such disruption need not affect discrimination learning (at least in some kinds of apparatus), possibly because the retina of the rat has a relatively poorly developed area centralis.

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