scholarly journals Predictive Saccade Target Selection in Superior Colliculus during Visual Search

2014 ◽  
Vol 34 (16) ◽  
pp. 5640-5648 ◽  
Author(s):  
K. Shen ◽  
M. Pare
Keyword(s):  
Visual Search ◽  
Superior Colliculus ◽  
Target Selection ◽  
Saccade Target ◽  
Predictive Saccade

Target Selection for Saccadic Eye Movements: Direction-Selective Visual Responses in the Superior Colliculus

2001 ◽  
Vol 86 (5) ◽  
pp. 2527-2542 ◽  
Author(s):  
Gregory D. Horwitz ◽  
William T. Newsome
Keyword(s):  
Superior Colliculus ◽  
Eye Movement ◽  
Discrimination Task ◽  
Visual Motion ◽  
Target Selection ◽  
Small Population ◽  
Saccade Target ◽  
Visual Responses ◽  
Direction Discrimination ◽  
Deep Layers

We investigated the role of the superior colliculus (SC) in saccade target selection in rhesus monkeys who were trained to perform a direction-discrimination task. In this task, the monkey discriminated between opposed directions of visual motion and indicated its judgment by making a saccadic eye movement to one of two visual targets that were spatially aligned with the two possible directions of motion in the display. Thus the neural circuits that implement target selection in this task are likely to receive directionally selective visual inputs and be closely linked to the saccadic system. We therefore studied prelude neurons in the intermediate and deep layers of the SC that can discharge up to several seconds before an impending saccade, indicating a relatively high-level role in saccade planning. We used the direction-discrimination task to identify neurons whose prelude activity “predicted” the impending perceptual report several seconds before the animal actually executed the operant eye movement; these “choice predicting” cells comprised ∼30% of the neurons we encountered in the intermediate and deep layers of the SC. Surprisingly, about half of these prelude cells yielded direction-selective responses to our motion stimulus during a passive fixation task. In general, these neurons responded to motion stimuli in many locations around the visual field including the center of gaze where the visual discriminanda were positioned during the direction-discrimination task. Preferred directions generally pointed toward the location of the movement field of the SC neuron in accordance with the sensorimotor demands of the discrimination task. Control experiments indicate that the directional responses do not simply reflect covertly planned saccades. Our results indicate that a small population of SC prelude neurons exhibits properties appropriate for linking stimulus cues to saccade target selection in the context of a visual discrimination task.

scholarly journals Saccade target selection in macaque during feature and conjunction visual search

1999 ◽  
Vol 16 (1) ◽  
pp. 81-89 ◽  
Author(s):  
NARCISSE P. BICHOT ◽  
JEFFREY D. SCHALL
Keyword(s):  
Visual Search ◽  
Computational Models ◽  
Selection Process ◽  
Target Selection ◽  
Conjunction Search ◽  
Saccade Target ◽  
Experimental Session ◽  
Shape Information ◽  
Feature Search ◽  
The Individual

To gain insight into how vision guides eye movements, monkeys were trained to make a single saccade to a specified target stimulus during feature and conjunction search with stimuli discriminated by color and shape. Monkeys performed both tasks at levels well above chance. The latencies of saccades to the target in conjunction search exhibited shallow positive slopes as a function of set size, comparable to slopes of reaction time of humans during target present/absent judgments, but significantly different than the slopes in feature search. Properties of the selection process were revealed by the occasional saccades to distractors. During feature search, errant saccades were directed more often to a distractor near the target than to a distractor at any other location. In contrast, during conjunction search, saccades to distractors were guided more by similarity than proximity to the target; monkeys were significantly more likely to shift gaze to a distractor that had one of the target features than to a distractor that had none. Overall, color and shape information were used to similar degrees in the search for the conjunction target. However, in single sessions we observed an increased tendency of saccades to a distractor that had been the target in the previous experimental session. The establishment of this tendency across sessions at least a day apart and its persistence throughout a session distinguish this phenomenon from the short-term (<10 trials) perceptual priming observed in this and earlier studies using feature visual search. Our findings support the hypothesis that the target in at least some conjunction visual searches can be detected efficiently based on visual similarity, most likely through parallel processing of the individual features that define the stimuli. These observations guide the interpretation of neurophysiological data and constrain the development of computational models.

Close interactions between “When” and “Where” in saccade target selection: Multiple saliency and distractor effects

1999 ◽  
Vol 22 (4) ◽  
pp. 693-694
Author(s):  
Christian Olivers ◽  
Dietmar Heinke ◽  
Glyn Humphreys ◽  
Hermann M&uuml;ller
Keyword(s):  
Visual Search ◽  
Target Selection ◽  
Saccade Target ◽  
Spatial Selection ◽  
Distractor Effect ◽  
Selection Processes ◽  
Remote Distractor Effect ◽  
Saccade Generation

A model of when and where saccades are made necessarily incorporates a model of the “When” and “Where” of target selection. We suggest that the framework proposed by Findlay & Walker does not specify sufficiently how (and by what means) selection processes contribute to the spatial and temporal determinants of saccade generation. Examples from across-trial priming in visual search and from the inhibition of temporally segmented distractors show linkage between the processes involved in computing when and where selection operates, so that there is cooperation rather than competition between so-called Where and When pathways. Aspects of spatial selection may also determine the remote distractor effect on saccades. The detailed relations between the processes involved in selection and saccade generation may be best understood in relation to detailed computational accounts of the processes.

scholarly journals Reversal of a Distractor Effect on Saccade Target Selection After Superior Colliculus Inactivation

2008 ◽  
Vol 99 (5) ◽  
pp. 2694-2702 ◽  
Author(s):  
Robert M. McPeek
Keyword(s):  
Superior Colliculus ◽  
Search Task ◽  
Target Location ◽  
Target Selection ◽  
Saccade Target ◽  
Search Array ◽  
Distractor Effect ◽  
Normal Trend ◽  
Winner Take All ◽  
Take All

Recent evidence indicates that inactivation of the primate superior colliculus (SC) results in an increase in saccade target-selection errors. The pattern of errors suggests that a winner-take-all competition selects the saccade goal and that SC inactivation perturbs this process by biasing the competition against stimuli in the inactivated field. To investigate this idea, the difficulty of target selection was manipulated in a color-oddity search task by varying the number of homogeneous distractors in the search array. Previous studies have shown that target selection is easier when a greater number of homogeneous distractors is present, due to perceptual grouping of the distractors. These results were replicated when testing with the SC intact. Surprisingly, during SC inactivation, this normal trend was reversed: target-selection performance declined significantly with more distractors, resulting in a greater proportion of errant saccades to distractors. Examination of the saccade endpoints indicates that after SC inactivation, many errant saccades were directed to distractors adjacent to the target. This pattern of results suggests that the salience signal used by the SC for target selection is relatively broad in spatial scope. As a result, when the area of the SC representing the target location is inactivated, distractors near the target are at a competitive advantage relative to more distant distractors and, consequently, are selected more often as the saccade goal. This contributes to the trend of worse performance with more distractors due to the greater proximity of distractors to the target.

scholarly journals Saccade target selection in visual search: the effect of information from the previous fixation

2001 ◽  
Vol 41 (1) ◽  
pp. 87-95 ◽  
Author(s):  
John M Findlay ◽  
Valerie Brown ◽  
Iain D Gilchrist
Keyword(s):  
Visual Search ◽  
Target Selection ◽  
Saccade Target
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