scholarly journals Microstimulation of frontal eye field samples the state of saccade preparation during visual search

2004 ◽  
Vol 4 (8) ◽  
pp. 641-641
Author(s):  
S. M. Shorter-Jacobi ◽  
J. D. Schall
Keyword(s):  
Visual Search ◽  
The State ◽  
Frontal Eye Field ◽  
Field Samples ◽  
Eye Field ◽  
Saccade Preparation

scholarly journals Neural Control of Visual Search by Frontal Eye Field: Effects of Unexpected Target Displacement on Visual Selection and Saccade Preparation

2009 ◽  
Vol 101 (5) ◽  
pp. 2485-2506 ◽  
Author(s):  
Aditya Murthy ◽  
Supriya Ray ◽  
Stephanie M. Shorter ◽  
Jeffrey D. Schall ◽  
Kirk G. Thompson
Keyword(s):  
Visual Search ◽  
Reaction Time ◽  
Receptive Field ◽  
Target Location ◽  
Visual Selection ◽  
Frontal Eye Field ◽  
Related Activity ◽  
Visual Neurons ◽  
Eye Field ◽  
Saccade Preparation

The dynamics of visual selection and saccade preparation by the frontal eye field was investigated in macaque monkeys performing a search-step task combining the classic double-step saccade task with visual search. Reward was earned for producing a saccade to a color singleton. On random trials the target and one distractor swapped locations before the saccade and monkeys were rewarded for shifting gaze to the new singleton location. A race model accounts for the probabilities and latencies of saccades to the initial and final singleton locations and provides a measure of the duration of a covert compensation process—target-step reaction time. When the target stepped out of a movement field, noncompensated saccades to the original location were produced when movement-related activity grew rapidly to a threshold. Compensated saccades to the final location were produced when the growth of the original movement-related activity was interrupted within target-step reaction time and was replaced by activation of other neurons producing the compensated saccade. When the target stepped into a receptive field, visual neurons selected the new target location regardless of the monkeys’ response. When the target stepped out of a receptive field most visual neurons maintained the representation of the original target location, but a minority of visual neurons showed reduced activity. Chronometric analyses of the neural responses to the target step revealed that the modulation of visually responsive neurons and movement-related neurons occurred early enough to shift attention and saccade preparation from the old to the new target location. These findings indicate that visual activity in the frontal eye field signals the location of targets for orienting, whereas movement-related activity instantiates saccade preparation.

scholarly journals Response variability of frontal eye field neurons modulates with sensory input and saccade preparation but not visual search salience

2012 ◽  
Vol 108 (10) ◽  
pp. 2737-2750 ◽  
Author(s):  
Braden A. Purcell ◽  
Richard P. Heitz ◽  
Jeremiah Y. Cohen ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Sensory Input ◽  
Discharge Rate ◽  
Stimulus Presentation ◽  
Fano Factor ◽  
Response Variability ◽  
Frontal Eye Field ◽  
Rate Modulation ◽  
Eye Field ◽  
Saccade Preparation

Discharge rate modulation of frontal eye field (FEF) neurons has been identified with a representation of visual search salience (physical conspicuity and behavioral relevance) and saccade preparation. We tested whether salience or saccade preparation are evident in the trial-to-trial variability of discharge rate. We quantified response variability via the Fano factor in FEF neurons recorded in monkeys performing efficient and inefficient visual search tasks. Response variability declined following stimulus presentation in most neurons, but despite clear discharge rate modulation, variability did not change with target salience. Instead, we found that response variability was modulated by stimulus luminance and the number of items in the visual field independently of attentional demands. Response variability declined to a minimum before saccade initiation, and presaccadic response variability was directionally tuned. In addition, response variability was correlated with the response time of memory-guided saccades. These results indicate that the trial-by-trial response variability of FEF neurons reflects saccade preparation and the strength of sensory input, but not visual search salience or attentional allocation.

Effects of unilateral frontal eye-field lesions on eye-head coordination in monkey

1986 ◽  
Vol 55 (4) ◽  
pp. 696-714 ◽  
Author(s):  
J. van der Steen ◽  
I. S. Russell ◽  
G. O. James
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Peak Velocity ◽  
Head Movements ◽  
Frontal Eye Field ◽  
Behavioral Task ◽  
Direct Gaze ◽  
Relative Neglect ◽  
Eye Field

We studied the effects of unilateral frontal eye-field (FEF) lesions on eye-head coordination in monkeys that were trained to perform a visual search task. Eye and head movements were recorded with the scleral search coil technique using phase angle detection in a homogeneous electromagnetic field. In the visual search task all three animals showed a neglect for stimuli presented in the field contralateral to the lesion. In two animals the neglect disappeared within 2-3 wk. One animal had a lasting deficit. We found that FEF lesions that are restricted to area 8 cause only temporary deficits in eye and head movements. Up to a week after the lesion the animals had a strong preference to direct gaze and head to the side ipsilateral to the lesion. Animals tracked objects in contralateral space with combined eye and head movements, but failed to do this with the eyes alone. It was found that within a few days after the lesion, eye and head movements in the direction of the target were initiated, but they were inadequate and had long latencies. Within 1 wk latencies had regained preoperative values. Parallel with the recovery on the behavioral task, head movements became more prominent than before the lesion. Four weeks after the lesion, peak velocity of the head movement had increased by a factor of two, whereas the duration showed a twofold decrease compared with head movements before the lesion. No effects were seen on the duration and peak velocity of gaze. After the recovery on the behavioral task had stabilized, a relative neglect in the hemifield contralateral to the lesion could still be demonstrated by simultaneously presenting two stimuli in the left and right visual hemifields. The neglect is not due to a sensory deficit, but to a disorder of programming. The recovery from unilateral neglect after a FEF lesion is the result of a different orienting behavior, in which head movements become more important. It is concluded that the FEF plays an important role in the organization and coordination of eye and head movements and that lesions of this area result in subtle but permanent changes in eye-head coordination.

Dynamic Dissociation of Visual Selection From Saccade Programming in Frontal Eye Field

2001 ◽  
Vol 86 (5) ◽  
pp. 2634-2637 ◽  
Author(s):  
Aditya Murthy ◽  
Kirk G. Thompson ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Selection Process ◽  
Frontal Eye Field ◽  
Frontal Eye Fields ◽  
Search Array ◽  
Visual Neurons ◽  
Current Location ◽  
Eye Field ◽  
Saccade Programming ◽  
Selection Of

Previous studies of visually responsive neurons in the frontal eye fields have identified a selection process preceding saccades during visual search. The goal of this experiment was to determine whether the selection process corresponds to the selection of a conspicuous stimulus or to preparation of the next saccade. This was accomplished with the use of a novel task, called search-step, in which the target of a singleton visual search array switches location with a distracter on random trials. The target step trials created a condition in which the same stimulus yielded saccades either toward or away from the target. Visually responsive neurons in frontal eye field selected the current location of the conspicuous target even when gaze shifted to the location of a distractor. This dissociation demonstrates that the selection process manifest in visual neurons in the frontal eye field may be an explicit interpretation of the image and not an obligatory saccade command.

scholarly journals Neural Correlates of Correct and Errant Attentional Selection Revealed Through N2pc and Frontal Eye Field Activity

2010 ◽  
Vol 104 (5) ◽  
pp. 2433-2441 ◽  
Author(s):  
Richard P. Heitz ◽  
Jeremiah Y. Cohen ◽  
Geoffrey F. Woodman ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Visual Processing ◽  
Neural Correlates ◽  
Event Related Potential ◽  
Covert Attention ◽  
Extrastriate Cortex ◽  
False Alarms ◽  
Frontal Eye Field ◽  
Physiological Basis ◽  
Eye Field

The goal of this study was to obtain a better understanding of the physiological basis of errors of visual search. Previous research has shown that search errors occur when visual neurons in the frontal eye field (FEF) treat distractors as if they were targets. We replicated this finding during an inefficient form search and extended it by measuring simultaneously a macaque homologue of an event-related potential indexing the allocation of covert attention known as the m-N2pc. Based on recent work, we expected errors of selection in FEF to propagate to areas of extrastriate cortex responsible for allocating attention and implicated in the generation of the m-N2pc. Consistent with this prediction, we discovered that when FEF neurons selected a distractor instead of the search target, the m-N2pc shifted in the same, incorrect direction prior to the erroneous saccade. This suggests that such errors are due to a systematic misorienting of attention from the initial stages of visual processing. Our analyses also revealed distinct neural correlates of false alarms and guesses. These results demonstrate that errant gaze shifts during visual search arise from errant attentional processing.

scholarly journals Neural mechanisms of speed-accuracy tradeoff of visual search: Saccade vigor, targeting errors, superior colliculus and frontal eye field

2017 ◽  
Author(s):  
Thomas R. Reppert ◽  
Mathieu Servant ◽  
Richard P. Heitz ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Superior Colliculus ◽  
Time Course ◽  
Frontal Eye Field ◽  
Visual Responses ◽  
Response Preparation ◽  
Eye Field ◽  
Neurophysiological Mechanisms ◽  
Speed Accuracy ◽  
Accuracy Tradeoff

AbstractBalancing the speed-accuracy tradeoff (SAT) is necessary for successful behavior. Using a visual search task with interleaved cues emphasizing speed or accuracy, we recently reported diverse contributions of frontal eye field (FEF) neurons instantiating salience evidence and response preparation. Here we report replication of visual search SAT performance in two macaque monkeys, new information about variation of saccade dynamics with SAT, extension of the neurophysiological investigation to describe processes in the superior colliculus, and description of the origin of search errors in this task. Saccade vigor varied idiosyncratically across SAT conditions and monkeys, but tended to decrease with response time. As observed in the FEF, speed-accuracy tradeoff was accomplished through several distinct adjustments in the superior colliculus. Visually-responsive neurons modulated baseline firing rate and the time course of salience evidence. Unlike FEF, the magnitude of visual responses in SC did not vary across SAT conditions, but the time to locate the target was longer in Accurate as compared to Fast trials. Also unlike FEF, the activity of SC movement neurons when saccades were initiated was equivalent in Fast and Accurate trials. Search errors occurred when visual salience neurons in FEF and SC treated distractors as targets, even in the Accurate condition. Saccade-related neural activity in SC but less FEF varied with saccade peak velocity. These results extend our understanding of the cortical and subcortical contributions to SAT.Significance statementNeurophysiological mechanisms of speed-accuracy tradeoff (SAT) have only recently been investigated. This paper reports the first replication of SAT performance in nonhuman primates, the first report of variation of saccade dynamics with SAT, the first description of superior colliculus contributions to SAT, and the first description of the origin of errors during SAT. These results inform and constrain new models of distributed decision-making.

scholarly journals Difficulty of Visual Search Modulates Neuronal Interactions and Response Variability in the Frontal Eye Field

2007 ◽  
Vol 98 (5) ◽  
pp. 2580-2587 ◽  
Author(s):  
Jeremiah Y. Cohen ◽  
Pierre Pouget ◽  
Geoffrey F. Woodman ◽  
Chenchal R. Subraveti ◽  
Jeffrey D. Schall ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Visual Search ◽  
Search Task ◽  
Response Variability ◽  
Frontal Eye Field ◽  
Search Tasks ◽  
Saccade Onset ◽  
Neuronal Interactions ◽  
Eye Field ◽  
Spiking Activity

The frontal eye field (FEF) is involved in selecting visual targets for eye movements. To understand how populations of FEF neurons interact during target selection, we recorded activity from multiple neurons simultaneously while macaques performed two versions of a visual search task. We used a multivariate analysis in a point process statistical framework to estimate the instantaneous firing rate and compare interactions among neurons between tasks. We found that FEF neurons were engaged in more interactions during easier visual search tasks compared with harder search tasks. In particular, eye movement–related neurons were involved in more interactions than visual-related neurons. In addition, our analysis revealed a decrease in the variability of spiking activity in the FEF beginning ∼100 ms before saccade onset. The minimum in response variability occurred ∼20 ms earlier for the easier search task compared with the harder one. This difference is positively correlated with the difference in saccade reaction times for the two tasks. These findings show that a multivariate analysis can provide a measure of neuronal interactions and characterize the spiking activity of FEF neurons in the context of a population of neurons.

Dissociation of Visual Discrimination From Saccade Programming in Macaque Frontal Eye Field

1997 ◽  
Vol 77 (2) ◽  
pp. 1046-1050 ◽  
Author(s):  
Kirk G. Thompson ◽  
Narcisse P. Bichot ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Eye Movements ◽  
Visual Stimulus ◽  
Visual Discrimination ◽  
Time Course ◽  
Selection Process ◽  
Frontal Eye Field ◽  
Visual Responses ◽  
Eye Field ◽  
Saccade Programming

Thompson, Kirk G., Narcisse P. Bichot, and Jeffrey D. Schall. Dissociation of visual discrimination from saccade programming in macaque frontal eye field. J. Neurophysiol. 77: 1046–1050, 1997. To determine whether visual discrimination in macaque frontal eye field (FEF) is contingent on saccade planning, unit activity was recorded in two monkeys during blocked go and no-go visual search trials. The eye movements made by monkeys after correct no-go trials, in addition to an attenuation of the visual responses in no-go trials compared with go trials, indicated that covert saccade planning was effectively discouraged. During no-go search trials, the activity of the majority of neurons evolved to signal the location of the oddball stimulus. The degree and time course of the stimulus discrimination process observed in no-go trials was not different from that observed in go trials. We conclude that the discrimination of a salient visual stimulus reflected by FEF neurons is not contingent on saccade production but rather may reflect the outcome of an automatic visual selection process.

scholarly journals Feature-Based Attention in the Frontal Eye Field and Area V4 during Visual Search

Neuron ◽  
2011 ◽  
Vol 70 (6) ◽  
pp. 1205-1217 ◽  
Author(s):  
Huihui Zhou ◽  
Robert Desimone
Keyword(s):  
Visual Search ◽  
Frontal Eye Field ◽  
Area V4 ◽  
Eye Field ◽  
Feature Based
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