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.

Effects of Search Efficiency on Surround Suppression During Visual Selection in Frontal Eye Field

2004 ◽  
Vol 91 (6) ◽  
pp. 2765-2769 ◽  
Author(s):  
Jeffrey D. Schall ◽  
Takashi R. Sato ◽  
Kirk G. Thompson ◽  
Amanda A. Vaughn ◽  
Chi-Hung Juan
Keyword(s):  
Visual Search ◽  
Receptive Field ◽  
Selection Process ◽  
Visual Selection ◽  
Frontal Eye Field ◽  
Search Efficiency ◽  
Surround Suppression ◽  
Macaque Monkeys ◽  
Feature Similarity ◽  
Eye Field

Previous research has shown that visually responsive neurons in the frontal eye field of macaque monkeys select the target for a saccade during efficient, pop-out visual search through suppression of the representation of the nontarget distractors. For a fraction of these neurons, the magnitude of this distractor suppression varied with the proximity of the target to the receptive field, exhibiting more suppression of the distractor representation when the target was nearby than when the target was distant. The purpose of this study was to determine whether the variation of distractor suppression related to target proximity varied with target-distractor feature similarity. The effect of target proximity on distractor suppression did not vary with target-distractor similarity and therefore may be an endogenous property of the selection process.

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 Frontal Eye Field Activity Enhances Object Identification During Covert Visual Search

2009 ◽  
Vol 102 (6) ◽  
pp. 3656-3672 ◽  
Author(s):  
Ilya E. Monosov ◽  
Kirk G. Thompson
Keyword(s):  
Visual Search ◽  
Spatial Attention ◽  
Visual Processing ◽  
Target Location ◽  
Target Identification ◽  
Object Identification ◽  
Frontal Eye Field ◽  
Search Array ◽  
Functional Link ◽  
Eye Field

We investigated the link between neuronal activity in the frontal eye field (FEF) and the enhancement of visual processing associated with covert spatial attention in the absence of eye movements. We correlated activity recorded in the FEF of monkeys manually reporting the identity of a visual search target to performance accuracy and reaction time. Monkeys were cued to the most probable target location with a cue array containing a popout color singleton. Neurons exhibited spatially selective responses for the popout cue stimulus and for the target of the search array. The magnitude of activity related to the location of the cue prior to the presentation of the search array was correlated with trends in behavioral performance across valid, invalid, and neutral cue trial conditions. However, the speed and accuracy of the behavioral report on individual trials were predicted by the magnitude of spatial selectivity related to the target to be identified, not for the spatial cue. A minimum level of selectivity was necessary for target detection and a higher level for target identification. Muscimol inactivation of FEF produced spatially selective perceptual deficits in the covert search task that were correlated with the effectiveness of the inactivation and were strongest on invalid cue trials that require an endogenous attention shift. These results demonstrate a strong functional link between FEF activity and covert spatial attention and suggest that spatial signals from FEF directly influence visual processing during the time that a stimulus to be identified is being processed by the visual system.

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.

scholarly journals Incomplete Suppression of Distractor-Related Activity in the Frontal Eye Field Results in Curved Saccades

2006 ◽  
Vol 96 (5) ◽  
pp. 2699-2711 ◽  
Author(s):  
Robert M. McPeek
Keyword(s):  
Target Location ◽  
Temporal Structure ◽  
Target Selection ◽  
Neural Correlates ◽  
Frontal Eye Field ◽  
Stimulation Site ◽  
Related Activity ◽  
Distractor Location ◽  
Significant Difference ◽  
Eye Field

Saccades in the presence of distractors show significant trajectory curvature. Based on previous work in the superior colliculus (SC), we speculated that curvature arises when a movement is initiated before competition between the target and distractor goals has been fully resolved. To test this hypothesis, we recorded frontal eye field (FEF) activity for curved and straight saccades in search. In contrast to the SC, activity in FEF is normally poorly correlated with saccade dynamics. However, the FEF, like the SC, is involved in target selection. Thus if curvature is caused by incomplete target selection, we expect to see its neural correlates in the FEF. We found that saccades that curve toward a distractor are accompanied by an increase in perisaccadic activity of FEF neurons coding the distractor location, and saccades that curve away are accompanied by a decrease in activity. In contrast, for FEF neurons coding the target location, there is no significant difference in activity between curved and straight saccades. To establish that the distractor-related activity is causally related to saccade curvature, we applied microstimulation to sites in the FEF before saccades to targets presented without distractors. The stimulation was subthreshold for evoking saccades and the temporal structure of the stimulation train resembled the activity recorded for curved saccades. The resulting movements curved toward the location coded by the stimulation site. These results support the idea that saccade curvature results from incomplete suppression of distractor-related activity during target selection.

Frontal Eye Field Contributions to Rapid Corrective Saccades

2007 ◽  
Vol 97 (2) ◽  
pp. 1457-1469 ◽  
Author(s):  
Aditya Murthy ◽  
Supriya Ray ◽  
Stephanie M. Shorter ◽  
Elizabeth G. Priddy ◽  
Jeffrey D. Schall ◽  
...  
Keyword(s):  
Performance Monitoring ◽  
Target Location ◽  
Internal Representation ◽  
Neural Mechanism ◽  
Macaque Monkey ◽  
Frontal Eye Field ◽  
Related Activity ◽  
Original Target ◽  
Corrective Saccades ◽  
Eye Field

Visually guided movements can be inaccurate, especially if unexpected events occur while the movement is programmed. Often errors of gaze are corrected before external feedback can be processed. Evidence is presented from macaque monkey frontal eye field (FEF), a cortical area that selects visual targets, allocates attention, and programs saccadic eye movements, for a neural mechanism that can correct saccade errors before visual afferent or performance monitoring signals can register the error. Macaques performed visual search for a color singleton that unpredictably changed position in a circular array as in classic double-step experiments. Consequently, some saccades were directed in error to the original target location. These were followed frequently by unrewarded, corrective saccades to the final target location. We previously showed that visually responsive neurons represent the new target location even if gaze shifted errantly to the original target location. Now we show that the latency of corrective saccades is predicted by the timing of movement-related activity in the FEF. Preceding rapid corrective saccades, the movement-related activity of all neurons began before explicit error signals arise in the medial frontal cortex. The movement-related activity of many neurons began before visual feedback of the error was registered and that of a few neurons began before the error saccade was completed. Thus movement-related activity leading to rapid corrective saccades can be guided by an internal representation of the environment updated with a forward model of the error.

scholarly journals Capacity sharing between concurrent movement plans in the frontal eye field during the planning of sequential saccades

2020 ◽  
Author(s):  
Debaleena Basu ◽  
Naveen Sendhilnathan ◽  
Aditya Murthy
Keyword(s):  
Growth Rate ◽  
Reaction Time ◽  
Reaction Times ◽  
Frontal Eye Field ◽  
Processing Capacity ◽  
Neural Responses ◽  
Related Activity ◽  
Capacity Sharing ◽  
Psychological Theories ◽  
Eye Field

SummaryA ramp to threshold activity of frontal Eye Field (FEF) movement-related neurons best explains the reaction time of single saccades. How such activity is modulated by a concurrent saccade plan is not known. Borrowing from psychological theories of capacity sharing that are designed to explain the concurrent planning of two decisions, we show that processing bottlenecks are brought about by decreasing the growth rate and increasing the threshold of saccade-related activity. Further, rate perturbation affects both saccade plans, indicating a capacity-sharing mechanism of processing bottlenecks, where both the saccade plans compete for processing capacity. To understand how capacity sharing was neurally instantiated, we designed a model in which movement fields that instantiate two saccade plans, mutually inhibit each other. In addition to predicting the greater reaction times for both saccades and changes in growth rate and threshold activity observed experimentally, we observed a greater separation of the two neural trajectories in neural state space, which was verified experimentally. Finally, we show that in contrast to movement related neurons, visual activity in FEF neurons are not affected by the presence of multiple saccade targets, indicating that inhibition amongst movement-related neurons instantiates capacity sharing. Taken together, we show how psychology-inspired models of capacity sharing can be mapped onto neural responses to understand the control of rapid saccade sequences.

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.

Activity of monkey frontal eye field neurons projecting to oculomotor regions of the pons

1992 ◽  
Vol 68 (6) ◽  
pp. 1967-1985 ◽  
Author(s):  
M. A. Segraves
Keyword(s):  
Electrical Stimulation ◽  
Visual Stimulation ◽  
Saccadic Eye Movements ◽  
Frontal Eye Field ◽  
Related Activity ◽  
Burst Neurons ◽  
Eye Field ◽  
Movement Field ◽  
Omnipause Neurons ◽  
Stimulation Of

1. This study identified neurons in the rhesus monkey's frontal eye field that projected to oculomotor regions of the pons and characterized the signals sent by these neurons from frontal eye field to pons. 2. In two behaving rhesus monkeys, frontal eye field neurons projecting to the pons were identified via antidromic excitation by a stimulating microelectrode whose tip was centered in or near the omnipause region of the pontine raphe. This stimulation site corresponded to the nucleus raphe interpositus (RIP). In addition, electrical stimulation of the frontal eye field was used to demonstrate the effects of frontal eye field input on neurons in the omnipause region and surrounding paramedian pontine reticular formation (PPRF). 3. Twenty-five corticopontine neurons were identified and characterized. Most frontal eye field neurons projecting to the pons were either movement neurons, firing in association with saccadic eye movements (48%), or foveal neurons responsive to visual stimulation of the fovea combined with activity related to fixation (28%). Corticopontine movement neurons fired before, during, and after saccades made within a restricted movement field. 4. The activity of identified corticopontine neurons was very similar to the activity of neurons antidromically excited from the superior colliculus where 59% had movement related activity, and 22% had foveal and fixation related activity. 5. High-intensity, short-duration electrical stimulation of the frontal eye field caused omnipause neurons to stop firing. The cessation in firing appeared to be immediate, within < or = 5 ms. The time that the omnipause neuron remained quiet depended on the intensity of the cortical stimulus and lasted up to 30 ms after a train of three stimulus pulses lasting a total of 6 ms at an intensity of 1,000 microA. Low-intensity, longer duration electrical stimuli (24 pulses, 75 microA, 70 ms) traditionally used to evoke saccades from the frontal eye field were also followed by a cessation in omnipause neuron firing, but only after a delay of approximately 30 ms. For these stimuli, the omnipause neuron resumed firing when the stimulus was turned off. 6. The same stimuli that caused omnipause neurons to stop firing excited burst neurons in the PPRF. The latency to excitation ranged from 4.2 to 9.8 ms, suggesting that there is at least one additional neuron between frontal eye field neurons and burst neurons in the PPRF. 7. The present study confirms and extends the results of previous work, with the use of retrograde and anterograde tracers, demonstrating direct projections from the frontal eye field to the pons.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document