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.

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.

scholarly journals On the Origin of Event-Related Potentials Indexing Covert Attentional Selection During Visual Search

2009 ◽  
Vol 102 (4) ◽  
pp. 2375-2386 ◽  
Author(s):  
Jeremiah Y. Cohen ◽  
Richard P. Heitz ◽  
Jeffrey D. Schall ◽  
Geoffrey F. Woodman
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Event Related Potentials ◽  
Frontal Eye Field ◽  
Field Potentials ◽  
Electrophysiological Studies ◽  
Human Experiments ◽  
Related Potentials ◽  
Eye Field

Despite nearly a century of electrophysiological studies recording extracranially from humans and intracranially from monkeys, the neural generators of nearly all human event-related potentials (ERPs) have not been definitively localized. We recorded an attention-related ERP component, known as the N2pc, simultaneously with intracranial spikes and local field potentials (LFPs) in macaques to test the hypothesis that an attentional-control structure, the frontal eye field (FEF), contributed to the generation of the macaque homologue of the N2pc (m-N2pc). While macaques performed a difficult visual search task, the search target was selected earliest by spikes from single FEF neurons, later by FEF LFPs, and latest by the m-N2pc. This neurochronometric comparison provides an empirical bridge connecting macaque and human experiments and a step toward localizing the neural generator of this important attention-related ERP component.

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 Frontal Eye Field Activity Before Visual Search Errors Reveals the Integration of Bottom-Up and Top-Down Salience

2005 ◽  
Vol 93 (1) ◽  
pp. 337-351 ◽  
Author(s):  
Kirk G. Thompson ◽  
Narcisse P. Bichot ◽  
Takashi R. Sato
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Target Selection ◽  
Saccade Target ◽  
Frontal Eye Field ◽  
Top Down ◽  
Bottom Up ◽  
Stimulus Response ◽  
Singleton Search ◽  
Eye Field

We investigated the saccade decision process by examining activity recorded in the frontal eye field (FEF) of monkeys performing 2 separate visual search experiments in which there were errors in saccade target choice. In the first experiment, the difficulty of a singleton search task was manipulated by varying the similarity between the target and distractors; errors were made more often when the distractors were similar to the target. On catch trials in which the target was absent the monkeys occasionally made false alarm errors by shifting gaze to one of the distractors. The second experiment was a popout color visual search task in which the target and distractor colors switched unpredictably across trials. Errors occurred most frequently on the first trial after the switch and less often on subsequent trials. In both experiments, FEF neurons selected the saccade goal on error trials, not the singleton target of the search array. Although saccades were made to the same stimulus locations, presaccadic activation and the magnitude of selection differed across trial conditions. The variation in presaccadic selective activity was accounted for by the variation in saccade probability across the stimulus–response conditions, but not by variations in saccade metrics. These results suggest that FEF serves as a saccade probability map derived from the combination of bottom-up and top-down influences. Peaks on this map represent the behavioral relevance of each item in the visual field rather than just reflecting saccade preparation. This map in FEF may correspond to the theoretical salience map of many models of attention and saccade target selection.

scholarly journals Sequential Operations Revealed by Serendipitous Feature Selectivity in Frontal Eye Field

2019 ◽  
Author(s):  
Kaleb A. Lowe ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Visual Search Task ◽  
Target Selection ◽  
Stimulus Orientation ◽  
Saccade Target ◽  
Frontal Eye Field ◽  
Eye Field ◽  
Feature Selectivity ◽  
Selection Indexes

ABSTRACTNeurons in macaque frontal eye field contribute to spatial but typically not feature selection during visual search. Using an innovative visual search task, we report a serendipitous discovery that some frontal eye field neurons can develop rapid selectivity for stimulus orientation that is used to guide gaze during a visual search task with pro-saccade and anti-saccade responses. This feature selectivity occurs simultaneously at multiple locations for all objects sharing that feature and coincides with when neurons select the singleton of a search array. This feature selectivity also reveals the distinct, subsequent operation of selecting the endpoint of the saccade in pro-saccade as well as anti-saccade trials. These results demonstrate that target selection preceding saccade preparation is composed of multiple operations. We conjecture that singleton selection indexes the allocation of attention, which can be divided, to conspicuous items. Consequently, endpoint selection indexes the focused allocation of attention to the endpoint of the saccade. These results demonstrate that saccade target selection is not a unitary process.SIGNIFICANCE STATEMENTFrontal eye field is well known to contribute to spatial selection for attention and eye movements. We discovered that some frontal eye field neurons can acquire selectivity for stimulus orientation when it guides visual search. The chronometry of neurons with and without feature selectivity reveal distinct operations accomplishing visual search.

scholarly journals Reading problems and their connection with visual search and attention: The search for a cause continues

2021 ◽  
Author(s):  
Heida Maria Sigurdardottir ◽  
Hilma Ros Omarsdóttir ◽  
Anna Sigridur Valgeirsdottir
Keyword(s):  
Visual Search ◽  
Internal Control ◽  
Search Task ◽  
Conjunction Search ◽  
Reading Problems ◽  
Visual Stream ◽  
Attentional Processes ◽  
Search Tasks ◽  
Reading Abilities ◽  
Gating Mechanism

Attention has been hypothesized to act as a sequential gating mechanism for the orderly processing of letters in words. These same visuo-attentional processes are assumed to partake in some but not all visual search tasks. In the current study, 60 adults with varying degrees of reading abilities, ranging from expert readers to severely impaired dyslexic readers, completed an attentionally demanding visual conjunction search task thought to heavily rely on the dorsal visual stream. A visual feature search task served as an internal control. According to the dorsal view of dyslexia, reading problems should go hand in hand with specific problems in visual conjunction search – particularly elevated conjunction search slopes (time per search item) – which would be interpreted as a problem with visual attention. Results showed that reading problems were associated with slower visual search, especially conjunction search. However, problems with reading were not associated with increased conjunction search slopes but instead with increased conjunction search intercepts, traditionally not interpreted as reflecting attentional processes. Our data are hard to reconcile with hypothesized problems in dyslexia with the serial moving of an attentional spotlight across a visual scene or a page of text.

scholarly journals Stable individual differences in strategies within, but not between, visual search tasks

2018 ◽  
Author(s):  
Alasdair D F Clarke ◽  
Jessica Irons ◽  
Warren James ◽  
Andrew B. Leber ◽  
Amelia R. Hunt
Keyword(s):  
Individual Differences ◽  
Visual Search ◽  
Search Task ◽  
The Other ◽  
Search Performance ◽  
Search Tasks ◽  
And Performance ◽  
Context Specific ◽  
Test Retest Reliability ◽  
Over Time

A striking range of individual differences has recently been reported in three different visual search tasks. These differences in performance can be attributed to strategy, that is, the efficiency with which participants control their search to complete the task quickly and accurately. Here we ask if an individual's strategy and performance in one search task is correlated with how they perform in the other two. We tested 64 observers in the three tasks mentioned above over two sessions. Even though the test-retest reliability of the tasks is high, an observer's performance and strategy in one task did not reliably predict their behaviour in the other two. These results suggest search strategies are stable over time, but context-specific. To understand visual search we therefore need to account not only for differences between individuals, but also how individuals interact with the search task and context. These context-specific but stable individual differences in strategy can account for a substantial proportion of variability in search performance.

The effects of audiovisual task-set in visual search

2012 ◽  
Vol 25 (0) ◽  
pp. 158
Author(s):  
Pawel J. Matusz ◽  
Martin Eimer
Keyword(s):  
Visual Search ◽  
Search Task ◽  
Target Selection ◽  
Top Down ◽  
Search Tasks ◽  
Attentional Control Settings ◽  
Sensory Modalities ◽  
Attentional Selectivity ◽  
Auditory Features ◽  
Target Matching

We investigated whether top-down attentional control settings can specify task-relevant features in different sensory modalities (vision and audition). Two audiovisual search tasks were used where a spatially uninformative visual singleton cue preceded a target search array. In different blocks, participants searched for a visual target (defined by colour or shape in Experiments 1 and 2, respectively), or target defined by a combination of visual and auditory features (e.g., red target accompanied by a high-pitch tone). Spatial cueing effects indicative of attentional capture by target-matching visual singleton cues in the unimodal visual search task were reduced or completely eliminated when targets were audiovisually defined. The N2pc component (i.e. index attentional target selection in vision) triggered by these cues was reduced and delayed during search for audiovisual as compared to unimodal visual targets. These results provide novel evidence that the top-down control settings which guide attentional selectivity can include perceptual features from different sensory modalities.

scholarly journals Stable individual differences in strategies within, but not between, visual search tasks

2020 ◽  
pp. 174702182092919 ◽  
Author(s):  
Alasdair DF Clarke ◽  
Jessica L Irons ◽  
Warren James ◽  
Andrew B Leber ◽  
Amelia R Hunt
Keyword(s):  
Individual Differences ◽  
Visual Search ◽  
Search Task ◽  
The Other ◽  
Retest Reliability ◽  
Search Tasks ◽  
And Performance ◽  
Context Specific ◽  
Test Retest Reliability ◽  
Over Time

A striking range of individual differences has recently been reported in three different visual search tasks. These differences in performance can be attributed to strategy, that is, the efficiency with which participants control their search to complete the task quickly and accurately. Here, we ask whether an individual’s strategy and performance in one search task is correlated with how they perform in the other two. We tested 64 observers and found that even though the test–retest reliability of the tasks was high, an observer’s performance and strategy in one task was not predictive of their behaviour in the other two. These results suggest search strategies are stable over time, but context-specific. To understand visual search, we therefore need to account not only for differences between individuals but also how individuals interact with the search task and context.

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