scholarly journals Distinct roles of prefrontal and parietal areas in the encoding of attentional priority

2018 ◽  
Vol 115 (37) ◽  
pp. E8755-E8764 ◽  
Author(s):  
Panagiotis Sapountzis ◽  
Sofia Paneri ◽  
Georgia G. Gregoriou
Keyword(s):  
Target Object ◽  
Frontal Eye Field ◽  
Neuronal Responses ◽  
Lateral Intraparietal Area ◽  
Hierarchical Processing ◽  
Cortical Areas ◽  
Free Viewing ◽  
Eye Field ◽  
Feature Based ◽  
Scene Information

When searching for an object in a crowded scene, information about the similarity of stimuli to the target object is thought to be encoded in spatial priority maps, which are subsequently used to guide shifts of attention and gaze to likely targets. Two key cortical areas that have been described as holding priority maps are the frontal eye field (FEF) and the lateral intraparietal area (LIP). However, little is known about their distinct contributions in priority encoding. Here, we compared neuronal responses in FEF and LIP during free-viewing visual search. Although saccade selection signals emerged earlier in FEF, information about the target emerged at similar latencies in distinct populations within the two areas. Notably, however, effects in FEF were more pronounced. Moreover, LIP neurons encoded the similarity of stimuli to the target independent of saccade selection, whereas in FEF, encoding of target similarity was strongly modulated by saccade selection. Taken together, our findings suggest hierarchical processing of saccade selection signals and parallel processing of feature-based attention signals within the parietofrontal network with FEF having a more prominent role in priority encoding. Furthermore, they suggest discrete roles of FEF and LIP in the construction of priority maps.

scholarly journals Propofol Anesthesia Increases Long-range Frontoparietal Corticocortical Interaction in the Oculomotor Circuit in Macaque Monkeys

2019 ◽  
Vol 130 (4) ◽  
pp. 560-571 ◽  
Author(s):  
Li Ma ◽  
Wentai Liu ◽  
Andrew E. Hudson
Keyword(s):  
Functional Connectivity ◽  
Long Range ◽  
Low Frequency ◽  
Fold Increase ◽  
Frontal Eye Field ◽  
Lateral Intraparietal Area ◽  
Cortical Areas ◽  
Eye Field ◽  
Phase Amplitude ◽  
Frequency Phase

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Frontoparietal functional connectivity decreases with multiple anesthetics using electrophysiology and functional imaging. This decrease has been proposed as a final common functional pathway to produce anesthesia. Two alternative measures of long-range cortical interaction are coherence and phase-amplitude coupling. Although phase-amplitude coupling within frontal cortex changes with propofol administration, the effects of propofol on phase-amplitude coupling between different cortical areas have not previously been reported. Based on phase-amplitude coupling observed within frontal lobe during the anesthetized period, it was hypothesized that between-lead phase-amplitude coupling analysis should decrease between frontal and parietal leads during propofol anesthesia. Methods A published monkey electrocorticography data set (N = 2 animals) was used to test for interactions in the cortical oculomotor circuit, which is robustly interconnected in primates, and in the visual system during propofol anesthesia using coherence and interarea phase-amplitude coupling. Results Propofol induces coherent slow oscillations in visual and oculomotor networks made up of cortical areas with strong anatomic projections. Frontal eye field within-area phase-amplitude coupling increases with a time course consistent with a bolus response to intravenous propofol (modulation index increase of 12.6-fold). Contrary to the hypothesis, interareal phase-amplitude coupling also increases with propofol, with the largest increase in phase-amplitude coupling in frontal eye field low-frequency phase modulating lateral intraparietal area β-power (27-fold increase) and visual area 2 low-frequency phase altering visual area 1 β-power (19-fold increase). Conclusions Propofol anesthesia induces coherent oscillations and increases certain frontoparietal interactions in oculomotor cortices. Frontal eye field and lateral intraparietal area show increased coherence and phase-amplitude coupling. Visual areas 2 and 1, which have similar anatomic projection patterns, show similar increases in phase-amplitude coupling, suggesting higher order feedback increases in influence during propofol anesthesia relative to wakefulness. This suggests that functional connectivity between frontal and parietal areas is not uniformly decreased by anesthetics.

scholarly journals Functional localization of the frontal eye fields in the common marmoset using microstimulation

2019 ◽  
Author(s):  
Janahan Selvanayagam ◽  
Kevin D. Johnston ◽  
David J. Schaeffer ◽  
Lauren K. Hayrynen ◽  
Stefan Everling
Keyword(s):  
Spatial Attention ◽  
Common Marmoset ◽  
Frontal Eye Field ◽  
Cortical Region ◽  
Compelling Evidence ◽  
Primate Model ◽  
Promising Alternative ◽  
Cortical Areas ◽  
Eye Field ◽  
The Common

AbstractThe frontal eye field (FEF) is a critical region for the deployment of overt and covert spatial attention. While investigations in the macaque continue to provide insight into the neural underpinnings of the FEF, due to its location within a sulcus the macaque FEF is virtually inaccessible to electrophysiological techniques such as high-density and laminar recordings. With a largely lissencephalic cortex, the common marmoset (Callithrix jacchus) is a promising alternative primate model for studying FEF microcircuitry. Putative homologies have been established with the macaque FEF on the basis of cytoarchitecture and connectivity, however physiological investigation in awake, behaving marmosets is necessary to physiologically locate this area. Here we addressed this gap using intracortical microstimulation in a broad range of frontal cortical areas in marmosets. We implanted marmosets with 96-channel Utah arrays and applied microstimulation trains while they freely viewed video clips. We evoked short-latency fixed vector saccades at low currents (<50 μA) in areas 45, 8aV, 8C and 6DR. We observed a topography of saccade direction and amplitude consistent with findings in macaques and humans; we observed small saccades in ventrolateral FEF and large saccades combined with contralateral neck and shoulder movements encoded in dorsomedial FEF. Our data provide compelling evidence supporting homology between marmoset and macaque FEF and suggest the marmoset is a useful primate model for investigating FEF microcircuitry and its contributions to oculomotor and cognitive functions.Significance StatementThe frontal eye field (FEF) is a critical cortical region for overt and covert spatial attention. The microcircuitry of this area remains poorly understood, as in the macaque, the most commonly used model, it is embedded within a sulcus and is inaccessible to modern electrophysiological and optical imaging techniques. The common marmoset is a promising alternative primate model due to its lissencephalic cortex and potential for genetic manipulation. However, evidence for homologous cortical areas in this model remains limited and unclear. Here we applied microstimulation in frontal cortical areas in marmosets to physiologically identify the FEF. Our results provide compelling evidence for a frontal eye field in the marmoset, and suggest that the marmoset is a useful model for FEF microcircuitry.

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

scholarly journals Neural Basis of the Set-Size Effect in Frontal Eye Field: Timing of Attention During Visual Search

2009 ◽  
Vol 101 (4) ◽  
pp. 1699-1704 ◽  
Author(s):  
Jeremiah Y. Cohen ◽  
Richard P. Heitz ◽  
Geoffrey F. Woodman ◽  
Jeffrey D. Schall
Keyword(s):  
Visual Search ◽  
Response Time ◽  
Visual Target ◽  
Target Selection ◽  
Target Object ◽  
Frontal Eye Field ◽  
Neural Basis ◽  
Set Size ◽  
Eye Field ◽  
Recorded Activity

Visual search for a target object among distractors often takes longer when more distractors are present. To understand the neural basis of this capacity limitation, we recorded activity from visually responsive neurons in the frontal eye field (FEF) of macaque monkeys searching for a target among distractors defined by form (randomly oriented T or L). To test the hypothesis that the delay of response time with increasing number of distractors originates in the delay of attention allocation by FEF neurons, we manipulated the number of distractors presented with the search target. When monkeys were presented with more distractors, visual target selection was delayed and neuronal activity was reduced in proportion to longer response time. These findings indicate that the time taken by FEF neurons to select the target contributes to the variation in visual search efficiency.

scholarly journals Neural correlations are attenuated in the transformation from the frontal cortex to movement

2021 ◽  
Author(s):  
Noga Larry ◽  
Mati Joshua
Keyword(s):  
Eye Movements ◽  
Frontal Cortex ◽  
Frontal Eye Field ◽  
Neuronal Responses ◽  
Distance Metric ◽  
Motor Pathway ◽  
Pursuit Eye Movements ◽  
Correlated Activity ◽  
Eye Field ◽  
Novel Method

Correlated activity between neurons can cause variability in behavior across trials. The extent to which correlated activity affects behavior depends on the properties of its translation into movement. We developed a novel method that estimates the contribution of correlations in the frontal eye field (FEF) to pursuit eye movements. We defined a distance metric between the behavior on different trials. Based on this metric, we applied a sequence of shuffles to the neuronal responses, allowing trials to be matched with increasingly distant trials. Correlations between neurons were strongly attenuated when applying even the most constrained shuffle. Thus, only a small fraction of FEF correlations affects the behavior. We used simulations to validate our approach and demonstrate its generalizability over different models. We show that the attenuation of correlated activity through the motor pathway could stem from the interplay between the structure of the correlations and the decoder of FEF activity.

scholarly journals Suppression of frontal eye field neuronal responses with maintained fixation

2018 ◽  
Vol 115 (4) ◽  
pp. 804-809 ◽  
Author(s):  
Koorosh Mirpour ◽  
Zeinab Bolandnazar ◽  
James W. Bisley
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Scene Perception ◽  
Receptive Fields ◽  
Movement Behavior ◽  
Frontal Eye Field ◽  
Neuronal Responses ◽  
Eye Field ◽  
Foraging Task ◽  
Temporal Flow

The decision of where to make an eye movement is thought to be driven primarily by responses to stimuli in neurons’ receptive fields (RFs) in oculomotor areas, including the frontal eye field (FEF) of prefrontal cortex. It is also thought that a saccade may be generated when the accumulation of this activity in favor of one location or another reaches a threshold. However, in the reading and scene perception fields, it is well known that the properties of the stimulus at the fovea often affect when the eyes leave that stimulus. We propose that if FEF plays a role in generating eye movements, then the identity of the stimulus at fixation should affect the FEF responses so as to reduce the probability of making a saccade when fixating an item of interest. Using a visual foraging task in which animals could make multiple eye movements within a single trial, we found that responses were strongly modulated by the identity of the stimulus at the fovea. Specifically, responses to the stimulus in the RF were suppressed when the animal maintained fixation for longer durations on a stimulus that could be associated with a reward. We suggest that this suppression, which was predicted by models of eye movement behavior, could be a mechanism by which FEF can modulate the temporal flow of saccades based on the importance of the stimulus at the fovea.

scholarly journals Feature-based attention and spatial selection in frontal eye fields during natural scene search

2016 ◽  
Vol 116 (3) ◽  
pp. 1328-1343 ◽  
Author(s):  
Pavan Ramkumar ◽  
Patrick N. Lawlor ◽  
Joshua I. Glaser ◽  
Daniel K. Wood ◽  
Adam N. Phillips ◽  
...  
Keyword(s):  
Eye Movement ◽  
Visual Features ◽  
Frontal Eye Field ◽  
Natural Scenes ◽  
Natural Scene ◽  
Spatial Selection ◽  
Visual Objects ◽  
Eye Field ◽  
Feature Based ◽  
Visual Landscape

When we search for visual objects, the features of those objects bias our attention across the visual landscape (feature-based attention). The brain uses these top-down cues to select eye movement targets (spatial selection). The frontal eye field (FEF) is a prefrontal brain region implicated in selecting eye movements and is thought to reflect feature-based attention and spatial selection. Here, we study how FEF facilitates attention and selection in complex natural scenes. We ask whether FEF neurons facilitate feature-based attention by representing search-relevant visual features or whether they are primarily involved in selecting eye movement targets in space. We show that search-relevant visual features are weakly predictive of gaze in natural scenes and additionally have no significant influence on FEF activity. Instead, FEF activity appears to primarily correlate with the direction of the upcoming eye movement. Our result demonstrates a concrete need for better models of natural scene search and suggests that FEF activity during natural scene search is explained primarily by spatial selection.

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