A unified and quantitative network model for spatial attention in area V4

2010 ◽  
Vol 104 (1-2) ◽  
pp. 84-90 ◽  
Author(s):  
Etienne Hugues ◽  
Jorge V. José
Keyword(s):  
Spatial Attention ◽  
Network Model ◽  
Area V4

scholarly journals Rhythmic neural spiking and attentional sampling arising from cortical receptive field interactions

2018 ◽  
Author(s):  
Ricardo Kienitz ◽  
Joscha T. Schmiedt ◽  
Katharine A. Shapcott ◽  
Kleopatra Kouroupaki ◽  
Richard C. Saunders ◽  
...  
Keyword(s):  
Eye Movements ◽  
Receptive Field ◽  
Spatial Attention ◽  
Receptive Fields ◽  
Reaction Times ◽  
List Type ◽  
Attention Task ◽  
Area V4 ◽  
Fixational Eye Movements ◽  
Visual Cortical Area

SummaryGrowing evidence suggests that distributed spatial attention may invoke theta (3-9 Hz) rhythmic sampling processes. The neuronal basis of such attentional sampling is however not fully understood. Here we show using array recordings in visual cortical area V4 of two awake macaques that presenting separate visual stimuli to the excitatory center and suppressive surround of neuronal receptive fields elicits rhythmic multi-unit activity (MUA) at 3-6 Hz. This neuronal rhythm did not depend on small fixational eye movements. In the context of a distributed spatial attention task, during which the monkeys detected a spatially and temporally uncertain target, reaction times (RT) exhibited similar rhythmic fluctuations. RTs were fast or slow depending on the target occurrence during high or low MUA, resulting in rhythmic MUA-RT cross-correlations at at theta frequencies. These findings suggest that theta-rhythmic neuronal activity arises from competitive receptive field interactions and that this rhythm may subserve attentional sampling.HighlightsCenter-surround interactions induce theta-rhythmic MUA of visual cortex neuronsThe MUA rhythm does not depend on small fixational eye movementsReaction time fluctuations lock to the neuronal rhythm under distributed attention

scholarly journals Effects of Task Difficulty and Target Likelihood in Area V4 of Macaque Monkeys

2006 ◽  
Vol 96 (5) ◽  
pp. 2377-2387 ◽  
Author(s):  
C. Elizabeth Boudreau ◽  
Tori H. Williford ◽  
John H. R. Maunsell
Keyword(s):  
Spatial Attention ◽  
Cortical Neurons ◽  
Task Difficulty ◽  
Focus Of Attention ◽  
Behavioral Performance ◽  
Neuronal Responses ◽  
Fixed Amount ◽  
Processing Resource ◽  
Area V4 ◽  
Sensory Responses

Spatial attention improves performance at attended locations and correspondingly modulates firing rates of cortical neurons. The size of these behavioral and neuronal effects depends on the difficulty of the task performed at the attended location. Psychological theorists have attributed this to a tighter focus of a fixed amount of processing resource at the attended location, but the effects of task difficulty on the distribution of neuronal effects of attention across the visual field have not been fully explored. We trained rhesus monkeys to do a detection task in which difficulty and spatial attention were manipulated independently. Probe stimuli were used to measure behavioral performance in different conditions of attention and difficulty. Animals performed better at attended locations and this advantage increased with difficulty, consistent with data from human psychophysics. Neuronal modulation by spatial attention was larger with greater difficulty. In two animals, increasing difficulty caused a modest increase in neuronal responses to visual stimuli regardless of the locus of spatial attention. In a third animal, which was previously trained to ignore multiple distracting stimuli, increasing task difficulty increased responses at the focus of attention and suppressed responses away from the focus of attention. The results show that difficulty can modulate effects of spatial attention in V4; it can alter the distribution of sensory responses across the visual scene in ways that may depend on the subject's behavioral strategy.

scholarly journals Spatial Attention Effects in Macaque Area V4

1997 ◽  
Vol 17 (9) ◽  
pp. 3201-3214 ◽  
Author(s):  
Charles E. Connor ◽  
Dean C. Preddie ◽  
Jack L. Gallant ◽  
David C. Van Essen
Keyword(s):  
Spatial Attention ◽  
Area V4

scholarly journals Role of Interneuron Diversity in the Cortical Microcircuit for Attention

2008 ◽  
Vol 99 (5) ◽  
pp. 2158-2182 ◽  
Author(s):  
Calin I. Buia ◽  
Paul H. Tiesinga
Keyword(s):  
Firing Rate ◽  
Spatial Attention ◽  
Cortical Area ◽  
Receptive Fields ◽  
Biophysical Model ◽  
Testable Hypothesis ◽  
Frequency Range ◽  
Area V4 ◽  
Gamma Frequency ◽  
Feature Based

Receptive fields of neurons in cortical area V4 are large enough to fit multiple stimuli, making V4 the ideal place to study the effects of selective attention at the single-neuron level. Experiments have revealed evidence for stimulus competition and have characterized the effect thereon of spatial and feature-based attention. We developed a biophysical model with spiking neurons and conductance-based synapses. To account for the comprehensive set of experimental results, it was necessary to include in the model, in addition to regular spiking excitatory (E) cells, two types of interneurons: feedforward interneurons (FFI) and top-down interneurons (TDI). Feature-based attention was mediated by a projection of the TDI to the FFI, stimulus competition was mediated by a cross-columnar excitatory connection to the FFI, whereas spatial attention was mediated by an increase in activity of the feedforward inputs from cortical area V2. The model predicts that spatial attention increases the FFI firing rate, whereas feature-based attention decreases the FFI firing rate and increases the TDI firing rate. During strong stimulus competition, the E cells were synchronous in the beta frequency range (15–35 Hz), but with feature-based attention, they became synchronous in the gamma frequency range (35–50 Hz). We propose that the FFI correspond to fast-spiking, parvalbumin-positive basket cells and that the TDI correspond to cells with a double-bouquet morphology that are immunoreactive to calbindin or calretinin. Taken together, the model results provide an experimentally testable hypothesis for the behavior of two interneuron types under attentional modulation.

Effects of Spatial Attention on Contrast Response Functions in Macaque Area V4

2006 ◽  
Vol 96 (1) ◽  
pp. 40-54 ◽  
Author(s):  
Tori Williford ◽  
John H. R. Maunsell
Keyword(s):  
Spatial Attention ◽  
Response Function ◽  
Response Functions ◽  
Stimulus Response ◽  
Area V4 ◽  
Leftward Shift ◽  
Contrast Response Function ◽  
Proportional Increase ◽  
V4 Neurons ◽  
Contrast Response

Previous single-unit studies of visual cortex have reported that spatial attention modulates responses to different orientations and directions proportionally, such that it does not change the width of tuning functions for these properties. Other studies have suggested that spatial attention causes a leftward shift in contrast response functions, such that its effects on responses to stimuli of different contrasts are not proportional. We have further explored the effects of attention on stimulus-response functions by measuring the responses of 131 individual V4 neurons in two monkeys while they did a task that controlled their spatial attention. Each neuron was tested with a set of stimuli that spanned complete ranges of orientation and contrast during different states of attention. Consistent with earlier reports, attention scaled responses to preferred and nonpreferred orientations proportionally. However, we did not find compelling evidence that the effects were best described by a leftward shift of the contrast response function. The modulation of neuronal responses by attention was well described by either a leftward shift or proportional scaling of the contrast response function. Consideration of differences in experimental design and analysis that may have contributed to this discrepancy suggests that it was premature to exclude a proportional scaling of responses to different contrasts by attention in favor of a leftward shift of contrast response functions. The current results reopen the possibility that the effects of attention on stimulus-response functions are well described by a single proportional increase in a neuron's response to all stimuli.

Spatial attention in area V4 is mediated by circuits in primary visual cortex

2009 ◽  
Vol 22 (8) ◽  
pp. 1039-1054 ◽  
Author(s):  
Paul H. Tiesinga ◽  
Calin I. Buia
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Primary Visual Cortex ◽  
Area V4
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