scholarly journals Response modulation in visual cortex by task, stimulus, and spatial attention

2011 ◽  
Vol 11 (11) ◽  
pp. 188-188
Author(s):  
E. Runeson ◽  
S. Murray ◽  
G. Boynton
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Response Modulation ◽  
Task Stimulus

scholarly journals Layer-dependent multiplicative effects of spatial attention on contrast responses in human early visual cortex

2020 ◽  
Author(s):  
Fanhua Guo ◽  
Chengwen Liu ◽  
Chencan Qian ◽  
Zihao Zhang ◽  
Kaibao Sun ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Middle Layer ◽  
Additive Effect ◽  
List Type ◽  
Strong Nonlinearity ◽  
Top Down ◽  
Contrast Gain ◽  
Early Visual Cortex ◽  
Deep Layers

AbstractAttention mechanisms at different cortical layers of human visual cortex remain poorly understood. Using submillimeter-resolution fMRI at 7T, we investigated the effects of top-down spatial attention on the contrast responses across different cortical depths in human early visual cortex. Gradient echo (GE) T2* weighted BOLD signal showed an additive effect of attention on contrast responses across cortical depths. Compared to the middle cortical depth, attention modulation was stronger in the superficial and deep depths of V1, and also stronger in the superficial depth of V2 and V3. Using ultra-high resolution (0.3mm in-plane) balanced steady-state free precession (bSSFP) fMRI, a multiplicative scaling effect of attention was found in the superficial and deep layers, but not in the middle layer of V1. Attention modulation of low contrast response was strongest in the middle cortical depths, indicating baseline enhancement or contrast gain of attention modulation on feedforward input. Finally, the additive effect of attention on T2* BOLD can be explained by strong nonlinearity of BOLD signals from large blood vessels, suggesting multiplicative effect of attention on neural activity. These findings support that top-down spatial attention mainly operates through feedback connections from higher order cortical areas, and a distinct mechanism of attention may also be associated with feedforward input through subcortical pathway.HighlightsResponse or activity gain of spatial attention in superficial and deep layersContrast gain or baseline shift of attention in V1 middle layerNonlinearity of large blood vessel causes additive effect of attention on T2* BOLD

scholarly journals Layer-specific modulation of top-down spatial attention in human early visual cortex

2019 ◽  
Vol 19 (10) ◽  
pp. 169
Author(s):  
Peng Zhang ◽  
Chengwen Liu ◽  
chencan Qian ◽  
Zihao Zhang ◽  
Sheng He ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Top Down ◽  
Early Visual Cortex

Ultrafast Object Detection in Naturalistic Vision Relies on Ultrafast Distractor Suppression

2019 ◽  
Vol 31 (10) ◽  
pp. 1563-1572 ◽  
Author(s):  
Clayton Hickey ◽  
Daniele Pollicino ◽  
Giacomo Bertazzoli ◽  
Ludwig Barbaro
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Brain Activity ◽  
Natural Scenes ◽  
Search Efficiency ◽  
Object Representations ◽  
Target Presence ◽  
Object Categories ◽  
Frontal Brain ◽  
Scene Information

People are quicker to detect examples of real-world object categories in natural scenes than is predicted by classic attention theories. One explanation for this puzzle suggests that experience renders the visual system sensitive to midlevel features diagnosing target presence. These are detected without the need for spatial attention, much as occurs for targets defined by low-level features like color or orientation. The alternative is that naturalistic search relies on spatial attention but is highly efficient because global scene information can be used to quickly reject nontarget objects and locations. Here, we use ERPs to differentiate between these possibilities. Results show that hallmark evidence of ultrafast target detection in frontal brain activity is preceded by an index of spatially specific distractor suppression in visual cortex. Naturalistic search for heterogenous targets therefore appears to rely on spatial operations that act on neural object representations, as predicted by classic attention theory. People appear able to rapidly reject nontarget objects and locations, consistent with the idea that global scene information is used to constrain naturalistic search and increase search efficiency.

Features of Neuronal Synchrony in Mouse Visual Cortex

2003 ◽  
Vol 90 (2) ◽  
pp. 1115-1123 ◽  
Author(s):  
Gabriele Nase ◽  
Wolf Singer ◽  
Hannah Monyer ◽  
Andreas K. Engel
Keyword(s):  
Visual Cortex ◽  
Field Potential ◽  
Response Modulation ◽  
Temporal Patterning ◽  
Cellular Mechanisms ◽  
Neuronal Synchrony ◽  
Significant Difference ◽  
Random Dot Patterns

Synchronization of neuronal discharges has been hypothesized to play a role in defining cell assemblies representing particular constellations of stimulus features. In many systems and species, synchronization is accompanied by an oscillatory response modulation at frequencies in the γ-band. The cellular mechanisms underlying these phenomena of synchronization and oscillatory patterning have been studied mainly in vitro due to the difficulty in designing a direct in vivo assay. With the prospect of using conditional genetic manipulations of cortical network components, our objective was to test whether the mouse would meet the criteria to provide a model system for the study of γ-band synchrony. Multi-unit and local field potential recordings were made from the primary visual cortex of anesthetized C57BL/6J mice. Neuronal responses evoked by moving gratings, bars, and random dot patterns were analyzed with respect to neuronal synchrony and temporal patterning. Oscillations at γ-frequencies were readily evoked with all types of stimuli used. Oscillation and synchronization strength were largest for gratings and decreased when the noise level was increased in random-dot patterns. The center peak width of cross-correlograms was smallest for bars and increased with noise, yielding a significant difference between coherent random dot patterns versus patterns with 70% noise. Field potential analysis typically revealed increases of power in the γ-band during response periods. Our findings are compatible with a role for neuronal synchrony in mediating perceptual binding and suggest the usefulness of the mouse model for testing hypotheses concerning both the mechanisms and the functional role of temporal patterning.

scholarly journals The Temporal Dynamics of Object Processing in Visual Cortex during the Transition from Distributed to Focused Spatial Attention

2011 ◽  
Vol 23 (12) ◽  
pp. 4094-4105 ◽  
Author(s):  
Chien-Te Wu ◽  
Melissa E. Libertus ◽  
Karen L. Meyerhoff ◽  
Marty G. Woldorff
Keyword(s):  
Visual Cortex ◽  
Spatial Attention ◽  
Cognitive Neuroscience ◽  
Visual Processing ◽  
Object Representation ◽  
Temporal Dynamics ◽  
Brain Activity ◽  
Object Processing ◽  
Electrical Brain Activity

Several major cognitive neuroscience models have posited that focal spatial attention is required to integrate different features of an object to form a coherent perception of it within a complex visual scene. Although many behavioral studies have supported this view, some have suggested that complex perceptual discrimination can be performed even with substantially reduced focal spatial attention, calling into question the complexity of object representation that can be achieved without focused spatial attention. In the present study, we took a cognitive neuroscience approach to this problem by recording cognition-related brain activity both to help resolve the questions about the role of focal spatial attention in object categorization processes and to investigate the underlying neural mechanisms, focusing particularly on the temporal cascade of these attentional and perceptual processes in visual cortex. More specifically, we recorded electrical brain activity in humans engaged in a specially designed cued visual search paradigm to probe the object-related visual processing before and during the transition from distributed to focal spatial attention. The onset times of the color popout cueing information, indicating where within an object array the subject was to shift attention, was parametrically varied relative to the presentation of the array (i.e., either occurring simultaneously or being delayed by 50 or 100 msec). The electrophysiological results demonstrate that some levels of object-specific representation can be formed in parallel for multiple items across the visual field under spatially distributed attention, before focal spatial attention is allocated to any of them. The object discrimination process appears to be subsequently amplified as soon as focal spatial attention is directed to a specific location and object. This set of novel neurophysiological findings thus provides important new insights on fundamental issues that have been long-debated in cognitive neuroscience concerning both object-related processing and the role of attention.

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