Contextual modulation of V1 receptive fields depends on their spatial symmetry |
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Authors: | Tatyana O Sharpee Jonathan D Victor |
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Institution: | (1) Computational Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA;(2) Center for Theoretical Biological Physics, University of California, San Diego, La Jolla, CA 92093, USA;(3) Weill Cornell Medical College, New York, NY 10065, USA |
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Abstract: | The apparent receptive field characteristics of sensory neurons depend on the statistics of the stimulus ensemble—a nonlinear
phenomenon often called contextual modulation. Since visual cortical receptive fields determined from simple stimuli typically
do not predict responses to complex stimuli, understanding contextual modulation is crucial to understanding responses to
natural scenes. To analyze contextual modulation, we examined how apparent receptive fields differ for two stimulus ensembles
that are matched in first- and second-order statistics, but differ in their feature content: one ensemble is enriched in elongated
contours. To identify systematic trends across the neural population, we used a multidimensional scaling method, the Procrustes
transformation. We found that contextual modulation of receptive field components increases with their spatial extent. More
surprisingly, we also found that odd-symmetric components change systematically, but even-symmetric components do not. This
symmetry dependence suggests that contextual modulation is driven by oriented On/Off dyads, i.e., modulation of the strength
of intracortically-generated signals.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Primary visual cortex Plasticity Linear– nonlinear model Reverse correlation |
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