Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN/BFNT AG-Seminar

Tuesday, 15.06.2010 17 c.t.

Summation and Competition in the Population Responses of Visual Cortex

by Dr. Laura Busse
from Cortical Circuits of Visual Perception, Centre for Integrative Neuroscience, Tübingen

Contact person: Fred Wolf

Location

Seminarraum Haus 2, 4. Stock (Bunsenstr.)

Abstract

How do neuronal populations represent concurrent stimuli? We measured population responses in cat primary visual cortex (V1) using electrode arrays. Population responses to two superimposed gratings were weighted sums of the individual grating res- ponses. The weights depended strongly on the relative contrasts of the gratings. When the contrasts were similar, the population performed an approximately equal summation. When the contrasts differed markedly, however, the population performed approximately a winner-take-all competition. Stimuli that were intermediate to these extremes elicited intermediate responses. This entire range of behaviors was explained by a single model of contrast normalization. Normalization has profound effects on V1 population responses and is likely to shape the interpretation of these responses by higher cortical areas.

Remarks

Bernstein Lecture Series 2010

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