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Abstract:
In a V1 model, we investigate contextual influences by studying the cell responses to a circular patch of grating as a function of the patch radius. The grating is centered on the receptive field of the cell and has the preferred orientation of the cell. The cells are orientation selective and interact with each other via intracortical connections which mediate contextual influences. For small gratings, cell responses increase with the size of the gratings. This area of the grating has been termed the center summation zone of the receptive field. For larger gratings, the cell response decreases with grating radius, and the area of the grating outside the center summation zone is called the suppressive surround. These phenomena have been observed physiologically. For even larger gratings, cell responses in our model rise again to a level comparable to the response to the center summation zone alone. This indicates an outer, disinhibiting, surround zone. A few additional but progressively weaker suppressing and disinhibiting outer surround zones follow. These findings can be tested physiologically. They manifest contextual influences which enables a cell's response to signal global features in inputs.
