On the characteristic of nonlinear spatial summation observed in the lateral geniculate cells of cats.

Abstract

The spatial summation characteristic in the receptive fields of cat lateral geniculate cells were investigated. First, the central area of the receptive field was determined using a spot of light. Then the response of the cell were obtained using disc-shaped stimuli of various radii located in the middle point of the receptive field center. When the radius was increased gradually, the response tended to increase, at first, until it reached a peak value and began to decrease thereafter. The radius where the peak response took place was generally less than that of the receptive field center. Furthermore, this radius decreased when the intensity of the stimulus light was increased. These neurophysiological findings could be simulated by a model. The model consists of two parts. The first part receives the input from the photoreceptors. It is of homogeneous structure with shunting inhibition. The second part receives the input from the first part. The structure is characterized by the conventional center-surround type lateral interaction.