Spatial summation of excitation and inhibition in receptive fields of neurons in the lateral geniculate body of the cat and the influence of visual deprivation.

Abstract

1. The spatial summation in receptive fields of neurons in the lateral geniculate body (LGB) of the cat was measured with continuously changing round light stimuli which were modulated sinusoidally. The mean impulse frequencies and the position of the phasic discharge in relation to the stimuli were investigated as a function of the size of stimuli. 2. The on-center neurons showed small receptive field centers and marked inhibition by the surrounding at frequencies from 1.5 to 20 cps. In the off-center neurons the on-excitation from the periphery exceeded the on-inhibition from the center when the entire receptive field was stimulated. Characteristic shifting of the discharges was ascertained. 3. Neurons fed by the visually deprived eye showed reduced effects of the surrounding. 4. The mechanisms of inhibition that can be derived from the results and the changes in the LGB during visual deprivation are discussed.