[Characteristics of the inhibition in receptive fields of class 1 and 3 in the frog retina]

Abstract

The poststimulus histograms of off-responses of the I and III class receptive fields in the frog retina were obtained with moving narrow dark bars of different vertical size (1-20 degrees). When increasing size of the stimulus over the summation zone, inhibitory action of the fields periphery increases due to spatial summation of inhibitory effects. The stimuli of adequate size produce a complete inhibition in the receptive fields of both classes. When increasing sizes of moving stimuli, contrary to the stationary those, the inhibition both depresses the reaction and increases the latency. The peripheral site revealing the greatest inhibitory effect under its stimulation, is far removed from the boundary of summation zone (by 1.5-2.5 degrees) in most fields. The similar decrease of the I class receptive field responses occurs under stimulation of the peripheral site (0.8-2.3 degrees) narrower than that of the III class ones (2.2-5.7 degrees). The receptive fields of the I class seem to have more powerful inhibitory zone than those of the III class.