Distribution of latencies in the receptive fields of superior colliculus neurons in cats

Visual receptive fields of superior colliculus neurons were investigated. The latencies of "on" and "off" responses were measured and their distribution all over the field was mapped. In 36 percent of the receptive fields the latency of the "off" response was shorter than the latency of the "on" response; 19 percent of the receptive fields had almost equal latencies; in 13 percent the latency of the "on" response was shorter than that of the "off" response in the majority of explored points; 32 percent were mixed receptive fields with different types of latency distribution. The hypothetical considerations of possible mechanisms of organization of receptive fields in cat midbrain are presented.