Evoked potentials in the cat inferior colliculus during exposure to signals simulating movement of sound sources at different speeds in opposite directions.

The relationships between changes in the amplitudes of evoked potentials (EP) in the inferior colliculus of anesthetized adult cats were studied during presentation of acoustic signals simulating sound sources moving in the azimuthal plane at different speeds and in opposite directions, as well as stationary sound sources. Movement was created by changing the interaural time differences in stimuli between clicks in binaurally presented series of clicks. These studies showed that the amplitude of EP arising as a result of presentation of these signals depended on the speed of movement. The upper border of the range of speeds in which responses to "moving" and stationary signals were different was 320 degrees/sec. Different experiments showed that the greatest difference in responses was seen at movement rates of 67-320 degrees/sec, though most were recorded at speeds of 125 and 170 degrees/sec. Responses to movement in the lateromedial direction, regardless of speed, had greater magnitudes than responses to movement at the same speed in the opposite direction.