The pattern of response of the inferior colliculus of the cat during the movement of a sound source.

During the application of a train of clicks simulating the movement of a sound source, evoked potentials (EP) of the inferior colliculus gradually changed their amplitude and form ("the movement effect") in 82% of the instances tested. The expression of the ipsilateral movement effect was on the average 1.5 times greater than the contralateral. The movement effect was observed over a wide range of velocities; but, in 65% of the instances, the effect was observed at movement velocities not less than 3.5 rad/sec. Velocities higher than 6.8 rad/sec were most effective in 78% of the instances. Differences in responses were discovered in 26% of the instances involving opposite directions of sound source movement. The movement effect depended substantially upon the site of the EP sampling.