UNIT RESPONSES TO SOUND FROM AUDITORY NERVE OF THE CAT

Abstract

Tungsten microelectrodes were placed in the auditory nerve of both anesthetized and unanesthetized cats and the sound-induced activity of 45 units was recorded and intensively studied. Three criteria (anatomical, slow-wave morphology, and spike latency) were used to establish unequivocally the location of the electrode tip and every eighth nerve unit described in this paper met all three criteria. Our results show that the spontaneous discharges of auditory nerve units can be inhibited by sounds, but since some are inhibited promptly and others considerably after tone onset, two mechanisms of inhibition are inferred. Some units discharge with interspike intervals related primarily to stimulus period while others do not. These latter units seem related to the stimulus intensity and presumably may mediate intensity information. Finally, some spontaneously active units respond to certain continuous tones by grouping their discharges with no increase in discharge rate. These results of the behavior of auditory nerve units suggest that highly complex processing occurs at the cochlear level where the impulses are generated.