Steady-state auditory evoked potentials (SSAEPs) in the rabbit. Contribution of the inferior colliculus

Steady-state auditory evoked potentials (SSAEPs) were recorded in rabbits with both surface and depth electrodes. Surface recording from the bregma provided the largest and most typical SSAEPs as compared to other surface locations when a stimulus rate of 50 Hz was used. The medial geniculate body (MGB) showed no potential corresponding to the surface SSAEP. On the other hand, the latency of SSAEP in the inferior colliculus (IC) corresponded closely to that of the surface potential. Furthermore, the amplitude of the IC potential tended to become large with the stimulus rate of 50 Hz as compared with transient stimuli. Although other auditory nuclei in the brain-stem, the ventral nucleus of the lateral lemniscus, the trapezoid body and the auditory nerve responded to transient stimuli with an amplitude larger than that of the IC, no amplification occurred with 50 Hz stimuli in these nuclei. These findings suggest that the IC contributes to the generation of SSAEP to a great extent.