Electrophysiological mapping of the auditory areas in the cerebellum of the cat.

We mapped the topographic distribution of auditory evoked potentials over the posterior cerebellum of the cat. Within the posterior vermis, positive-going evoked potentials were primarily recorded in lobule VI and negative ones in lobule VII. Peak latencies of these evoked potentials were between 8 and 18 ms. The amplitudes of evoked potentials from adjacent surface cortical sites often differed significantly. Thus, besides the segregation of positive and negative polarities in the evoked potentials from lobules VI and VII, the distribution of cerebellar auditory evoked potentials within a given lobule contained high- and low-amplitude sites arranged in a patchy pattern. Within the posterior vermis, the evoked potentials showed significant polarity and amplitude changes as a function of depth during microelectrode penetrations which were vertical to the surface of the cerebellar cortex. Cerebellar auditory evoked potentials were not detected over the paramedian lobules and most of the cerebellar hemispheres. There were no significant changes in the electrical activities as a function of depth in these areas. Auditory responses, however, were observed in the most lateral part of the cerebellar hemispheres.