INHIBITION OF DISCHARGE IN INFERIOR COLLICULUS, A(II) CORTEX AND EP CORTEX AFTER PRESENTATIONS OF CLICK STIMULI

A temporally related reduction of discharge in response to 70-dB click s was identified in secondary auditory (A(II)) cortex (48-56 ms after click), posterior ectosylvian (Ep) cortex (40-56 ms after click) and i nferior colliculus (IC) (56-76 ms after click). Units in primary audit ory (A(I)) cortex, dorsal cochlear nucleus (DCN) and ventral cochlear nucleus (VCN) did not demonstrate arge at comparable periods. Neurons of A(I) cortex showed increased activity 36-40 ms after click. The tim ing of the periods of inhibited discharge in A(II), Ep and IC, taken w ith the earlier activation of A(I), supported the hypothesis of an inh ibitory auditory pathway emanating from A(I), affecting secondary audi tory cortical regions and IC.