THE BRAIN-STEM EVOKED-RESPONSE AND MEDIAL NUCLEUS OF THE TRAPEZOID BODY

Single-unit responses of cat superior olivary complex neurons to acous tic stimuli were examined to determine whether the units' action poten tials were sufficiently synchronized to contribute to the brain stem e voked response. The medial nucleus of the trapezoid body and lateral s uperior olive are two major nuclei within the cat superior olivary com plex. The first-spike, discharge latencies of medial nucleus of the tr apezoid body and lateral superior olivary neurons to monaural presenta tions of tone burst stimuli were measured as a function of stimulus le vel. Evidence is provided to support the hypotheses that in cat the me dial nucleus of the trapezoid body may contribute directly to the mona ural brain stem evoked response by producing action potentials synchro nized to stimulus onset and may also contribute indirectly to the brai n stem evoked response binaural difference wave b(c) by inhibiting the lateral superior olive unit excitatory responses synchronized to stim ulus onset.