Evidence for direct cortical innervation of medial olivocochlear neurones in rats.

We have investigated the morphological relationship between auditory cortex efferents and medial olivocochlear neurones. Using combined retrograde and anterograde tracing we describe close contacts between medial olivocochlear neurones and corticofugal terminals in the ventral nucleus of the trapezoid body. The data indicate a possible direct action of the auditory cortex on the activity of the medial olivocochlear neurones and thus possibly the sensitivity of the cochlea.