Efferent innervation to the cochlea

Abstract

The auditory system consists of ascending and descending neuronal pathways. The beststudied is the ascending pathway, whereby sounds that are transduced in the cochlea intoelectrical signals are sent to the brain via the auditory nerve. Before reaching the auditorycortex, auditory ascending information has several central relays: the cochlear nucleus andsuperior olivary complex in the brainstem, the lateral lemniscal nuclei and inferior colliculusin the midbrain, and the medial geniculate body in the thalamus. The function(s) of the descendingcorticofugal pathway is less well understood. It plays important roles in shaping oreven creating the response properties of central auditory neurons and in the plasticity of theauditory system, such as reorganizing cochleotopic and computational maps. Corticofugalprojections are present at different relays of the auditory system. This review focuses on thephysiology and plasticity of the medial efferent olivocochlear system.