The medial olivocochlear efferent system in humans: structure and function

The mammalian cochlea receives innervation from the central nervous system via two efferent systems: the lateral and the medial olivocochlear bundles. Advances in cochlear physiology have clarified the origins and termination s of these fibers. However, to date, while the functional significance of l ateral efferents remains totally unknown, that of medial efferents is still controversial. The peripheral effects of medial olivocochlear system activ ation have been described, but the role of this inhibitory feedback onto th e cochlea is still unclear. This overview summarizes the main results of se veral psychophysiological studies performed in humans dealing with the func tional significance of medial olivocochlear efferents in hearing.