Figure 6. Efferent re-arrangements on inner hair cells.

Inner hair cells of the cochlea are temporarily innervated by efferent neurons (red) prior to the onset of hearing (postnatal day 12–14 in rats and mice). Efferent contacts may reappear under conditions that reduce afferent (blue) innervation: age-related hearing loss, acoustic trauma (?), ototoxic damage (?). Thin green lines at efferent contacts represent postsynaptic cisterns. Ribbons (turquoise) surrounded by vesicles (yellow) face afferent boutons.