Anatomy of Olivocochlear Neurons
Hair cell receptors for the hearing and balance organs, and the lateral line, are unique among the senses by receiving an efferent innervation of the periphery. Olivocochlear (OC) neurons supply this efferent innervation, and they are the most peripheral of the many descending neural systems of the central auditory pathway (see Schofield, Chap. 9). OC neurons are named by their origins in the superior olivary complex and terminations in the cochlea (Fig. 2.1). In the cochlea, they innervate the hair cells and auditory-nerve fibers. This chapter mainly covers the new ground on OC anatomy in mammals since Warr’s (1992) comprehensive chapter on this topic about 15 years ago. Since that time, there is even stronger evidence for the separate innervation of the periphery by the two major groups of OC neurons. It is also now clear that both of these groups consist of distinct subgroups. There is additional information on the reflex pathways leading up to OC neurons that enables their response to sound. Overall, this anatomy may help to define the functions that OC neurons perform in the sense of hearing.
KeywordsHair Cell Cochlear Nucleus Auditory Nerve Fiber Lateral Superior Olive Inner Hair Cell
I thank Dr. M. Charles Liberman for comments on the manuscript and Ms. Marie Drottar for assistance with the figures. This work was Supported by NIH grant DCD 01089.
- Brown MC (2002) Cochlear projections of single medial olivocochlear (MOC) axons in the guinea pig. ARO Absts 25:310Google Scholar
- Smith PH, Joris PX, Banks MI, Yin TCT (1993) Responses of cochlear nucleus cells and projections of their axons. In: Merchan MA, Juiz JM, Godfrey DA, Mugnaini E (eds) The mammalian cochlear nuclei: Organization and function. Plenum Press, New York, pp 349–360Google Scholar
- Spangler KM, White JS, Warr WB (1986) Electron microscopic features of axon terminals on olivocochlear neurons in the cat. Assoc Res Otolaryngol Abstr 9:37–38Google Scholar
- Stopp PE (1983) The distribution of the olivocochlear bundle and its possible role in frequency/intensity coding. In: Klinke R, Hartmann R (eds) Hearing-physiological bases and physchophysics. Springer, Berlin, pp 176–179Google Scholar
- Warr WB (1992) Organization of olivocochlear efferent systems in mammals. In: Webster DB, Popper AN, Fay RR (eds) The mammalian auditory pathway: Neuroanatomy. Springer, New York, pp 410–448Google Scholar
- White JS (1984) Fine structure of medial olivocochlear neurons in the rat. Soc Neurosci Abstr 10:393Google Scholar
- White JS (1986) Differences in the ultrastructure of labyrinthine efferent neurons in the albino rat. ARO Abstr 9:34–35Google Scholar