| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, 02114; 2 Department of Otology and Laryngology, Harvard Medical School, Boston, 02114; 3 Program in Speech and Hearing Bioscience and Technology, Division of Health Science and Technology, Harvard/Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Submitted 3 July 2003; accepted in final form 12 August 2003
The olivocochlear (OC) efferent innervation of the mammalian inner ear consists of two subdivisions, medial (MOC) and lateral (LOC), with different peripheral terminations on outer hair cells and cochlear afferent terminals, respectively. The cochlear effects of electrically activating MOC efferents are well known, i.e., response suppression effected by reducing outer hair cells' contribution to cochlear amplification. LOC peripheral effects are unknown, because their unmyelinated axons are difficult to electrically stimulate. Here, stimulating electrodes are placed in the inferior colliculus (IC) to indirectly activate the LOC system, while recording cochlear responses bilaterally from anesthetized guinea pigs. Shocks at some IC sites produced novel cochlear effects attributable to activation of the LOC system: long-lasting (5–20 min) enhancement or suppression of cochlear neural responses (compound action potentials and round window noise), without changes in cochlear responses dominated by outer hair cells (otoacoustic emissions and cochlear microphonics). These novel effects also differed from classic MOC effects in their lack of dependence on the level and frequency of the acoustic stimulus. These effects disappeared on sectioning the entire OC bundle, but not after selective lesioning of the MOC tracts or the cochlea's autonomic innervation. We conclude that the LOC pathway comprises two functional subdivisions, capable of inducing slow increases or decreases in response magnitudes in the auditory nerve. Such a system may be useful in maintaining accurate binaural comparisons necessary for sound localization in the face of slow changes in interaural sensitivity.
This article has been cited by other articles:
|
|
 |
|
  D. S. Velenovsky Suppression of Otoacoustic Emissions: An Overview Hearing and Hearing Disorders: Research and Diagnostics, August 1, 2008; 12(1): 4 - 16. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. F. Maison, D. E. Vetter, and M. C. Liberman A Novel Effect of Cochlear Efferents: In Vivo Response Enhancement Does Not Require {alpha}9 Cholinergic Receptors J Neurophysiol, May 1, 2007; 97(5): 3269 - 3278. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. H. Delano, D. Elgueda, C. M. Hamame, and L. Robles Selective Attention to Visual Stimuli Reduces Cochlear Sensitivity in Chinchillas J. Neurosci., April 11, 2007; 27(15): 4146 - 4153. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. N. Darrow, S. F. Maison, and M. C. Liberman Selective Removal of Lateral Olivocochlear Efferents Increases Vulnerability to Acute Acoustic Injury J Neurophysiol, February 1, 2007; 97(2): 1775 - 1785. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. F. Maison, T. W. Rosahl, G. E. Homanics, and M. C. Liberman Functional Role of GABAergic Innervation of the Cochlea: Phenotypic Analysis of Mice Lacking GABAA Receptor Subunits {alpha}1, {alpha}2, {alpha}5, {alpha}6, beta2, beta3, or {delta} J. Neurosci., October 4, 2006; 26(40): 10315 - 10326. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. P. Cooper and J. J. Guinan Jr Efferent-mediated control of basilar membrane motion J. Physiol., October 1, 2006; 576(1): 49 - 54. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
