Middle and Inner Ear Reflexes - Olivocochlear Effects on Signals in Noise

Liberman, M Charles

Abstract

This project investigates the functional significance of the feedback pathway to the inner ear, the olivocochlear bundle (OCB). We have long known that electrical stimulation of the OCB raises thresholds in the auditory periphery, when acoustic stimuli are tones in a quiet environment. More recent work has suggested that shock-induced OCB activity might act to decrease thresholds to tones in certain noisy environments. Since OCB activation can be elicited in response to sound, this efferent reflex could function in enhancing signal detection in noise.
The aim of this project is to quantify efferent-mediated improvements in signal-to-noise ratios in the response of single auditory nerve fibers. Such basic animal studies are needed to understand the function of the OCB in the human. Malfunction of this feedback system in the hearing impaired may prove to be a significant cause of their well-known difficulties with communication in noisy environments.

Funding Agency

• Agency: National Institute of Health (NIH)
• Institute: National Institute on Deafness and Other Communication Disorders (NIDCD)
• Type: Research Program Projects (P01)
• Project #: 5P01DC000119-20
• Application #: 3732171
• Support Year: 20
• Fiscal Year: 1995

Institution

• Name: Massachusetts Eye and Ear Infirmary
• DUNS #: 073825945
• City: Boston
• State: MA
• Country: United States
• Zip Code: 02114

Publications

Gutschalk, Alexander; Oxenham, Andrew J; Micheyl, Christophe et al. (2007) Human cortical activity during streaming without spectral cues suggests a general neural substrate for auditory stream segregation. J Neurosci 27:13074-81

Micheyl, Christophe; Carlyon, Robert P; Gutschalk, Alexander et al. (2007) The role of auditory cortex in the formation of auditory streams. Hear Res 229:116-31

Wilson, E Courtenay; Melcher, Jennifer R; Micheyl, Christophe et al. (2007) Cortical FMRI activation to sequences of tones alternating in frequency: relationship to perceived rate and streaming. J Neurophysiol 97:2230-8

Fullerton, Barbara C; Pandya, Deepak N (2007) Architectonic analysis of the auditory-related areas of the superior temporal region in human brain. J Comp Neurol 504:470-98

Sigalovsky, Irina S; Fischl, Bruce; Melcher, Jennifer R (2006) Mapping an intrinsic MR property of gray matter in auditory cortex of living humans: a possible marker for primary cortex and hemispheric differences. Neuroimage 32:1524-37

Sigalovsky, Irina S; Melcher, Jennifer R (2006) Effects of sound level on fMRI activation in human brainstem, thalamic and cortical centers. Hear Res 215:67-76

Hawley, Monica L; Melcher, Jennifer R; Fullerton, Barbara C (2005) Effects of sound bandwidth on fMRI activation in human auditory brainstem nuclei. Hear Res 204:101-10

Harms, Michael P; Guinan Jr, John J; Sigalovsky, Irina S et al. (2005) Short-term sound temporal envelope characteristics determine multisecond time patterns of activity in human auditory cortex as shown by fMRI. J Neurophysiol 93:210-22

Talavage, Thomas M; Edmister, Whitney B (2004) Nonlinearity of FMRI responses in human auditory cortex. Hum Brain Mapp 22:216-28

Penagos, Hector; Melcher, Jennifer R; Oxenham, Andrew J (2004) A neural representation of pitch salience in nonprimary human auditory cortex revealed with functional magnetic resonance imaging. J Neurosci 24:6810-5