Frequency tuning of medial-olivocochlear-efferent acoustic reflexes in humans as functions of probe frequency
Open Access
- 15 March 2012
- journal article
- research article
- Published by American Physiological Society in Journal of Neurophysiology
- Vol. 107 (6), 1598-1611
- https://doi.org/10.1152/jn.00549.2011
Abstract
The medial-olivocochlear (MOC) acoustic reflex is thought to provide frequency-specific feedback that adjusts the gain of cochlear amplification, but little is known about how frequency specific the reflex actually is. We measured human MOC tuning through changes in stimulus frequency otoacoustic emissions (SFOAEs) from 40-dB-SPL tones at probe frequencies ( fps) near 0.5, 1.0, and 4.0 kHz. MOC activity was elicited by 60-dB-SPL ipsilateral, contralateral, or bilateral tones or half-octave noise bands, with elicitor frequency ( fe) varied in half-octave steps. Tone and noise elicitors produced similar results. At all probe frequencies, SFOAE changes were produced by a wide range of elicitor frequencies with elicitor frequencies near 0.7–2.0 kHz being particularly effective. MOC-induced changes in SFOAE magnitude and SFOAE phase were surprisingly different functions of fe: magnitude inhibition largest for fe close to fp, phase change largest for fe remote from fp. The metric ΔSFOAE, which combines both magnitude and phase changes, provided the best match to reported (cat) MOC neural inhibition. Ipsilateral and contralateral MOC reflexes often showed dramatic differences in plots of MOC effect vs. elicitor frequency, indicating that the contralateral reflex does not give an accurate picture of ipsilateral-reflex properties. These differences in MOC effects appear to imply that ipsilateral and contralateral reflexes have different actions in the cochlea. The implication of these results for MOC function, cochlear mechanics, and the production of SFOAEs are discussed.Keywords
This publication has 72 references indexed in Scilit:
- Evaluating Adaptation and Olivocochlear Efferent Feedback as Potential Explanations of Psychophysical OvershootJournal of the Association for Research in Otolaryngology, 2011
- Acoustic stimulation of human medial olivocochlear efferents reduces stimulus-frequency and click-evoked otoacoustic emission delays: Implications for cochlear filter bandwidthsHearing Research, 2010
- Otoacoustic Estimation of Cochlear Tuning: Validation in the ChinchillaJournal of the Association for Research in Otolaryngology, 2010
- Contralateral acoustic stimulation alters the magnitude and phase of distortion product otoacoustic emissionsThe Journal of the Acoustical Society of America, 2009
- Human Medial Olivocochlear Reflex: Effects as Functions of Contralateral, Ipsilateral, and Bilateral Elicitor BandwidthsJournal of the Association for Research in Otolaryngology, 2009
- Considering distortion product otoacoustic emission fine structure in measurements of the medial olivocochlear reflexThe Journal of the Acoustical Society of America, 2009
- Reciprocal Synapses Between Outer Hair Cells and their Afferent Terminals: Evidence for a Local Neural Network in the Mammalian CochleaJournal of the Association for Research in Otolaryngology, 2008
- Medial olivocochlear efferent inhibition of basilar-membrane responses to clicks: Evidence for two modes of cochlear mechanical excitationThe Journal of the Acoustical Society of America, 2008
- Testing coherent reflection in chinchilla: Auditory-nerve responses predict stimulus-frequency emissionsThe Journal of the Acoustical Society of America, 2008
- Measurement of the Distribution of Medial Olivocochlear Acoustic Reflex Strengths Across Normal-Hearing Individuals via Otoacoustic EmissionsJournal of the Association for Research in Otolaryngology, 2007