| Frequency Tuning of Medial-Olivocochlear-Efferent Acoustic Reflexes in Humans as Functions of Probe Frequency. | |
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MedLine Citation:
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PMID: 22190630 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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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 (f(p)'s) near 0.5, 1 and 4 kHz. MOC activity was elicited by 60 dB SPL ipsilateral, contralateral or bilateral tones or half-octave noise bands, with elicitor frequency (f(e)) 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 kHz being particularly effective. MOC-induced changes in SFOAE magnitude and SFOAE phase were surprisingly different functions of elicitor frequency: magnitude inhibition largest for f(e) close to fp, phase change largest for f(e) remote from f(p). 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 versus 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. |
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Authors:
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Watjana Lilaonitkul; John J Guinan |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-12-21 |
Journal Detail:
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Title: Journal of neurophysiology Volume: - ISSN: 1522-1598 ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2011-12-22 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375404 Medline TA: J Neurophysiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1Massachusetts Institute of Technology. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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