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The frequency limit of outer hair cell motility measured in vivo

Outer hair cells (OHCs) in the mammalian ear exhibit electromotility, electrically driven somatic length changes that are thought to mechanically amplify sound-evoked vibrations. For this amplification to work, OHCs must respond to sounds on a cycle-by-cycle basis even at frequencies that exceed the...

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Autores principales: Vavakou, Anna, Cooper, Nigel P, van der Heijden, Marcel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759357/
https://www.ncbi.nlm.nih.gov/pubmed/31547906
http://dx.doi.org/10.7554/eLife.47667
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author Vavakou, Anna
Cooper, Nigel P
van der Heijden, Marcel
author_facet Vavakou, Anna
Cooper, Nigel P
van der Heijden, Marcel
author_sort Vavakou, Anna
collection PubMed
description Outer hair cells (OHCs) in the mammalian ear exhibit electromotility, electrically driven somatic length changes that are thought to mechanically amplify sound-evoked vibrations. For this amplification to work, OHCs must respond to sounds on a cycle-by-cycle basis even at frequencies that exceed the low-pass corner frequency of their cell membranes. Using in vivo optical vibrometry we tested this theory by measuring sound-evoked motility in the 13–25 kHz region of the gerbil cochlea. OHC vibrations were strongly rectified, and motility exhibited first-order low-pass characteristics with corner frequencies around 3 kHz– more than 2.5 octaves below the frequencies the OHCs are expected to amplify. These observations lead us to suggest that the OHCs operate more like the envelope detectors in a classical gain-control scheme than like high-frequency sound amplifiers. These findings call for a fundamental reconsideration of the role of the OHCs in cochlear function and the causes of cochlear hearing loss.
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spelling pubmed-67593572019-09-26 The frequency limit of outer hair cell motility measured in vivo Vavakou, Anna Cooper, Nigel P van der Heijden, Marcel eLife Neuroscience Outer hair cells (OHCs) in the mammalian ear exhibit electromotility, electrically driven somatic length changes that are thought to mechanically amplify sound-evoked vibrations. For this amplification to work, OHCs must respond to sounds on a cycle-by-cycle basis even at frequencies that exceed the low-pass corner frequency of their cell membranes. Using in vivo optical vibrometry we tested this theory by measuring sound-evoked motility in the 13–25 kHz region of the gerbil cochlea. OHC vibrations were strongly rectified, and motility exhibited first-order low-pass characteristics with corner frequencies around 3 kHz– more than 2.5 octaves below the frequencies the OHCs are expected to amplify. These observations lead us to suggest that the OHCs operate more like the envelope detectors in a classical gain-control scheme than like high-frequency sound amplifiers. These findings call for a fundamental reconsideration of the role of the OHCs in cochlear function and the causes of cochlear hearing loss. eLife Sciences Publications, Ltd 2019-09-24 /pmc/articles/PMC6759357/ /pubmed/31547906 http://dx.doi.org/10.7554/eLife.47667 Text en © 2019, Vavakou et al http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Neuroscience
Vavakou, Anna
Cooper, Nigel P
van der Heijden, Marcel
The frequency limit of outer hair cell motility measured in vivo
title The frequency limit of outer hair cell motility measured in vivo
title_full The frequency limit of outer hair cell motility measured in vivo
title_fullStr The frequency limit of outer hair cell motility measured in vivo
title_full_unstemmed The frequency limit of outer hair cell motility measured in vivo
title_short The frequency limit of outer hair cell motility measured in vivo
title_sort frequency limit of outer hair cell motility measured in vivo
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6759357/
https://www.ncbi.nlm.nih.gov/pubmed/31547906
http://dx.doi.org/10.7554/eLife.47667
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