Tectorial membrane porosity controls spread of excitation and tuning in the cochlea

Jonathan B. Sellon, Roozbeh Ghaffari, Shirin Farrahi, Guy P. Richardson, Dennis M. Freeman

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Modifications of genes that encode proteins found exclusively in the tectorial membrane (TM) alter mechanical properties and produce a wide range of hearing deficits. However, the changes in TM physical properties responsible for these deficits remain unclear. In particular, the cochlear tuning of Tectb-/- mice is significantly sharper than that of TectaY1870C/+ mice, even though the stiffnesses of TectaY1870C/+ and Tectb-/- TMs are similarly reduced relative to wild-type TMs. Here we show that differences in TM wave properties that are governed by shear viscosity account for these differences in tuning. The shear viscosity of the TM results from the interaction of interstitial fluid with the porous structure of the TM's macromolecular matrix. In basal regions of the cochlea, nanoscale pores of TectaY1870C/+ TMs are significantly larger than those of Tectb-/- TMs. The larger pores in TectaY1870C/+ TMs gives rise to lower shear viscosity (by ∼70%), which in turn, reduces wave speed and increases wave decay constants relative to Tectb-/- TM wave properties. These results demonstrate the importance of TM porosity in cochlear tuning and that TM porosity, not stiffness, underlies the striking differences in hearing between TectaY1870C/+ and Tectb-/- mice.

Original languageEnglish (US)
Title of host publicationMechanics of Hearing
Subtitle of host publicationProtein to Perception - Proceedings of the 12th International Workshop on the Mechanics of Hearing
EditorsDavid P. Corey, K. Domenica Karavitaki
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735413504
DOIs
StatePublished - Dec 31 2015
Event12th International Workshop on the Mechanics of Hearing: Protein to Perception - Cape Sounio, Greece
Duration: Jun 23 2014Jun 29 2014

Publication series

NameAIP Conference Proceedings
Volume1703
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other12th International Workshop on the Mechanics of Hearing: Protein to Perception
CountryGreece
CityCape Sounio
Period6/23/146/29/14

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Sellon, J. B., Ghaffari, R., Farrahi, S., Richardson, G. P., & Freeman, D. M. (2015). Tectorial membrane porosity controls spread of excitation and tuning in the cochlea. In D. P. Corey, & K. D. Karavitaki (Eds.), Mechanics of Hearing: Protein to Perception - Proceedings of the 12th International Workshop on the Mechanics of Hearing [080003] (AIP Conference Proceedings; Vol. 1703). American Institute of Physics Inc.. https://doi.org/10.1063/1.4939394