Porosity Controls Spread of Excitation in Tectorial Membrane Traveling Waves
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Freeman_Porosity controls.pdf
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Author(s)
Ghaffari, Roozbeh
Farrahi, Shirin
Richardson, Guy P.
Freeman, Dennis M.
Sellon, Jonathan Blake
Date Issued
March 2014
Journal
Biophysical Journal
Publisher
Elsevier
Citation
Sellon, Jonathan B., Roozbeh Ghaffari, Shirin Farrahi, Guy P. Richardson, and Dennis M. Freeman. “Porosity Controls Spread of Excitation in Tectorial Membrane Traveling Waves.” Biophysical Journal 106, no. 6 (March 2014): 1406–1413.
Version
Final published version
Abstract
Cochlear frequency selectivity plays a key role in our ability to understand speech, and is widely believed to be associated with cochlear amplification. However, genetic studies targeting the tectorial membrane (TM) have demonstrated both sharper and broader tuning with no obvious changes in hair bundle or somatic motility mechanisms. For example, cochlear tuning of Tectb[superscript –/–] mice is significantly sharper than that of Tecta[superscript Y1870C/+] mice, even though TM stiffnesses are similarly reduced relative to wild-type TMs. Here we show that differences in TM viscosity can account for these differences in tuning. In the basal cochlear turn, nanoscale pores of Tecta[superscript Y1870C/+] TMs are significantly larger than those of Tectb[superscript –/–] TMs. The larger pore size reduces shear viscosity (by ∼70%), thereby reducing traveling wave speed and increasing spread of excitation. These results demonstrate the previously unrecognized importance of TM porosity in cochlear and neural tuning.
MIT Department
Whitaker College of Health Sciences and Technology
Harvard University--MIT Division of Health Sciences and Technology
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Research Laboratory of Electronics
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Creative Commons Attribution‐NonCommercial License
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DOI of Published Version
https://doi.org/10.1016/j.bpj.2014.02.012
