This Article Full Text Full Text (PDF) Supplemental All Versions of this Article: biophysj.106.083634v1 92/9/3294    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Karavitaki, K. D. Articles by Mountain, D. C. Search for Related Content PubMed PubMed Citation Articles by Karavitaki, K. D. Articles by Mountain, D. C.

Imaging Electrically Evoked Micromechanical Motion within the Organ of Corti of the Excised Gerbil Cochlea

K. Domenica Karavitaki ^*  and David C. Mountain   

^* Harvard-Massachusetts Institute of Technology, Division of Health Sciences and Technology, Speech and Hearing Bioscience and Technology Program, Massachusetts Institute of Technology, Cambridge, Massachusetts; and Hearing Research Center, Department of Biomedical Engineering, and Department of Otolaryngology, Boston University, Boston, Massachusetts

Correspondence: Address reprint requests to K. Domenica Karavitaki, Harvard Medical School, Department of Neurobiology, 220 Longwood Ave., Goldenson 443, Boston, MA 02115. Tel.: 617-432 2479; Fax: 617-432-2508; E-mail: domenica{at}alum.mit.edu.

The outer hair cell (OHC) of the mammalian inner ear exhibits an unusual form of somatic motility that can follow membrane-potential changes at acoustic frequencies. The cellular forces that produce this motility are believed to amplify the motion of the cochlear partition, thereby playing a key role in increasing hearing sensitivity. To better understand the role of OHC somatic motility in cochlear micromechanics, we developed an excised cochlea preparation to visualize simultaneously the electrically-evoked motion of hundreds of cells within the organ of Corti (OC). The motion was captured using stroboscopic video microscopy and quantified using cross-correlation techniques. The OC motion at 2–6 octaves below the characteristic frequency of the region was complex: OHC, Deiter's cell, and Hensen's cell motion were hundreds of times larger than the tectorial membrane, reticular lamina (RL), and pillar cell motion; the inner rows of OHCs moved antiphasic to the outer row; OHCs pivoted about the RL; and Hensen's cells followed the motion of the outer row of OHCs. Our results suggest that the effective stimulus to the inner hair cell hair bundles results not from a simple OC lever action, as assumed by classical models, but by a complex internal motion coupled to the RL.

This article has been cited by other articles:

				J. Ashmore Cochlear Outer Hair Cell Motility Physiol Rev, January 1, 2008; 88(1): 173 - 210. [Abstract] [Full Text] [PDF]