Imaging electrically evoked micromechanical motion within the organ of corti of the excised gerbil cochlea

Biophys J. 2007 May 1;92(9):3294-316. doi: 10.1529/biophysj.106.083634. Epub 2007 Feb 2.

Abstract

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 approximately 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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Biological Clocks / physiology*
  • Cells, Cultured
  • Electric Stimulation / methods
  • Female
  • Gerbillinae
  • Hair Cells, Auditory, Outer / cytology
  • Hair Cells, Auditory, Outer / physiology*
  • Image Interpretation, Computer-Assisted / methods
  • Mechanotransduction, Cellular / physiology*
  • Microfluidics / methods*
  • Microscopy, Video / methods*
  • Movement / physiology*
  • Organ of Corti / cytology
  • Organ of Corti / physiology*
  • Stress, Mechanical