title: Imaging electrically evoked micromechanical motion within the organ of corti of the excised gerbil cochlea.
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.
authors.affiliation: Harvard-Massachusetts Institute of Technology, Division of Health Sciences and Technology, Speech and Hearing Bioscience and Technology Program, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. domenica@alum.mit.edu
authors.forename: K Domenica
authors.initials: KD
authors.lastname: Karavitaki
authors.forename: David C
authors.initials: DC
authors.lastname: Mountain
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002478:Cells, Cultured; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D005849:Gerbillinae; D018072:Hair Cells, Auditory, Outer / Q000166:cytology / Q000502:physiology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D044085:Microfluidics / Q000379:methods*; D018715:Microscopy, Video / Q000379:methods*; D009068:Movement / Q000502:physiology*; D009925:Organ of Corti / Q000166:cytology / Q000502:physiology*; D013314:Stress, Mechanical