[Abstract Title]. - Society for Neuroscience

Topic: D.02.a. Mechanoreceptors and cochlea
Support: NIH NIDCD DC 00141
NIH NIDCD DC 006273
Title: Measurement of sound-evoked vibrations in the organ of Corti of living guinea pigs using
optical coherence tomography
Authors: J. ZHENG 1 , F. CHEN 1 , N. CHOUDHURY 2 , S. L. JACQUES 2 , *A. L. NUTTALL 1 ;
1 Oregon Hearing Res. Ctr., 2 Biomed. Engineering, Oregon Grad. Inst., Oregon Hlth. Sci. Univ.,
Portland, OR
Abstract: Measurement of sound-evoked vibrations in the organ of Corti of living guinea pigs
using optical coherence tomography
In mammals, the cochlear sensitivity depends on the function of an active mechanism termed
“cochlear amplification” (CA) in the organ of Corti, in which the outer hair cells (OHCs)
generate mechanical forces to enhance the basilar membrane (BM) vibration.CA causes the
sharp tuning and exquisite sensitivity of hearing. In such a unique mechanically- physiologically
coupled system with active mechanical force generation, knowledge of the differential motion of
the key components within the organ of Corti is of crucial importance in understanding cochlear
amplification. Using a newly developed optical coherence tomography (OCT) system and
homodyne interferometry, we observed sound-induced differential motions of two importance
surfaces, the BM and reticular laminar (RL), in the sensitive cochlea of living guinea pigs. We
found that at the same radial location, the vibrations of BM and RL exhibit similar sharp tuning
and sound-level dependent magnitude compression, which are features of mechanical responses
in the sensitive cochlea. Differential motion between the BM and RL was observed, as shown by
differences in magnitude and phase. We observed that the RL has both a higher level of vibration
and a relative phase lead compared the BM. These data represent the first in vivo measurements
of the micromechanical motions of the organ of Corti. The data support the CA mechanism
involves a phase shift for the production of outer hair cell force such that vibration generated
viscous energy losses are compensated. Supported by NIH NIDCD DC 00141 and DC 006273.
Disclosures: J. Zheng, None; F. Chen, None; N. Choudhury, None; S.L. Jacques, None; A.L.
Nuttall , None.
Poster
259. Cochlear Mechanoreceptors
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 259.8/BB4