Proceedings of The Physiological Society

Physiology 2015 (Cardiff, UK) (2015) Proc Physiol Soc 34, PC248

Poster Communications

Spontaneous vibration of cochlear basilar membrane:
A model of transient receptor potential coupled with the tip link vibration

A. Shiraishi1,2, H. Konno2,3, N. Takahashi2,3

1. UNIADEX, Tokyo, Japan. 2. Information Science, Hokkaido University of Education, Hakodate, Hakodate, Hokkaido, Japan. 3. International Regional Science, Hokkaido University of Education, Hakodate, Hakodate, Japan.

A mechanism of spontaneous generation of cochlear basilar membrane vibration by hair cells was examined under non-firing hair cell conditions simulated using a transient receptor potential (TRP) channel model equipped with the tandem repeats of outer hair cells driven by the membrane potential based on the Hodgkin-Huxley (HH) equations for their channels including TRP channel. We proposed a model of the TRP channel opening coupled with the tip link vibration, which resulted spontaneous oscillations of the membrane potential gated by TRP channel and the spontaneous vibrations of the basilar membrane through outer hair cell (OHC) electro-motility. The 1 kHz vibration of the basilar membrane associated with the spontaneous motion of TRP channels was found to appear localized in high characteristic frequency region possible to yield otoacoustic emissions. The functional roles of spontaneous otoacoustic emissions were discussed for the maturation process of the auditory system. Maturation of auditory systems needs coincidental projection of action potentials from spiral ganglion neurons subjected to periodic excitation from nearby inner hair cells and the excitation on hair cells changes from autonomous chemical signaling to airborne stimuli after onset of hearing function [1, 2]. A synchronized firing of spiral ganglion neurons is expected for the higher characteristic frequency region than 0.8 kHz in the maturation process because of the imperfect phase rocking. We propose a model explaining the function of spontaneous otoacoustic emission in the maturation process. We used a simplified model for the TRP channel to produce channel current to get membrane potential oscillation resulting spontaneous vibration of the basilar membrane corresponding to the otoacoustic emission [3]. Our model showed a localized generation of spontaneous basilar membrane 1 kHz vibration in high characteristic frequency region on the side of basal turn. A possibility of periodic excitation of spiral ganglion neurons in synchronized fashion was discussed as a role of spontaneous vibration for the maturation process [4, 5].

Where applicable, experiments conform with Society ethical requirements