Finite element modelling of electrical coupling in the cochlea

Teal, Paul D. and Ni, Guingjian (2018) Finite element modelling of electrical coupling in the cochlea. In To the Ear and Back Again - Advances in Auditory Biophysics: Proceedings of the 13th Mechanics of Hearing Workshop. vol. 1965, American Institute of Physics.. (doi:10.1063/1.5038455).

Abstract

The operation of each hair cell within the cochlea involves an influx of ions, resulting in an electrical potential at the frequency of the vibration of the basilar membrane at the hair cell location. The electrical potential influences the operation of the cochlea at nearby locations, and can also be detected as the cochlear microphonic signal. The effect of these potentials has been proposed as a mechanism for the non-local operation of the cochlear amplifier, and the interaction of such potentials has been thought to be the cause of the broadness of cochlear microphonic tuning curves. The spatial extent of influence of these potentials is an important parameter for determining the significance of its effects. Calculations of this range has typically been based on calculating the longitudinal resistance of each of the scalae from the scala cross sectional area, and the conductivity of the lymph. The voltage has been thought to decay exponentially with distance along the cochlea from the site of its generation, although the values of the length constant vary considerably between experiments. In this paper, the range of influence of the electrical potential is examined using an electrical finite element model. The behaviour of the voltage is found to decay as a power law with distance rather than exponentially. The results can be interpreted as a result of the small size of the hair cells: The coupling required for the cross-sectional areas of the scalae to be relevant does not occur.

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Contributors

Author: Guingjian Ni

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