A revised model of the inner-hair cell and auditory-nerve complex

Abstract

A revised computational model of the inner-hair cell (IHC) and auditory-nerve (AN) complex is presented and evaluated. Building on previous models, the algorithm is intended as a component for use in more comprehensive models of the auditory periphery. It combines smaller components that aim to be faithful to physiology in so far as is practicable and known. Transduction between cochlear mechanical motion and IHC receptor potential (RP) is simulated using a modification of an existing biophysical IHC model. Changes in RP control the opening of calcium ion channels near the synapse, and local calcium levels determine the probability of the release of neurotransmitter. AN adaptation results from transmitter depletion. The exact timing of AN action potentials is determined by the quantal and stochastic release of neurotransmitter into the cleft. The model reproduces a wide range of animal RP and AN observations. When the input to the model is taken from a suitably nonlinear simulation of the motion of the cochlear partition, the new algorithm is able to simulate the rate-intensity functions of low-, medium-, and high-spontaneous rate AN fibers in response to stimulation both at best frequency and at other frequencies. The variation in fiber type arises in large part from the manipulation of a single parameter in the model: maximum calcium conductance. The model also reproduces quantitatively phase-locking characteristics, relative refractory effects, mean-to-variance ratio, and first- and second-order discharge history effects.

Basic auditory processes involved in the analysis of speech sounds

“…Also, the transformation from basilar-membrane vibration to neural activity can be simulated more accurately using a hair-cell model (Sumner et al 2002). However, the basic features of the internal representation can be represented reasonably well using models of the type defined by stages (i)-(iv).…”

A phenomenological model of the synapse between the inner hair cell and auditory nerve: Long-term adaptation with power-law dynamics

“…The diversity and complexity of adaptation pose a great challenge for successful modeling of the dynamics of this synapse. Two models with different structures have been developed independently in a series of studies ͑Meddis, 1986͑Meddis, , 1988Westerman and Smith, 1988;Carney, 1993;Zhang et al, 2001;Sumner et al, 2002. However, the mathematical descriptions of these two models are essentially equivalent despite their structural differences ͑Zhang and Carney, 2005͒.…”

Roughness Prediction Based on a Model of Cochlear Hydrodynamics

“…This equation ensures that the stereocilia move in phase with the BM velocity at low frequencies and in phase with the BM displacement at high frequencies (Shamma et al, 1986;Sumner et al, 2002). Bending of the stereocilia opens ion channels.…”

“…Bending of the stereocilia opens ion channels. This is, according to (Sumner et al, 2002), modelled as a change of the apical conductance, G(u), given by a Boltzmann function…”

“…where τ ICa is a time constant (Sumner et al, 2002). The concentration of calcium ions in the cell [Ca 2+ ] is calculated from the calcium current I Ca by…”