Cellular approach to auditory signal transmission

Abstract

The aim of this article is to review the findings of current research on the synaptic transmission of the auditory efferent tract from hair cells to brain-stem auditory nuclei. The depolarization of inner hair cells by the activation of mechano-electrical transduction channels induces the entry of Ca ions through the voltage-gated Ca2+ channel. This Ca2+ influx triggers the transmitter release. The transmitter is likely glutamate, and it generates EPSPs at the afferent terminal and elicits action potentials. The intensity and the temporal information of sounds are processed separately by specific auditory tracts and coded as frequency-selective and phase-locked behaviors of action potentials. Recent studies using the whole-cell patch-clamp technique revealed several voltage-gated and chemically gated ion channels; these channels characterize the intensity coding and the time-coding functions of auditory neurons.