The effects of the activation of the inner-hair-cell basolateral K+ channels on auditory nerve responses

Hear Res. 2018 Jul;364:68-80. doi: 10.1016/j.heares.2018.03.029. Epub 2018 Apr 6.

Abstract

The basolateral membrane of the mammalian inner hair cell (IHC) expresses large voltage and Ca2+ gated outward K+ currents. To quantify how the voltage-dependent activation of the K+ channels affects the functionality of the auditory nerve innervating the IHC, this study adopts a model of mechanical-to-neural transduction in which the basolateral K+ conductances of the IHC can be made voltage-dependent or not. The model shows that the voltage-dependent activation of the K+ channels (i) enhances the phase-locking properties of the auditory fiber (AF) responses; (ii) enables the auditory nerve to encode a large dynamic range of sound levels; (iii) enables the AF responses to synchronize precisely with the envelope of amplitude modulated stimuli; and (iv), is responsible for the steep offset responses of the AFs. These results suggest that the basolateral K+ channels play a major role in determining the well-known response properties of the AFs and challenge the classical view that describes the IHC membrane as an electrical low-pass filter. In contrast to previous models of the IHC-AF complex, this study ascribes many of the AF response properties to fairly basic mechanisms in the IHC membrane rather than to complex mechanisms in the synapse.

Keywords: Adaptation; Auditory nerve; Inner hair cell; K(+) channels; Phase-locking; Recovery.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Cell Membrane / metabolism*
  • Cochlea / innervation*
  • Cochlear Nerve / metabolism*
  • Hair Cells, Auditory, Inner / metabolism*
  • Hearing*
  • Humans
  • Large-Conductance Calcium-Activated Potassium Channels / metabolism*
  • Mechanotransduction, Cellular
  • Membrane Potentials
  • Models, Neurological*
  • Nonlinear Dynamics
  • Potassium / metabolism*
  • Synaptic Transmission
  • Time Factors
  • Vibration

Substances

  • Large-Conductance Calcium-Activated Potassium Channels
  • Potassium