Inner Hair Cells(IHCs)
Overview / Synapses / Physiology
Drawings: S. Blatrix

From mechano-transduction to neurotransmission

Schematically, the bending of stereocilia allows K+ to flow into the IHC, which is thus depolarised (see also animation from the transduction page).

This opens voltage-gated Ca2+ channels.

Calcium is involved in neurotransmitter (glutamate) release and also in a K+ active exit mechanism.

Main characteristics of IHC physiology
(to be developed)

IHC resting potential is low (around -40 mV). This is a value very close to that needed for the opening of voltage-gated Ca2+ channels; thus the synapse can be activated quickly.

Micro-electrode recordings (see ref.a) show that IHC tuning is as sharp as that of auditory nerve fibres, thus indicating that tuning is a presynaptic issue (see later: OHC active mechanism). In addition, the IHC tuning properties disappear when OHCs are damaged.

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