Karim Al-Fayed Neurobiology of Hearing Laboratory
Hair Cell Transduction
The sensory cells of the inner ear, called hair cells, transduce acoustic and accelerational stimuli into electrical signals that are transmitted to the brain via primary afferent neurons. Stimuli deflect the cells' hair bundles, evoking transduction current through mechanically-gated ion channels. The transduction current changes membrane voltage, modulating voltage-gated ion channels (principally potassium (K) channels).
The net result of current through mechanically- and voltage-gated channels is the receptor potential, which modulates release of neurotransmitter onto afferent neurons. Properties of the ion channels affect the transmitted signal in ways that dramatically affect perception - for example, through adaptation or frequency tuning.
The Karim Al-Fayed Neurobiology of Hearing Laboratory has studied these properties using patch-clamp techniques to record membrane currents and voltages. In some experiments we recorded the transduction currents or receptor potentials evoked by bundle deflection, and in others we recorded the currents or potentials evoked by voltage pulses.
The focus was on processing by hair cells in vestibular organs that detect low-frequency head movements and static head position. The principle model system is the mouse utricle. Relatively little is known about transduction by hair cells in such organs, and there are reasons to expect significant differences relative to the better-studied hair cells in auditory and vibration-sensitive organs. Not only do they operate over very different frequency ranges, but vestibular organs have an unusual hair cell, the type I cell, in addition to the type II cells found in every hair cell organ.