Cochlear Hair Cells: From Mechanotransduction to Synaptic Transmission
Grand Rounds – Sponsored by the Department of Otolaryngology - Head and Neck Surgery
Featuring David He, M.D., Ph.D.
Associate Professor, Bio-Medical Sciences Department
Location: Gillespie Conference Room, 1st Floor (Building 837)
Questions can be directed to Abby Copeland at email@example.com; 949-824-9107
The organ of Corti in the mammalian cochlea, situated between the basilar membrane (BM) and the tectorial membrane (TM), is an elaborate matrix of sensory cells and supporting cells. The organ transforms transversal BM vibration into a radial shearing stimulus at the apices of the sensory hair cells. There are two types of sensory receptor cells in the organ of Corti: the inner hair cell (IHC) and the outer hair cell (OHC). Both types of hair cells have elongated villi, named stereocilia, emerging from their apical surface. The deflection of the ciliary bundle during BM vibration, and the subsequent flow of transducer current through the mechanotransducer (MET) channels at the tips of the stereocilia produce the receptor potential in both inner and outer hair cells. The receptor potential generated by IHCs facilitates the release of neurotransmitters at their synaptic end. The receptor potential produced by OHCs, however, provides the input to their motor activity. Consequently, the OHC is thought to perform two transducer functions, a conventional mechanoelectrical or forward transduction in the stereocilia, and a specialized electromechanical or reverse transduction in the basolateral membrane. It is generally believed that OHCs provide a frequency-dependent boost to BM motion which enhances the mechanical input to IHCs, thereby promoting enhanced tuning and amplification. The talk will cover some basic properties of mechanoelectrical and electromechanical transduction of OHCs. Recent development in this area will also be covered.