Dr. Dolores Bozovic, Rockefeller University

Mechano-electrical transduction and amplification by inner ear hair cells

The first step in auditory processing occurs when sound impinges upon an array of inner ear hair cells, which detect mechanical deflections and convert them into electrical signals. The array of hair cells performs a spectral analysis on the incoming sound, with each cell acting as a filter that is tuned to optimally detect a particular frequency. Several lines of evidence indicate that hair cells furthermore possess an active process, a mechanical amplifier that partially overcomes the viscous damping in the inner ear. In non-mammalian organisms, active hair-bundle motility provides the underlying amplification mechanism. In this talk, we shall discuss recordings of mechanical responses obtained from hair bundles of the bullfrog's sacculus. The spontaneous oscillations and electrically evoked movements of the bundles, as well as the effects of pharmacological agents on both processes, can be explained by a model that posits an interaction of myosin-based adaptation and Ca2+-driven reclosure of transduction channels.