I work in the peripheral vestibular and auditory system, focussing on the sensory hair cell. In general, I am interested in signal transduction, calcium homeostasis and synaptic transmission. Over the last several years my work has been directed at understanding the initial stages of sensory transduction, the conversion of a mechanical signal into an electrical signal. The mechanically-gated channels are located at the top of the sensory hair bundle so that deflection of this bundle in one direction opens channels, while deflection of the hair bundle in the other direction closes channels. We have quantitated this calcium permeability and demonstrated a direct correlation between calcium entry and the rate of transducer adaptation.
Adaptation is a complex process involving multiple components.
The rate of fast adaptation varies with the frequency at which the hair cell is tuned. This has allowed us to postulate that fast adaptation underlies a mechanical tuning mechanism in hair cells that may provide both an amplification and filtering mechanism for these cells. In support of this is the recent finding that the transducer current undergoes oscillations at the best frequency for the hair cell and that these oscillations are driven by the fast component of transducer adaptation. In addition to our investigations of calcium homeostasis in hair bundles we have been studying the mechanics of hair bundle movements, in particular focussing on active movements underlying fast adaptation. We have found a correlate of fast adaptation in hair bundle movement that suggests adaptation is a force- generating process.