Place: 4274 Chamberlin (refreshments will be served)
Speaker: Robert Fettiplace, UW Department of Neuroscience
Abstract: Hair cells, the sensory receptors of the vertebrate inner ear, convert incident sound stimuli into electrical signals. They also separate the sound frequency components along the cochlea behaving like an acoustic prism. Frequency analysis underlies the ability to identify environmental sounds and categorize conspecific calls, and is implemented by two distinct mechanisms. In all vertebrates except mammals, the hair cell receptor potential is electrically tuned by voltage-dependent membrane ion channels, but this process has a limited upper frequency range of a few kHz. In mammals, broad mechanical tuning is augmented by contractions of outer hair cells, underpinned by the piezoelectric protein prestin. Both mechanisms are supported by gradients in hair cell properties along the cochlea. Examples of such gradients include the numbers and types of voltage-dependent potassium channel and of the mechanically-sensitive transducer channel. An important clinical correlate is that hair cells tuned to high frequencies are much more vulnerable to damage by noise and ototoxic agents, and are the first to be lost with aging.