Hearing links

Hair cells in the inner ear are among the most sensitive mechanical transducers in the human body. The key players in the conversion of sound waves and motion into the electrical impulses that underlie our senses of hearing and balance are bundles of bristly stereocilia that protrude from the top of the hair cells. As seen in this scanning electron micrograph (top) of rodent hair cells, the stereocilia are arranged in rows, with each row taller than the one in front of it. Connecting the tops of stereocilia in adjacent rows are filaments called tip links. In addition to ensuring that the entire bundle moves together, the tip links are thought to be responsible for the mechanoelectrical transduction: As the stereocilia get pushed toward the taller rows, the tip links stretch and open ion channels that generate an electrical response; movement toward the shorter rows inhibits the opening of the...