An intrinsic frequency limit to the cochlear amplifier

摘要: Hearing in mammals depends on a feedback process within the inner ear termed 'cochlear amplifier'. The essential components of this amplifier are sensorimotor cells, outer hair which transduce motion basilar membrane induced by sound and generate forces to cancel viscous damping cochlear partition. Outer cells alter passive mechanics cochlea, enhancing both sensitivity frequency selectivity auditory system. molecular basis mechanism is thought be voltage-sensitive 'motor' protein, as yet unidentified, embedded basolateral cell. operates up at least 22 kHz, but measuring charge mechanical movements associated with motor isolated patches under voltage clamp, we show here that limiting lies near 25 kHz. This value therefore sets an upper limit range hearing mammalian cochleas using mechanism. fast movement, arising from displacement presumed molecule, further suggests protein more likely related transporter than modified ion channel.