title: Relative stereociliary motion in a hair bundle opposes amplification at distortion frequencies.
abstract: Direct gating of mechanoelectrical transduction channels by mechanical force is a basic feature of hair cells that assures fast transduction and underpins the mechanical amplification of acoustic inputs, but the associated non-linearity - the gating compliance - inevitably distorts signals. Because reducing distortion would make the ear a better detector, we sought mechanisms with that effect. Mimicking in vivo stimulation, we used stiff probes to displace individual hair bundles at physiological amplitudes and measured the coherence and phase of the relative stereociliary motions with a dual-beam differential interferometer. Although stereocilia moved coherently and in phase at the stimulus frequencies, large phase lags at the frequencies of the internally generated distortion products indicated dissipative relative motions. Tip links engaged these relative modes and decreased the coherence in both stimulated and free hair bundles. These results show that a hair bundle breaks into a highly dissipative serial arrangement of stereocilia at distortion frequencies, precluding their amplification.
authors: Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, New York, NY, USA.
authors: Andrei S
authors: AS
authors: Kozlov
authors: Thomas
authors: T
authors: Risler
authors: Armin J
authors: AJ
authors: Hinterwirth
authors: A J
authors: AJ
authors: Hudspeth
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D005260:Female; D006199:Hair Cells, Auditory, Inner / Q000502:physiology*; D015640:Ion Channel Gating / Q000502:physiology; D007473:Ion Channels / Q000502:physiology; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D023421:Models, Animal; D010469:Perceptual Distortion / Q000502:physiology*; D011892:Rana catesbeiana; D059547:Stereocilia / Q000502:physiology*
chemical_list: D007473:Ion Channels