Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, New York, NY, USA.
J Physiol. 2012 Jan 15;590(2):301-8. doi: 10.1113/jphysiol.2011.218362. Epub 2011 Nov 28.
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.
机械力直接控制机械电转换通道是毛细胞的基本特征，可确保快速转换，并为声输入提供机械放大，但相关的非线性 - 门控顺应性 - 不可避免地会使信号失真。由于减少失真会使耳朵成为更好的探测器，因此我们寻找具有这种效果的机制。我们模仿体内刺激，使用刚性探头以生理幅度位移单个毛束，并使用双光束差动干涉仪测量相对静纤毛运动的相干性和相位。尽管静纤毛在刺激频率下以相干和同相的方式运动，但在内部产生的失真产物的频率下，大的相位滞后表明存在耗散的相对运动。尖端链接参与了这些相对模式，并降低了刺激和自由毛束中的相干性。这些结果表明，在失真频率下，毛束会分解为高度耗散的静纤毛串联排列，从而阻止其放大。
