Negative hair-bundle stiffness betrays a mechanism for mechanical amplification by the hair cell
Negative hair-bundle stiffness betrays a mechanism for mechanical amplification by the hair cell
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DOI：
10.1073/pnas.210389497
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发表时间：
2000-10-24
影响因子：
11.1
通讯作者：
Hudspeth, AJ
中科院分区：
文献类型：
--
作者：
Martin, P;Mehta, AD;Hudspeth, AJ
听力和平衡依赖于内耳毛细胞感知微小机械刺激的能力。在每个细胞中，声音或加速度使机械敏感的毛束偏转，毛束是从细胞顶端表面突出的一簇刚性静纤毛。通过改变与机械敏感的转导通道相连的门控弹簧的张力，这种偏转改变了通道的打开概率并消除了电响应。为了检测微弱的刺激，尽管粘性耗散引起的能量损失，毛细胞可以使用主动的发束运动来放大其机械输入。这种放大过程也产生自发的束振荡。使用位移钳系统来测量机械：牛蛙的耳朵的个别的头发束的属性，我们发现，振荡束显示负斜率刚度在其区域的mechanosensitivity的心脏。偏移发束的位置会激活一个自适应过程，该过程会沿位移轴移动负刚度沿着区域。建模表明，负束刚度和负责机械适应的电机之间的相互作用产生类似于观察到的束振荡。除了负性：电可激发细胞和隧道二极管的电阻可以嵌入偏置电路中以放大电信号，负刚度可以被利用以放大耳中的机械刺激。
Hearing and balance rely on the ability of hair cells in the inner ear to sense miniscule mechanical stimuli. In each cell, sound or acceleration deflects the mechanosensitive hair bundle, a tuft of rigid stereocilia protruding from the cell's apical surface. By altering the tension in gating springs linked to mechanically sensitive transduction channels, this deflection changes the channels' open probability and elicits an electrical response. To detect weak stimuli despite energy losses caused by viscous dissipation, a hair cell can use active hair-bundle movement to amplify its mechanical inputs. This amplificatory process also yields spontaneous bundle oscillations. Using a displacement-clamp system to measure the mechanical:properties of individual hair bundles from the bullfrog's ear, we found that an oscillatory bundle displays negative slope stiffness at the heart of its region of mechanosensitivity. Offsetting the hair bundle's position activates an adaptation process that shifts the region: of negative stiffness along the displacement axis. Modeling indicates that the interplay between negative bundle stiffness and the motor responsible for mechanical adaptation produces bundle oscillation similar to that observed. lust as the negative:resistance of electrically excitable cells and of tunnel diodes can be embedded in a biasing circuit to amplify electrical signals, negative stiffness can be harnessed to amplify mechanical stimuli in the ear.