Coupling a sensory hair-cell bundle to cyber clones enhances nonlinear amplification
Coupling a sensory hair-cell bundle to cyber clones enhances nonlinear amplification
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DOI：
10.1073/pnas.0913657107
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发表时间：
2010-05-04
影响因子：
11.1
通讯作者：
Martin, Pascal
中科院分区：
文献类型：
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作者：
Barral, Jeremie;Dierkes, Kai;Martin, Pascal
脊椎动物的耳朵受益于非线性机械放大，可以在很大的声音强度范围内工作。放大过程被认为是由感觉毛细胞产生的主动力。从每个毛细胞的顶面突出的机械感觉毛束可以自发地振荡，并且作为频率选择性的非线性放大器起作用。然而，内在的波动会干扰单个发束对弱刺激的反应，严重限制放大。大多数毛束通过上覆的凝胶状结构机械连接。在这里，我们分析了毛束放大器上的机械耦合的影响，结合牛蛙球囊的毛束的动态力夹与实时随机模拟的毛束力学。这种设置将发束耦合到两个虚拟发束，称为网络克隆，并模拟发束弹性链接到具有相似特征的两个邻居的情况。我们发现，耦合增加了自发发束振荡的相干性。通过有效地降低噪音，毛束和其网络克隆之间的协同相互作用也增强了正弦刺激的放大。所有观察到的耦合效应与模拟定量一致。我们认为，听觉放大器依赖于发束合作，以克服固有的噪声限制，实现高灵敏度和尖锐的频率选择性。
The vertebrate ear benefits from nonlinear mechanical amplification to operate over a vast range of sound intensities. The amplificatory process is thought to emerge from active force production by sensory hair cells. The mechano-sensory hair bundle that protrudes from the apical surface of each hair cell can oscillate spontaneously and function as a frequency-selective, nonlinear amplifier. Intrinsic fluctuations, however, jostle the response of a single hair bundle to weak stimuli and seriously limit amplification. Most hair bundles are mechanically coupled by overlying gelatinous structures. Here, we assayed the effects of mechanical coupling on the hair-bundle amplifier by combining dynamic force clamp of a hair bundle from the bullfrog's saccule with real-time stochastic simulations of hair-bundle mechanics. This setup couples the hair bundle to two virtual hair bundles, called cyber clones, and mimics a situation in which the hair bundle is elastically linked to two neighbors with similar characteristics. We found that coupling increased the coherence of spontaneous hair-bundle oscillations. By effectively reducing noise, the synergic interplay between the hair bundle and its cyber clones also enhanced amplification of sinusoidal stimuli. All observed effects of coupling were in quantitative agreement with simulations. We argue that the auditory amplifier relies on hair-bundle cooperation to overcome intrinsic noise limitations and achieve high sensitivity and sharp frequency selectivity.