Amplification and Suppression of Traveling Waves along the Mouse Organ of Corti: Evidence for Spatial Variation in the Longitudinal Coupling of Outer Hair Cell-Generated Forces
Amplification and Suppression of Traveling Waves along the Mouse Organ of Corti: Evidence for Spatial Variation in the Longitudinal Coupling of Outer Hair Cell-Generated Forces
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DOI：
10.1523/jneurosci.2608-18.2019
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发表时间：
2019-03-06
影响因子：
5.3
通讯作者：
Oghalai, John S.
中科院分区：
文献类型：
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作者：
Dewey, James B.;Applegate, Brian E.;Oghalai, John S.
哺乳动物的听力敏感性和频率选择性依赖于外毛细胞(OHCs)介导的机械放大过程。内耳细胞位于基底膜(BM)顶端的Corti器官内，该器官支持声诱发的行波。众所周知，OHC会产生力量，在它们达到峰值的地方选择性地放大BM行波，并且这种放大会在这个狭窄的耳蜗区从一个位置累积到下一个位置。然而，最近的测量表明，沿Corti器官顶面的行波，即网状板(RL)，在更广泛的区域内被放大。目前尚不清楚OHC的力量是否会沿着RL行波的长度累积，以提供一种形式的“全球”耳蜗放大。在这里，我们研究了RL扩增的空间积累。在不同性别的小鼠中，我们使用音调抑制来自不同耳蜗区的放大，并检查了在行波峰值附近和远离行波峰值附近对RL振动的影响。我们发现，尽管OHC力放大了整个RL行波，但放大只在峰值附近积累，在BM运动被放大的同一区域。这与RL运动参与全局放大机制的概念相矛盾，并揭示了BM和Corti器官的力学性质调节了OHC力如何在空间积累。限制放大的空间组合通过锐化耳蜗行波峰来增强频率选择性，并限制每个位置负责机械敏感性的OHC的数量。
Mammalian hearing sensitivity and frequency selectivity depend on a mechanical amplification process mediated by outer hair cells (OHCs). OHCs are situated within the organ of Corti atop the basilar membrane (BM), which supports sound-evoked traveling waves. It is well established that OHCs generate force to selectively amplify BM traveling waves where they peak, and that amplification accumulates from one location to the next over this narrow cochlear region. However, recent measurements demonstrate that traveling waves along the apical surface of the organ of Corti, the reticular lamina (RL), are amplified over a much broader region. Whether OHC forces accumulate along the length of the RL traveling wave to provide a form of "global" cochlear amplification is unclear. Here we examined the spatial accumulation of RL amplification. In mice of either sex, we used tones to suppress amplification from different cochlear regions and examined the effect on RL vibrations near and far from the traveling-wave peak. We found that although OHC forces amplify the entire RL traveling wave, amplification only accumulates near the peak, over the same region where BM motion is amplified. This contradicts the notion that RL motion is involved in a global amplification mechanism and reveals that the mechanical properties of the BM and organ of Corti tune how OHC forces accumulate spatially. Restricting the spatial buildup of amplification enhances frequency selectivity by sharpening the peaks of cochlear traveling waves and constrains the number of OHCs responsible for mechanical sensitivity at each location.