Vibration of the organ of Corti within the cochlear apex in mice
Vibration of the organ of Corti within the cochlear apex in mice
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DOI：
10.1152/jn.00306.2014
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发表时间：
2014-09-01
影响因子：
2.5
通讯作者：
Oghalai, John S.
中科院分区：
文献类型：
--
作者：
Gao, Simon S.;Wang, Rosalie;Oghalai, John S.
哺乳动物耳蜗的音调分布图通常被认为是由基底膜的被动机械特性决定的。构成Corti器官的其他组织和细胞也具有被动力学特性;然而，它们的作用还不太清楚。此外，由外毛细胞（OHC）产生的主动力增强基底膜的振动，称为耳蜗放大。在这里，我们研究了这些生物力学组件如何使用光学相干断层扫描，它允许组织内的振动测量相互作用。我们不仅测量了经典的基底膜调谐曲线，但也振动反应的其余部分的Corti器官内的小鼠耳蜗尖在体内。正如预期的那样，基底膜调谐在活小鼠中是尖锐的，而在死小鼠中是广泛的。有趣的是，振动响应的区域外侧的OHC，“外侧室”，表现出频率依赖性的相位差相对于基底膜。这在活的和死的老鼠身上都有明显的调整。然后，我们测量了耳蜗力学有针对性的改变转基因小鼠的基底膜和外侧隔室振动。普雷斯廷（499/499）、普雷斯廷（-/-）和Tecta（C1509 G/C1509 G）小鼠没有表现出耳蜗放大，但保持了侧隔室相位差。相反，Sfswap（Tg/Tg）小鼠保持耳蜗放大，但没有表现出侧隔室相位差。这些数据表明，Corti器官具有复杂的微机械振动特性，具有与支持细胞相关的被动但急剧调谐的振动特性。这些特性可以调节OHC力的产生，以产生哺乳动物听觉的尖锐频率选择性。
The tonotopic map of the mammalian cochlea is commonly thought to be determined by the passive mechanical properties of the basilar membrane. The other tissues and cells that make up the organ of Corti also have passive mechanical properties; however, their roles are less well understood. In addition, active forces produced by outer hair cells (OHCs) enhance the vibration of the basilar membrane, termed cochlear amplification. Here, we studied how these biomechanical components interact using optical coherence tomography, which permits vibratory measurements within tissue. We measured not only classical basilar membrane tuning curves, but also vibratory responses from the rest of the organ of Corti within the mouse cochlear apex in vivo. As expected, basilar membrane tuning was sharp in live mice and broad in dead mice. Interestingly, the vibratory response of the region lateral to the OHCs, the "lateral compartment," demonstrated frequency-dependent phase differences relative to the basilar membrane. This was sharply tuned in both live and dead mice. We then measured basilar membrane and lateral compartment vibration in transgenic mice with targeted alterations in cochlear mechanics. Prestin(499/499), Prestin(-/-), and Tecta(C1509G/C1509G) mice demonstrated no cochlear amplification but maintained the lateral compartment phase difference. In contrast, Sfswap(Tg/Tg) mice maintained cochlear amplification but did not demonstrate the lateral compartment phase difference. These data indicate that the organ of Corti has complex micromechanical vibratory characteristics, with passive, yet sharply tuned, vibratory characteristics associated with the supporting cells. These characteristics may tune OHC force generation to produce the sharp frequency selectivity of mammalian hearing.