Sensory Neuroscience Research Group, School of Applied Science, University of Brighton, Brighton, United Kingdom.
Sensory Neuroscience Research Group, School of Applied Science, University of Brighton, Brighton, United Kingdom.
Biophys J. 2024 Sep 17;123(18):3163-3175. doi: 10.1016/j.bpj.2024.07.015. Epub 2024 Jul 15.
Sensory hair cells, including the sensorimotor outer hair cells, which enable the sensitive, sharply tuned responses of the mammalian cochlea, are excited by radial shear between the organ of Corti and the overlying tectorial membrane. It is not currently possible to measure directly in vivo mechanical responses in the narrow cleft between the tectorial membrane and organ of Corti over a wide range of stimulus frequencies and intensities. The mechanical responses can, however, be derived by measuring hair cell receptor potentials. We demonstrate that the seemingly complex frequency- and intensity-dependent behavior of outer hair cell receptor potentials could be qualitatively explained by a two degrees of freedom system with local cochlear partition and tectorial membrane resonances strongly coupled by the outer hair cell stereocilia. A local minimum in the receptor potential below the characteristic frequency should always be observed at a frequency where the tectorial membrane mechanical impedance is minimal, i.e., at the presumed tectorial membrane resonance frequency. The tectorial membrane resonance frequency might, however, shift with stimulus intensity in accordance with a shift in the maximum of the tectorial membrane radial mechanical responses to lower frequencies, as observed in experiments.
感觉毛细胞，包括感觉运动性外毛细胞，使哺乳动物耳蜗具有敏感、精确调谐的反应，它们通过耳蜗和覆盖的盖膜之间的径向剪切而被激发。目前还不可能直接测量在覆盖的盖膜和耳蜗之间的狭窄缝隙中的机械反应，其频率和强度范围很广。然而，可以通过测量毛细胞的感受器电位来推导机械反应。我们证明，外毛细胞感受器电位的看似复杂的频率和强度依赖性行为，可以通过一个具有局部耳蜗分区和盖膜共振的两个自由度系统来定性解释，该系统通过外毛细胞纤毛强烈耦合。在特征频率以下的感受器电位的局部最小值应该总是在一个频率处观察到，在这个频率处，盖膜的机械阻抗最小，即，在假定的盖膜共振频率处。然而，盖膜共振频率可能会随着刺激强度而变化，与实验中观察到的盖膜径向机械反应的最大值向更低频率的偏移相一致。
