Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
Biophys J. 2011 Jun 8;100(11):2576-85. doi: 10.1016/j.bpj.2011.04.049.
One of the central questions in the biophysics of the mammalian cochlea is determining the contributions of the two active processes, prestin-based somatic motility and hair bundle (HB) motility, to cochlear amplification. HB force generation is linked to fast adaptation of the transduction current via a calcium-dependent process and somatic force generation is driven by the depolarization caused by the transduction current. In this article, we construct a global mechanical-electrical-acoustical mathematical model of the cochlea based on a three-dimensional fluid representation. The global cochlear model is coupled to linearizations of nonlinear somatic motility and HB activity as well as to the micromechanics of the passive structural and electrical elements of the cochlea. We find that the active HB force alone is not sufficient to power high frequency cochlear amplification. However, somatic motility can overcome resistor-capacitor filtering by the basolateral membrane and deliver sufficient mechanical energy for amplification at basal locations. The results suggest a new theory for high frequency active cochlear mechanics, in which fast adaptation controls the transduction channel sensitivity and thereby the magnitude of the energy delivered by somatic motility.
哺乳动物耳蜗生物物理学的核心问题之一是确定两种主动过程（基于 prestin 的体运动和毛束（HB）运动）对耳蜗放大的贡献。HB 力的产生与通过钙依赖性过程快速适应转导电流有关，而体运动的产生则由转导电流引起的去极化驱动。在本文中，我们基于三维流体表示构建了一个耳蜗的全局机械-电气-声学数学模型。全局耳蜗模型与非线性体运动和 HB 活性的线性化以及耳蜗被动结构和电学元件的细观力学耦合。我们发现，单独的主动 HB 力不足以提供高频耳蜗放大。然而，体运动可以克服基底外侧膜的电阻-电容滤波，并为基底位置的放大提供足够的机械能。结果表明，高频主动耳蜗力学的新理论，其中快速适应控制转导通道的敏感性，从而控制体运动传递的能量大小。
