ACTIVE FILTERING IN THE COCHLEA

最近的实验证据表明，人的外毛细胞 哺乳动物的耳蜗作为机电放大器，增加了 听力敏感度提高了一百倍。建议的长期目标是 研究是为了证实这一假设，并澄清我们对 潜在的机制。这项提议的具体目的是获得 支持详细假说的实验证据 耳蜗功放的功能。我们的具体假设是 外毛细胞受体电流调节力的产生过程 它位于毛细胞胞体内。这个力量产生的过程是 耦合到两种模式的行波传播。世界经济发展的速度 两种模式不同，但在有限的耳蜗区 平起平坐。在这个等速放大的区域中， 对内毛细胞的机械刺激显著增加。 我们计划通过以下方式来表征外毛细胞产生的力量 刺激电压依赖的外毛细胞长度通过 将交流电注入耳蜗骨中阶。这个 所产生的机械反应将被测量为耳声 基底膜的发射和移动与光纤 位移探头。我们还将研究其他人工耳蜗的影响 传出刺激和同步声学等操作 刺激。我们将寻找第二种模式的直接证据 用我们的测力探头测量刚度和行波传播 用我们的位移探头测量位移梯度。 建议的实验结果以及之前的实验结果由 我们自己和其他人将在计算的帮助下被解释 模特们。将使用两种类型的模型：微型机械和 巨型机械。计算模型将以物理为基础，并 包括对器官的机械性能的具体描述 Corti和覆盖膜以及毛细胞机电 转导和外毛细胞运动。

Recent experimental evidence suggests that the outer hair cells of the mammalian cochlea act as electromechanical amplifiers which increase hearing sensitivity one-hundred fold. The long term goal of the proposed research is to confirm this hypothesis and to clarify our understanding of the underlying mechanisms. The specific aim of this proposal is to obtain experimental evidence in support of a detailed hypothesis describing the function of the cochlear amplifier. Our specific hypothesis is that the outer hair cell receptor current regulates a force-generation process which is located in the hair cell soma. This force generation process is coupled to two modes of traveling-wave propagation. The velocities of the two modes differ except over a limited cochlear region where they are equal. In this region of equal velocity amplification takes place and the mechanical stimulus to the inner hair cells is significantly increased. We plan to characterize the forces produced by outer hair cells by stimulating voltage-dependent outer hair cell length changes through the injection of alternating-current into the scala media of the cochlea. The resulting mechanical response will be measured both as an otoacoustic emission as well as movement of the basilar membrane with a fiber-optic displacement probe. We will also study the effects of other cochlear manipulations such as efferent stimulation and simultaneous acoustic stimulation. We will search for direct evidence of a second mode of traveling wave propagation by measuring stiffness with our force probe and displacement gradients with our displacement probe. The results of the proposed experiments as well as previous experiments by ourselves and others will be interpreted with the aid of computational models. Two types of models will be used: micromechanical and macromechanical. The computational models will be physically based and include specific descriptions of the mechanical properties of the organ of Corti and tectorial membrane as well as hair cell mechano-electric transduction and outer hair cell motility.