Olivocochlear Efferent Systems and Cochlear Physiology

描述（由申请人提供）：我们发现了一种新的耳蜗运动，它在耳蜗顶叶的声音神经编码中起着重要作用，该区域对人类语言很重要。这种新的运动不包含在耳蜗基底基底膜运动所显示的经典行波的横向振动中。刺激支配外毛细胞（ohc）的内侧耳蜗（MOC）传出神经抑制这种新的运动，这意味着它是由ohc产生或放大的。了解在新的运动中到底是什么在运动，这种新运动的性质，以及它对神经编码的影响，将对我们对耳蜗力学的看法产生深远的影响。为此，我们提出了三个目标：(1)为了找到新运动的力学表现，并了解它是如何被OHCs产生或放大的，我们将测量顶端转Corti器官的结构运动，并确定这些运动如何受到MOC刺激和偏置音调的影响。(2)为了表征新运动的特性并理解它如何在整个耳蜗中形成声音的神经编码，我们将测量听神经（AN）反应，确定哪些反应特征是由新运动产生的，哪些是由经典横波产生的，并确定这些反应特征的特性。(3)为了揭示经典横向振动与其他运动的相互作用，这些相互作用可能是耳蜗放大的基础，我们将在平行实验中测量MOC对基底转动BM和AN响应的影响。这项工作的结果将充实耳蜗力学的新图景，特别是语音频率。力学是耳蜗功能的一个关键领域，它被许多影响听力的遗传和获得性病理所破坏。缺乏正确的耳蜗力学概念框架阻碍了对这些病理的理解、诊断和治疗。了解耳蜗力学，以及OHCs在力学中的作用，对于听力几乎所有方面的进步都是必不可少的。

DESCRIPTION (provided by applicant): We have discovered a new cochlear motion that plays a major role in the neural coding of sound in the apical half of the cochlea, the region important for human speech. This new motion is not contained in the transverse vibration of the classic traveling wave that is shown by basilar-membrane (BM) motion in the cochlear base. Stimulation of medial olivocochlear (MOC) efferents that innervate outer hair cells (OHCs) inhibits this new motion, implying that it is produced, or amplified, by OHCs. Understanding what is actually moving in the new motion, the properties of this new motion, and its effect on neural coding, promises to have a profound impact on our view of cochlear mechanics. To achieve this, we propose three Aims: (1) To find the mechanical manifestation of the new motion and understand how it is produced or amplified by OHCs, we will measure the motion of structures in the organ of Corti of the apical turn, and determine how these motions are affected by MOC stimulation and bias tones. (2) To characterize the properties of the new motion and understand how it shapes the neural coding of sound throughout the cochlea, we will measure auditory-nerve (AN) responses, determine which response features are produced by the new motion vs. by the classic transverse wave, and determine the properties of these response features. (3) To reveal interactions of classic transverse vibration with other motions, interactions that may be the basis of cochlear amplification, we will measure MOC effects on basal-turn BM and AN responses in parallel experiments. The results of the proposed work will flesh out a new picture of cochlear mechanics especially for speech frequencies. Mechanics is a key area of cochlear function that is disrupted by many inherited and acquired pathologies that affect hearing. The lack of a correct conceptual framework for cochlear mechanics hinders progress in understanding, diagnosing, and treating these pathologies. Understanding cochlear mechanics, and the role of OHCs in mechanics, is essential for progress in almost all aspects of hearing.