Olivocochlear Efferent Systems and Cochlear Physiology

描述(申请人提供)：我们发现了一种新的耳蜗运动，它在耳蜗尖半部分的声音神经编码中起着主要作用，耳蜗尖半部分是人类说话的重要区域。这种新的运动不包含在经典行波的横向振动中，而经典行波的横向振动表现为耳蜗基底部的基底膜运动。刺激支配外毛细胞的内侧橄榄耳(MOC)传出抑制这一新的运动，暗示它是由外毛细胞产生或放大的。了解新运动中的实际运动，这一新运动的特性，以及它对神经编码的影响，有望对我们对耳蜗力学的看法产生深远的影响。为了实现这一目标，我们提出了三个目标：(1)为了找到新运动的力学表现，并了解它是如何由毛细胞产生或放大的，我们将测量尖转时Corti器官中结构的运动，并确定这些运动如何受到MOC刺激和偏音的影响。(2)为了表征新运动的特性并了解它如何塑造整个耳蜗声的神经编码，我们将测量听神经(AN)反应，确定新运动与经典横波产生哪些反应特征，并确定这些反应特征的性质。(3)为了揭示经典横向振动与其他运动的相互作用，我们将在平行实验中测量MOC对基转BM和AN反应的影响，这些相互作用可能是耳蜗声放大的基础。这项拟议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，许多影响听力的遗传和后天病理都会破坏这一领域。缺乏正确的耳蜗力学概念框架阻碍了对这些病理的理解、诊断和治疗的进展。了解耳蜗力学，以及OHC在力学中的作用，对于听力几乎所有方面的进步都是至关重要的。

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.