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，它在耳蜗顶半部分的声音神经编码中起着重要作用，该区域对人类语音很重要。这种新的运动不包含在经典行波的横向振动中，所述横向振动由耳蜗基底中的基底膜（BM）运动示出。刺激内侧橄榄耳蜗（MOC）传出神经支配外毛细胞（OHC）抑制这种新的运动，这意味着它是由OHC产生或放大的。了解新运动中的实际运动、新运动的性质及其对神经编码的影响，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）为了找到新的运动的机械表现，并了解它是如何产生或放大的OHC，我们将测量Corti器官的顶转结构的运动，并确定这些运动是如何受到MOC刺激和偏置音。(2)为了表征新运动的特性并了解它如何在整个耳蜗中塑造声音的神经编码，我们将测量耳蜗神经（AN）反应，确定新运动与经典横波产生的反应特征，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，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BM和AN反应的影响。所提出的工作的结果将充实一个新的图片耳蜗力学，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后天性病理所破坏。耳蜗力学缺乏正确的概念框架，阻碍了理解，诊断和治疗这些疾病的进展。理解耳蜗力学以及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.