Auditory Mechanics and the Cochlear Amplifier 2020

项目摘要/摘要：听觉力学和耳蜗学放大2020 声音输入到耳蜗会引起感觉组织运动的频率排序的波型， 将声音信息传递给听觉神经元，从而导致听力。目前无法治愈的一个方面 听力障碍的主要原因是耳蜗对声音的敏锐分离能力的恶化 频率耳蜗健康的频率调谐很大程度上是由耳蜗放大器提供的，一种 外毛细胞驱动、位置频率局部化的机电反馈机制，既 强大而脆弱。本项目的目标1-3探索耳蜗声放大的细胞/结构基础。 这些研究使用了耳壳内传感器以及尖端的成像和振动测量技术， 光谱域光学相干层析成像(SD-OCT)。力学的本地化测量 在健康的两个人中，耳蜗感觉组织和内部的电反应都会发生 正常和改良后的耳蜗内。沙土鼠和豚鼠是耳蜗的关键方面 在目标2中对两个物种的扩增进行了比较。在目标1中，测量是在 耳蜗腔内注射修饰被膜物质前后的变化 (TM)机械学。由于TM控制毛细胞中的转导，因此TM在 耳蜗放大；我们的研究测试了基于耳蜗模型和 在分离的TMS和TM突变小鼠中进行测量。目标3利用SD-OCT的穿透性 测试之前无法测试的科尔蒂器官的流体机械性能的能力。目标4探索 通过中耳将声音传递到耳蜗处，以及这种传递是如何被 来自中耳肌，鼓膜张肌的反馈。在前期工作中，鼓室张肌改良 以一种微妙的、依赖于频率的方式进行传输，这可能涉及到聚焦于特定的 声源，例如在通信期间。鼓室张肌张紧的实验 电压脉冲将决定肌肉如何影响传输的声音信号。

Project Summary / Abstract: Auditory Mechanics and Cochlear Amplification 2020 Sound input to the cochlea causes a frequency-sorted wave-pattern of sensory tissue motion that conveys sound information to the auditory neurons, leading to hearing. A currently untreatable aspect of hearing impairment is the deterioration of the cochlea's ability to sharply separate sound by frequency. The cochlea's healthy frequency tuning is largely provided by the cochlear amplifier, an outer-hair-cell-driven, place-frequency-localized electromechanical feedback mechanism that is both powerful and fragile. This project's aims 1-3 explore the cell/structure basis of cochlear amplification. The studies use intracochlear sensors and a cutting-edge imaging and vibrometry technology, spectral-domain optical-coherence-tomography (SD-OCT). Localized measurements of mechanical and electrical responses at and within the cochlea's sensory tissue will be made both in healthy normal and in modified cochleae. Gerbils and guinea pigs are used and critical aspects of cochlear amplification are compared in the two species in aim 2. In aim 1, measurements are made in cochleae before and after intracochlear injection of substances that will modify tectorial membrane (TM) mechanics. Because it governs transduction in hair cells, the TM plays a profound role in cochlear amplification; our studies test hypotheses that are based on cochlear models and measurements in isolated TMs and in TM-mutant mice. Aim 3 makes use of SD-OCT's penetrating abilities to test previously untestable fluid-mechanical properties of the organ of Corti. Aim 4 explores the transmission of sound to the cochlea by the middle ear, and how this transmission is modified by feedback from the middle ear muscle, tensor tympani. In preliminary work, tensor tympani modified transmission in a subtle, frequency-dependent manner that could be involved in focusing on particular sound sources, for example during communication. Experiments in which tensor tympani is tensed with voltage pulses will determine how the muscle affects the transmitted sound signal.