Olivocochlear Reflex in Humans

描述（由申请人提供）：尽管有许多研究者的工作，我们仍然不知道内侧耳蜗（MOC）传出神经的功能作用。在之前试图将MOC强度与受试者的表现联系起来时，测量的是MOC声反射的被动反应，而不是任务期间MOC的激活。我们现在能够在心理物理任务中测量MOC的激活，这一新的范式极大地提高了我们测试人类听觉系统中MOC功能和下行控制的能力。基于耳声发射（OAE）测量的MOC测试在科学上和临床上都得到了应用，但这种测试的准确性从未得到确定。为了最大限度地提高OAE测试的科学和临床用途，我们将：Aim （1A，B）使用三种类型的诱发OAE来测量MOC效应，并使用对侧和同侧激发子比较MOC强度指标的信噪比和受试者排名准确性；Aim （1C）根据MOC诱导的听觉脑干反应I波的变化来确定人类耳蜗敏感性变化的MOC反射强度。为了解决MOC系统的功能意义，我们将系统地测量心理物理任务中的MOC激活水平：（Aim 2A-C） MOC激活预计有助于性能（在噪声中识别瞬态信号）与那些没有预期益处的任务，以及（Aim 2D-E）确定主动任务中的MOC频率选择性。在这项工作中开发的MOC强度测试应该在临床和科学背景下有用，以预测对噪声损伤的易感性，疾病的诊断和跟踪，评估药物的毒性，并显示MOC反馈在正常听力中的作用。拟议的工作也将有助于指出这种反馈应该在多大程度上用于助听器和人工耳蜗植入等假肢装置。

DESCRIPTION (provided by applicant): Despite work by many investigators, we still do not know the functional role of medial olivocochlear (MOC) efferents. In previous attempts to correlate MOC strength with subject performance, the passive response of the MOC acoustic reflex was measured, not the MOC activation during the task. We are now able to measure MOC activation during a psychophysical task, a new paradigm that greatly increases our ability to test MOC function and descending control in the human auditory system. MOC tests based on otoacoustic emission (OAE) measurements are being used both scientifically and clinically, but the accuracy of such tests has never been ascertained. To maximize the scientific and clinical usefulness of OAE tests we will: Aim (1A,B) Measure MOC effects using the three types of evoked OAEs and compare the resulting MOC-strength metrics in terms of signal/noise ratios and accuracy of subject ranking, using both contralateral and ipsilateral elicitors, and Aim (1C) determine, in humans, MOC reflex strength in terms of changes in cochlear sensitivity, as shown by MOC-induced changes in wave I of the auditory brainstem response. To address the functional significance of the MOC system, we will systematically measure MOC activation levels in psychophysical tasks: (Aim 2A-C) in which MOC activation is expected to aid performance (discrimination of transient signals in noise) vs. those in which no benefit is anticipated, and (Aim 2D-E) to determine MOC frequency selectivity in an active task. The MOC strength tests developed in this work should be useful in clinical and scientific contexts to predict susceptibility to noise damage, in the diagnosis and tracking of diseases, in evaluating the toxicity of drugs and to show the role of MOC feedback in normal hearing. The proposed work will also help to indicate the extent to which such feedback should be put in hearing aids and prosthetic devices such as cochlear implants.