Olivocochlear Reflex in Humans

人类的橄榄耳蜗反射

• 批准号: 6851708
• 负责人: JOHN J GUINAN
• 金额: $ 24.88万
• 依托单位: MASSACHUSETTS EYE AND EAR INFIRMARY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6851708
• 关键词: acoustic nerve; auditory discrimination; auditory reflex; auditory stimulus; clinical research; cochlea; ear hair cell; efferent nerve; electrodes; handedness; human subject; olivocochlear bundle; otoacoustic emission; psychoacoustics; psychological tests; sensory signal detection; sound frequency; sound perception; visual stimulus

DESCRIPTION (provided by applicant): Despite advances in understanding many peripheral effects of activating medial olivocochlear (MOC) efferents to outer hair cells (OHCs), as well as the molecular mechanisms underlying those effects, the functional significance of MOC efferents in human audition remains controversial. Basic properties of the MOC reflexes, such as their frequency specificity, are poorly understood. Studies of human efferent function in attention, and detection and/or discrimination of signals, have given seemingly contradictory results, but no study has systematically varied parameters in an effort to resolve these issues. MOC fibers alter the state of the OHCs and thereby affect the generation of otoacoustic emissions (OAEs). Our approach is to use OAEs as a non-invasive assay of MOC activation levels in normal human subjects, and to compare activation levels in a variety of listening contexts. Substantial technical advances allow us to use only a single low-level probe tone, which we can demonstrate evokes little or no MOC activity, to measure MOC activation elicited reflexly by contralateral and/or ipsilateral sounds, or elicited by higher brain centers, and to determine whether these effects are produced by MOC efferents or middle-ear-muscles. To understand the functional organization of the human MOC system, we will determine in humans as functions of probe frequency: (Aim la) the relative strength of the ipsilateral, contralateral and bilateral MOC reflexes, (Aim lb) the frequency specificity of MOC reflexes, and (Aim lc) MOC reflex strength in terms of the changes in cochlear sensitivity produced. To determine if efferents affect cochlear tuning, we will (Aim 2) measure the changes in cochlear tuning produced by efferent activity. To address the functional significance of the MOC system, we will systematically measure MOC activation levels (Aim 3a) in psychophysical tasks in which we predict that MOC activation will aid performance (discrimination of transient signals in noise) and those in which no benefit is anticipated, and (Aim 3b) during selective attention to auditory vs. visual stimuli, or to one component of an auditory stimulus. The results of our experiments will provide the first comprehensive assessment of the functional organization of the human MOC system and should provide significant insight into the functional significance of the MOC system in human audition.

描述（由申请人提供）：尽管在了解激活内侧橄榄耳蜗（MOC）传出神经对外毛细胞（OHC）的许多外周效应以及这些效应背后的分子机制方面取得了进展，但MOC传出神经在人类听力中的功能意义仍然存在争议。MOC反射的基本特性，如频率特异性，知之甚少。对人类注意力传出功能以及信号检测和/或辨别的研究给出了看似矛盾的结果，但没有研究系统地改变参数以解决这些问题。MOC纤维改变OHC的状态，从而影响耳声发射（OAE）的产生。我们的方法是使用耳声发射作为一种非侵入性的测定MOC激活水平在正常人受试者，并比较激活水平在各种听力环境。实质性的技术进步使我们能够仅使用一个低水平的探测音，我们可以证明唤起很少或没有MOC活动，以测量由对侧和/或同侧声音反射引起的MOC激活，或由更高的大脑中心引起的MOC激活，并确定这些效应是否由MOC传出神经或中耳肌肉产生。为了理解人类MOC系统的功能组织，我们将在人类中确定探测频率的函数：（Aim 1a）同侧、对侧和双侧MOC反射的相对强度，（Aim 1b）MOC反射的频率特异性，以及（Aim 1c）根据所产生的耳蜗灵敏度的变化的MOC反射强度。为了确定传出神经是否影响耳蜗调谐，我们将（目的2）测量传出神经活动产生的耳蜗调谐变化。为了解决MOC系统的功能意义，我们将系统地测量MOC激活水平（目标3a）在心理物理任务中，我们预测，MOC激活将有助于性能（噪声中的瞬态信号的歧视）和那些没有预期的好处，和（目标3b）在选择性注意听觉与视觉刺激，或听觉刺激的一个组成部分。我们的实验结果将提供第一次全面评估的功能组织的人类MOC系统，并应提供显着的洞察MOC系统在人类听觉的功能意义。