Olivocochlear Reflex in Humans

人类的橄榄耳蜗反射

• 批准号: 6727453
• 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/6727453
• 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。人们对 MOC 反射的基本特性（例如频率特异性）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来努力解决这些问题。 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 OAE 作为正常人类受试者 MOC 激活水平的非侵入性测定，并比较各种听力环境中的激活水平。实质性的技术进步使我们能够仅使用单一的低水平探测音（我们可以证明它很少或不会引起MOC活动）来测量由对侧和/或同侧声音反射性引起的MOC激活，或由更高的大脑中心引起的MOC激活，并确定这些效应是由MOC传出还是中耳肌肉产生。为了了解人类 MOC 系统的功能组织，我们将在人类中确定探头频率的函数：（目标 la）同侧、对侧和双侧 MOC 反射的相对强度，（目标 lb）MOC 反射的频率特异性，以及（目标 lc）根据耳蜗敏感性变化的 MOC 反射强度。为了确定传出神经是否影响耳蜗调谐，我们将（目标 2）测量传出活动产生的耳蜗调谐变化。为了解决 MOC 系统的功能意义，我们将系统地测量心理物理任务中的 MOC 激活水平（目标 3a），在这些任务中，我们预测 MOC 激活将有助于表现（区分噪声中的瞬态信号）和预期不会带来任何好处的任务，以及（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期间。我们的实验结果将首次对人类 MOC 系统的功能组织进行全面评估，并为理解 MOC 系统在人类听觉中的功能意义提供重要的见解。