OLIVOCOCHLEAR EFFERENT SYSTEMS

多年来，人们一直不知道内侧橄榄耳蜗 神经元，只终止于外毛细胞，可以强烈地 抑制有髓神经纤维的活动， 只起源于内毛细胞。 近些年来却因为 对外毛细胞作用的思考发生了根本性的变化 在耳蜗力学方面， 传出神经可在耳蜗内产生机械变化。 这些都导致了一种假设，即抑制 内侧橄榄耳蜗传出活动的神经纤维， 通过毛细胞水平的机械偶联介导。 然而，几乎没有数据表明， 产生这种耦合的机制或 偶合器. 我们的目标是确定这些属性， 了解如何实现耦合。 另一个目标是 确定传出活动可能发生的条件 功能上很重要。 通过这些结合，我们 试图了解中枢神经系统是如何影响 耳蜗功能 建议在两个领域开展工作。 第一个项目是针对 测量产生的耳蜗中的宏观机械变化 通过内侧橄榄耳蜗传出神经的活动，使用 在过去的两年里，方法学发展。 要执行此操作， 传出引起的耳道声压变化将 测定了 具体的实验将确定基本的 这些机械变化的性质，沿着 发生变化的耳蜗长度，以及 它们提供声音放大的程度 在耳蜗内。 第二个项目旨在确定 声诱发橄榄耳蜗电活动对耳蜗的影响 传出神经 这将通过测量声音诱发的变化来完成 耳道声压和复合动作电位 听觉神经。

For many years it was unknown how medial olivocochlear neurons, which terminate only on outer hair cells, can strongly suppress activity of myelinated auditory-nerve fibers, which originate only from inner hair cells. Recently there has been a fundamental change in thinking about the role of outer hair cells in cochlear mechanics, and the demonstration that cochlear efferents can produce mechanical changes within the cochlea. These have led to the hypothesis that the suppression of auditory-nerve fibers by medial olivocochlear efferent activity is mediated through mechanical coupling at the hair cell level. There are almost no data, however, which indicate the mechanisms which produce this coupling or the properties of the coupling. Our goals are to determine these properties and to understand how the coupling is achieved. Another goal is to determine the conditions under which efferent activity might be functionally significant. Through the combination of these, we seek to learn how the central nervous system is able to influence cochlear function. Work in two areas is proposed. The first project is aimed at measuring the macromechanical changes in the cochlea produced by activity in medial olivocochlear efferents, using a methodology developed during the past two years. To do this, efferent-induced changes in ear-canal sound pressure will be measured. Specific experiments will determine the basic properties of these mechanical changes, the extent along the length of the cochlea over which the changes occur, and the degree to which they provide a measure of sound amplification within the cochlea. The second project seeks to determine the effects on the cochlea of sound-evoked activity of olivocochlear efferents. This will be done by measuring sound-evoked changes in ear-canal sound pressure and in the compound action potential of the auditory nerve.