LOCAL EFFERENT ACTIVATION THROUGH INFERIOR COLLICULUS

描述：(改编自调查人员摘要)这一目标 这个项目是为了加深我们对下行的传出神经的理解 系统。我们提出了一种新的局部电刺激传出激活的方法 刺激下丘(IC)。集成电路大体上分为 三个亚核，中央核(ICC)、外部核(ICx)和背侧核(ICD)。这个 对IC的下降投影来自于 中枢神经系统。ICx的输入来自听觉和 非听觉区域。ICD的输入来自听觉神经中心。这个 ICC不接收递减投影，但将传出投影发送到LOWER 脑干位置，以及ICx和ICD。不同的投入和产出 根据IC建议每个IC可能扮演的不同角色或职能 下行系统。初步研究表明，对ICC的刺激具有 频率对耳蜗神经输出的特定影响。具体的 目的是描述研究电刺激对大脑的影响。 对侧和同侧IC的单个亚核。目标I 假设局部刺激ICx导致弥漫性 耳蜗神经输出减少。这种普遍的减少 耳蜗输出可能是选择性注意现象的基础 到另一个感官事件。Aim I还假设局部刺激 ICC和ICD对耳蜗声强直定位的影响 回应。耳蜗神经动作电位与耳道的关系 使用IC和不使用IC将测量耳声发射响应 刺激。这两项应对措施允许潜在地区分 外侧和内侧传出系统。内侧传出神经激活影响 转导过程通过其对外毛细胞的影响来实现。侧向 系统只影响内毛细胞下方的传入突触。AIM II 假设局部IC刺激将导致特定频率 掩蔽噪声条件下的耳蜗神经输出增加。这些 研究将重点放在改善信号检测的传出作用上 在嘈杂声中。与以往的传出激活方法相比，IC刺激 可以更接近地模仿传出系统在清醒行为中的作用 动物。这些研究有很大的潜力来提高我们对 传出系统及其在听觉加工中的作用。

DESCRIPTION: (Adapted from the Investigator's Abstract) The goal of this project is to further our understanding of the descending, efferent neural system. We present a new method of efferent activation by localized electrical stimulation of the inferior colliculus (IC). The IC is grossly divided into three subnuclei, the central (ICC), external (ICX) and dorsal (ICD). The descending projections to the IC derive from a variety of locations within the central nervous system. The inputs to the ICX derive from auditory as well as nonauditory areas. The input to the ICD is from auditory neural centers. The ICC receives no descending projections but sends efferent projections to lower brainstem locations, as do ICX and ICD. The divergent inputs to and outputs from the IC suggest possible different roles or functions for each IC descending system. The preliminary studies show that ICC stimulation has frequency specific affects on the neural output of the cochlea. The Specific Aims describe studies that examine the effects of electrical stimulation of the individual subnuclei of the contralateral and ipsilateral IC. Aim I hypothesizes that localized stimulation of the ICX results in diffuse reductions of neural output of the cochlea. Such a generalized reduction in cochlear output might form the basis of the phenomenon of selective attention to another sensory event. Aim I also hypothesizes that localized stimulation of the ICC and ICD results in tonotopically localized effects on the cochlear responses. The cochlear whole-nerve action potential and the ear canal otoacoustic emission responses will be measured with and without IC stimulation. The two response measures allow potential differentiation of lateral and medial efferent systems. Medial efferent activation affects the transduction process through its influence on the outer hair cell. The lateral system only affects the afferent synapse below the inner hair cell. Aim II hypothesizes that localized IC stimulation will result in frequency specific increases in cochlear neural output under conditions of masking noise. These studies will focus on the efferent role in the improvement of signal detection in noise. Compared to previous methods of efferent activation, IC stimulation may mimic more closely the role of the efferent system in the awake behaving animal. These studies have great potential to improve our understanding of the efferent system and its role in auditory processing.