LOCAL EFFERENT ACTIVATION THROUGH INFERIOR COLLICULUS

描述：（改编自研究者摘要） 这个项目是为了进一步了解下行传出神经 系统我们提出了一种新的传出激活的方法， 刺激下丘（IC）。IC大致分为 三个亚核，中央（ICC），外部（ICX）和背侧（ICD）。的 IC的下降投影来自于IC内的各种位置。 中枢神经系统ICX的输入来自听觉以及 非听觉区ICD的输入来自听觉神经中心。的 ICC不接受下行投射，但向下丘脑发出传出投射。 脑干位置，如ICX和ICD。不同的输入和输出 建议每个IC可能的不同角色或功能 下降系统初步研究表明，刺激ICC具有 频率特异性影响耳蜗的神经输出。具体 目的描述了检查电刺激对大脑影响的研究 对侧和同侧IC的单个亚核。AIM I 假设ICX的局部刺激导致弥漫性 耳蜗神经输出的减少。这种普遍的减少， 耳蜗输出可能是选择性注意现象的基础 另一个感官事件。目的我还假设，局部刺激 ICC和ICD对耳蜗产生音调定位效应 应答耳蜗全神经动作电位与耳道 耳声发射响应将在有和没有IC的情况下进行测量 刺激.这两种应对措施可以区分 外侧和内侧传出系统。内侧传出激活影响 转导过程通过其对外毛细胞的影响。横向 系统只影响内毛细胞下面的传入突触。Aim II 假设局部IC刺激将导致频率特异性 在掩蔽噪声条件下耳蜗神经输出增加。这些 研究将集中在改善信号检测的传出作用 噪音。与以前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，以提高我们的理解， 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.