PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

下丘是几个听觉通路的目标， 在脑干中上升 问题是这些目标如何 通路在下丘构成中彼此相关 一个基本的问题，在了解中央结构， 听觉系统 回声定位蝙蝠提供了一个特殊的机会， 研究这个问题。 在蝙蝠的脑干下部， 这些通路中的一些是肥大的或特化的， 可以容易地检查连接。 蝙蝠的独特之处在于 产生容易表征的声纳信号提供了信息 它的听觉系统处理的声音刺激。 的 这个建议的总体目标是回答这个问题， 从下脑干开始的上行听觉连接汇聚， 在回声定位蝙蝠的下丘分叉。 重点将 放置在外侧丘系核的通路上，因为这些 回声定位蝙蝠的核团肥大且高度组织化。 具体的实验设计，以建立个人的联系， 外侧丘系腹侧核的细胞层。 其他 设计实验来检查向下的带状投射 丘，并发现来自一个来源的投影是否重叠， 与来自第二源投影相互交叉。 这些方法联合收割机 使用[3 H]-亮氨酸和 与辣根过氧化物酶结合的麦胚凝集素。 与 使用同一微量移液管注入示踪剂并记录的方法 神经反应，注射部位的特征在于， 生理测量，如对频率或位置的反应， 声音 蝙蝠听觉通路的特殊部分可能是 其他哺乳动物的模型。 关于结构的信息 蝙蝠的听觉系统可能为研究结构和 听觉通路的功能在所有哺乳动物，包括人。详细 关于听觉通路连接的知识提供了信息， 关于系统在处理听觉信息时的可能性和局限性， 信号. 这一信息对于诊断脑梗死的病理学至关重要。 以及人工刺激听觉的假肢装置的设计 该系统的情况下，深度耳聋的人。

The inferior colliculus is the target of several auditory pathways which ascend in the brain stem. The question of how the targets of these pathways are related to one another in the inferior colliculus constitutes a fundamental problem in understanding the structure of the central auditory system. The echolocating bat provides a special opportunity for studying this problem. In the lower brain stem of the bat the origins of some of these pathways are hypertrophied or specialized so that their connections can be readily examined. The bat is unique in that its production of an easily characterized sonar signal provides information about the sound stimuli that are processed by its auditory system. The general goal of this proposal is to answer the question of how different ascending auditory connections from the lower brain stem converge or diverge at the inferior colliculus in echolocating bats. Emphasis will be placed on pathways from the nuclei of the lateral lemniscus, because these nuclei are hypertrophied and highly organized in echolocating bats. Specific experiments are designed to establish the connection of individual layers of cells in the ventral nucleus of the lateral lemniscus. Other experiments are designed to examine banded projections to the inferior colliculus and to discover whether projections from one source overlap or interdigitate with projections from a second source. The methods combine electrophysiology and neuronal tracing techniques using [3H]-leucine and wheat germ agglutinin conjugated to horseradish peroxidase. With the method of using the same micropipette to inject the tracer and to record neural responses, the injection site is characterized according to physiological measures, such as response to frequency or location of sound. The specialized parts of the bat's auditory pathway may serve as models of these parts in other mammals. Information about the structure of the bat's auditory system may provide clues for the study of structure and function of auditory pathways in all mammals, including man. Detailed knowledge about the connections of auditory pathways provides information about possibilities and limitations of the system in processing auditory signals. This information is essential to the diagnosis of pathologies of hearing and to the design of prosthetic devices to artificially stimulate the system in cases of profound deafness in man.