PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

下丘是几种听觉通路的靶点 在脑干中上升。问题是，这些目标如何 在下丘的构成中，通路相互关联。 理解中央政治局体制的一个根本问题 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。在蝙蝠的下部脑干中， 其中一些通路肥大或特化，因此它们的 可以很容易地检查连接。蝙蝠的独特之处在于它的 容易表征的声纳信号的产生提供了信息 关于它的听觉系统处理的声音刺激。这个 这项提议的总体目标是回答这样一个问题： 来自低位脑干的上行听觉连接汇聚或 在回声定位蝙蝠的下丘发散。重点将是 位于外侧丘系核的通路上，因为这些 回声定位蝙蝠的细胞核肥大且高度组织化。 设计了具体的实验来建立个体之间的联系 外侧丘系腹侧核内的细胞层。其他 设计实验是为了检查向下级的带状投射。 并发现来自一个来源的投射是重叠的还是 与来自第二个来源的投影相互交错。这些方法结合了 [~3H]-亮氨酸和神经示踪技术 小麦胚芽凝集素与辣根过氧化物酶结合。与 使用同一微吸管注射示踪剂并记录的方法 神经反应，注射部位的特征是根据 生理指标，如对频率或位置的反应 声音。蝙蝠听觉通路的特殊部分可以作为 在其他哺乳动物身上的这些部分的模型。有关结构的信息 蝙蝠的听觉系统可能会为研究蝙蝠的结构和 包括人类在内的所有哺乳动物的听觉通路的功能。详细 关于听觉通路连接的知识提供了信息 关于该系统在处理听觉方面的可能性和局限性 信号。这一信息对于诊断本病的病理学是必不可少的。 听力和人工刺激假体装置的设计 在人类严重耳聋的情况下的这一系统。

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.