PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

中央听觉系统分成多个平行的 脑干中的上行通路 大多数这些途径 终止于下丘（IC），但少数绕过它。 了解每个途径中的专业化和 在他们的目标，IC的途径之间的关系，是一个 理解中央结构的基本问题 听觉系统 回声定位蝙蝠提供了一种特殊的 有机会研究这个问题。 在脑干下部， 这些通路的起源是肥大的 或高度分化，以便它们的连接可以容易地 考察 蝙蝠听觉通路的这些部分可以作为 所有哺乳动物的同源物的模型。 蝙蝠的生产 容易表征的声纳信号提供的信息， 在其他哺乳动物中， 由听觉系统处理。 疆方略 这项研究的目的是回答这个问题， 从低位脑干开始的上行听觉通路 或者在回声定位蝙蝠的下丘分叉， 这些投影与结构、色调和 IC的细胞化学组织，以及个体 通路可能在处理关于声音刺激的信息中起作用。 另一个目标是研究生理学的途径， 旁路集成电路，并可能发挥重要作用， 连接. 设计了具体的实验来比较 生理反应特性和上升连接， 外侧丘系的不同核;这些核是 在回声定位蝙蝠中是肥大的高度组织化的。 其他 实验的目的是比较模式的连接与 生理反应特性，内源性 IC中的物质和内在连接。 述的方法 联合收割机结合电生理学和神经元追踪技术， （3 H）-亮氨酸、菜豆白细胞凝集素、HRP和小麦 与HRP结合的细菌凝集素。 同样的微量吸液管 用于注射示踪剂并记录神经反应， 注射部位根据生理学特征来表征， 措施 关于蝙蝠听觉结构的信息 路径提供了有关可能性和限制的信息 处理听觉信号的能力。 信息 对听力疾病的诊断至关重要。

The central auditory system diverges into multiple parallel ascending pathways in the brain stem. Most of these pathways terminate in the inferior colliculus (IC), but a few bypass it. Understanding the specializations within each pathway and the relationships among the pathways at their target, the IC, is 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 highly differentiated so that their connections can be readily examined. These parts of the bat's auditory pathway may serve as models of their homologues in all mammals. The bat's production of an easily characterized sonar signal provides information not available in other mammals about the sound stimuli that are processed by the auditory system. The general goal of the proposed research is to answer the question of how different ascending auditory pathways from the lower brain stem converge or diverge at the inferior colliculus in echolocating bats, how these projections are related to the structural, tonotopic and cytochemical organization of the IC, and what role individual pathways may play in processing information about sound stimuli. An additional goal is to examine the physiology of pathways that bypass the IC and may play an important role in auditory-motor connections. Specific experiments are designed to compare physiological response properties and ascending connections from the different nuclei of the lateral lemniscus; these nuclei are hypertrophied and highly organized in echolocating bats. Other experiments are designed to compare patterns of connections with physiological response properties, distribution of endogenous substances and intrinsic connections in the IC. The method combine electrophysiology and neuronal tracing techniques using (3H)-leucine, phaseolus vulgaris leucoagglutinin, HRP and wheat germ agglutinin conjugated to HRP. The same micropipette is used to inject the tracer and to record neural responses, so that the injection site is characterized according to physiological measures. Information about the structure of the bat's auditory pathways provides information about possibilities and limitations of the system in processing auditory signals. The information is essential to the diagnosis of pathologies of hearing.