PARALLEL AUDITORY PATHWAYS IN THE BRAIN STEM

中枢听觉系统分成多个平行的 脑干中的上升通道。这些途径中的大多数 终止于下丘(IC)，但少数绕过它。 了解每条途径中的专业化认证和 在他们的目标，IC，的通路之间的关系是一个 认识中央政治局体制的根本问题 听觉系统。回声定位蝙蝠提供了一种特殊的 这是研究这一问题的机会。在脑干的下部 蝙蝠这些通路中的一些起源是肥大的 或高度差异化，以便他们的连接可以很容易地 检查过了。蝙蝠听觉通路的这些部分可能起到 它们的同源物在所有哺乳动物中的模型。蝙蝠的制作 容易表征的声纳信号提供的信息不是 在其他哺乳动物中可获得关于声音刺激的信息 由听觉系统处理。该计划的总体目标 提出的研究是为了回答这样一个问题： 来自低位脑干的上行听觉通路会聚 或在回声定位蝙蝠的下丘发散，如何 这些投射与结构、色调和 IC的细胞化学组织，以及个体的作用 通路可能在处理有关声音刺激的信息方面发挥作用。 另一个目标是检查路径的生理学， 绕过IC，可能在听觉运动中发挥重要作用 关系。专门设计的实验是为了比较 的生理反应特性和上行连接 外侧丘系的不同核；这些核是 在回声定位蝙蝠中肥大且高度组织化。其他 设计实验的目的是将连接模式与 生理反应特性、内源分布 IC中的物质和内在联系。方法 结合电生理学和神经元追踪技术 (~3H)-亮氨酸、四季豆亮氨酸凝集素、辣根过氧化物酶和小麦 生殖细胞凝集素与HRP偶联。同样的微吸管 用来注射示踪剂和记录神经反应，所以 注射部位的特征是根据生理学 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 系统在处理听觉信号方面的优势。这些信息是 对于诊断听力的病理学来说是必不可少的。

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.