SINGLE CELL MARKING STUDIES OF THE AUDITORY NERVE

描述（研究者摘要）：在哺乳动物的听觉系统中， 与听觉有关的信息通过听觉通道进入大脑， 神经。 两种类型的初级神经元的轴突，I型和II型 螺旋神经节细胞，组成神经并终止于耳蜗 原子核 一般来说，耳蜗核的功能是 接收传入的听觉神经活动，以保存或转换听觉神经。 信号，并将外向活动分配到更高的大脑中心。 我们 长期目标是（1）描述大脑中的神经元回路 耳蜗核和（2）了解机制的早期 大脑中声音信号处理的各个阶段。 了解这些 问题将在很大程度上取决于听觉神经的组织 耳蜗核的输入。 细胞内记录和染色 方法将用于标记单个I型听觉神经纤维。 用辣根过氧化物酶（HRP）标记单纤维， 表征它们的响应特性允许直接比较 纤维的反应特征，轴突和突触形态 以及它与其他神经元的联系。由于难以 从II型听觉神经纤维记录，我们将集中我们的 光镜和电镜特征的分析与比较 I型纤维的那些。 II型纤维将使用以下标记 HRP在听神经或螺旋神经节中的细胞外注射。 我们将检验II型纤维表现出系统性的 在它们的突触形态和连接的差异相比，类型 我纤维。 拟议的研究应产生新的信息， 刺激编码和神经回路的解剖学基础， 听神经和耳蜗核。 这些数据也将与以下方面相关： 感觉神经生物学中更广泛的问题， 用于设计替代无功能耳蜗的假体装置 或听觉神经。

DESCRIPTION (Investigator's Abstract): In the mammalian auditory system, information pertaining to hearing enters the brain by way of the auditory nerve. The axons of two types of primary neurons, type I and type II spiral ganglion cells, compose the nerve and terminate in the cochlear nucleus. In a general way, the function of the cochlear nucleus is to receive incoming auditory nerve activity, to preserve or transform the signals, and to distribute outgoing activity to higher brain centers. Our long-term objectives are (1) to describe the neuronal circuitry in the cochlear nucleus and (2) to understand the mechanisms underlying the early stages of acoustic signal processing in the brain. Knowledge of these issues will depend substantially on the organization of auditory nerve input to the cochlear nucleus. Intracellular recording and staining methods will be used to label individual type I auditory nerve fibers. The marking of single fibers with horseradish peroxidase (HRP) after first characterizing their response properties allows a direct comparison between a fiber's response features, its axonal and synaptic morphology and its connections with other neurons. Because of the difficulty in recording from type II auditory nerve fibers, we will concentrate our analysis on their light and electron microscopic features and compare them to those of type I fibers. Type II fibers will be labeled using extracellular injections of HRP in the auditory nerve or spiral ganglion. We will test the hypothesis that type II fibers exhibit systematic differences in their synaptic morphology and connections compared to type I fibers. The proposed studies should generate new information regarding the anatomical foundations of stimulus coding and neural circuitry in the auditory nerve and cochlear nucleus. The data will also have relevance to broader issues in sensory neurobiology and could be especially important for the design of prosthetic devices that replace nonfunctioning cochleas or auditory nerves.