PHYSIOLOGY OF DORSAL COCHLEAR NUCLEUS MOLECULAR LAYER

耳蜗背核分子层的生理学

• 批准号: 3216852
• 负责人: Paul B Manis
• 金额: $ 8.94万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-01 至 1992-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3216852
• 关键词: aminoacid; antibody receptor; auditory feedback; auditory pathways; auditory stimulus; axon; dendrites; electrophysiology; electrostimulus; guinea pigs; histology; interneurons; neural information processing; neural inhibition; neural initiation; neuropharmacology; neurotransmitters; sequential perception; single cell analysis; stimulus /response; synapses

The first stage of information processing in the central auditory system is mediated by the neural circuits and membrane properties of cells in the cochlear nucleus. One subdivision of the cochlear nucleus, the dorsal cochlear nucleus (DCN), has a particularly complex internal architecture, and the responses of cells in the DCN to acoustic stimuli are substantially modified from their eights nerve inputs. In most superficial layer of this nucleus, a system of fine unmyelinated parallel fibers (axons of granule cells.) make numerous synapses upon the principal projection neurons of the DCN (pyramidal cells) and small interneurons (cartwheel and stellate cells). The parallel fibers provide the substrate for a unique and extensive set of interactions occurring orthogonal to the tonotopic axis of the DCN. It is likely that the parallel fiber system plays an important role in shaping the complex receptive fields and temporal response patterns of the DCN pyramidal cells. In order to understand how the granule cells and their associated local circuitry can influence pyramidal cells, we are studying responses to electrical stimulation of the axons of the granule cells, the parallel fibers. The experiments in this proposal investigate four specific aspects of parallel fiber influences on DCN neurons both in an in vitro brain slice preparation, and in vivo. First, extra- and intracellular recordings will be made from single DCN neurons to study synaptic responses to parallel fiber stimulation. Subsequent to intracellular recordings, neurons will be stained for morphological identification. Responses will be correlated with cell type and laminar position. Second, current source=density analysis will be used to determine the spatial and temporal distribution of current sinks and sources produced by electrical stimulation of the parallel fibers at the pial surface of the nucleus. This analysis will reveal the laminar distribution of synaptic connections between the parallel fibers and DCN neurons. Third, pre- and post-synaptic mechanisms influencing synaptic potentiation at the parallel fiber synapse will be explored. The time course of potentiation will be determined. Fourth, the pharmacology of excitatory synaptic transmission from parallel fibers to their postsynaptic targets, and also of possible inhibitory amino-acid local circuits that can be activated by parallel fibers in the DCN molecular layer, will be investigated. The results of these studies will provide important information on the role of the parallel fiber system in the DCN, and will help generate new theories about the role that this system plays in processing incoming acoustic information. These experiments will also set the stage for subsequent investigations of changes in central physiology that may occur as a function of peripheral acoustic trauma and aging, as well as investigations of the synaptic plasticity and membrane biophysics of DCN neurons.

听觉中枢信息处理的第一阶段 系统由神经回路和膜介导 耳蜗核细胞的特性。 一个细分的 耳蜗背核（DCN）具有一个 特别是复杂的内部结构， DCN中的细胞对声刺激的反应被显著改变 从他们的第八神经输入。 在这片土地的最表层 细胞核，一个细的无髓鞘平行纤维系统（ 颗粒细胞）。在主体上形成无数突触 DCN的投射神经元（锥体细胞）和小 中间神经元（侧手翻和星状细胞）。 平行纤维 为一组独特而广泛的 相互作用发生正交的tonotopic轴 DCN。 平行光纤系统很可能在 在形成复杂的感受野和颞叶中的作用 DCN锥体细胞的反应模式。 为了了解颗粒细胞及其相关的 局部回路可以影响锥体细胞，我们正在研究 对颗粒轴突的电刺激的反应 细胞，平行纤维。 该提案中的实验 研究平行纤维影响的四个具体方面 DCN神经元在体外脑切片制备， vivo. 首先，细胞外和细胞内的记录将从 单个DCN神经元研究对平行纤维的突触反应 刺激. 在细胞内记录之后，神经元将 染色用于形态学鉴定。 答复将 与细胞类型和层位有关。 第二，当前 源=密度分析将用于确定空间和 产生的电流汇和电流源的时间分布 电刺激软膜表面的平行纤维， 原子核 该分析将揭示 平行纤维与DCN之间的突触连接 神经元 第三，突触前和突触后机制影响 在平行纤维突触的突触增强将是 探讨了 将确定增强的时间过程。 第四，兴奋性突触传递的药理学 从平行纤维到它们的突触后靶点， 可能的抑制性氨基酸局部回路， 通过DCN分子层中的平行纤维， 研究了 这些研究的结果将提供重要信息， 并行光纤系统在DCN中的作用， 产生了关于这个系统所起作用的新理论， 处理传入的声学信息。 这些实验将 也为随后调查变化奠定了基础 中枢生理学可能作为外周神经系统的功能发生， 声损伤和老化，以及调查的 DCN神经元的突触可塑性和膜生物物理学。