ANATOMY OF COCHLEAR NUCLEUS--CORRELATION WITH PHYSIOLOGY

我们将探索这样一种假设，即 耳蜗核改变大脑对正在进行的反应的功能 声学刺激。我们的方法是确定结构和 局部回路对信息影响的神经化学基础 并将这些发现与耳蜗核的 在同伴的相同回路上进行的生理观察 项目。两者之间的相互联系，可能是抑制联系 耳蜗核腹侧和背侧的特定类型的神经元 对其进行定义，并定位其推定的神经递质。我们的计划是 确定相互联系所涉及的神经元类型 这些细胞核通过结合顺行和逆行追踪方法与 标记神经元的位置。突触的分布 标记神经元上的末端将被映射到它们各自的目标上 以评估其潜在的影响范围，以查看 如果神经元之间存在相互连接的离散映射，或者如果 它们更广泛地投射到更大的领域，与频率相对应 一定尺寸的带子。光镜和电子显微镜 免疫细胞化学将与顺行和 逆行示踪器，以确定这些投影中的哪些提供 含有抑制性递质甘氨酸或GABA的末端 目标单元格。解剖学的发现将与 结合倒数显微镜标记的生理数据 声学改变的连接和生理记录 刺激或抑制这些刺激或抑制引起的反应特性 关系。从长远来看，这些研究将延伸到其他原子核。 脑干及其与耳蜗核的相互联系。 这项研究将阐明局部回路和抑制的作用 单耳和双耳听力中的中间神经元。最终，他们应该 提供对感知现象的神经生物学的见解，例如 单声道回声抑制、双耳交互等优先 效果，以及一般的感官控制机制。

We shall explore the hypothesis that inhibitory processes within the cochlear nucleus modify the functional response of the brain to ongoing acoustic stimuli. Our approach is to determine the structural and neurochemical bases for the effects of local circuits on information processing in the cochlear nucleus and to link these findings to the physiological observations made on the same circuits in a companion project. The reciprocal, and possibly inhibitory, connections between specific types of neurons in the ventral and dorsal cochlear nucleus will be defined and their putative neurotransmitters localized. The plan is to identify the neuronal types involved in reciprocal connections between these nuclei by combining anterograde and retrograde tracing methods with the locations of the labeled neurons. The distribution of the synaptic endings on the labeled neurons will be mapped in their respective target areas in order to estimate their potential spheres of influence, to see if there is a discrete mapping of interconnections between neurons or if they project more diffusely to larger domains, corresponding to frequency bands of certain dimensions. Light and electron microscopic immunocytochemistry will be used in combination with anterograde and retrograde tracers to determine which of these projections supplies endings containing the inhibitory transmitters, glycine or GABA, to their target cells. The anatomical findings will be related to the physiological data by combining microscopic labeling of the reciprocal connections and physiological recording of the alterations in acoustical response properties induced by stimulating or inhibiting these connections. In the long term these studies will extend to other nuclei of the brain stem and their interconnections with the cochlear nucleus. This research will elucidate the roles of local circuits and inhibitory interneurons in monaural and binaural hearing. Ultimately they should provide insight into the neurobiology of perceptual phenomena, such as monaural echo suppression, binaural interactions, such as the precedence effect, and sensory control mechanisms in general.