DORSAL COLUMN NUCLEI PROJECTIONS TO THE INFERIOR OLIVE

缺乏协调性不仅是由于结构的损伤，如 小脑，它通常被认为在 控制移动，但也来自结构的妥协，如 背柱和它们的中继器，背柱核，提供 感觉信息传到小脑。来自背柱的信息 核团通过许多投射到达小脑，其中大多数 它们是由广泛散布的神经元产生的，这些神经元不能 详细的实验评估。这个实验室的研究表明， 然而，在猫中，来自背部松弛部分的连接 下橄榄背侧副核的柱状核 (DAO)不仅是躯体感觉的重要来源 为小脑提供的信息，但一个服从于实验的信息 操纵。 薄束核中的DAO投射神经元似乎优先 与发生在意外时间的外部对象的信号约定 在运动过程中。拟议的电子显微镜实验将 研究这种信号背后的解剖学基础。这个 第一个实验将确定突触机制，通过它 外部接触激活的背柱纤维可能与DAO相互作用 薄束核内的投射神经元。DAO投射神经元将 用逆行示踪剂识别；来自背侧的突触输入 列将被标记为退化。可能存在的抑制因素 调节DAO投射神经元对这些输入的反应性 使用神经递质GABA的抗体进行鉴定。第二 实验试图确定DAO投射神经元的抑制 可能会实现。这将通过评估是否以及在什么情况下进行 DAO投射神经元附近的GABA能神经元的定位 接收可能发出任何一个电机命令发生的信号的输入 (大脑皮层)或与外部物体(背部)接触 列)。 从本实验室的这些和其他实验中收集的数据将 帮助确定背柱和背柱的折中程度 核团可能会导致运动障碍的产生，并最终导致 更好地理解感官信息是如何被用来产生 协调运动。

Lack of coordination results not only from lesions of structures such as the cerebellum, which ar generally thought to play an important role in controlling movement, but also from compromise of structures such as the dorsal columns and their relay, the dorsal column nuclei, that provide sensory information to the cerebellum. Information from the dorsal column nuclei reaches the cerebellum through a number of projections, most of which arise from widely scattered neurons that cannot be subjected to detailed experimental evaluation. Work from this laboratory has shown, however, that in cat the connection from the gracile portion of the dorsal column nuclei to the dorsal accessory subdivision of the inferior olive (DAO) constitutes not only a substantial source of somatosensory information for the cerebellum but one amenable to experimental manipulation. The DAO projection neurons in the gracile nucleus appear to preferentially signal contracts with external objects that occur at unexpected times during movement. The proposed electron microscopic experiments will investigate the anatomical substrates that underlie such signalling. The first experiment will determine the synaptic mechanisms through which the dorsal column fibers activated by external contact might interact with DAO projection neurons in the gracile nucleus. The DAO projection neurons will be identified with a retrograde tracer; synaptic inputs from the dorsal columns will be labeled with degeneration. Inhibitory elements that might regulate responsiveness of DAO projection neurons to these inputs will be identified using antibodies to the neurotransmitter GABA. The second experiment seeks to determine how inhibition of the DAO projection neurons might be achieved. This will be done by evaluating whether, and at what sites, putative GABAergic neurons adjacent to DAO projection neurons receive inputs that might signal the occurrence of either motor commands (the cerebral cortex) or contact with external objects (the dorsal columns). The data collected from these and other experiments in this laboratory will help determine how compromise of the dorsal columns and dorsal column nuclei might contribute to production of motor deficits and, ultimately, to a greater understanding of how sensory information is used to generate coordinated movement.