STRUCTURAL ORGANIZATION OF THE SUPERIOR COLLICULUS

对控制凝视的细胞群体的研究做出了贡献 对我们理解感应器运动整合有很大帮助。 脊椎动物的大脑。拟议研究的长期目标是 通过研究提高对凝视神经控制的认识 丘脑中间灰层内的突触关系 上丘，一个在凝视机制中起中心作用的区域 久负盛名。中间灰层包含的细胞是 前驱运动在眼球跳动之前作出反应的意义 并通过一种称为背前束的途径将轴突发送到 较低的脑干凝视中心。这些脑干中心，反过来，投射 到参与凝视转移的运动神经元。为 理解感觉-运动整合的机制 中间灰度层，必须对输入进行表征 负责背前束细胞的反应。上一首 研究表明，中间灰层的厚度很大 被利用神经递质的纤维所支配- 氨基丁酸(GABA)和乙酰胆碱。拟议中的实验 检查这两个光纤系统和 猫背前束细胞。这些实验验证了这一假设 位于丘脑腹侧的Incerta区是一个 这些细胞的GABA能输入的重要来源。他们还测试 认为网状结构中的一群细胞， 桥脑脚被盖核是胆碱能神经元之间的一种传递。 基底节和背前束细胞的输出。 具体地说，这些实验是设计的：1.定位，使用 轴突逆行运输的方法，细胞的起源 提示顶盖通路，并通过组合使用 逆行追踪和免疫细胞化学方法，无论是不确定带 是中间灰层GABA能输入的来源。2.至 海马神经元超微结构特征及突触后靶点的研究 中间灰层和TO层的顶盖终末 检查这些终末是否直接接触背前束 细胞，通过结合使用顺行和逆行追踪 方法在组织中制备电子显微镜。3.为了确定， 在组织中采用顺行和逆行相结合的方法 制备电子显微镜，观察胆碱能细胞是否在 脚丘脑被盖核接受黑质的输入 网状部，基底节的传出核之一。4.至 胆碱能投射的突触后靶S的特征 从脚被盖核到中间灰质 层，检查胆碱能终末是否接触 背前束细胞，通过使用顺行、 组织中的逆行和免疫细胞化学方法 电子显微镜。

The study of the cell populations that control gaze has contributed greatly to our understanding of sensorimotor integration in the vertebrate brain. The long term goal of the proposed research is to increase understanding of the neural control of gaze by studying synaptic relationships within the intermediate grey layer of the superior colliculus, an area whose central role in gaze mechanisms is well-established. The intermediate grey layer contains cells which are premotor in the sense that they respond before saccadic eye movements and send axons, by way of a pathway called the predorsal bundle, to the lower brainstem gaze centers. These brainstem centers, in turn, project to the motor neurons that are involved in shifts in gaze. For understanding the mechanisms of sensorimotor integration in the intermediate grey layer, it is essential to characterize the inputs responsible for the responses of the predorsal bundle cells. Previous studies have shown that the intermediate grey layer is heavily innervated by fibers that utilize the neurotransmitters gamma- aminobutryic acid (GABA) and acteylcholine. The proposed experiments examine the relationships between these two fiber systems and the predorsal bundle cells in the cat. The experiments test the hypothesis that zone incerta, a nucleus located in the ventral thalamus, is an important source of the GABA ergic input to these cells. They also test the idea that a population of cells in the reticular formation, the pedunculopontine tegmental nucleus, is a cholinergic relay between the output of the basal ganglia and the predorsal bundle cells. Specifically, these experiments are designed: 1. To locate, using retrograde axonal transport methods, the cells of origin of the incertotectal pathway and to determine, by using a combination of retrograde tracing and immunocytochemical methods, whether zona incerta is a source of GABAergic input to the intermediate grey layer. 2. To characterize the ultrastructural features and postsynaptic targets of the incertotectal terminations in the intermediate grey layer and to examine whether those terminations directly contact predorsal bundle cells, by using a combination of anterograde and retrograde tracing methods in tissue prepared for electron microscopy. 3. To determine, using a combination of anterograde and retrograde methods in tissue prepared for electron microscopy, whether the cholinergic cells in the pedunculopotine tegmental nucleus receive input from substantia nigra pars reticulata, one of the efferent nuclei of the basal ganglia. 4. To characterize the postsynaptic target(s) of the cholinergic projection from the pedunculopotine tegmental nucleus to the intermediate grey layer, and to examine whether the cholinergic terminals contact predorsal bundle cells, by using a combination of anterograde, retrograde and immunocytochemical methods in tissue prepared for electron microscopy.