STRUCTURAL ORGANIZATION OF THE SUPERIOR COLLICULUS

对控制凝视的细胞群的研究 这对我们理解大脑中的感觉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 通过研究增加对凝视神经控制的理解 中间灰层内的突触关系 上级丘，一个在凝视机制中起中心作用的区域， 很好的。 中间灰色层包含的细胞是 在扫视眼球运动之前， 并通过一条叫做背前束的路径将轴突送到 下脑干凝视中心 这些脑干中心反过来投射出 与注视转移有关的运动神经元。 为 理解感觉运动整合的机制， 中间灰色层，它是必不可少的特征输入 负责背前束细胞的反应。 先前 研究表明，中间灰色层 由利用神经递质γ- 氨基丁酸（GABA）和乙酰胆碱。 拟议的实验 研究这两种纤维系统之间的关系， 背前束细胞。实验验证了这一假设 位于腹侧丘脑的未定区是一个神经元， GABA能输入这些细胞的重要来源。 他们还测试 网状结构中的细胞群， 脚桥被盖核，是一个胆碱能中继之间的 基底神经节和背前束细胞的输出。 具体而言，这些实验设计：1。定位，使用 逆行轴突运输方法，起源的细胞， 并确定，通过使用的组合 逆行追踪和免疫细胞化学方法，是否 是中间灰色层的GABA能输入源。 2.到 表征的超微结构特征和突触后靶点 中间灰色层中的顶盖内终端， 检查这些末梢是否直接接触背前束 细胞，通过使用顺行和逆行追踪的组合 方法在组织准备电子显微镜。 3.为了确定， 在组织中使用顺行和逆行方法的组合 准备电子显微镜，无论是胆碱能细胞在 脚桥被盖核接受来自黑质的输入 网状部，基底神经节的传出核之一。 4.到 表征胆碱能投射的突触后靶点 从脚桥被盖核到中间灰质 层，并检查胆碱能末梢是否接触 前背束细胞，通过使用顺行， 逆行和免疫细胞化学方法， 电镜

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.