Cerebellar Afferent Integration Studied In Vitro

描述(申请人提供)：小脑皮质(CB)是由相同的重复处理模块组成的灰质连续神经层。尽管所有脊椎动物的这些模块的电路都是相似的，但在鸟类和哺乳动物中，皮质表面高度分叶，具有复杂的区域专门化。因此，由于在暴露的叶表面上只观察到一小部分皮质区域，因此很难分析CB的地形图及其功能。 我们假设从分离的CB传入到浦肯野细胞的径向输入系统和 上升颗粒细胞轴突是CB模块的主要加工单位。这个初级系统由平行纤维和抑制性中间神经元组成的次级、正交系统作用。这项拟议的研究将用一种独特的体外海龟CB制剂来验证这一假设，该制剂带有脑干和感觉神经。平龟CB的主要优点是它足够薄，可以在转换照明期间对整个CB表面进行光学记录。使用电压敏感的吸收染料，CB地形图可以通过对单个感官刺激的大反应来表征。较小的皮质大小也允许在连续切片的完整重建的基础上对传入输入进行地形解剖分析。 将进行光学记录和路径追踪实验，以揭示感觉传入如何映射到CB以及这些不同的映射如何重叠。这个项目将通过测量体外对脑干内自然刺激或电刺激的光学反应来关注视觉和前庭传入的影响。其他实验将检查小脑的基本模块：苔藓纤维输入，颗粒细胞的径向和垂直轴突输出，以及兴奋性和抑制性输入到浦肯野细胞的会聚。最后，我们将从解剖学和生理学的角度测量进入CB的攀爬纤维输入，以了解它们在小脑基本模块的可塑性和信息流调节中的作用。因此，这种体外制备将为运动行为的学习和适应研究提供一个独特的模型系统。

DESCRIPTION (provided by applicant): The cerebellar cortex (Cb) is a continuous neural layer of gray matter made up of identical repeating processing modules. Although the circuitry of these modules is similar for all vertebrates, the cortical surface is highly foliated in birds and mammals with complex regional specializations. Therefore, an analysis of Cb topography and its function is difficult because only a small fraction of cortical area is observed on the exposed folial surface. We posit that a radial system of inputs onto Purkinje cells from segregated Cb afferents and ascending granule cell axons is the primary processing unit of the Cb module. This primary system is acted on by a secondary, orthogonal system of parallel fibers and inhibitory interneurons. The proposed study will test this hypothesis with a unique in vitro turtle Cb preparation with the brainstem and sensory nerves attached. The primary advantage of the flat turtle Cb is that it is thin enough to permit optical recordings of the entire Cb surface during trans-illumination. Using voltage-sensitive absorbance dyes, Cb topography can be characterized from large responses to individual sensory stimuli. The small cortical size also permits a topographic anatomical analysis of afferent inputs based on a complete reconstruction of serial sections. Optical recording and pathway tracing experiments will be performed to reveal how sensory afferents map onto the Cb and how these different maps overlap. This project will focus on the effects of visual and vestibular afferents by measuring optical responses in vitro to natural stimulation or electrical microstimulation within the brainstem. Additional experiments will examine the basic cerebellar module: mossy fiber inputs, the radial and orthogonal axonal outputs of the granule cell and the convergence of excitatory and inhibitory inputs onto the Purkinje cell. Finally, climbing fiber inputs to Cb will be measured anatomically and physiologically to understand their role in plasticity and modulation of information flow through the basic cerebellar module. This in vitro preparation will thereby provide a unique model system for the study of learning and adaptation of motor behaviors.