CEREBELLAR DYSFUNCTION AND REACH TO GRASP MOVEMENTS

这些实验旨在比较reach-to- 掌握正常人和小脑患者的运动， 深入了解小脑在调节这一过程中的作用， 有组织，高度整合的行为。一般的假设是 测试表明，小脑有助于显着 腕部转运和抓握之间的一致的、刻板的关系 孔径，这种结构是必要的，以保持这种一致的 模式一旦建立，它是优化所需的 获取和执行预先计划的伸手抓取运动 针对移动目标，这是必不可少的获取 进行在线校正所需的自适应策略， 这些运动的扰动一旦开始。了实验 基于一系列对人体的初步研究， 从PI实验室的相关实验中获得的见解， 采用小脑功能障碍的动物模型。 将开展五个具体项目。第一个将描述 “伸手抓”运动的组织特征， 由于小脑病变而改变。第二个项目 将探讨小脑功能障碍与 整合视觉线索在两个阶段的达到，早期 在形成抓地力之前的运输阶段和之后的抓地力阶段 在接近目标时发生。第三项研究将评估 小脑患者对两种不同类型的 目标位置的可预测变化，一步一步地改变位置 第二个是位置的变化， 受试者的腕部速度。第四个实验 将评估小脑患者改善其 当目标位置的这些相同类型的变化被 在连续的审判中出现。在第五个项目中， 小脑患者获得弹性负荷适应策略 在到达的运输和抓地力阶段施加的扰动- 将探索抓的运动。除了测试特定的 假设这些实验的设计，数据将 使我们对小脑的作用的一般概念有了更深入的了解， 调节目标定向肢体的获得和执行 运动，也将有助于了解电机 在小脑患者中观察到的异常。

These experiments are designed to compare several features of reach-to- grasp movements in normal subjects and cerebellar patients in order to obtain insights into the role of the cerebellum in regulating this well- organized, highly integrated behavior. The general hypotheses to be tested are that the cerebellum contributes significantly to the consistent, stereotypic relationship between wrist transport and grip aperture, that this structure is necessary to maintain this consistent pattern once it is established, that it is required for optimizing the acquisition and performance of pre-planned reach-to-grasp movements directed toward moving targets, and that it is essential for acquiring adaptive strategies necessary for making on-line corrections for perturbations of these movements once initiated. The experiments are based on a series of preliminary studies in human subjects as well as insights obtained from related experiments from the PI's laboratory that employed animal models of cerebellar dysfunction. Five specific projects will be undertaken. The first will characterize the organizational features of the reach-to-grasp movement that are modified as a consequence of cerebellar pathology. The second project will explore the relationship between cerebellar dysfunction and the integration of visual cues during two phases of the reach, the early transport phase before the grip is formulated and the later grip phase occurring as the target is approached. The third study will evaluate the capacity of cerebellar patients to respond to two different types of predictable changes in target position, one a step change in position and the second a change in position that is continuously proportional to the subjects' wrist velocity during the reach. The fourth experiment will assess the capacity of cerebellar patients to improve their performance when these same types of changes in target position are presented in successive trials. In the fifth project, the capacity of cerebellar patients to acquire adaptive strategies to elastic load perturbations applied during the transport and grip phases of the reach- to-grasp movement will be explored. In addition to testing specific hypotheses underlying the design of these experiments, the data will lend insights into general concepts regarding the cerebellum's role in regulating the acquisition and performance of goal-directed limb movements and also will contribute to the understanding of the motor abnormalities observed in cerebellar patients.