INTERLIMB DIFFERENCES IN CONTROL OF MULTIJOINT DYNAMICS

描述：（申请书中的逐字记录）惯用手，手动不对称 以倾向于用一只手来完成熟练的动作为特征的 单手任务，是人类运动表现的一个突出特征， 这被认为是由每一肢的神经控制差异造成的。 然而，决定利手的确切机制仍然存在， 争议拟议的研究建立在我们目前的发现基础上， 表明在控制节段间动力学方面的肢体间差异。 以前的研究表明，达到运动最初计划在 任务相关变量，如手部运动方向和幅度 （Krakauer和Ghez，1999年），这一计划必须转化为肌肉 激活，以使运动发生。这种转变依赖于 肌肉骨骼和任务特定动力学的内部表征 （Gandolfo等人，1996年; Goodbody和Wolpert，1998年; Jordan和Rumelhart，1992年; Lackner和Dizio，1994年; Sainburg等人，1999年; Shadmehr和Mussa-Ivaldi， 1994年）。我们假设优势臂控制器专门用于 发展和更新这些神经表征。为了验证这个假设， 我们采用了一种独特的实验模式， 研究学习新的节间动力与优势臂 （Sainburg等人，1999年）。我们将分析以下运动策略 适应改变的惯性动力学，通过将质量附加到 外伸支架，前臂内侧或外侧。因为这种操纵 特别是改变了作用在 我们可以研究中枢神经系统在多大程度上 (CNS)表示这些动态，并反过来利用这些表示， 计划和执行后续行动。我们将比较肢间 在适应新的视觉运动转换和新的视觉运动转换方面的差异 惯性动力学，以确定电机控制过程的水平， 用手习惯被表达出来。我们将研究两种预期的差异 机制，以及基于视觉和体感的错误纠正 机制等通过专门操纵运动的特征 目标，我们将确定学习转移是否更大， 相互作用力矩或净力矩保持恒定的运动。 然后，我们将研究肢体间的差异，在何种程度上学习， 传递相关扭矩的变化。这些研究将提供一个 对利手背后的神经机制有了更深入的了解， 这对于解决运动问题的临床康复应用是至关重要的 单侧运动缺陷患者的学习能力。

DESCRIPTION: (Verbatim from application) Handedness, the manual asymmetry characterized by the tendency to favor one hand for performance of skilled unimanual tasks, is a prominent feature of human motor performance that is believed to result from differences in the neural control of each limb. However, the precise mechanisms responsible for handedness remain controversial. The proposed studies build on our current findings, which indicate interlimb disparities in the control of intersegmental dynamics. Previous research indicates that reaching movements are initially planned in terms of task relevant variables, such as hand movement direction and amplitude (Krakauer and Ghez, 1999), and that this plan must be transformed into muscle activations in order for movement to take place. This transformation relies on internal representations of musculoskeletal and task specific dynamics (Gandolfo, et at, 1996; Goodbody and Wolpert, 1998; Jordan and Rumelhart, 1992; Lackner and Dizio, 1994; Sainburg, et al, 1999; Shadmehr and Mussa-Ivaldi, 1994). We hypothesize that the dominant arm controller is specialized for developing and updating such neural representations. To test this hypothesis, we employ a unique experimental paradigm that we previously developed to investigate learning of novel intersegmental dynamics with the dominant arm (Sainburg et al., 1999). We will analyze movement strategies following adaptation to altered inertial dynamics, imposed by attaching a mass to an outrigger, either medial or lateral to the forearm. Because this manipulation specifically alters the amplitude of interaction torques acting between the segments, we can investigate the extent to which the Central Nervous System (CNS) represents these dynamics and, in turn, utilizes such representations for planning and executing subsequent movements. We will compare interlimb differences in adaptation to novel visual-motor transformations and to novel inertial dynamics, to determine the level of the motor control process at which handedness is expressed. We will investigate differences in both anticipatory mechanisms, as well as, visual and somatosensory based error correction mechanisms. By specifically manipulating the characteristics of movement targets, we will determine whether transfer of learning is greater for movements in which either interaction torques or net torques remain constant. We will then examine interlimb differences in the extent to which learning transfers across changes in the relevant torque. These studies will provide a more thorough understanding of the neural mechanisms underlying handedness, which is critical for clinical rehabilitation applications that address motor learning in patients with unilateral movement deficits.