Trajectory Control and Motor Learning in Stroke

描述（由申请人提供）：约80%的卒中患者发生急性轻偏瘫，约40%的患者发生慢性轻偏瘫。这种损伤严重限制了手臂的功能使用。传统上，轻偏瘫的特征是虚弱、痉挛和不必要的协同作用。这些异常通常使用临床量表进行评估。在这里，我们建议从更定量和模块化的运动控制的角度来处理轻偏瘫的问题。我们以前的工作，在健康的年轻受试者的平面达到运动的调查，表明，准确的达到取决于两种类型的视觉转换。第一种方法将视觉目标转换为以手为中心的向量空间中的规划轨迹，具有独立的方向和范围指定。这种空间转换需要学习特定于任务的参考框架和缩放因子。一旦确定了外在坐标中的计划，第二次变换就在内在（关节）坐标中生成所需的扭矩。这种动态转换需要学习肢体的生物力学特性。这个提议的主要假设是，轻偏瘫患者在使用和学习视觉转换方面有障碍。我们的第二个假设是，将有不同的损害，在这些视觉转换取决于是否占主导地位的或非占主导地位的手臂受到影响和病变部位。我们将纳入首次卒中后6个月或更长时间内在卒中发作时具有临床可证实的手臂无力的患者。研究中的所有患者都将进行弥散和灌注加权成像的结构性脑MRI。将排除有一处以上病变或无法遵循说明的患者。患者（和年龄匹配的对照组）将进行平面伸展运动，其手臂支撑在水平表面上以消除重力。手的位置和关节角度数据将使用磁记录系统获得。将通过让受试者适应光标旋转或横向放置的质量来评估运动学习。病变位置将由神经放射科医生确定。通过使用SPM 2将T1图像转换到Tailarach空间，确认患者的常见病变位置。我们的研究结果将有助于偏瘫的机械理解，提出新的康复策略，并帮助找到更好的恢复措施。

DESCRIPTION (provided by applicant): Approximately 80% of stroke patients experience acute hemiparesis and approximately 40% have chronic hemiparesis. This impairment significantly limits functional use of the arm. Traditionally, hemiparesis has been characterized by weakness, spasticity and unwanted synergies. These abnormalities are usually assessed using clinical scales. Here we propose to approach the problem of hemiparesis from a more quantitative and modular motor control perspective. Our previous work, investigating planar reaching movements in healthy young subjects, demonstrates that accurate reaching depends en two types of visuomotor transformation. The first transforms a visual target into a planned trajectory in vectorial space centered at the hand with independent specification of direction and extent. This spatial transformation requires the learning of a task-specific reference frame and scaling factor. Once a plan in extrinsic coordinates is determined, a second transformation generates the required torques in intrinsic (joint) coordinates. This dynamic transformation requires learning of the biomechanical properties of the limb. The principal hypothesis of this proposal is that patients with hemiparesis have impairments in using and learning visuomotor transformations. Our secondary hypotheses are that there will be differential impairments in these visuomotor transformations depending on whether the dominant or non-dominant arm is affected and on lesion location. We will include patients who are six months or more out from their first stroke with clinically demonstrable arm weakness at stroke onset. All patients in the study will have had a structural brain MRI with diffusion and perfusion-weighted imaging. Patients with more than one lesion or inability to follow instructions will be excluded. Patients (and age-matched controls) will perform planar reaching movements with their arm supported on a horizontal surface to eliminate gravity. Hand position and joint angle data will be obtained using a magnetic recording system. Motor learning will be assessed by having subjects adapt to a cursor rotation or a laterally-placed mass. Lesion location will be determined by a neuroradiologist. Confirmation of common lesion locations across patients will be made by transforming the T1 images into Tailarach space using SPM2. Our findings will contribute to a mechanistic understanding of hemiparesis, suggest novel rehabilitation strategies and help find better measures of recovery.