Trajectory Control and Motor Learning in Stroke

描述（由申请人提供）：大约80%的中风患者患有急性偏瘫，大约40%患有慢性偏瘫。这种损伤严重限制了手臂的功能性使用。传统上，偏瘫的特点是虚弱，痉挛和不必要的协同作用。这些异常通常用临床量表来评估。在这里，我们建议从更定量和模块化的运动控制角度来解决偏瘫问题。我们之前的工作，研究了健康的年轻受试者的平面到达运动，表明准确的到达取决于两种类型的视觉运动转换。第一种方法是将视觉目标转化为以手为中心的矢量空间中具有独立方向和范围的规划轨迹。这种空间转换需要学习特定于任务的参考框架和比例因子。一旦确定了外在坐标中的计划，第二次变换将在内在（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。本建议的主要假设是偏瘫患者在使用和学习视觉运动转换方面存在障碍。我们的次要假设是，视运动转化中会有不同的损伤，这取决于优势臂或非优势臂是否受到影响以及病变的位置。我们将包括首次中风后六个月或更长时间且中风发作时临床表现出手臂无力的患者。研究中的所有患者都将进行结构脑MRI扩散和灌注加权成像。有一个以上病变或不能遵循指示的患者将被排除在外。患者（和年龄匹配的对照组）将进行平面伸展运动，手臂支撑在水平面上以消除重力。手的位置和关节角度数据将通过磁记录系统获得。运动学习将通过让受试者适应光标旋转或横向放置的肿块来评估。病变位置将由神经放射学家确定。通过SPM2将T1图像转换为Tailarach空间，确定患者之间的常见病变位置。我们的研究结果将有助于对偏瘫的机制理解，提出新的康复策略，并有助于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.