Trajectory Control and Motor Learning in Stroke

描述(申请人提供)：约80%的中风患者经历急性偏瘫，约40%的患者患有慢性偏瘫。这种损伤严重限制了手臂的功能使用。传统上，偏瘫的特点是虚弱、痉挛和不必要的协同作用。这些异常通常使用临床评分表进行评估。在这里，我们建议从更定量和模块化的运动控制角度来处理偏瘫的问题。我们以前的工作，研究了健康青年受试者的平面伸展运动，证明了准确伸展依赖于两种类型的视觉运动转换。第一种方法将视觉目标转化为以手部为中心的矢量空间中的规划轨迹，并独立指定方向和范围。这种空间转换需要学习特定于任务的参照系和比例因子。一旦确定了外部坐标中的平面，第二个变换就会在内部(关节)坐标中生成所需的力矩。这种动态转换需要学习肢体的生物力学特性。这一建议的主要假设是，偏瘫患者在使用和学习视觉运动转换方面存在障碍。我们的第二个假设是，根据优势臂或非优势臂是否受到影响以及病变位置的不同，在这些视觉运动转换中将会有不同的损害。我们将包括首次中风后六个月或更长时间且在中风发病时临床表现为手臂无力的患者。所有参与研究的患者都将接受弥散和灌注加权成像的结构性脑MRI检查。有一个以上病变或不能遵循说明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，手臂支撑在水平表面以消除重力。手部位置和关节角度数据将使用磁记录系统获得。运动学习将通过让受试者适应光标旋转或横向放置的质量来进行评估。损伤位置将由神经放射科医生确定。通过使用SPM2将T1图像转换到Tailarach空间来确认患者中常见的病变位置。我们的发现将有助于对偏瘫的机械性理解，建议新的康复策略，并帮助找到更好的康复措施。

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.