Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California.
Department of Physical Therapy, Jeonju University, Jeonju, Republic of Korea.
J Neurophysiol. 2022 Jan 1;127(1):255-266. doi: 10.1152/jn.00532.2020. Epub 2021 Dec 8.
In neurotypical individuals, arm choice in reaching movements depends on expected biomechanical effort, expected success, and a handedness bias. Following a stroke, does arm choice change to account for the decreased motor performance, or does it follow a preinjury habitual preference pattern? Participants with mild-to-moderate chronic stroke who were right-handed before stroke performed reaching movements in both spontaneous and forced-choice blocks, under no-time, medium-time, and fast-time constraint conditions designed to modulate reaching success. Mixed-effects logistic regression models of arm choice revealed that expected effort predicted choices. However, expected success only strongly predicted choice in left-hemiparetic individuals. In addition, reaction times decreased in left-hemiparetic individuals between the no-time and the fast-time constraint conditions but showed no changes in right-hemiparetic individuals. Finally, arm choice in the no-time constraint condition correlated with a clinical measure of spontaneous arm use for right-, but not for left-hemiparetic individuals. Our results are consistent with the view that right-hemiparetic individuals show a habitual pattern of arm choice for reaching movements relatively independent of failures. In contrast, left-hemiparetic individuals appear to choose their paretic left arm more optimally: that is, if a movement with the paretic arm is predicted to be not successful in the upcoming movement, the nonparetic right arm is chosen instead. Although we are seldom aware of it, we constantly make decisions to use one arm or the other in daily activities. Here, we studied whether these decisions change following stroke. Our results show that effort, success, and side of lesion determine arm choice in a reaching task: whereas left-paretic individuals modified their arm choice in response to failures in reaching the target, right-paretic individuals showed a pattern of choice independent of failures.
在神经典型个体中，伸手动作的手臂选择取决于预期的生物力学努力、预期的成功以及惯用手偏好。中风后，手臂选择是否会发生变化以适应运动表现下降，还是遵循受伤前的习惯性偏好模式？在中风前为右利手的轻度至中度慢性中风参与者，在无时间、中时间和快时间约束条件下，以设计来调节伸手成功的方式，在自发性和强制性选择块中进行伸手动作。手臂选择的混合效应逻辑回归模型显示，预期的努力预测了选择。然而，预期的成功仅在左偏瘫个体中强烈预测了选择。此外，左偏瘫个体的反应时间在无时间和快时间约束条件之间下降，但右偏瘫个体没有变化。最后，无时间约束条件下的手臂选择与自发性手臂使用的临床测量值相关，对于右偏瘫个体是这样，但对于左偏瘫个体则不然。我们的结果与以下观点一致，即右偏瘫个体表现出习惯性的手臂选择模式，用于伸手动作，相对独立于失败。相比之下，左偏瘫个体似乎更能优化地选择他们的患侧左手臂：也就是说，如果用患侧手臂进行的运动在即将进行的运动中预测不会成功，那么会选择非患侧的右侧手臂。尽管我们很少意识到这一点，但我们在日常生活中经常做出使用一只手臂或另一只手臂的决定。在这里，我们研究了这些决定在中风后是否会发生变化。我们的结果表明，努力、成功和病变侧决定了伸手任务中的手臂选择：而左偏瘫个体根据伸手到目标的失败来调整手臂选择，右偏瘫个体则表现出一种独立于失败的选择模式。
