Università degli Studi di Bologna, Bologna, Italy.
J Cogn Neurosci. 2010 Mar;22(3):413-26. doi: 10.1162/jocn.2009.21206.
Several studies have shown that the motor system is involved in action perception, suggesting that action concepts are represented through sensory-motor processes. Such conclusions imply that motor system impairments should diminish action perception. To test this hypothesis, a group of 10 brain-damaged patients with hemiplegia (specifically, a lesion at the motor system that affected the contralesional arm) viewed point-light displays of arm gestures and attempted to name each gesture. To create the dynamic stimuli, patients individually performed simple gestures with their unaffected arm while being videotaped. The videotapes were converted into point-light animations. Each action was presented as it had been performed, that is, as having been produced by the observer's unaffected arm, and in its mirror reversed orientation, that is, as having been produced by the observer's hemiplegic arm. Action recognition accuracy by patients with hemiplegia was compared with that by 8 brain-damaged patients without any motor deficit and by 10 healthy controls. Overall, performance was better in control observers than in patients. Most importantly, performance by hemiplegic patients, but not by nonhemiplegic patients and controls, varied systematically as a function of the observed limb. Action recognition was best when hemiplegic patients viewed actions that appeared to have been performed by their unaffected arm. Action recognition performance dropped significantly when hemiplegic patients viewed actions that appeared to have been produced with their hemiplegic arm or the corresponding arm of another person. The results of a control study involving the recognition of point-light defined animals in motion indicate that a generic deficit to visual and cognitive functions cannot account for this laterality-specific deficit in action recognition. Taken together, these results suggest that motor cortex impairment decreases visual sensitivity to human action. Specifically, when a cortical lesion renders an observer incapable of performing an observed action, action perception is compromised, possibly by a failure to map the observed action onto the observer's contralesional hemisoma.
一些研究表明，运动系统参与了动作感知，这表明动作概念是通过感觉运动过程来表示的。这些结论意味着运动系统的损伤应该会降低动作感知能力。为了验证这一假设，一组 10 名偏瘫脑损伤患者（具体来说，运动系统的损伤影响了对侧手臂）观看了手臂动作的光点显示，并试图命名每个动作。为了创建动态刺激，患者单独使用未受影响的手臂进行简单的动作，并被录像。录像被转换成光点动画。每个动作都是按照观察者未受影响的手臂进行的方式呈现的，即观察者的未受影响的手臂产生的动作，以及镜像反转的方向，即观察者的偏瘫手臂产生的动作。偏瘫患者的动作识别准确性与 8 名无运动缺陷的脑损伤患者和 10 名健康对照者进行了比较。总的来说，控制观察者的表现优于患者。最重要的是，偏瘫患者的表现（而不是非偏瘫患者和对照组）系统地随观察到的肢体而变化。当偏瘫患者观察到似乎是由未受影响的手臂完成的动作时，他们的动作识别效果最佳。当偏瘫患者观察到似乎是由偏瘫手臂或另一个人的相应手臂产生的动作时，动作识别性能显著下降。涉及识别运动中的光点定义动物的控制研究的结果表明，视觉和认知功能的一般缺陷不能解释这种对侧特定的动作识别缺陷。总之，这些结果表明，运动皮层损伤降低了对人类动作的视觉敏感性。具体来说，当皮质损伤使观察者无法执行观察到的动作时，动作感知就会受到影响，可能是因为无法将观察到的动作映射到观察者的对侧半体上。
