Buxbaum Laurel J, Johnson-Frey Scott H, Bartlett-Williams Megan
Moss Rehabilitation Research Institute, Korman Research Pavilion, Philadelphia, PA 19141, USA.
Neuropsychologia. 2005;43(6):917-29. doi: 10.1016/j.neuropsychologia.2004.09.006.
Motor imagery (MI) has been associated with planning stages of motor production, and in particular, with internal models that predict the sensory consequences of motor commands and specify the motor commands required to achieve a given outcome. In this study we investigated several predictions derived from the hypothesis that ideomotor apraxia (IM), a deficit in pantomime and imitation of skilled actions, may be attributable in part to deficits in internal models for planning object-related actions, in the face of relatively intact on-line, feedback-driven control of action. This hypothesis predicts that in IM, motor imagery should be (a) strongly correlated with other motor tasks not providing strong visual, tactile, and proprioceptive feedback from objects, i.e., object-related pantomime and imitation; (b) poorly correlated with performance tasks providing strong environmental feedback about the locations of effectors and targets, i.e., actual interaction with objects; and (c) particularly deficient in conditions that are computationally difficult for the motor planning system. Eight left fronto-parietal stroke patients with IM, five stroke patients without IM, and six healthy matched controls imagined grasping dowels and widgets presented at varying orientations, and actually grasped the same objects. The experimental predictions were confirmed. In addition, patients with IM and motor imagery deficits were significantly more likely than the non-apraxic group to have lesions in the intraparietal sulcus, a region previously implicated in imagery for hand-object interactions. The findings suggest a principled explanation for the deficits of IM patients in object-related gesture pantomime, imitation, and learning of new object-related gestures.
运动想象（MI）与运动产生的计划阶段相关，特别是与内部模型相关，这些内部模型预测运动指令的感觉后果，并指定实现给定结果所需的运动指令。在本研究中，我们调查了从以下假设得出的几个预测：观念运动性失用症（IM），即模仿和执行熟练动作的缺陷，可能部分归因于计划与物体相关动作的内部模型存在缺陷，尽管在线的、反馈驱动的动作控制相对完好。该假设预测，在IM中，运动想象应该（a）与其他不提供来自物体的强烈视觉、触觉和本体感觉反馈的运动任务，即与物体相关的模仿和执行动作，高度相关；（b）与提供关于效应器和目标位置的强烈环境反馈的执行任务，即与物体的实际交互，相关性较差；（c）在对运动计划系统计算困难的条件下尤其不足。八名患有IM的左额顶叶中风患者、五名没有IM的中风患者和六名健康匹配对照组想象以不同方向呈现的抓取木钉和小部件，并实际抓取相同的物体。实验预测得到了证实。此外，患有IM和运动想象缺陷的患者比非失用症组更有可能在顶内沟有病变，该区域先前与手与物体交互的想象有关。这些发现为IM患者在与物体相关的手势模仿、执行和学习新的与物体相关的手势方面的缺陷提供了一个有原则的解释。
