Buxbaum Laurel J, Kyle Kathleen, Grossman Murray, Coslett H Branch
Moss Rehabilitation Research Institute, Philadelphia, PA 19141, USA.
Cortex. 2007 Apr;43(3):411-23. doi: 10.1016/s0010-9452(08)70466-0.
Patients with ideomotor apraxia (IM) are frequently more impaired in the production and imitation of object-related (transitive) than non-object-related, symbolic (intransitive) gestures, but reasons for this dissociation, and its anatomical underpinnings, remain unclear. Our theoretical model of praxis (Buxbaum, 2001) postulates that left inferior parietal lobe (IPL) gesture representations store information about postures and movements of the body and hand for skillful manipulation of familiar objects; in contrast, bilateral fronto-parietal dynamic calculations provide constantly-updated information about the current position and movement of the body and hand for both familiar and novel, transitive and intransitive movements. This account predicts distinct patterns of IM in patients with left IPL damage versus bilateral fronto-parietal involvement. Consistent with predictions, 16 stroke patients with left IPL damage were more impaired with transitive than intransitive gestures, whereas 4 patients with bilateral fronto-parietal damage due to corticobasal degeneration (CBD) were not [F (1, 18) = 8.5 p < .01]. Additionally, the hand posture component of transitive gestures was the most impaired aspect of gesture in CVA, but tended to be the least impaired aspect of gesture in CBD [F (3, 54) = 5.1, p < .005]. Finally, CVA patients were more impaired with transitive hand postures than meaningless or intransitive hand postures, whereas CBD patients showed the opposite pattern. These data indicate that the left IPL mediates representations of skilled hand-object interactions, as distinct from dynamic coding of the body in space, and suggest that the IPL maps between representations of object identity in the ventral stream and spatial body representations mediated by the dorsal system.
观念运动性失用症（IM）患者在与物体相关的（及物的）动作产生和模仿方面，通常比与非物体相关的、象征性的（不及物的）手势受到更严重的损害，但这种分离现象的原因及其解剖学基础仍不清楚。我们的动作理论模型（Buxbaum，2001）假设，左顶下小叶（IPL）的手势表征存储了有关身体和手部姿势及动作的信息，以便熟练操作熟悉的物体；相比之下，双侧额顶叶的动态计算为熟悉和新颖的、及物和不及物的动作提供了有关身体和手部当前位置及动作的不断更新的信息。这一解释预测了左IPL损伤患者与双侧额顶叶受累患者IM的不同模式。与预测一致，16名左IPL损伤的中风患者在及物手势方面比不及物手势受损更严重，而4名因皮质基底节变性（CBD）导致双侧额顶叶损伤的患者则并非如此[F（1, 18）= 8.5，p <.01]。此外，及物手势的手部姿势成分在脑卒患者中是手势受损最严重的方面，但在CBD患者中往往是受损最轻的方面[F（3, 54）= 5.1，p <.005]。最后，中风患者在及物手部姿势方面比无意义或不及物手部姿势受损更严重，而CBD患者则表现出相反的模式。这些数据表明，左IPL介导了熟练的手 - 物体交互的表征，这与身体在空间中的动态编码不同，并表明IPL在腹侧流中物体身份表征与背侧系统介导的空间身体表征之间进行映射。
