Janssen Loes, Steenbergen Bert, Carson Richard G
Donders Institute for Brain, Cognition and Behaviour Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, 6500 HE, The Netherlands Department of Clinical Epidemiology, VieCuri Medical Centre, Venlo, 5912 BL, The Netherlands.
Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, 6500 HE, The Netherlands.
Cereb Cortex. 2015 Jan;25(1):192-201. doi: 10.1093/cercor/bht220. Epub 2013 Aug 19.
It has been argued that the variation in brain activity that occurs when observing another person reflects a representation of actions that is indivisible, and which plays out in full once the intent of the actor can be discerned. We used transcranial magnetic stimulation to probe the excitability of corticospinal projections to 2 intrinsic hand muscles while motions to reach and grasp an object were observed. A symbolic cue either faithfully indicated the required final orientation of the object and thus the nature of the grasp that was required, or was in conflict with the movement subsequently displayed. When the cue was veridical, modulation of excitability was in accordance with the functional role of the muscles in the action observed. If however the cue had indicated that the alternative grasp would be required, modulation of output to first dorsal interosseus was consistent with the action specified, rather than the action observed--until the terminal phase of the motion sequence during which the object was seen lifted. Modulation of corticospinal output during observation is thus segmented--it progresses initially in accordance with the action anticipated, and if discrepancies are revealed by visual input, coincides thereafter with that of the action seen.
有人认为，观察他人时大脑活动的变化反映了一种不可分割的动作表征，一旦能够识别出行为者的意图，这种表征就会完整呈现出来。我们使用经颅磁刺激来探测皮质脊髓投射到两块手部固有肌肉的兴奋性，同时观察伸手抓握物体的动作。一个符号线索要么忠实地指示了物体所需的最终方向，从而表明所需抓握的性质，要么与随后显示的动作相冲突。当线索真实时，兴奋性的调节与观察到的动作中肌肉的功能作用一致。然而，如果线索表明需要另一种抓握方式，那么对第一背侧骨间肌的输出调节与指定的动作一致，而不是与观察到的动作一致——直到动作序列的末期，此时看到物体被提起。因此，观察过程中皮质脊髓输出的调节是分段的——它最初根据预期的动作进行，并且如果视觉输入显示出差异，此后则与看到的动作一致。
