Mapping phantom movement representations in the motor cortex of amputees
Mapping phantom movement representations in the motor cortex of amputees
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DOI：
10.1093/brain/awl180
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发表时间：
2006-08-01
期刊：
影响因子：
14.5
通讯作者：
Sirigu, Angela
中科院分区：
文献类型：
--
作者：
Mercier, Catherine;Reilly, Karen T.;Sirigu, Angela
截肢导致大脑和肌肉之间连接的可塑性，缺失肢体的皮质运动表征似乎缩小了，这对与现在缺失的肢体相邻的具有皮质表征的剩余身体部位有利。令人惊讶的是，相应的知觉表征并没有遭受类似的命运，而是作为一个被赋予感觉和运动品质的幻肢而持续存在。截肢后的皮层重组如何与大脑中幻肢的运动表征保持一致？为了回答这个问题，我们探索了剩余手臂肌肉的皮质表征与幻肢运动的皮质表征之间的关系。使用经颅磁刺激（TMS），我们系统地映射幻影运动的看法，同时记录残肢肌肉活动在肘部以上截肢者。经颅磁刺激引起的感觉运动的幻手时，适用于假定的手区的运动皮层。在一个主题的感知运动的幅度与刺激的强度呈正相关。有趣的是，患者不能自主产生的幻肢运动很容易被TMS触发，这表明不能自主移动幻肢并不等同于失去相应的运动表征。我们认为，手运动表示生存在截肢者的重组运动区，即使这些不能直接访问。这些表征的激活对于幻身运动的体验可能是必要的。
Limb amputation results in plasticity of connections between the brain and muscles, with the cortical motor representation of the missing limb seemingly shrinking, to the presumed benefit of remaining body parts that have cortical representations adjacent to the now-missing limb. Surprisingly, the corresponding perceptual representation does not suffer a similar fate but instead persists as a phantom limb endowed with sensory and motor qualities. How can cortical reorganization after amputation be reconciled with the maintenance of a motor representation of the phantom limb in the brain? In an attempt to answer this question we explored the relationship between the cortical representation of the remaining arm muscles and that of phantom movements. Using transcranial magnetic stimulation (TMS) we systematically mapped phantom movement perceptions while simultaneously recording stump muscle activity in three above-elbow amputees. TMS elicited sensations of movement in the phantom hand when applied over the presumed hand area of the motor cortex. In one subject the amplitude of the perceived movement was positively correlated with the intensity of stimulation. Interestingly, phantom limb movements that the patient could not produce voluntarily were easily triggered by TMS, suggesting that the inability to voluntarily move the phantom is not equivalent to a loss of the corresponding movement representation. We suggest that hand movement representations survive in the reorganized motor area of amputees even when these cannot be directly accessed. The activation of these representations is probably necessary for the experience of phantom movement.