Reilly Karen T, Mercier Catherine, Schieber Marc H, Sirigu Angela
Institut des Sciences Cognitives, Bron, France.
Brain. 2006 Aug;129(Pt 8):2211-23. doi: 10.1093/brain/awl154. Epub 2006 Jun 24.
The loss of a limb leads to sensorimotor modifications that are frequently accompanied by the vivid experience that the missing limb is still present, and that it can be moved at will. Furthermore, amputees can clearly distinguish between phantom movements of the fingers and of more proximal joints, like movements of the elbow. This phenomenon raises the question of whether these specific phantom movement experiences are translated into differentiated activity within the remaining muscles. We recorded stump muscle activity when above-elbow amputees voluntarily moved their phantom limb. Voluntary movements of the phantom hand triggered specific patterns of stump muscle activity, which differed from activity recorded in the same muscle groups during movements of the proximal limb. This result indicates that the brain's motor areas can be differentially activated according to the phantom movement the patient intends to perform, and suggests that hand motor commands are preserved after amputation. To further understand the interaction between central commands and sensory feedback in the perception of phantom movement we also measured stump muscle EMG activity in an amputee experiencing a frozen phantom limb, and in three below-elbow amputees with vivid phantom movements after inducing an ischaemic block. Failed attempts to move the paralysed phantom limb always resulted in the same EMG pattern, no matter what type of phantom movement was attempted, while ischaemic nerve block reduced or eliminated the ability to voluntarily move the phantom limb and produced a dramatic reduction in the amplitude of stump muscle EMG activity. Our data suggest that the experience of phantom hand movement involves the activation of hand motor commands. We propose that preserved hand movement representations re-target the stump muscles to express themselves and that when these representations are voluntarily accessible they can instruct the remaining muscles to move in such a way as if the limb is still there.
肢体缺失会导致感觉运动发生改变，常常伴随着一种生动的体验，即感觉缺失的肢体仍然存在，并且可以随意移动。此外，截肢者能够清楚地区分手指的幻肢运动和更近端关节（如肘部运动）的幻肢运动。这种现象引发了一个问题，即这些特定的幻肢运动体验是否会转化为剩余肌肉内的差异化活动。我们记录了肘上截肢者在自愿移动幻肢时残肢肌肉的活动。幻手的自愿运动会引发残肢肌肉活动的特定模式，这与近端肢体运动期间相同肌肉群记录的活动不同。这一结果表明，大脑的运动区域可以根据患者想要执行的幻肢运动而被差异化激活，这表明截肢后手的运动指令得以保留。为了进一步了解在幻肢运动感知中中枢指令与感觉反馈之间的相互作用，我们还测量了一名患有冻结幻肢的截肢者以及三名在诱导缺血性阻滞后有生动幻肢运动的肘下截肢者的残肢肌肉肌电图活动。无论尝试何种类型的幻肢运动，试图移动麻痹的幻肢的失败尝试总是导致相同的肌电图模式，而缺血性神经阻滞降低或消除了自愿移动幻肢的能力，并使残肢肌肉肌电图活动的幅度显著降低。我们的数据表明，幻手运动的体验涉及手运动指令的激活。我们提出，保留的手部运动表征重新将目标指向残肢肌肉以表达自身，并且当这些表征可以被自愿获取时，它们可以指示剩余肌肉以肢体仍然存在的方式进行运动。
