Service de Médecine Physique et de Réadaptation, Hôpital Bellevue, CHU de Saint-Etienne, F-42055 Saint-Etienne, France.
Brain. 2012 Feb;135(Pt 2):582-95. doi: 10.1093/brain/awr337.
Amputees can move their phantom limb at will. These 'movements without movements' have generally been considered as motor imagery rather than motor execution, but amputees can in fact perform both executed and imagined movements with their phantom and they report distinct perceptions during each task. Behavioural evidence for this dual ability comes from the fact that executed movements are associated with stump muscle contractions whereas imagined movements are not, and that phantom executed movements are slower than intact hand executed movements whereas the speed of imagined movements is identical for both hands. Since neither execution nor imagination produces any visible movement, we hypothesized that the perceptual difference between these two motor tasks relies on the activation of distinct cerebral networks. Using functional magnetic resonance imaging and changes in functional connectivity (dynamic causal modelling), we examined the activity associated with imagined and executed movements of the intact and phantom hands of 14 upper-limb amputees. Distinct but partially overlapping cerebral networks were active during both executed and imagined phantom limb movements (both performed at the same speed). A region of interest analysis revealed a 'switch' between execution and imagination; during execution there was more activity in the primary somatosensory cortex, the primary motor cortex and the anterior lobe of the cerebellum, while during imagination there was more activity in the parietal and occipital lobes, and the posterior lobe of the cerebellum. In overlapping areas, task-related differences were detected in the location of activation peaks. The dynamic causal modelling analysis further confirmed the presence of a clear neurophysiological distinction between imagination and execution, as motor imagery and motor execution had opposite effects on the supplementary motor area-primary motor cortex network. This is the first imaging evidence that the neurophysiological network activated during phantom limb movements is similar to that of executed movements of intact limbs and differs from the phantom limb imagination network. The dual ability of amputees to execute and imagine movements of their phantom limb and the fact that these two tasks activate distinct cortical networks are important factors to consider when designing rehabilitation programmes for the treatment of phantom limb pain.
截肢者可以随意移动他们的幻肢。这些“无运动的运动”通常被认为是运动想象，而不是运动执行，但实际上截肢者可以用他们的幻肢执行和想象运动，并且在每种任务中报告不同的感觉。这种双重能力的行为证据来自于执行运动与残肢肌肉收缩有关，而想象运动则没有，并且幻肢执行运动比健全手执行运动慢，而双手想象运动的速度相同。由于执行和想象都不会产生任何可见的运动，我们假设这两个运动任务之间的感知差异依赖于不同大脑网络的激活。使用功能磁共振成像和功能连接变化（动态因果建模），我们检查了 14 名上肢截肢者的健全手和幻肢执行和想象运动相关的活动。在执行和想象幻肢运动（以相同速度进行）期间，会激活明显但部分重叠的大脑网络。感兴趣区域分析显示执行和想象之间存在“切换”；在执行期间，初级体感皮层、初级运动皮层和小脑前叶的活动更多，而在想象期间，顶叶和枕叶以及小脑后叶的活动更多。在重叠区域，检测到激活峰位置的任务相关差异。动态因果建模分析进一步证实了想象和执行之间存在明显的神经生理区别，因为运动想象和运动执行对辅助运动区-初级运动皮层网络有相反的影响。这是首次影像学证据表明，幻肢运动期间激活的神经生理网络与健全肢体执行运动的网络相似，并且与幻肢想象网络不同。截肢者执行和想象幻肢运动的双重能力，以及这两个任务激活不同的皮质网络，是设计治疗幻肢痛康复计划时需要考虑的重要因素。
