Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
Wellcome Centre for Integrative Neuroimaging, MRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Nuffield Division of Anaesthetics, University of Oxford, Oxford, United Kingdom.
Cortex. 2018 Sep;106:174-184. doi: 10.1016/j.cortex.2018.05.013. Epub 2018 May 31.
Phantom limb pain (PLP) is commonly considered to be a result of maladaptive brain plasticity. This model proposes that PLP is mainly caused by reorganisation in the primary somatosensory cortex, presumably characterised by functional degradation of the missing hand representation and remapping of other body part representations. In the current study, we replicate our previous results by showing that chronic PLP correlates with maintained representation of the missing hand in the primary sensorimotor missing hand cortex. We asked unilateral upper-limb amputees to move their phantom hand, lips or other body parts and measured the associated neural responses using functional magnetic resonance imaging (fMRI). We confirm that amputees suffering from worse chronic PLP have stronger activity in the primary sensorimotor missing hand cortex while performing phantom hand movements. We find no evidence of lip representation remapping into the missing hand territory, as assessed by measuring activity in the primary sensorimotor missing hand cortex during lip movements. We further show that the correlation between chronic PLP and maintained representation of the missing hand cannot be explained by the experience of chronic non-painful phantom sensations or compensatory usage of the residual arm or an artificial arm (prosthesis). Together, our results reaffirm a likely relationship between persistent peripheral inputs pertaining to the missing hand representation and chronic PLP. Our findings emphasise a need to further study the role of peripheral inputs from the residual nerves to better understand the mechanisms underlying chronic PLP.
幻肢痛（PLP）通常被认为是大脑适应不良可塑性的结果。该模型提出，PLP 主要是由初级躯体感觉皮层的重组引起的，可能表现为缺失手代表的功能退化和其他身体部位代表的重新映射。在当前的研究中，我们通过显示慢性 PLP 与初级感觉运动缺失手皮层中缺失手的持续代表相关，复制了我们之前的结果。我们要求单侧上肢截肢者移动他们的幻手、嘴唇或其他身体部位，并使用功能磁共振成像（fMRI）测量相关的神经反应。我们确认患有更严重慢性 PLP 的截肢者在执行幻手运动时，初级感觉运动缺失手皮层的活动更强。我们没有发现嘴唇代表向缺失手区域重新映射的证据，这可以通过测量嘴唇运动期间初级感觉运动缺失手皮层的活动来评估。我们进一步表明，慢性 PLP 与缺失手的持续代表之间的相关性不能用慢性无痛幻觉的经验或对残臂或人工臂（假肢）的补偿使用来解释。总之，我们的结果再次证实了持续的与缺失手代表相关的外周输入与慢性 PLP 之间的可能关系。我们的发现强调需要进一步研究残留神经的外周输入的作用，以更好地理解慢性 PLP 的机制。
