MacIver, K., Lloyd, D. M., Kelly, S., Roberts, N., & Nurmikko, T. (2008). Phantom limb pain, cortical reorganization and the therapeutic effect of mental imagery. Brain, 131, 2181-2191

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Using functional MRI (fMRI) upper limb amputees (N = 13) with phantom limb pain were investigated during hand and lip movements, before and after intensive 6-week training in mental imagery.

Before training, activation elicited during a lip purse showed evidence of cortical reorganization of the motor and somatosensory cortices, expanding from the lip area to the hand area, which correlated with pain scores. In addition, during imagined movement of the phantom hand, and executed movement of the intact hand, group maps demonstrated activation not only in bilateral motor and somatosensory hand areas, but also the lip area, showing a two-way process of reorganization. In healthy individuals, activation during a lip purse and imagined and executed movement of the non-dominant hand was confined to the respective cortical representation areas. Following training, Ss reported a significant reduction in intensity and unpleasantness of constant pain and exacerbations, with a corresponding elimination of cortical reorganization. Post hoc analyses showed that intensity of constant pain, but not exacerbations, correlated with reduction in cortical reorganization.

Implication. This study added to the understanding of the pathophysiology of phantom limb pain, underlining the reversibility of neuroplastic changes while offering a novel, simple method of pain relief. [A significant statement was: "Brain scans made by people who actually physically practiced a series of finger movements showed changes that were identical to scans made by people who imagined those movements but were prohibited from physical motion".]

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