Phantom limb pain in the human brain: Unraveling neural circuitries of phantom limb sensations using positron emission tomography

Pain and other phantom limb (PL) sensations have been proposed to be genera ted in the brain and to be reflected in activation of specific neural circu its. To test this hypothesis, hypnosis was used as a cognitive tool to alte rnate between the sensation of PL movement and pain in 8 amputees. Brain ac tivity was measured using positron emission tomography. PL movement and pai n were represented by a propagation of neuronal activity within the corresp onding sensorimotor and pain-processing networks. The sensation of movement was significantly (corrected for multiple comparisons) related to activity in the supplementary motor area and the primary sensorimotor cortex. The s ensation of a painful pi, posture activated the same brain areas but was we aker and less extended in the supplementary motor area. In contrast to the sensation of movement, pain was significantly related to activity in the th alamus, anterior cingulate, and lateral prefrontal cortex. Subjectively rat ed PL, pain sensation correlated positively to activations in the anterior and posterior cingulate. These findings provide evidence that PL sensations are produced by the same central nervous processes that underlie the exper ience of the body when it is intact and that the corporeal awareness of PL pain is encoded in a thalamocortical network.