PAIN AFFECT ENCODED IN HUMAN ANTERIOR CINGULATE BUT NOT SOMATOSENSORYCORTEX

Recent evidence demonstrating multiple regions of human cerebral corte x activated by pain has prompted speculation about their individual co ntributions to this complex experience. To differentiate cortical area s involved in pain affect, hypnotic suggestions were used to alter sel ectively the unpleasantness of noxious stimuli, without changing the p erceived intensity. Positron emission tomography revealed significant changes in pain-evoked activity within anterior cingulate cortex, cons istent with the encoding of perceived unpleasantness, whereas primary somatosensory cortex activation was unaltered. These findings provide direct experimental evidence in humans linking frontal-lobe limbic act ivity with pain affect, as originally suggested by early clinical lesi on studies.