Topographic brain measures of human pain and pain responsivity.

Individual differences in human pain responsivity were characterized by the 1 degree C cold-pressor test. Behaviorally, a pain-tolerant group (PT = 29 Ss) tolerated the entire 3-min test (means = 180 +/- 0 sec), while a pain-sensitive group (PS = 13 Ss) averaged only 50.31 +/- 20.81 sec of the cold-pressor test (t = 16.75, P less than 0.0001), replicating our earlier studies. Physiologically, the PT group exhibited no mean differences from the PS group in cortical power densities at the baseline stage. Under the noxious stress of the cold-pressor test, both groups exhibited markedly heightened delta and beta cortical power densities. However, the PS subjects showed significantly higher delta power, but not beta power, than the PT subjects. We conclude that heightened delta activity may reflect the stress component of human pain responsivity, and that beta activity reflects the vigilance scanning of pain processes.