Subjective ratings of pain correlate with subcortical-limbic blood flow: an fMRI study

Studies investigating the cerebral representations of pain using functional imaging techniques failed to elucidate the affective aspects of pain. This investigation used functional magnetic resonance imaging to measure pain-related changes in cerebral activity during painful stimulation with a strong affective component. Vascular pain was induced via balloon dilatation of a dorsal foot vein of healthy volunteers. The subjects rated their perceived pain uninterruptedly during imaging, allowing cerebral activity to be correlated with both stimulus function (boxcar) and, more importantly, subjective ratings reflecting individual pain experience. The findings indicated signal increases in subcortical-limbic regions, particularly in the amygdala. This region is suggested to be involved in the affective dimension of pain.