Depression, pain, and hemispheric activation.

The present study attempts to delineate the role of hemispheric activation in depression and pain. It was hypothesized that the right hemisphere is specialized to become activated by and to process negative affective stimuli, and that this specialization may play a role in the co-occurrence of depression and pain. The relationship between depression, experimental pain, and cerebral laterality was investigated in 16 depressed and 16 nondepressed, right-handed, female students. Cerebral laterality was measured via tasks assessing visual and auditory biases, and pain was assessed via a cold pressor task. The proposition that the right hemisphere mediates the co-occurrence of pain and depression was not supported, but specific findings did suggest that the right hemisphere may play a unique role in pain perception. Data from the visual task indicated that prior exposure to pain results in increased right hemisphere activation as indicated by a left visual field bias. Pain perception was a complex function of mood, preceding tasks, and the hand tested, and it was suggested that exposure to a typical right-hemisphere task increased the left side lateralization of pain in nondepressed subjects. Implications of these findings are discussed for coexisting problems of pain and depression and for the lateralization of pain in disorders judged to involve a significant psychogenic component.