Evoked potential evidence for right brain activity during the recall of traumatic memories.

Auditory probe evoked potential attenuation was measured as an index of hemispheric activity in 10 subjects with a history of childhood trauma and 10 matched subjects without such history while they recalled a neutral memory and then a traumatic memory. There were prominent group differences in degree of cerebral laterality between memory tasks (P = 0.02). The trauma group had a significant left dominant asymmetry during the neutral memory (P = 0.02), which markedly shifted to the right during the unpleasant memory (P = 0.007 for degree of shift). Normal control subjects did not display a significant asymmetry during either task, nor did they show a significant shift between tasks.