Sex-related hemispheric lateralization of electrical potentials evoked by arousing negative stimuli

Recent studies suggest that both sex and cerebral hemisphere influence brain mechanisms associated with emotional memory. Here we used evoked potentials to examine the influence of sex and hemisphere on brain responses to emotional stimuli. Given that the P300 component of the event-related brain potential (ERP) is considered a cognitive neuroelectric phenomenon, we compared left and right hemisphere P300 responses to brief (2 s) presentations of emotionally arousing pictures in men and women. P300 waves were recorded from sites overlying left (F3 and P3) and right (F4 and P4) hemisphere frontal and parietal locations in response to a series of standardized pictures rated as emotionally negative, positive, or neutral. Negative pictures elicited more robust P300 effects, as indexed by both amplitude and latency measures, in the left hemisphere in women than in men, yet elicited a stronger P300 component in the right hemisphere in men than in women. The variables of sex and hemisphere interacted significantly to influence the strength of the P300 component to the negative slides. Negative slides were also best recalled at a long-term, incidental memory test, a fact potentially related to the differential P300 waves at encoding. These data further support the view that both sex and cerebral hemisphere represent relevant, interacting influences on neural correlates of emotion, and of emotionally influenced memory.