The interaction of social and emotional processes in the brain.

Social stimuli function as emotional barometers for the immediate environment are the catalysts for many emotional reactions, and have inherent value for relationships and survival independent of their current emotional content. We, therefore, propose that the neural mechanisms underlying social and emotional information processing may be interconnected. In the current study, we examined the independent and interactive effects of social and emotional processes on brain activation. Whole-brain images were acquired while participants viewed and categorized affective pictures that varied on two dimensions: emotional content (i. e., neutral, emotional) and social content (i. e., faces/people, objects/scenes). Patterns of activation were consistent with past findings demonstrating that the amygdala and part of the visual cortex were more active to emotionally evocative pictures than to neutral pictures and that the superior temporal sulcus was more active to social than to nonsocial pictures. Furthermore, activation of the superior temporal sulcus and middle occipito-temporal cortex showed evidence of the interactive processing of emotional and social information, whereas activation of the amygdala showed evidence of additive effects. These results indicate that interactive effects occur early in the stream of processing, suggesting that social and emotional information garner greater attentional resources and that the conjunction of social and emotional cues results in synergistic early processing, whereas the amygdala appears to be primarily implicated in processing biologically or personally relevant stimuli, regardless of the nature of the relevance (i. e., social, emotional, or both).