Socially shared emotions shape the activity of the medial prefrontal cortex during inference of others' emotional states.

The medial prefrontal cortex (mPFC) weighs options during decision-making, but its role in inferring competing emotional states and how this process changes with age, remain unclear. We recorded brain activity with functional MRI while 20 young and 40 older adults inferred the emotions of actors shown in ecological yet controlled social interactions. Socially shared representations about the timing, accuracy, and uncertainty of emotional inferences were defined using response distributions from an independent sample viewing the same scenes. mPFC activity is sensitive to emotional inference and scales with the social uncertainty of alternative emotional hypotheses. Social consensus regarding the emotional conflict elicited by the actors' interaction is associated with increased representational similarity in the mPFC, with this effect being modulated by age. Together, these results indicate that the mPFC integrates the variability of social representations to infer emotions in others and provide an account of age-related changes in social cognition.