Social risk coding by amygdala activity and connectivity with dorsal anterior cingulate cortex

Abstract

Risk is a fundamental factor affecting individual and social economic decisions, but its neural correlates are largely unexplored in the social domain. The amygdala, together with the dorsal anterior cingulate cortex (dACC), is thought to play a central role in risk taking. Here, we investigated in human volunteers (n=20; 11 females) how risk (defined as variance of reward probability distributions) in a social situation affects decisions and concomitant neural activity as measured with fMRI. We found social variance-risk signals in the amygdala. Activity in lateral parts of the amygdala increased parametrically with social reward variance of the presented options. Behaviorally, 75% of participants were averse to social risk as estimated in a Becker-DeGroot-Marschak auction-like procedure. The stronger this aversion, the more negative was the coupling between risk-related amygdala regions and dACC. This negative relation was significant for social risk attitude but not for the attitude towards variance-risk in juice outcomes. Our results indicate that the amygdala and its coupling with dACC process objective and subjectively evaluated social risk. Moreover, while social risk can be captured with a framework originally established by finance theory for individual risk, the amygdala appears to processes social risk largely separately from individual risk.