Prosocial Decision-Making and Human Brain: A Graph Theory Analysis on Resting-State Functional Magnetic Resonance Image

Prosocial behavior is the cornerstone of a harmonious society. However, the functional organization of the brain underlying prosocial decision-making needs to be further explored. Here, we used graph theory analysis to investigate the brain functional connectivity derived from functional magnetic resonance imaging (fMRI) scans during rest in 55 female Chinese university students. The behavioral responses were collected in another fMRI scan during which participants completed an economic exchange game task by making multiple choices between a prosocial and a selfish option against either human counterparts (i.e., social environment) or robot counterparts (i.e., non-social environment). We found that making more prosocial decisions is accompanied by a longer path length in the right anterior superior temporal gyrus (aSTG), higher degree centrality in the posterior cingulate cortex (PCC), and higher betweenness centrality in the left aSTG. Our results suggest that human prosocial decisions are associated with greater inter-regional collaborations that are dominated by a few core nodes within the brain network of Theory of Mind (ToM). Moreover, an individuals preference for making prosocial decisions could be uncovered by graph theory analysis of the functional brain network even without explicit task requirements.