Rearrangement of anti-synchronous activities in the brain functional network plays a crucial role in behavioral contagion

Abstract Behavioral contagion has been defined as the tendency of individuals to imitate the behavior of others after observing them. Despite the important role that behavioral contagion plays in societies, its mechanism in the brain is still not fully understood. In this study, we hypothesized that the brain tends to go to a more stable state after updating behavior by observation of the others’ behaviors. Therefore, the stability of the brain network before and after observing others’ preferences was assessed using structural balance theory (SBT) on the fMRI data. To this end, we developed a version of the Dictator Game as the task, and recorded participants' brain responses using fMRI (before and after observing others' preferences). A threshold for changes in participants' preferences was considered to be the occurrence of behavioral contagion. With regard to this threshold, the participants were classified into two groups, the Contagion and No Contagion. The changes in SBT parameters of the brain network were calculated for both groups. A distinct pattern of changes in SBT parameters was observed for each group. The results of the Contagion group suggested that behavioral contagion is accompanied with a rearrangement of links in the network to transform imbalanced triads into balanced triads. This process lowers the balance energy of the brain network and pushes the network to a more stable state. We hope that these findings on the restructuring of the functional brain network could pave the way to a better understanding of behavioral contagion.