A Causal Role of Right Temporoparietal Junction in Prosocial Learning: A Transcranial Direct Current Stimulation Study.

Prosocial behavior is a common and important aspect of everyday social life. To behave prosocially, we need to learn the consequences of our actions for other people, known as prosocial learning. Previous studies have identified the right temporoparietal junction (rTPJ) as the critical neurological substrate for prosocial behavior. However, little is known about the causal role of the rTPJ in prosocial learning. To clarify the role of the rTPJ in prosocial learning, we used a reinforcement learning paradigm and transcranial direct current stimulation (tDCS). A total of 75 participants were recruited and randomly assigned to the anodal or sham tDCS group. While receiving tDCS stimulation over the rTPJ, participants were instructed to choose between different stimuli that were probabilistically associated with rewards for themselves in the self-learning condition or for another person in the prosocial-learning condition. Participants were able to learn to obtain rewards for themselves or others, and learning performance in the self-learning condition was better than that in the prosocial-learning condition. However, anodal tDCS over the rTPJ significantly improved learning performance in the prosocial-learning condition. These results indicate that the rTPJ plays a causal role in prosocial learning.