PT - JOURNAL ARTICLE AU - Masahiko Haruno AU - Mitsuo Kawato TI - Activity in the Superior Temporal Sulcus Highlights Learning Competence in an Interaction Game AID - 10.1523/JNEUROSCI.2707-08.2009 DP - 2009 Apr 08 TA - The Journal of Neuroscience PG - 4542--4547 VI - 29 IP - 14 4099 - http://www.jneurosci.org/content/29/14/4542.short 4100 - http://www.jneurosci.org/content/29/14/4542.full SO - J. Neurosci.2009 Apr 08; 29 AB - During behavioral adaptation through interaction with human and nonhuman agents, marked individual differences are seen in both real-life situations and games. However, the underlying neural mechanism is not well understood. We conducted a neuroimaging experiment in which subjects maximized monetary rewards by learning in a prisoner's dilemma game with two computer agents: agent A, a tit-for-tat player who repeats the subject's previous action, and agent B, a simple stochastic cooperator oblivious to the subject's action. Approximately 1/3 of the subjects (group I) learned optimally in relation to both A and B, while another 1/3 (group II) did so only for B. Postexperiment interviews indicated that group I exploited the agent strategies more often than group II. Significant differences in learning-related brain activity between the two groups were only found in the superior temporal sulcus (STS) for both A and B. Furthermore, the learning performance of each group I subject was predictable based on this STS activity, but not in the group II subjects. This differential activity could not be attributed to a behavioral difference since it persisted in relation to agent B for which the two groups behaved similarly. In sharp contrast, the brain structures for reward processing were recruited similarly by both groups. These results suggest that STS provides knowledge of the other agent's strategies for association between action and reward and highlights learning competence during interactive reinforcement learning.