This study investigates the neural mechanisms underlying cooperation in two-person reciprocal exchange through functional MRI (fMRI) experiments. The researchers hypothesized that the medial prefrontal cortex plays a crucial role in integrating theory-of-mind processing with cooperative actions. Participants played "trust and reciprocity" games with both human and computer counterparts, receiving cash rewards. Behavioral data showed that seven subjects consistently attempted cooperation with their human counterparts. Within this group, prefrontal regions were more active when playing with a human compared to a computer, following a fixed probabilistic strategy. In contrast, noncooperators showed no significant differences in prefrontal activation between computer and human conditions. The study found that cooperators exhibited significant increases in activation in the medial prefrontal cortex during human interactions, suggesting that cooperation requires an active convergence zone that binds joint attention to mutual gains and inhibits immediate reward gratification. The results support the hypothesis that the medial prefrontal cortex is involved in integrating theory-of-mind processing with cooperative actions.This study investigates the neural mechanisms underlying cooperation in two-person reciprocal exchange through functional MRI (fMRI) experiments. The researchers hypothesized that the medial prefrontal cortex plays a crucial role in integrating theory-of-mind processing with cooperative actions. Participants played "trust and reciprocity" games with both human and computer counterparts, receiving cash rewards. Behavioral data showed that seven subjects consistently attempted cooperation with their human counterparts. Within this group, prefrontal regions were more active when playing with a human compared to a computer, following a fixed probabilistic strategy. In contrast, noncooperators showed no significant differences in prefrontal activation between computer and human conditions. The study found that cooperators exhibited significant increases in activation in the medial prefrontal cortex during human interactions, suggesting that cooperation requires an active convergence zone that binds joint attention to mutual gains and inhibits immediate reward gratification. The results support the hypothesis that the medial prefrontal cortex is involved in integrating theory-of-mind processing with cooperative actions.