Unveiling the neural dynamics of the theory of mind: a fMRI study on belief processing phases

Theory of mind (ToM), the ability to interpret others' behaviors in terms of mental states, has been extensively studied through the False-Belief Task (FBT). However, limited research exists regarding the distinction between different phases of FBT, suggesting that they are subserved by separate neural mechanisms. Further inquiry into this matter seems crucial for deepening our knowledge of the neurocognitive basis of mental-state processing. Therefore, we employed functional Magnetic Resonance Imaging (fMRI) to examine neural responses and functional connectivity within the core network for ToM across phases of the FBT, which was administered to 61 healthy adults during scanning. The region-of-interest analysis revealed heightened responses of the temporoparietal junction (TPJ) during and increased activation of medial prefrontal cortex (mPFC) during the outcome phase. Negative connectivity between these regions was observed during belief-formation. Unlike the TPJ, mPFC responded similarly to conditions that require belief reasoning and to control conditions that do not entail tracking mental states. Our results indicate a functional dissociation within the core network for ToM. While the TPJ is possibly engaged in coding beliefs, the mPFC shows no such specificity. These findings advance our understanding of the unique roles of the TPJ and mPFC in mental-state processing.