Decomposing Cognitive Processes in the mPFC During Self-Thinking

Past cognitive neuroscience research has demonstrated that thinking about both the self and other activate the medial prefrontal cortex (mPFC), a central hub of the default mode network. The mPFC is also implicated in other cognitive processes, such as introspection and autobiographical memory, rendering elusive its exact role during thinking about the self. Specifically, it is unclear whether the same cognitive process explains the common mPFC involvement or distinct processes are responsible for the mPFC activation overlap. In this preregistered functional magnetic resonance imaging (fMRI) study with 35 male and female human participants, we investigated whether and to what extent mPFC activation patterns during self-reference judgment could be explained by activation patterns during the tasks of other-reference judgment, introspection, and autobiographical memory. Multi-voxel pattern analysis (MVPA) showed that only in the mPFC were neural responses both concurrently different and similar across tasks. Furthermore, multiple regression and variance partitioning analyses indicated that each task (i.e., other-reference, introspection, memory) uniquely and jointly explained significant variances in mPFC activation during self-reference. These findings suggest that the self-reference task engages multiple cognitive processes shared with other tasks, with the mPFC serving as a crucial hub where essential information is gathered and integrated to support judgments based on internally constructed representations. Significance statement This study advances our understanding of the medial prefrontal cortex (mPFC), a central hub of the default mode network, in self-referential thinking. By using fMRI, multi-voxel pattern analysis, and variance partitioning, we demonstrate that mPFC activation during self-reference judgment is explained by shared and unique contributions from other cognitive processes, including other-reference, introspection, and autobiographical memory. Importantly, the mPFC is the only region where neural responses were concurrently similar and different across these tasks, suggesting its role in integrating diverse cognitive processes. These findings highlight the mPFC’s critical function in gathering and integrating information for judgments based on internal representations, shedding light on its multifaceted role in self-related cognition.