Mapping the self in the brain's default mode network

The brain's default mode network (DMN) is linked to self-referential thought during rest, but it also serves other functions, and self-reference involves regions outside the DMN. In 88 participants, self-referential and resting-state brain activity were compared to identify DMN areas common to both conditions that also show specialization for self-reference. The 'core-self' DMN regions—medial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobule—were analyzed with dynamic causal modeling. The optimal model indicated that self-related processes are driven by posterior cingulate activity and moderated by the medial prefrontal cortex. This confirms these regions' importance for self-reference and clarifies their specialized roles.

Study at a glance

Abstract

The brain's default mode network (DMN) has become closely associated with self-referential mental activity, particularly in the resting-state. While the DMN is important for such processes, it has functions other than self-reference, and self-referential processes are supported by regions outside of the DMN. In our study of 88 participants, we examined self-referential and resting-state processes to clarify the extent to which DMN activity was common and distinct between the conditions. Within areas commonly activated by self-reference and rest we sought to identify those that showed additional functional specialization for self-referential processes: these being not only activated by self-reference and rest but also showing increased activity in self-reference versus rest. We examined the neural network properties of the identified 'core-self' DMN regions-in medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), and inferior parietal lobule-using dynamic causal modeling. The optimal model identified was one in which self-related processes were driven via PCC activity and moderated by the regulatory influences of MPFC. We thus confirm the significance of these regions for self-related processes and extend our understanding of their functionally specialized roles.