Mapping the self in the brain's default mode network
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.
NeuroImage