How does brain activity differ when you think about yourself from someone else's perspective?

Details

The core regions of the default mode network (DMN)—the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), and inferior parietal lobules (IPL)—are consistently engaged across mental states involving self-oriented processing. Exactly how these regions interact to support such processing remains an important unanswered question.

This functional magnetic resonance imaging (fMRI) study examined dynamic interactions among these “core-self” DMN regions during two forms of self-referential cognition: direct self-appraisal, meaning thinking about oneself, and reflected self-appraisal, meaning thinking about oneself from a third-person perspective. A total of 111 participants completed a dual self-appraisal task during fMRI. The researchers used general linear models to characterize neural responses that were shared between the two conditions and those that differed.

Guided by those results, the researchers applied dynamic causal modelling to examine causal interactions among the core-self regions within the model and how direct and reflected self-appraisal specifically modulated those interactions. The main modelling finding was a distinct inhibitory influence of the left IPL on the PCC during reflected compared with direct self-appraisal. This was accompanied by evidence of greater activation in both regions during reflected self-appraisal.

The researchers suggest that the greater engagement of posterior DMN regions during reflected self-appraisal reflects the higher-order processing this form of self-appraisal requires. In their interpretation, the left IPL supports abstract self-related processes, including episodic memory retrieval and shifts of perspective.

Overall, the findings indicate that core DMN regions interact in functionally distinct ways to support self-referential processes, even when those processes are related to one another. The researchers suggest that further characterization of DMN functional interactions across self-related mental states is likely to deepen understanding of how this brain network orchestrates the self.