Default Mode Network
A coordinated set of brain regions associated with self-referential thinking and the construction of a continuous narrative self.
The Default Mode Network (DMN) is a set of interconnected brain regions — including the medial prefrontal cortex, posterior cingulate cortex, precuneus, and parts of the inferior parietal lobe — that became famous because of a counterintuitive observation: these regions decrease their activity when a person engages with focused external tasks and reactivate when the mind is at rest.
Subsequent research has linked DMN activity to a cluster of self-referential mental processes: mind-wandering, autobiographical memory, mental time travel, theory of mind, and the ongoing construction of a continuous “I.” The DMN is, in some practical sense, the hardware on which a person’s identity simulation runs.
Psilocybin produces measurable decreases in DMN coherence and increases in global brain connectivity. These changes are now a leading candidate mechanism for the “ego dissolution” reported by participants in clinical trials.