Default Mode Network and Ego Dissolution

The default mode network (DMN) is the set of brain regions most active when we are not doing much — daydreaming, remembering, planning, thinking about ourselves. It is, in a real sense, the neural correlate of the ongoing autobiographical narrative most of us call the self.

Psilocybin and related psychedelics reliably quiet the DMN. Functional imaging shows reduced within-network connectivity and increased cross-talk between networks that usually stay in their lanes. Subjectively, this correlates with what participants describe as ego dissolution: a temporary softening or disappearance of the boundary between self and world.

The experience is not always comfortable. It can be beautiful, terrifying, revelatory or all three within the same session. What matters clinically is that the phenomenon is repeatable, measurable, and correlated with therapeutic outcomes in trials for depression, addiction and existential distress.

The philosophical implications are large and unresolved. If the self can be neurally softened, what does that tell us about what a self is? The contemplative traditions have said, for millennia, that the felt boundary of the ego is more constructed than most people notice. Neuroscience appears to be belatedly arriving at a compatible view.