What is Default mode network?
The default mode network (DMN) is a set of interconnected brain regions that become active when a person is not focused on external tasks: during rest, mind-wandering, self-reflection, future planning, and remembering the past.
How it works
The DMN includes the medial prefrontal cortex, posterior cingulate cortex, and angular gyrus. Raichle et al. (2001) discovered that these regions are more active during ‘rest’ than during demanding tasks, suggesting the brain is not idle when it appears to be doing nothing but is engaged in internally-directed cognition. The DMN supports self-referential thought, theory of mind (understanding others’ mental states), moral reasoning, and autobiographical memory. Its activity typically decreases when attention is focused on external tasks.
Applied example
A person lying in an fMRI scanner with no task to perform shows strong DMN activation as their mind drifts to what they will have for dinner, a conversation from yesterday, and worry about an upcoming meeting. This ‘resting’ brain is actually highly active in self-relevant processing.
Why it matters
The default mode network revolutionized our understanding of the resting brain, showing that internally-directed cognition is a major consumer of brain resources and plays essential roles in self-understanding and social cognition.
