Default mode network
Also known as: DMN, default network, task-negative network
A set of brain regions that are most active when the mind is at rest and not focused on an external task — linked to self-referential thinking, memory retrieval, and mind-wandering.
The default mode network (DMN) is one of the brain's core functional networks — a constellation of regions that reliably co-activate when a person is not engaged in an externally directed task. The name comes from the observation that these regions show their highest metabolic activity during rest and decrease activity (or "deactivate") when the brain switches to focused external attention.
Core regions
The DMN is not a single structure but a distributed network. Its key nodes include:
- Medial prefrontal cortex — self-referential processing, value judgements
- Posterior cingulate cortex / precuneus — autobiographical memory retrieval, mind-wandering
- Angular gyrus — semantic processing, narrative integration
- Hippocampal formation — memory consolidation and prospective thinking
- Lateral temporal cortex — social cognition, conceptual knowledge
What the DMN does
Contrary to the idea that the "resting" brain is idle, the DMN is metabolically expensive and functionally active. It supports:
- Self-referential thought — thinking about oneself, one's past and future
- Autobiographical memory — retrieving personal memories
- Mental simulation — imagining future scenarios, counterfactuals
- Theory of mind — reasoning about other people's mental states
- Mind-wandering and creativity — the spontaneous, generative thought that occurs in the absence of a focused task
DMN and brain ageing
The DMN changes reliably with age. Key findings from the literature:
- Reduced connectivity between DMN nodes is one of the most consistent findings in ageing, beginning in midlife
- Failure to deactivate during tasks — a hallmark of healthy DMN function — is impaired in older adults and is associated with worse memory performance
- Overlap with Alzheimer's pathology — amyloid plaques preferentially deposit in DMN regions, and the network's high metabolic activity and connectivity to the hippocampus may explain this vulnerability
Because of this overlap, DMN connectivity (measured with resting-state fMRI) is increasingly used alongside structural measures in brain age research.
Read more
Related terms
Neuroplasticity
The brain's capacity to change its structure and function in response to experience, learning, injury, or environmental demands — present throughout the lifespan, though it shifts in character with age.
Cognitive reserve
The brain's accumulated resilience against pathology — built over a lifetime through education, cognitive engagement, and social activity — which allows some people to sustain function despite significant structural brain changes.
Dementia / Alzheimer's disease
Dementia is a syndrome of progressive cognitive decline severe enough to impair daily life; Alzheimer's disease is its most common cause, characterised by amyloid plaques, tau tangles, and gradual neurodegeneration.
Brain age gap
The difference between brain age and chronological age. A positive gap means the brain looks older than it should; a negative gap, younger.