Glossary
Default mode network
What is the default mode network?
The default mode network (DMN) is a set of brain regions whose activity often decreases during demanding external tasks compared with rest. It is associated with internally directed thought, including remembering the past and imagining the future; it is not simply an on/off switch for mind-wandering.
How it works
The DMN includes the medial prefrontal cortex, posterior cingulate cortex, and angular gyrus. Raichle and colleagues’ 2001 paper described a pattern of activity that decreased from a resting baseline during tasks. This helped challenge the idea that a resting brain is an idle brain. The comparison does not assign every internal thought or social judgment to this network.
Memory, imagination, and social thought
A 2008 review by Buckner, Andrews-Hanna, and Schacter connects the network with tasks that involve recalling personal experiences, envisioning future events, and considering other people’s perspectives. These activities can use memories and associations to construct situations beyond the immediate surroundings. The review describes interacting subsystems, rather than one region performing every function.
Applied example
When someone rests in a scanner, researchers can measure organized activity without assigning an external task. The scan alone does not reveal whether the person is planning dinner, remembering a conversation, or worrying about a meeting.
For example, imagine recalling yesterday’s conversation, using it to picture tomorrow’s meeting, and considering how a colleague might respond. That sequence illustrates the kinds of memory, simulation, and perspective-taking questions studied in this research. To relate activity to those processes, researchers need an appropriate task or reports of experience, rather than assuming what a resting person was thinking.
Why it matters
The finding helped establish that resting activity has organization and is important for interpreting task comparisons. A resting baseline is not an inactive brain, and default-mode activity is not a readout of one particular kind of thought.