The default mode network (DMN; also known as default network) describes the neurological pattern that occurs when the brain is at rest. Brain imaging technology such as functional magnetic resonance imaging (fMRI) has allowed researchers to begin to understand how our brain works in a physiological sense: activity, inactivity, connections and relationships between different parts of the brain.
When the brain is ‘resting’ is enters the DMN. It uses less energy and engages in low activity oscillations. The brain will leave the DMN for another network when it begins focusing on a task or giving attention to a stimulus. It is essentially like a screensaver for your brain: after a period of mental dormancy it enters the DMN and stays there on low power until it is engaged again. There is evidence that suggests there may be more than one DMN.
Areas of the brain shown to be involved with the DMN include the parietal cortex, medial prefrontal cortex, temporal lobe, and posterior cingulate cortex. The DMN has been shown to be affected by a host of brain disorders including Attention Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorders, bipolar disorder, schizophrenia, depression, and post-traumatic stress disorder.