LUCY READING-IKKANDASome people are amazingly focused, energized, and attentive. Others always seem to have their heads in the clouds, dreaming the day away. One might think that our brains doze off and switch to a resting state when we let our minds wander, but research using functional magnetic resonance imaging (fMRI) to visualize brain activity has shown the reverse: brains are particularly active during these mind-wandering episodes.
One of the key brain networks active during the resting state is aptly termed the default-mode network (DMN). It is inactivated by task-related networks in a push-pull fashion. Perhaps not surprisingly, impairments in the ability to dynamically activate or inactivate the DMN have been found to be associated with attention deficits, depression, schizophrenia, Alzheimer’s, and many other psychiatric disorders. These findings are challenging one particular, dominant school of thought among neuroscientists—that brains are mainly reactive, computing adaptive behaviors from available sensory input.
The discoverer of the DMN, Marcus Raichle at Washington University in St. Louis, portrays the brain as an active organ, constantly producing spontaneous activity which is only modulated by incoming stimuli. It seems intuitive that brains are both reactive and active, depending on ...
