Whenever you\u2019re actively performing a task \u2014 say, lifting weights at the gym or taking a hard exam \u2014 the parts of your brain required to carry it out become \u201cactive\u201d when neurons step up their electrical activity. But is your brain active even when you\u2019re zoning out on the couch?<\/p>\n

The answer, researchers have found, is yes. Over the past two decades they\u2019ve defined what\u2019s known as the default mode network, a collection of seemingly unrelated areas of the brain that activate when you\u2019re not doing much at all. Its discovery has offered insights into how the brain functions outside of well-defined tasks and has also prompted research into the role of brain networks \u2014 not just brain regions \u2014 in managing our internal experience.<\/p>\n

In the late 20th century, neuroscientists began using new techniques to take images of people\u2019s brains as they performed tasks in scanning machines. As expected, activity in certain brain areas increased during tasks \u2014 and to the researchers\u2019 surprise, activity in other brain areas declined simultaneously. The neuroscientists were intrigued that during a wide variety of tasks, the very same brain areas consistently dialed back their activity.<\/p>\n

It was as if these areas had been active when the person wasn\u2019t doing anything, and then turned off when the mind had to concentrate on something external.<\/p>\n