[Marcus] Raichle and a handful of others are finally tackling this fundamental question - what exactly is the idling brain up to, anyway? Their work has led to the discovery of a major system within the brain, an organ within an organ, that hid for decades right before our eyes. Some call it the neural dynamo of daydreaming. Others assign it a more mysterious role, possibly selecting memories and knitting them seamlessly into a personal narrative. Whatever it does, it fires up whenever the brain is otherwise unoccupied and burns white hot, guzzling more oxygen, gram for gram, than your beating heart.-- from The secret life of the brain by Douglas Fox.
"It's a very important thing," says Giulio Tononi, a neuroscientist at the University of Wisconsin-Madison. "It's not very frequent that a new functional system is identified in the brain, in fact it hasn't happened for I don't know how many years. It's like finding a new continent."