the active idle brain

Every now and then, NewScientist publishes concurrent or even consecutive articles that, taken together, pose a dilemma unnoticed by the editors. The latest issue has a great example of a hidden paradox concerning the value of idling.

In the first, Douglas Fox reports that scientists have discovered a neural network that may form and strengthen memory when we're not actively thinking. [sub. req.]

"There is a huge amount of activity in the [resting] brain that has been largely unaccounted for," says Marcus Raichle, a neuroscientist at Washington University in St Louis. "The brain is a very expensive organ, but nobody had asked deeply what this cost is all about."

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.

"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...."

The brain areas in the network were known and previously studied by researchers. What they hadn't known before was that they chattered non-stop to one another when the person was unoccupied but quietened down as soon as a task requiring focused attention came along. Measurements of metabolic activity showed that some parts of this network devoured 30 per cent more calories, gram for gram, than nearly any other area of the brain.

In the pages immediately following, Lewis Dartnell describes how researchers are turning to a modified form of "distributed computing" to harness strangers' idle minds.

But there are limits to what even a million computers can do. "Despite computers being very quick and accurate at certain problems, for many tasks they are still far surpassed by the human brain, such as in visual processing, spatial reasoning or problem solving," says Aaron Sloman, who studies artificial intelligence at the University of Birmingham, UK. So now the idea of distributed computing is being turned on its head. Instead of harnessing idle machines, researchers are inventing ways of using the processing power inside the brains of "idle" computer owners.

There seems to be no shortage of this intellectual power going begging. Clay Shirky at New York University has calculated that every weekend in the US alone, 100 million person hours are spent watching TV adverts - the same amount of time it took to create and edit the 2.5 million encyclopedia entries on Wikipedia. If only a fraction of this spare brainpower could instead be channelled into simple online tasks that help science, the contribution would be enormous.

Now the dilemma arises. The brain, at idle, is doing absolutely critical work, consuming 20% of the body's energy. Yet scientists want to essentially de-idle the minds of millions to help solve bafflingly complex problems, at unknown cost. Compound that with the problems of multitasking, and we have no idea of the potential net neurological losses cause by a lack of laziness.