NewScientist
People have long envisaged the brain as being like a computer on standby, lying dormant until called upon to do a task, such as solving a Sudoku, reading a newspaper, or looking for a face in a crowd. Sokoloff’s experiment provided the first glimpse of a different truth: that the brain enjoys a rich private life. This amazing organ, which accounts for only 2 per cent of our body mass but devours 20 per cent of the calories we eat, fritters away much of that energy doing, as far as we can tell, absolutely nothing.
“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.”
Daydreaming may sound like a mental luxury, but its purpose is deadly serious: Buckner and his Harvard colleague Daniel Gilbert see it as the ultimate tool for incorporating lessons learned in the past into our plans for the future. So important is this exercise, it seems, that the brain engages in it whenever possible, breaking off only when it has to divert its limited supply of blood, oxygen and glucose to a more urgent task. But people are starting to suspect that the default network does more than just daydream. More
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