You might be the laziest person on the planet, but your brain never rests. So what does it get up to when you’re more or less checked out?
In the 1930s, Hans Berger, a German psychiatrist who had recently invented the electroencephalogram (EEG), suggested that our brains are always active, even when we don’t seem to be doing much with them. Few people took the idea seriously at the time (maybe because Berger had spent much of his career trying to prove telepathy, or perhaps because he was just ahead of his time). Some 40 years later, in the 1970s, researchers confirmed that blood flow to the brain, a useful proxy for brain activity, varies depending on what you’re doing.
Still, it was difficult to learn much about which regions of the brain are active during various activities until the advent of modern brain imaging technology, such as positron emission ...
