Default Mode Network
The idea that the brain could be constantly busy is not new. An early proponent of that notion was Hans Berger, inventor of the familiar electroencephalogram, which records electrical activity in the brain with a set of wavy lines on a graph. In seminal papers on his findings, published in 1929, Berger deduced from the ceaseless electrical oscillations detected by the device that “we have to assume that the central nervous system is always, and not only during wakefulness, in a state of considerable activity". Over the years, however, others became curious about what was happening when someone was simply resting and just letting the mind wander. This interest arose from a set of hints from various studies that suggested the extent of this behind-the-scenes activity. One clue came from mere visual inspections of the images. The pictures showed that areas in many regions of the brain were quite busy in both the test and the control conditions. In part because of this shared backgrou