It's called the default network. If the brain on a whole is one of the least understood parts of the human anatomy, the default network may be the least of the least. You can think of it as like the background processes in a computer: always running or on standby to accept your input or figure calculations. The default network is thought by some to be responsible for daydreaming, taking over when your conscious thought wanders. And it's a part of the brain that can stay active even when the brain has sustained a severe injury, which is why the Belgian researchers were attracted to it.