What Is the Default Mode Network?

Researchers noticed that when the participant was resting, the brain wasn't it was still active. It seemed to slip into what was almost casually called the default mode. This network continues working unless it is damped down by a task which demands more focused attention at which point another network switches on. When you are preoccupied by brooding and worrying, the default mod network is highly active. Why? Because brooding and worry involves imagination prediction in the service of possible action.