The default mode network (DMN) is a set of interconnected brain regions known to be most active when humans are awake but not engaged in physical activities, such as relaxing, resting or daydreaming.

As you read this, in the background—or perhaps the foreground—is the wandering mind. This basal activity may be best represented in current neuroscience by the Default Mode Network (DMN). The DMN is ...

When your mind is wandering, your brain’s “default mode” network is active. Its discovery 20 years ago inspired a raft of research into networks of brain regions and how they interact with each other.

The original version of this story appeared in Quanta Magazine. Whenever you’re actively performing a task—say, lifting weights at the gym or taking a hard exam—the parts of your brain required to ...