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Laura Ziesel
Contributing Education Writer
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How Daydreaming Can Boost the Brain

What’s going on in our brain when we daydream or rest? More than you might think.

My husband does not believe me when I tell him that I cannot stop thinking. He claims that he can “shut off his brain” whenever he wants. But it turns out that even when we think we’re zoning out or taking a mental break, the brain keeps going—it’s impossible to turn it off.

A common myth about the brain is that it rests, just like other parts of our body. Just reflect for a moment on your own thinking patterns. Don’t solutions to problems that have been bugging you occasionally pop into your brain while you are lying in bed or working out on the treadmill? For a long time, even neuroscientists thought that brain circuits were turned on only when needed for a specific activity. Even as brain-imaging technology evolved (PET scans, MRIs, fMRIs), scientists were focusing on brain activity related to specific tasks, and any background activity—the brain’s so-called “white noise”—was often overlooked. What slowly emerged, however, is that this white noise reflects an enormous amount of activity going on in circuits unrelated to the task at hand yet connected in specific ways. These areas, which are less active when the brain is busy focusing on a specific task (solving a math problem, shooting a basketball), actually pick up in intensity when we’re doing nothing—daydreaming, lying down, lightly sleeping or even when we’re under anesthesia. They make up what is now called the default mode network (DMN), and the process by which these areas “talk” to each other is called functional connectivity.

Researchers are still figuring out the exact role of the DMN. One that it relates to retrieving memories in order to solve problems and develop future plans. Some studies have found that the activity of the DMN in patients with Alzheimer’s Disease, schizophrenia, autism and depression is different than in healthy subjects.

Scientists also recently discovered that what you do during active brain time affects DMN activity. Researchers at Washington University School of Medicine in St. Louis, in collaboration with scientists at the University of Chieti, in Italy, found changes in the brain’s functional connectivity patterns after an individual learned a new task—the brain networks used in the task were more active than they had been prior to the research experiment, with learning seemingly “sculpting” the connections. In other words, the more input your brain gets—from a new experience, solving a problem, reading new information—the stronger the brain’s scaffolding gets, linking various components together. Some of these same researchers more recently found that DMN activity could predict an individual’s performance on a visual perception task.

When I presented these facts about the DMN to my husband, I said, “See, you’re not able to turn your brain off.” He looked at me, exhausted from a full day of work, and said, “Well, if my brain silently works without my knowledge, then that’s fine with me. I’m the one who needs a break; if my brain doesn’t, more power to it.”

Learn More:

“The Computer Between Our Ears,” a brain primer by Barbara Landau

Related Reading:

Watch a Brief Introduction to the Default Mode Network

“A Brain at Rest Tends to Stay . . . in Motion,” by Kayt Sukel, the Dana Foundation

“Brain’s default mode network may hold key to better psychiatric diagnoses,” by Melissa Healy, Los Angeles Times