The brains of experienced meditators appear to be fitter, more disciplined and more "on task" than do the brains of those trying out meditation for the first time. And the differences between the two groups are evident not only during meditation, when brain scans detect a pattern of better control over the wandering mind among experienced meditators, but when the mind is allowed to wander freely.
Those insights emerge from a study to be published next week in the Proceedings of the National Academy of Sciences, which looked at two groups: highly experienced meditators and meditation novices, and compared the operations of the "Default Mode Network" -- a newly identified cluster of brain regions that go to work when our brains appear to be "offline."
"I think it's safe to say this is brain-training at work," says Yale University psychiatrist Judson Brewer, who conducted the study with psychologists from Yale, the University of Oregon and Columbia University. "It makes sense," adds Brewer. "Anything you train to do, you do better."
By the definition of the latest study, mental control was defined as the ability to keep two key nodes of the default mode network from becoming active during meditation. The posterior cingulate cortex and the medial prefrontal cortex appear to be hubs of the brain's "neutral" setting--areas that come alive when we are not engaged in a task that requires more specialized attention and let our minds wander. (Not coincidentally, they are also areas that tend to become active when we remember events in our past and think about other peoples' motives and intentions.) In the 12 veteran meditators who participated in the current study, those two regions were quieter during meditation than they were in the brains of the 12 meditation novices with which they were compared.
The study also detected greater connectivity between some of the brain's key cognitive control areas and elements of the default mode network. During meditation and in the mental rest periods in between, a brain region known to be important in focusing and maintaining attention, the dorsolateral anterior cingulate cortex, was more likely to activate in tandem with the posterior cingulate cortex in regular meditators than in those who are new to the practice: that, says Brewer, suggests that during meditation and in everyday life, meditators may have more skill in reining in their wandering thoughts and bringing the brain back "on task"-- than those who don't routinely meditate.
Why would mental control over our daydreams make us more healthy? It turns out that having a well-functioning default mode network--one that lets us explore ourselves and our lives but doesn't intrude into our efforts to concentrate when that's what's needed--is critical to mental health.
Those of us who daydream more often are more likely to be depressed--either because we get caught in a cycle of rumination or because depressed people have poorer concentration (which comes first isn't clear). A study that tracked the daily activities and moods of iPhone users-published in Science magazine last November--found that those whose minds were wandering off task more often were more depressed. People who suffer from attention deficit disorder also have difficulty keeping mind-wandering at bay, which may be why many studies have found that meditation helps those with attention deficit disorder.