One of the most interesting areas of research on the effects of contemplative practices has explored the possibility that the actual structure of the brain is changed by meditation practice. Several neuroscientists have shown that some of the brain regions activated during meditation are actually different in people who meditate regularly, and the most recent evidence suggests that the changes can occur in as little as eight weeks. This finding is at odds with what we think we know about brain structure in adults. We used to believe that sometime shortly after twenty-five or thirty years of age the brain was finished with growth and development. From then on, the brain became progressively impaired by age and injury, and it was all downhill from there. But recent meditation research suggests that this glum outcome may not be inevitable. Meditation practice is associated with changes of specific brain areas that are essential for attention, learning, and the regulation of emotion.

Maybe this shouldn’t be such a surprise. When you exercise your muscles in the gym, they become larger as well as stronger. Their structure changes. In fact, almost any structure of the body changes when it is used more often. It now seems that this is also true for the brain. For instance, we know that when you learn to juggle, the part of the brain involved with tracking objects in space becomes larger. Meditation shouldn’t be any different. Like all cutting-edge research, this work on brain size is controversial, but it has already become an area for deeper investigation by more researchers.

The first researcher to report the effect of meditation on brain structure was Harvard neuroscientist Sara Lazar, a researcher in the psychiatry department at Massachusetts General Hospital. She performed magnetic resonance imaging (MRI) to obtain highly detailed pictures of the brains of twenty meditators recruited from meditation practice centers near Boston, and compared them with images obtained from a control group of twenty nonmeditators. The meditators were experienced practitioners, but they were not monks, nuns, or full-time retreatants. They had practiced for an average of about nine years, and spent, on average, a little less than an hour a day meditating. All were Westerners, living in the United States and working in typical jobs. The nonmeditators were local volunteers, matched to the meditators for characteristics like age and gender, but with no experience in yoga or meditation.

Lazar was looking at the brain’s cortex—the outermost surface of the brain. This is the most evolutionarily recent part of the brain. When the brain images of the two groups were compared, she found that some cortical areas in the brains of the meditators were significantly thicker than the same areas in nonmeditators. The cortex atrophies with age; in Lazar’s meditating subjects, however, these enlarged areas were the same thickness as what was measured in nonpractitioners twenty years younger. Previous work had already shown that these areas were more active during meditation practice. One of the areas was in the prefrontal cortex, the part of the brain that is farthest forward inside the skull, closest to the forehead. The other area identified by Lazar was in a different region of the cortex called the insula.