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Lions Roar : July 2011
SHAMBHALA SUN JULY 2011 47 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 sur- face of the brain. This is the most evolutionarily recent part of the brain. When the brain images of the two groups were com- pared, she found that some cortical areas in the brains of the meditators were significantly thicker than the same areas in non- meditators. 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. Although it is extremely difficult to isolate a specific mental function to a particular brain region (and the results of efforts to do so are controversial in the scientific community), the particular areas that Lazar identified in the frontal cortex are essential for a variety of critically important capabilities. The prefrontal cortex manages higher cognitive “executive” functions like planning, deci- sion making, and judgment, and keeps us out of trouble by facilitat- ing socially appropriate behavior. It allows us to hold two concepts or experiences in mind simultaneously so that we can compare and evaluate plans, ideas, and memories. It also helps us to link memory with sensory input so we can connect what we have learned from the past with what is happening in the present moment. The other major region identified by Lazar, the insula, seems to integrate sensation and emotion, and to process social emo- tions—such as empathy and love. It is thought to be essential for the capacity for self-awareness. Although no region of the brain is unimportant, the activities supported by these brain areas are especially crucial for our effective functioning in the world. This research is still viewed as preliminary, partly because it contradicts a lot of what we thought we knew, and partly because it studied only twenty meditators. Lazar says that among her sci- entific peers, some are enthusiastic while others are skeptical. Sub- sequently, however, Lazar’s work was confirmed by a researcher in Brain scans of the hippocampus, showing the regions that were affected by meditation. Images adapted from Britta Hölzel, et al., Psychiatry Research: Neuroimaging Vol. 191 (1), January 30, 2011, pp. 36-43. Cortical areas are thicker in meditators. Image © Sara Lazar. Areas that showed increase in gray matter concentration following eight weeks of mindfulness-based stress reduction. A: posterior cingulate cortex and cerebellum, B: temporo-parietal junction, C: cerebellum and brain stem. Images © Britta Hölzel.