Meditation thickens gray matter
Researchers at Harvard, Yale and MIT found that meditation can alter the physical structure of the brain. Scans showed that experienced meditators had increased thickeness in parts of the brain’s cortex (or ‘thinking cap’, part dealing with attention and processing sensory input), which normally get thinner with age. According to Sara Lazar, Harvard Medical School psychologist, "these increases are proportional to the time a person has been meditating during their lives… this suggests that the thickness differences are acquired through extensive practice and not simply due to differences between meditators and nonmeditators." The increase of gray matter thickeness was .004-.008 inches. "Data suggest that meditation practice can promote cortical plasticity in adults in areas important for cognitive and emotional processing and well-being," says Lazar.
Meditation found to increase brain size, Harvard Gazette