Christie Nicholson writes in Scientific American:
The benefits of meditation have received newfound evidence from neuroscience in the last five years, as researchers are finding real physiological changes due to a sort of formally practiced introspection.
Recently scientists from Massachusetts General Hospital had 16 participants take an eight-week mindfulness meditation program. This sort of meditation focuses on nonjudgmental awareness of sensations and feelings. Subjects practiced for about 30 minutes a day.
Brain images were taken of each subject before and after the training. Scientists found increases in gray-matter density in the hippocampus — an area responsible for learning and memory. And they saw decreased density in the amygdala— which is responsible for our anxiety and stress responses …
All this reminds us of two things: 1) The brain is much more plastic than scientists thought even just a decade ago and 2) the way we feel—calm or anxious—can be correlated with real structural indicators in our brains.