The practice of meditation is associated with a sense of peacefulness and physical relaxation.  Sara W. Lazar, from Massachusetts General Hospital (Massachusetts, USA), and colleagues studied the role of a mindfulness meditation program on brain structure, and resultant psychological changes.  Sixteen men and women were enrolled in an eight-week long mindfulness meditation program.  The researchers conducted magnetic resonance imaging (MRI) of the subjects’ brains, two weeks before and after they participated in the meditation program.  In addition to weekly meetings that included practice of mindfulness meditation – which focuses on nonjudgmental awareness of sensations, feelings and state of mind – participants received audio recordings for guided meditation practice and were asked to keep track of how much time they practiced each day. A set of MRIs were also taken of a control group of non-meditators over a similar time interval.  The team found that the meditation group participants spent  an average of 27 minutes each day practicing mindfulness exercises, and their responses to a mindfulness questionnaire indicated significant improvements compared with pre-participation responses. When the researchers analyzed the MRIs, they found increased grey-matter density in the hippocampus, known to be important for learning and memory, and in structures associated with self-awareness, compassion and introspection. Participant-reported reductions in stress also were correlated with decreased grey-matter density in the amygdala, which is known to play an important role in anxiety and stress. Noting that none of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time, the team concludes that: “Participation in [Mindfulness-Based Stress Reduction] is associated with changes in gray matter concentration in brain regions involved in learning and memory processes, emotion regulation, self-referential processing, and perspective taking.