Meditation and relaxation-based interventions are becoming more widely accepted in clinical settings because of their low cost, low risk, and proven effectiveness as a complementary intervention in a wide range of diseases. Despite the success and growing use of relaxation-based treatments, few studies have addressed the basic mechanism by which these treatments work. This study will use functional magnetic resonance imaging (fMRI) to define the brain mechanisms underlying the meditative state, to differentiate this state from other states, and to determine how meditation-induced brain changes affect autonomic function.

Participants in this study will have an fMRI brain scan. Brain activity, breathing rate, and heart rate will be measured while the participant engages in three different activities: lying quietly, meditating, and mentally generating numbers.

Inclusion Criteria:

• Daily practice of Vipassana or Kundalini meditation for at least 1 year and participation in at least one 1-week meditation retreat

Exclusion Criteria:

• Current medical or psychological illness
• Use of antidepressants, antianxiolytics, or compounds that alter cerebral blood flow
• Claustrophobia
• Pregnancy