The increasingly widespread use of meditation for stress-related emotional and medical conditions motivates a detailed study of its physiological, anatomical, biochemical, and neuronal mechanisms. In order to effectively apply meditation as a treatment, both the dose-response relationship between practice time and outcome, and the detailed nature of the meditation practice itself, are of fundamental importance. The term meditation includes a broad range of techniques which emphasize either mindfulness (focused attention), compassion (a.k.a. loving-kindness), or more advanced techniques such as Tibetan gTummo practice. While mindfulness meditation has been the most intensively studied, the scientific exploration of compassion meditation has only recently begun and recent results suggest important and measurable neuro-endocrine and immunological benefits associated with compassion meditation. There are two specific aims in the present proposal, based on the use of Magnetic Resonance Imaging at both the cerebral (brain) and sub-cerebral (spinal) levels. The first specific aim is to assess the doseresponse relationship of both mindfulness and compassion meditation methods that are being studied under a large (N=360) research trial (NIH 1R01AT004698-01) now beginning at Emory University. The goal is to determine the dose-response relationship of the pre and post effect of meditation training with structural and functional brain imaging methods that will be performed on a subset of the Emory subjects at the Martinos Biomedical Imaging Laboratory of Massachusetts General Hospital, and to compare these results to the neuro-endocrine and other stress measures obtained in the Emory study. The hypothesis to be tested is that the biomarkers measured in the Emory study will show similar longitudinal effects to functional and structural brain imaging longitudinal measurements. The second specific aim is to perform the first imaging exploration of the nature of bodily states of awareness that are traditionally reported in conjungation with advanced yoga meditation practices, via the application of MRI thermometric imaging, and to discriminate between two major hypotheses concerning the physiological basis of these effects. Together, these two specific aims provide a basic measurement, from the point of view of brain imaging, of the dose-response relationship of two major forms of meditation practice that are under increasing clinical application, and additionally provide a basic scientific exploration of a third major form of meditation.