 The purpose of this study is to evaluate the effects of a Zen meditation retreat Sesshin on psychophysiological parameters in healthy volunteers regular meditators and non-meditators and in cancer patients and to observe possible changes in the attentional circuitry through functional Magnetic Resonance Imaging- fMRI and in psychological tests Beck Anxiety and Depression Inventories, Self-Compassion Scale, Mindfulness Attention Awareness Scale, Lipp Stress Scale for Adults. 