Meditation has been practiced around the world for thousands of years and has during the past decade become increasingly popular in the Western world. Meditation can be seen as a form of mental exercise and refers to a family of complex emotional and attentional regulatory practices that involves different attentional, cognitive monitoring and awareness processes. Clinical research on meditation has demonstrated that meditation seem to reduce stress, anxiety, and depression. Recent interest in how meditation affect the human brain and body have lead to an increase in research regarding the neural correlates of meditation, structural changes induced by meditation, and the potential attentional and emotional benefits mediated by meditation. This thesis investigates expert related changes in neural activity, brain structure, and attentional performance induced by focused attention meditation (FAM) and open monitoring meditation (OMM). The research on meditation and the brain is still in its infancy but despite this, there seem to be some converging evidence of meditation’s impact on the human brain and mind. The results from the included studies in this thesis indicates that expert meditators show greater activation in some meditation related brain areas, as well as less activation in other areas when compared to novice meditators. The results also suggest that long-term meditation practice induce some structural changes in the brain and that meditation seem to enhance the practitioners’ attentional control.