For hundreds of years, Tibetan monks and other religious people have used meditation to calm the mind and improve concentration. This week, a new study shows exactly how one common type of meditation affects the brain.

Using a scanner that reveals which parts of the brain are active at any given moment, the researchers found that meditation increased activity in the brain regions used for paying attention and making decisions.

The changes were associated with the practice of concentration meditation, says study leader Richard Davidson, professor of psychology and psychiatry at the University of Wisconsin School of Medicine and Public Health and the Waisman Center. Practitioners were instructed to focus attention intently on a stimulus, and when the attention wandered off, to simply bring the attention back to the object, explains Davidson.

"In one sense, concentration mediation is ridiculously simple, but in another, it's extraordinarily difficult," adds Davidson. "If you try it for two minutes, you will see that it's not so easy. Minds have a propensity to wander."

In collaboration with colleagues Julie Brefczynski-Lewis and Antoine Lutz of the UW-Madison W.M. Keck Laboratory for Functional Brain Imaging and Behavior, Davidson compared newly trained meditators to people with up to 54,000 hours of meditation experience. The study is being published this week in the online edition of the Proceedings of the National Academy of Science.

After the novices were taught to meditate, all subjects underwent a magnetic resonance imaging scan of the brain while they were meditating. Among all experienced meditators, the MRI scan found greater activity in brain circuits involved in paying attention.