From CNN's Dan Gilgoff:

Can people strengthen the brain circuits associated with happiness and positive behavior, just as we’re able to strengthen muscles with exercise?

Richard Davidson, who for decades has practiced Buddhist-style meditation - a form of mental exercise, he says - insists that we can.

And Davidson, who has been meditating since visiting India as a Harvard grad student in the 1970s, has credibility on the subject beyond his own experience.

A trained psychologist based at the University of Wisconsin, Madison, he has become the leader of a relatively new field called contemplative neuroscience - the brain science of meditation.

Over the last decade, Davidson and his colleagues have produced scientific evidence for the theory that meditation - the ancient eastern practice of sitting, usually accompanied by focusing on certain objects - permanently changes the brain for the better.

“We all know that if you engage in certain kinds of exercise on a regular basis you can strengthen certain muscle groups in predictable ways,” Davidson says in his office at the University of Wisconsin, where his research team has hosted scores of Buddhist monks and other meditators for brain scans.

“Strengthening neural systems is not fundamentally different,” he says. “It’s basically replacing certain habits of mind with other habits.”

Contemplative neuroscientists say that making a habit of meditation can strengthen brain circuits responsible for maintaining concentration and generating empathy.

One recent study by Davidson’s team found that novice meditators stimulated their limbic systems - the brain’s emotional network - during the practice of compassion meditation, an ancient Tibetan Buddhist practice.

That’s no great surprise, given that compassion meditation aims to produce a specific emotional state of intense empathy, sometimes call “lovingkindness.”

But the study also found that expert meditators - monks with more than 10,000 hours of practice - showed significantly greater activation of their limbic systems. The monks appeared to have permanently changed their brains to be more empathetic.

An earlier study by some of the same researchers found that committed meditators experienced sustained changes in baseline brain function, meaning that they had changed the way their brains operated even outside of meditation.

These changes included ramped-up activation of a brain region thought to be responsible for generating positive emotions, called the left-sided anterior region. The researchers found this change in novice meditators who’d enrolled in a course in mindfulness meditation - a technique that borrows heavily from Buddhism - that lasted just eight weeks.

But most brain research around meditation is still preliminary, waiting to be corroborated by other scientists. Meditation’s psychological benefits and its use in treatments for conditions as diverse as depression and chronic pain are more widely acknowledged.

Serious brain science around meditation has emerged only in about the last decade, since the birth of functional MRI allowed scientists to begin watching the brain and monitoring its changes in relatively real time.

Beginning in the late 1990s, a University of Pennsylvania-based researcher named Andrew Newberg said that his brain scans of experienced meditators showed the prefrontal cortex - the area of the brain that houses attention - surging into overdrive during meditation while the brain region governing our orientation in time and space, called the superior parietal lobe, went dark. (One of his scans is pictured, above.)

Newberg said his findings explained why meditators are able to cultivate intense concentration while also describing feelings of transcendence during meditation.

But some scientists said Newberg was over-interpreting his brain scans. Others said he failed to specify the kind of meditation he was studying, making his studies impossible to reproduce. His popular books, like Why God Won’t Go Away, caused more eye-rolling among neuroscientists, who said he hyped his findings to goose sales.

“It caused mainstream scientists to say that the only work that has been done in the field is of terrible quality,” says Alasdair Coles, a lecturer in neurology at England’s University of Cambridge.

Newberg, now at Thomas Jefferson University and Hospital in Philadelphia, stands by his research.

And contemplative neuroscience had gained more credibility in the scientific community since his early scans.

One sign of that is increased funding from the National Institutes of Health, which has helped establish new contemplative science research centers at Stanford University, Emory University, and the University of Wisconsin, where the world’s first brain imaging lab with a meditation room next door is now under construction.

The NIH could not provide numbers on how much it gives specifically to meditation brain research but its grants in complementary and alternative medicine - which encompass many meditation studies - have risen from around $300 million in 2007 to an estimated $541 million in 2011.

“The original investigations by people like Davidson in the 1990s were seen as intriguing, but it took some time to be convinced that brain processes were really changing during meditation,” says Josephine Briggs, Director of the NIH’s National Center for Complementary and Alternative Medicine.

Most studies so far have examined so-called focused-attention meditation, in which the practitioner concentrates on a particular subject, such as the breath. The meditator monitors the quality of attention and, when it drifts, returns attention to the object.

Over time, practitioners are supposed to find it easier to sustain attention during and outside of meditation.

In a 2007 study, Davidson compared the attentional abilities of novice meditators to experts in the Tibetan Buddhist tradition. Participants in both groups were asked to practice focused-attention meditation on a fixed dot on a screen while researchers ran fMRI scans of their brains.

To challenge the participants’ attentional abilities, the scientists interrupted the meditations with distracting sounds.

The brain scans found that both experienced and novice meditators activated a network of attention-related regions of the brain during meditation. But the experienced meditators showed more activation in some of those regions.

The inexperienced meditators, meanwhile, showed increased activation in brain regions that have been shown to negatively correlate with sustaining attention. Experienced meditators were better able to activate their attentional networks to maintain concentration on the dot. They had, the study suggested, changed their brains.

The fMRI scans also showed that experienced meditators had less neural response to the distracting noises that interrupted the meditation.

In fact, the more hours of experience a meditator had, the scans found, the less active his or her emotional networks were during the distracting sounds, which meant the easier it was to focus.

More recently, contemplative neuroscience has turned toward compassion meditation, which involves generating empathy through objectless awareness; practitioners call it non-referential compassion meditation.

New neuroscientific interest in the practice comes largely at the urging of the Dalai Lama, the spiritual and politial leader of Tibetan Buddhists, for whom compassion meditation is a time-worn tradition.

The Dalai Lama has arranged for Tibetan monks to travel to American universities for brain scans and has spoken at the annual meeting of the Society for Neuroscience, the world’s largest gathering of brain scientists.

A religious leader, the Dalai Lama has said he supports contemplative neuroscience even though scientists are stripping meditation of its Buddhist roots, treating it purely as a mental exercise that more or less anyone can do.

“This is not a project about religion,” says Davidson. “Meditation is mental activity that could be understood in secular terms.”

Still, the nascent field faces challenges. Scientists have scanned just a few hundred brains on meditation do date, which makes for a pretty small research sample. And some scientists say researchers are over eager to use brain science to prove the that meditation “works.”

“This is a field that has been populated by true believers,” says Emory University scientist Charles Raison, who has studied meditation’s effect on the immune system. “Many of the people doing this research are trying to prove scientifically what they already know from experience, which is a major flaw."

But Davidson says that other types of scientists also have deep personal interest in what they’re studying. And he argues that that’s a good thing.

“There’s a cadre of grad students and post docs who’ve found personal value in meditation and have been inspired to study it scientifically,” Davidson says. “These are people at the very best universities and they want to do this for a career.

“In ten years,” he says, “we’ll find that meditation research has become mainstream.”