Scientists study links between brain, meditation

by Joe Rojas-Burke, The Oregonian
Thursday June 19, 2008, 11:05 AM


Meditation matters. Brain scientists are using the age-old practice to understand stress and pain reduction, attention spans, even compassion.


To unravel the workings of the brain, neuroscientist Michael Posner and colleagues at the University of Oregon have turned to an ancient discipline: meditation.

A recent experiment tested college students' ability to focus their attention and filter out distractions. Half the students received training in mindfulness meditation while the other half received relaxation training.

After five days, meditators outpaced nonmeditators on the attention test, and they became significantly better at handling stress. Saliva samples revealed lower levels of the hormone cortisol when the meditators were subjected to an anxiety-inducing math quiz.

"This is the first time I've ever been involved in anything like meditation," says Posner, who conducted the experiment with Yi-Yuan Tang, a visiting scholar. But he sees promise in using the ancient mind-training practice to understand how the brain regulates awareness and attention, an area of neuroscience he helped pioneer.

Meditation is making a big comeback among brain scientists after its first heyday in the 1970s. Advances in brain imaging and monitoring have made it possible to see inside the brain and explore the biological forces creating and driving conscious thoughts.

"Now we are in a position to ask questions about people's experience and measure brain activity in close to real time," says Clifford Saron, a scientist at the Center for Mind and Brain at the University of California at Davis. And with growing numbers of people turning to meditation for stress relief, Saron says, there's a pressing need to figure out how the many forms of mental practice actually work.

Already, studies reveal the brain may be far more flexible and capable of reorganization than long assumed. Evidence suggests that even the capacities for happiness and compassion may be trainable skills that meditation can improve, says Antoine Lutz, a scientist at the Waisman Lab for Brain Imaging & Behavior at the University of Wisconsin at Madison.

Sharpening attention

Meditation may sharpen the ability to focus by training the brain to apply limited processing power more efficiently.

In a recent study by Lutz's group, volunteers had to identify two numbers flashed on a computer screen amid a stream of letters. Because of limits of the brain's attention system, people often fail to see the second number if it's flashed a fraction of a second after the first. After three months of meditation training, volunteers were able to name the second number significantly more often. EEG recordings of brain activity showed that those subjects devoted less effort to finding the first target, thus freeing more brainpower to focus on finding the second.

At UO, Posner and Tang plan to use a kind of MRI that can detect changes in blood flow to explore how meditation changes brain activity during tests of attention. They expect to find that it improves communication links between separate brain regions that must act together.

"We think the network will improve," Posner says. "The different brain areas will operate together more efficiently."

Cultivating compassion

Specific brain regions become active when a person responds to another's pain.

Lutz's group compared activity between Tibetan monks and a control group of beginning meditators who practiced so-called "loving kindness" meditation -- progressively directing wishes of well-being and freedom from suffering to loved ones, adversaries, strangers and all beings.

While the volunteers meditated, researchers played emotional sounds, such as a woman crying in distress, and neutral sounds. On brain scans, regions used to empathize and process emotions were significantly more active in the experienced meditators in response to the emotional sounds, but no different in response to neutral sounds.

Lutz and co-author Richard Davidson of the University of Wisconsin, who reported the study in March, speculate that teaching such meditation to children could help prevent bullying, aggression and violence.

Power over pain

Feats of pain endurance are among the most striking displays of the power of meditation.

To explore the phenomenon, researchers at San Francisco State University used a system called qEEG to map electrical activity in the brain of a yoga master while he had his tongue pierced. The researchers found that the pattern of brain activity suggests that the meditating yogi entered a state similar to that produced by pain-numbing drugs.

Brain adaptations to pain may persist during times between meditation practice. Researchers at the University of California at Irvine and Maharishi University of Management in Iowa used MRI scanning to measure brain activity in practitioners of Transcendental Meditation while their fingers were dunked in hot water.

Long-term meditators showed a 40 percent to 50 percent reduction in brain activity in response to pain compared with a control group of non-meditators. After meditation training and five months of practice, people in the control group also showed a 40 percent to 50 percent decrease in brain activity during the painful hot water stimulus. Meditation did not change the volunteers' rating of pain intensity, suggesting that its effect was in reducing anxiety and distress, researchers concluded.

A few studies suggest that meditation can change how the brain responds to advancing age. Researchers at Emory University in Atlanta compared 13 older adults who regularly practiced Zen meditation with non-meditators of similar age. Among the latter, shrinking brain size and declining performance on attention tests correlated with age: The older the subject, the smaller the brain volume and the worse the performance. Among meditators, advancing age did not correlate with brain shrinkage or declining attention skills.

The findings match those of a 2005 study at Harvard Medical School, which found that brain regions involved in focusing attention and processing sense information were thicker in meditators than age-matched non-meditators.

Coming up next

These studies highlight the weaknesses common in research on meditation, says Dr. Barry Oken, a professor of neurology and behavioral neuroscience at Oregon Health & Science University. Often, he says, it's impossible to rule out the effects of other variables, such as differences in language, culture and other factors between meditators and control groups.

"Long-term Buddhist meditators -- they are intrinsically different from people you can compare them to," Oken says.

To nail down the effects, researchers must track brain activity changes over time. Researchers are just beginning to explore how different types of meditation compare and which might work best for training specific mental and emotional skills.

Oken is leading a long-term study of the effects of meditation training on people subject to the stress of caring for loved ones with Alzheimer's disease. Researchers hope to show that meditation can lower stress, as rated by caregivers and revealed in levels of stress hormones. The study also tracks changes over time in brain activity.

The results so far meet the expectations of Kyogen Carlson, an ordained Zen Buddhist teacher in Portland. But Carlson isn't concerned with whether science proves the health benefits of meditation or improved mental performance from its practice.

"I see that as an interesting side effect," says Carlson, abbot of the Dharma Rain Zen Center in Portland. Meditation, he says, "is part of a path to authenticity and being who we are supposed to be."