SCIY.Org Archives

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Researchers used MRI to examine the physical structure of the brains of meditation practitioners in the U.S. “Our findings provide the first evidence that alterations in brain structure are associated with western-style meditation practice, possibly reflecting increased use of specific brain regions,” says Sara Lazar, PhD, of Harvard Medical School.

Lazar and her colleagues compared the brains of 20 western-style meditators with 15 people who had no meditation or yoga experience. The meditators were students of Buddhist “Insight” meditation, which focuses on the cultivation of a trait called mindfulness, a specific, non-judgmental awareness of present-moment sensory stimuli. All study participants laid quietly in the MRI scanner while detailed images were taken of the structure of their brains.

“We found that brain regions associated with attention and sensory processing were thicker in meditators than in the non-meditators,” says Lazar. “Also, in one of the regions, the differences in thickness were most pronounced in older subjects, suggesting that regular practice of meditation might reduce normal age-related thinning of the brain.” This region is an area of the brain’s outer layer or cortex, which is thought to be involved in integrating emotional and cognitive processes.

This result is especially interesting in light of cutting-edge scientific evidence suggesting that evolutionary forces are still at work in human populations (NY Times, free reg. req'd). Researchers at the University of Chicago have found that genes responsible for skin color, taste, smell, and brain development were still evolving as little as 6,000 years ago.

"There is ample evidence that selection has been a major driving point in our evolution during the last 10,000 years, and there is no reason to suppose that it has stopped," said Jonathan Pritchard, a population geneticist at the University of Chicago who headed the study. ...

Dr. Pritchard detected selection at work in brain genes, including a group known as microcephaly genes because, when disrupted, they cause people to be born with unusually small brains.

Dr. Bruce Lahn, also of the University of Chicago, theorizes that successive changes in the microcephaly genes may have enabled the brain to enlarge in primate evolution, a process that may have continued in the recent human past.

All of this evidence suggests that our brains are far more modifiable than we are currently led to believe. Not only are evolutionary pressures are still at work that are changing the structure of our brains across generations, but individuals can also influence their own brain structure within their own lifetime.

But what functional changes do meditators actually experience? Dr. Lazar hypothesizes that meditation aids mental performance and increases our attentional capacity. Additionally, it is increasingly being used in the west as a stress-reduction technique and is losing its traditional eastern religious associations.


References:
Lazar, et al. (2005) Meditation experience is associated with increased cortical thickness. Neuroreport. 16:1893-1897.

Voight, et al. (2006) A Map of Recent Positive Selection in the Human Genome. PLoS Biology. 4: e72.

There is also an interview with Sara Lazar at Science and Consciousness Review.