It comes as no surprise that the brain's relaxation response is initiated during meditation. What's more surprising is that meditation may well have a long-term effect on brain architecture. A few years back, Sara Lazar and her team at Harvard University studied meditators who had practiced the art for about six hours weekly for nine years on the average. The researchers found that the right anterior insula and prefrontal cortex in the brains of these "experienced meditators" were thicker than in nonmeditators of the same age. Meditation, Lazar suggested, reverses the thinning of these structures that usually occurs over time. Since the prefrontal cortex is the brain's center for higher thought and planning, meditation may an important tool for helping aging brains function like young ones.
Now, a new study from UCLA suggests that people who meditate also have stronger connections between brain regions and show less of the brain shrinkage that typically occurs with age. Having stronger connections influences the ability to rapidly relay electrical signals in the brain. And significantly, these effects are evident throughout the entire brain, not just in specific areas.
Using an innovative brain-imaging technique, Eileen Luders, a visiting assistant professor at the UCLA Laboratory of Neuro Imaging, and colleagues have found that the differences between meditators and controls involve large-scale networks that include the frontal, temporal, parietal and occipital lobes and the anterior corpus callosum, as well as limbic structures and the brain stem.
"Our results suggest that long-term meditators have white-matter fibers that are either more numerous, more dense or more insulated throughout the brain," Luders said. "We also found that the normal age-related decline of white-matter tissue is considerably reduced in active meditation practitioners. . . . It is possible that actively meditating, especially over a long period of time, can induce changes on a micro-anatomical level." As a consequence, the robustness of fiber connections in meditators may increase and possibly lead to the macroscopic effects seen in this study.
"Meditation, however, might not only cause changes in brain anatomy by inducing growth but also by preventing reduction," Luders said. "That is, if practiced regularly and over years, meditation may slow down aging-related brain atrophy, perhaps by positively affecting the immune system."
But there is a "but." While it is tempting to assume that the differences between the two groups constitute actual meditation-induced effects, there is still the unanswered question of nature versus nurture. "It's possible that meditators might have brains that are fundamentally different to begin with," Luders said. "For example, a particular brain anatomy may have drawn an individual to meditation or helped maintain an ongoing practice - meaning that the enhanced fiber connectivity in meditators constitutes a predisposition towards meditation, rather than being the consequence of the practice."
Thus, more research is needed before meditation can be recommended as a brain-health promoter. Nevertheless, Luders (herself a meditator) said, "Meditation appears to be a powerful mental exercise with the potential to change the physical structure of the brain."
For More Information:
"Primer on the Brain" in Brain Sense explains these parts of the brain--their locations and functions.
S. W. Lazar, C. E. Kerr, R. H. Wasserman, et al., "Meditation Experience Is Associated with Increased Cortical Thickness," Neuroreport (November 28, 2000), 1893-1897.
Eileen Luders, Kristi Clark, Katherine L. Narr, and Arthur W. Toga. "Enhanced Brain Connectivity in Long-term Meditation Practitioners," NeuroImage, Volume 57, Issue 4, 15 August 2011, Pages 1308-1316