The impact of meditation on the brain

Delanceyplace.com has a selection from Mind of the Meditator by Matthieu Ricard, Antoine Lutz, and Richard J. Davidson:

Brain imaging shows that when we master a task, such as playing an instrument or an advanced performance in a sport, specific parts of the brain are transformed and certain neural pathways grow and strengthen. Neuroscientists have now shown that the same is true for mastery of meditation with direct benefits for improving focus, overcoming depression, dealing with pain and cultivating emotional well-being:

A comparison of the brain scans of meditators with tens of thousands of hours of practice with those of neophytes and non-meditators has started to explain why this set of techniques for training the mind holds great potential for supplying cognitive and emotional benefits.
The discovery of meditation's benefits coincides with recent neuroscientific findings showing that the adult brain can still be deeply transformed through experience. These studies show that when we learn how to juggle or play a musical instrument, the brain undergoes changes through a process called neuroplasticity. A brain region that controls the movement of a violinist's fingers becomes progressively larger with mastery of the instrument. A similar process appears to happen when we meditate. Nothing changes in the surrounding environment, but the meditator regulates mental states to achieve a form of inner enrichment, an experience that affects brain functioning and its physical structure. The evidence amassed from this research has begun to show that meditation can rewire brain circuits to produce salutary effects not just on the mind and the brain but on the entire body.
The illustration shows that twelve expert meditators had greater overlap of increased activation of attention-related brain regions, while twelve non-meditators had less overlap and activation. Orange hues equal higher correlation between individuals & activation. Blue hues equal little to no correlation between regions of activation.
Neuroscientists have now begun to probe what happens inside the brain during the various types of meditation. Wendy Hasenkamp, then at Emory University, and her colleagues used brain imaging to identify the neural networks activated by focused- attention meditation. Advanced meditators appear to acquire a level of skill that enables them to achieve a focused state of mind with less effort. These effects resemble the skill of expert musicians and athletes capable of immersing themselves in the 'flow' of their performances with a minimal sense of effortful control.
In their Wisconsin lab, they studied experienced practitioners while they performed an advanced form of mindfulness meditation called open presence. In open presence, sometimes called pure awareness, the mind is calm and relaxed, not focused on anything in particular, yet vividly clear, free from excitation or dullness. The meditator observes and is open to experience without making any attempt to interpret, change, reject, or ignore painful sensation. The intensity of the pain was not reduced in meditators, but it bothered them less than it did members of a control group. Compared with novices, expert meditators' brain activity diminished in anxiety-related regions, the insular cortex and the amygdala, in the period preceding the painful stimulus. The meditators' brain response in pain-related regions became accustomed to the stimulus more quickly than that of novices after repeated exposures to it. Other tests in the lab have shown that meditation training increases one's ability to better control and buffer basic physiological responses, inflammation or levels of a stress hormone, to a socially stressful task such as giving a public speech or doing mental arithmetic in front of a harsh jury.
Several studies have documented the benefits of mindfulness on symptoms of anxiety and depression and its ability to improve sleep patterns. By deliberately monitoring and observing their thoughts and emotions when they feel sad or worried, depressed patients can use meditation to manage negative thoughts and feelings as they arise spontaneously and so lessen rumination. Clinical psychologists John Teasdale, then at the University of Cambridge in England and Zindel Segal of the University of Toronto in Canada showed in 2000 that, for patients who had previously suffered at least three episodes of depression, six months of mindfulness practice, along with cognitive therapy, reduced the risk of relapse by nearly forty percent in the year following the onset of a severe depression. More recently, Segal demonstrated that the intervention is superior to a placebo and has a protective effect against relapse comparable to standard maintenance antidepressant therapy.
About fifteen years of research have done more than show that meditation produces significant changes in both the function and structure of the brains of experienced practitioners. These studies are now starting to demonstrate that contemplative practices may have a substantive impact on biological processes critical for physical health.

Rico says that learning to really meditate is non-trivial...