Tuesday, January 11, 2011

Putting Meditation to the Test

The suggestion that meditation can improve attention is worth considering, given that focus is crucial to so much in life, from the learning and application of skills to everyday judgement and decision-making, or simply concentrating on your computer screen at work without thinking about what you will be eating for dinner. But how does dwelling on your breath for a period each day lead to such a pronounced cognitive change?
One possibility is that it involves working memory, the capacity to hold in mind information needed for short-term reasoning and comprehension. The link with meditation was established recently by Amishi Jha at the University of Miami in Coral Gables. She trained a group of American marines to focus their attention using mindfulness meditation and found that this increased their working memory (Emotion, vol 10, p 54). MacLean points out that meditation is partly about observing how our sensory experiences change from moment to moment, which requires us to hold information about decaying sensory traces in working memory.
MacLean and others also believe that meditation training enhances some central cognitive faculty - as yet unknown - that is used in all basic perception tasks. "It's like a muscle that can be used in lots of different ways," she says. Then, once perception becomes less effortful, the brain can direct more of its limited resources to concentration. Backing up this idea, Slagter's measurements of electrical activity in the brain during the attentional blink task revealed that as meditation training progressed, volunteers used fewer resources when processing the first stimulus, meaning they were less likely to get "stuck" on it and miss the second stimulus.

The ability to manage one's emotions could also be key to why meditation can improve physical health. Studies have shown it to be an effective treatment for eating disorders, substance abuse, psoriasis and in particular for recurrent depression and chronic pain. Last year, psychologist Fadel Zeidan, at Wake Forest University School of Medicine in Winston-Salem, reported that his volunteers noticed a decreased sensitivity to pain after just a few sessions of mindfulness meditation (
Journal of Pain, vol 11, p 199). He believes meditation doesn't remove the sensation of pain so much as teach sufferers to control their emotional reaction to it and reduce the stress response. He is now using fMRI in an attempt to understand why that helps. "There's something very empowering about knowing you can alleviate some of these things yourself," he says.

The positive effect of meditation on psychological well-being could also explain recent findings from the Shamatha project that regular meditation practice can lead to a significant increase in the activity of telomerase, an enzyme that protects against cellular ageing and which is suppressed in response to psychological stress. The work will appear in
Psychoneuroendocrinology.

Emotions may also be at the heart of another benefit of meditation. One of the hottest areas in meditation research is whether the practice can enhance feelings towards others. This arose partly because fMRI studies by Lutz and his team showed that brain circuits linked to empathy and the sharing of emotions - such as the insula and the anterior cingulate cortex - are much more active in long-term meditators than in novices (
NeuroImage, vol 47, p 1038).

The great thing about meditation is that anyone can practise it anywhere. What's more you don't have to be an expert or spend five hours a day at it to reap the benefits. The novices in Zeidan's pain experiment reported improvements after meditating for just 20 minutes a day for three days. In a second experiment he found that similarly brief sessions can improve cognitive performance on tasks that demand continuous attention, such as remembering and reciting a series of digits (
Consciousness and Cognition, vol 19, p 597). "It is possible to produce substantial changes in brain function through short-term practice of meditation," says Richard Davidson, director of the Waisman Laboratory. He says data from a new unpublished study by his lab shows "demonstrable changes in brain function" in novice meditators after just two weeks of training for 30 minutes a day. "Even small amounts of practice can make a discernible difference."

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