Σάββατο 29 Ιανουαρίου 2011

Δευτέρα 24 Ιανουαρίου 2011

Mindfulness meditation training changes brain structure in 8 weeks

General-led study shows changes over time in areas associated with awareness, empathy, stress

Participating in an 8-week mindfulness meditation program appears to make measurable changes in brain regions associated with memory, sense of self, empathy and stress. In a study that will appear in the January 30 issue of Psychiatry Research: Neuroimaging, a team led by Massachusetts General Hospital (MGH) researchers report the results of their study, the first to document meditation-produced changes over time in the brain's grey matter.

"Although the practice of meditation is associated with a sense of peacefulness and physical relaxation, practitioners have long claimed that meditation also provides cognitive and psychological benefits that persist throughout the day," says Sara Lazar, PhD, of the MGH Psychiatric Neuroimaging Research Program, the study's senior author. "This study demonstrates that changes in brain structure may underlie some of these reported improvements and that people are not just feeling better because they are spending time relaxing."

Previous studies from Lazar's group and others found structural differences between the brains of experienced mediation practitioners and individuals with no history of meditation, observing thickening of the cerebral cortex in areas associated with attention and emotional integration. But those investigations could not document that those differences were actually produced by meditation.

For the current study, MR images were take of the brain structure of 16 study participants two weeks before and after they took part in the 8-week Mindfulness-Based Stress Reduction (MBSR) Program at the University of Massachusetts Center for Mindfulness. In addition to weekly meetings that included practice of mindfulness meditation – which focuses on nonjudgmental awareness of sensations, feelings and state of mind – participants received audio recordings for guided meditation practice and were asked to keep track of how much time they practiced each day. A set of MR brain images were also taken of a control group of non-meditators over a similar time interval.

Meditation group participants reported spending an average of 27 minutes each day practicing mindfulness exercises, and their responses to a mindfulness questionnaire indicated significant improvements compared with pre-participation responses. The analysis of MR images, which focused on areas where meditation-associated differences were seen in earlier studies, found increased grey-matter density in the hippocampus, known to be important for learning and memory, and in structures associated with self-awareness, compassion and introspection. Participant-reported reductions in stress also were correlated with decreased grey-matter density in the amygdala, which is known to play an important role in anxiety and stress. Although no change was seen in a self-awareness-associated structure called the insula, which had been identified in earlier studies, the authors suggest that longer-term meditation practice might be needed to produce changes in that area. None of these changes were seen in the control group, indicating that they had not resulted merely from the passage of time.

"It is fascinating to see the brain's plasticity and that, by practicing meditation, we can play an active role in changing the brain and can increase our well-being and quality of life." says Britta Hölzel, PhD, first author of the paper and a research fellow at MGH and Giessen University in Germany. "Other studies in different patient populations have shown that meditation can make significant improvements in a variety of symptoms, and we are now investigating the underlying mechanisms in the brain that facilitate this change."

Amishi Jha, PhD, a University of Miami neuroscientist who investigates mindfulness-training's effects on individuals in high-stress situations, says, "These results shed light on the mechanisms of action of mindfulness-based training. They demonstrate that the first-person experience of stress can not only be reduced with an 8-week mindfulness training program but that this experiential change corresponds with structural changes in the amydala, a finding that opens doors to many possibilities for further research on MBSR's potential to protect against stress-related disorders, such as post-traumatic stress disorder." Jha was not one of the study investigators.

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Τρίτη 4 Ιανουαρίου 2011

Trust Your Gut…but Only Sometimes

When faced with decisions, we often follow our intuition—our self-described “gut feelings”—without understanding why. Our ability to make hunch decisions varies considerably: Intuition can either be a useful ally or it can lead to costly and dangerous mistakes. A new study published in Psychological Science, a journal of the Association for Psychological Science, finds that the trustworthiness of our intuition is really influenced by what is happening physically in our bodies.

“We often talk about intuition coming from the body—following our gut instincts and trusting our hearts”, says Barnaby D. Dunn, of the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, U.K., first author of the new paper. What isn’t certain is whether we should follow, or be suspicious of, what our bodies are telling us. And do we differ in the influence that our gut feelings have on how we make decisions?

To investigate how different bodily reactions can influence decision making, Dunn and his co-authors asked study participants to try to learn how to win at a card game they had never played before. The game was designed so that there was no obvious strategy to follow and instead players had to follow their hunches. While playing the game, each participant wore a heart rate monitor and a sensor that measured the amount of sweat on their fingertips.

Most players gradually found a way to win at the card game and they reported having relied on intuition rather than reason. Subtle changes in the players’ heart rates and sweat responses affected how quickly they learned to make the best choices during the game.

Interestingly, the quality of the advice that people’s bodies gave them varied. Some people’s gut feelings were spot on, meaning they mastered the card game quickly. Other people’s bodies told them exactly the wrong moves to make, so they learned slowly or never found a way to win.

Dunn and his co-authors found this link between gut feelings and intuitive decision making to be stronger in people who were more aware of their own heartbeat. So for some individuals being able to ‘listen to their heart’ helped them make wise choices, whereas for others it led to costly mistakes.

“What happens in our bodies really does appear to influence what goes in our minds. We should be careful about following these gut instincts, however, as sometimes they help and sometimes they hinder our decision making,” says Dunn.