Wednesday, November 21, 2012

Different Forms Of Meditation May Have Varying Effects On Key Brain Structure


I'm a sucker for meditation-related research, so here's a recent article I saw in Medical News Today and then found the original research article in Frontiers in Human Neuroscience. Using Mindful Attention Training or Mindfulness Based Compassion Training (vs. control group), the authors conclude that their study "suggests that the effects of meditation training on emotional processing might transfer to non-meditative states. This is consistent with the hypothesis that meditation training may induce learning that is not stimulus- or task-specific, but process-specific, and thereby may result in enduring changes in mental function." Essentially, both forms of meditation impacted amgydala processing and attenuated response to emotional stimuli in the subjects daily lives.

Full Citation: 
Desbordes G, Negi LT, Pace TWW, Wallace BA, Raison CL and Schwartz EL. (2012). Effects of mindful-attention and compassion meditation training on amygdala response to emotional stimuli in an ordinary, non-meditative state. Frontiers in Human Neuroscience, 6:292. doi: 10.3389/fnhum.2012.00292

The full abstract is included below the summary article.

Imaging Study Finds Different Forms Of Meditation May Have Varying Effects On Key Brain Structure

Article Date: 15 Nov 2012

A new study has found that participating in an 8-week meditation training program can have measurable effects on how the brain functions even when someone is not actively meditating. In their report in the November issue of Frontiers in Human Neuroscience, investigators at Massachusetts General Hospital (MGH), Boston University (BU), and several other research centers also found differences in those effects based on the specific type of meditation practiced.

"The two different types of meditation training our study participants completed yielded some differences in the response of the amygdala - a part of the brain known for decades to be important for emotion - to images with emotional content," says Gaëlle Desbordes, PhD, a research fellow at the Athinoula A. Martinos Center for Biomedical Imaging at MGH and at the BU Center for Computational Neuroscience and Neural Technology, corresponding author of the report. "This is the first time that meditation training has been shown to affect emotional processing in the brain outside of a meditative state."

Several previous studies have supported the hypothesis that meditation training improves practitioners' emotional regulation. While neuroimaging studies have found that meditation training appeared to decrease activation of the amygdala - a structure at the base of the brain that is known to have a role in processing memory and emotion - those changes were only observed while study participants were meditating. The current study was designed to test the hypothesis that meditation training could also produce a generalized reduction in amygdala response to emotional stimuli, measurable by functional magnetic resonance imaging (fMRI).

Participants had enrolled in a larger investigation into the effects of two forms of meditation, based at Emory University in Atlanta. Healthy adults with no experience meditating participated in 8-week courses in either mindful attention meditation - the most commonly studied form that focuses on developing attention and awareness of breathing, thoughts and emotions - and compassion meditation, a less-studied form that includes methods designed to develop loving kindness and compassion for oneself and for others. A control group participated in an 8-week health education course.

Within three weeks before beginning and three weeks after completing the training, 12 participants from each group traveled to Boston for fMRI brain imaging at the Martinos Center's state-of-the-art imaging facilities. Brain scans were performed as the volunteers viewed a series of 216 different images - 108 per session - of people in situations with either positive, negative or neutral emotional content. Meditation was not mentioned in pre-imaging instructions to participants, and investigators confirmed afterwards that the volunteers had not meditated while in the scanner. Participants also completed assessments of symptoms of depression and anxiety before and after the training programs.

In the mindful attention group, the after-training brain scans showed a decrease in activation in the right amygdala in response to all images, supporting the hypothesis that meditation can improve emotional stability and response to stress. In the compassion meditation group, right amygdala activity also decreased in response to positive or neutral images. But among those who reported practicing compassion meditation most frequently outside of the training sessions, right amygdala activity tended to increase in response to negative images - all of which depicted some form of human suffering. No significant changes were seen in the control group or in the left amygdala of any study participants.

"We think these two forms of meditation cultivate different aspects of mind," Desbordes explains. "Since compassion meditation is designed to enhance compassionate feelings, it makes sense that it could increase amygdala response to seeing people suffer. Increased amygdala activation was also correlated with decreased depression scores in the compassion meditation group, which suggests that having more compassion towards others may also be beneficial for oneself. Overall, these results are consistent with the overarching hypothesis that meditation may result in enduring, beneficial changes in brain function, especially in the area of emotional processing."   

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 The full Frontiers article is open access and available online or as a PDF download.

Effects of mindful-attention and compassion meditation training on amygdala response to emotional stimuli in an ordinary, non-meditative state

Gaëlle Desbordes1,2*, Lobsang T. Negi3, Thaddeus W. W. Pace4, B. Alan Wallace5, Charles L. Raison6 and Eric L. Schwartz2,7
  • 1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
  • 2Center for Computational Neuroscience and Neural Technology, Boston University, Boston, MA, USA
  • 3Department of Religion, Emory University, Atlanta, GA, USA
  • 4Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
  • 5Santa Barbara Institute for Consciousness Studies, Santa Barbara, CA, USA
  • 6Department of Psychiatry, College of Medicine and Norton School of Family and Consumer Sciences, College of Agriculture, University of Arizona, Tucson, AZ, USA
  • 7Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA
The amygdala has been repeatedly implicated in emotional processing of both positive and negative-valence stimuli. Previous studies suggest that the amygdala response to emotional stimuli is lower when the subject is in a meditative state of mindful-attention, both in beginner meditators after an 8-week meditation intervention and in expert meditators. However, the longitudinal effects of meditation training on amygdala responses have not been reported when participants are in an ordinary, non-meditative state. In this study, we investigated how 8 weeks of training in meditation affects amygdala responses to emotional stimuli in subjects when in a non-meditative state. Healthy adults with no prior meditation experience took part in 8 weeks of either Mindful Attention Training (MAT), Cognitively-Based Compassion Training (CBCT; a program based on Tibetan Buddhist compassion meditation practices), or an active control intervention. Before and after the intervention, participants underwent an fMRI experiment during which they were presented images with positive, negative, and neutral emotional valences from the IAPS database while remaining in an ordinary, non-meditative state. Using a region-of-interest analysis, we found a longitudinal decrease in right amygdala activation in the Mindful Attention group in response to positive images, and in response to images of all valences overall. In the CBCT group, we found a trend increase in right amygdala response to negative images, which was significantly correlated with a decrease in depression score. No effects or trends were observed in the control group. This finding suggests that the effects of meditation training on emotional processing might transfer to non-meditative states. This is consistent with the hypothesis that meditation training may induce learning that is not stimulus- or task-specific, but process-specific, and thereby may result in enduring changes in mental function.
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