Meditation Experience Predicts Less Negative Appraisal of Pain: Electrophysiological Evidence for the Involvement of Anticipatory Neural Responses

In a recent study, researchers in the United Kingdom examined the impact of meditation experience and the anticipation of and experience of pain. The control group consisted of 15 people with no previous experience in meditation. They were compared with 12 people who came from a variety of Buddhist and non-Buddhist meditative backgrounds. It was a pretty heterogeneous sample of meditators.

The researchers encountered difficulty developing a reliable estimate of meditation experience. They eventually disregarded the amount of hours per week of practice and instead looked at the overall lifetime experience with meditation. These ranged from less than 1 year to more than 30 years experience.

The researchers used a laser to induce a painful burning sensation in the participants. Anticipation of pain was created through a visual stimulus that indicated to the participants that they would be exposed to the laser within 3 seconds.  Because of the design, the researchers suggest they may have over-estimated the impact of the anticipation of pain on the actual pain response. In addition to self-report by the participants, the researchers used an EEG (e.g., brain scan) to measure participants' anticipation to and experience of pain.

Initially, the researchers found no significant difference in perceived pain between the mediation and control groups. Once the researchers dropped participants with less than 6 years of meditation experience from the analyses, however, participants with more meditation experience showed a lower response to anticipated pain unpleasantness.  This relationship was accounted for by the age of the meditators.  However, there was no correlation in the control group between pain response and age.  Although the relationship is not entirely clear, it appears that meditation experience may impact anticipation of pain.

In looking at the EEG results, an interesting pattern emerges. The researchers suggest that those with meditation experience were more likely to process and contextutalize the experience of pain before responding to it emotionally.

In summary, the researchers suggest that the cultivation of acceptance through practicing attentional control (i.e., through regular meditation practice) may allow people to show more equanimity in both in their anticipation of pain and their actual experience of it.

There are some limitations with the pain assessment in this study. As noted, researchers admitted that they had a difficult time determining if the pain assessment was in fact influenced by the anticipation of the pain. Also, because of the design of the study, we can't completely rule out that people who take up meditation are inherently different from those who don't meditate, and that these differences--rather than the actual meditation practice--better explain the results.

To download a  copy of the article, click on the full citation is below:

Brown, C.A., & Jones, A.K.P. (2010). Mediation Experience Predicts Less Negative Appraisal of Pain: Electrophysiological Evidence for the Involvement of Anticipatory Neural Responses. Pain, 150, 428-438.

I’d like to thank Molly Ellis for her help with drafting this post!

Neural Correlates of Focused Attention and Cognitive Monitoring in Meditation

A former classmate from graduate school sent me a nifty neuroimaging study by a group of researchers in Italy. The article compared 8 Buddhist monks against 8 novice meditators. The monks were part of the Thai Forest Tradition founded by Ajahn Chah. They averaged 15,750 hours of meditation experience! By contrast, the novice sample were people who expressed an interest in meditation but had no prior meditative experience. They were given 10 days of meditation practice prior to the study.

Using an fMRI (e.g., functional brain scans), the researchers recorded brain patterns during an hour block involving alternating periods of focused attention (FA) and open monitoring (OM). For those familiar with Buddhist practices, FA corresponded to Samatha meditation (Pali: calm abiding) and OM was a form of Vipassana (Pali: clear seeing or insight), according the researchers. (Our garden variety mindfulness meditation is more or less based on Vipassana meditation.) Participants alternated between 6 minutes of Samatha and Vipassana with 3 minutes of non-meditative rest preceding and following these conditions.

The article is pretty technical. Since I can't really do it justice, I won't parrot back the specific results (e.g., which parts of neuroanatomy relate to which forms of attention). Overall, results suggest that meditation practice reorganizes brain activity. More simply, experienced meditators showed a different pattern of brain activity than novices on these tasks.

Reorganization of brain processes is called neuroplasticity. Previously researchers believed the brain doesn't change much after we're born. Recent research has shown that this isn't so--the brain can and does change--and regular meditation practice can re-map the way the brain processes stuff.

For the full citation:

Manna, A., Raffone, A., Perrucci, M.G., Nardo, D., Ferretti, A., et al. (2010). Neural Correlates of Focused Attention and Cognitive Monitoring in Meditation. Brain Research Bulletin, 82, 46-56.

Mindfulness-Based Treatments for Co-Occurring Depression and Substance Use Disorders: What Can We Learn from the Brain?

In a previous post, I wrote about the implications if a pilot study that Mindfulness-Based Relapse Prevention (MBRP) may help people in recovery avoid relapse during depressed moods (Witkiewitz & Bowen, 2010). A recent article in Addiction by Brewer and colleagues explores how mindfulness-based treatments may be useful in treating people with both substance use problems and depression. (The authors of the article include a few of the developers of MBRP--Drs. Alan Marlatt and Sarah Bowen.)

The article is largely theoretical and includes explorations of potential neurobiological processes that may change through mindfulness training. It's relatively brief, so feel free to check it yourself!

To download a copy of the article, click on the citation below:

Brewer, J.A., Bowen, S., Smith, J.T., Marlatt, G.A., & Potenza, M.N. (2010). Mindfulness-Based Treatments for Co-Occurring Depression and Substance Use Disorders: What Can We Learn from the Brain? Addiction, 105(10), 1698-1706.

Mindfulness Practice Leads to Increases in Regional Brain Gray Density Matter

Last week, I posted a New York Times article about a study looking at brain changes following an 8-week mindfulness program. As promised, I've since read the study on which the article was based and am posting my own summary.

Lead by Dr. Britta Hölzel, a group of researchers, mainly located at Massachusetts General Hospital, examined changes in the brain following an 8-week Mindfulness-Based Stress Reduction (MBSR) program. As I've posted about before, previous research has indicated differences in cortical thickness in areas of the brains of experience meditators compared to age-matched control groups. The weakness of the previous studies is that it doesn't rule out that people with pre-existing differences in brain structure may be more likely to gravitate towards meditation.

In the current study, the researchers conducted MRI scans of 16 people 2 weeks before and 2 weeks after an 8-week MBSR course. This scans were compared against a control sample of 17 people on wait list for the course. Researchers scanned the wait list group twice about 2 months apart. In addition the scans, participants also completed the Five-Facet Mindfulness Questionnaire (FFMQ; Baer et al., 2006), a self-report measure of mindfulness.

As the researchers predicted, MBSR participants showed significant increases in gray matter density in the left hippocampus, an area of the brain associated with arousal, responsiveness, and emotion regulation, according to the researchers. They suggest these changes may reflect improvements in regulating emotional responding. These changes were unrelated to self-reported mindfulness scores on the FFMQ and to the amount of time people practiced mindfulness outside the course. Contrary to the researchers' predictions, there was no changes in the insula, a region of the brain associated with awareness.

I'll note here that the researchers predicted changes in the hippocampus and insula prior to conducting the study. After looking at these regions, they also conducted exploratory analyses to examine whether there were changes in other parts of the brain that they did not make specific hypotheses about. What this means is that the researchers had no prior expectations about whether these other areas would change. Since they had the data, they thought, "Hey, let's take a look!" There's nothing wrong with this, but it does mean these results should be interpreted more cautiously, since there were no prior reasons to believe they would change.

These exploratory analyses found increases in density in the posterior cingulate cortex (PCC), the left temporo-parietal junction (TPJ), and in two regions of the cerebellum. In addition, there were changes in density within the brain stem. In the interests of space, I'll give a more general summary of the functions associated with these regions. According to the researchers, these regions of the brain appear to be associated with consciousness of one's self (TPJ), assessment of the self-relevance of stimuli (PCC), regulation of emotion and cognition (cerebellum).

This is a general summary of what the study found. As I'm not an expert in neuroscience, any errors in what I reported are likely mine. I encourage anyone interested to consult the original study if you want more detail.

Although this study shows greater methodological rigor in controlling for other possible influences other than meditation, as the authors note, their methodology is not completely airtight. Perhaps the biggest weakness is comparing a wait list control group against an active treatment. It's perfectly reasonable comparison, but the downside is that it doesn't control for the possibility of non-specific factors other than meditation influencing outcome. Said less technically, simply being in a group for 8 week may have caused changes independent of the actual mindfulness practices. In addition, the sample size is pretty small--which is understandable as neuroimaging research is expensive!

These caveats aside, this is a really important study in gathering further evidence that people may show actual physical changes in relevant areas brain through mindfulness practice. That significant differences were shown with only 8 weeks of mindfulness practice is pretty remarkable.

To download the article, click on the citation below:

Hölzel, B.K., Carmody, J., Vangel, M., Congleton, C., Yerramsetti, S.M., et al. (2011). Mindfulness Practice Leads to Increases in Regional Brain Gray Density Matter. Psychiatry Research: Neuroimagining, 191, 36-43.

New York Times: How Meditation Changes the Brain

The New York Times published an article today on a recent study that provides further evidence that regular meditation practice  affects the brain. Compared to a control group, people who meditated 30 minutes a day for 8 weeks showed changes in brain gray-matter density. The affected regions of the brain are associated with memory, stress, empathy, and what they call "sense of self."

The research article was published in Psychiatry Research: Neuroimaging. Dr. Britta Hölzel, a psychologist at Mass General and Harvard Medical School, is first author. (Coincidentally, I printed out a copy of the article last week but haven't had a chance to look at it yet. I guess I'll move it up in my queue and will hopefully post a summary within the next few weeks.) According to the article:Times

M.R.I. brain scans taken before and after the participants’ meditation regimen found increased gray matter in the hippocampus, an area important for learning and memory. The images also showed a reduction of gray matter in the amygdala, a region connected to anxiety and stress. A control group that did not practice meditation showed no such changes.

I've written about changes in gray matter in meditators in a previous post, in which long-term meditators showed greater cortical thickness compared to non-meditators matched for age. A major difference between this study and those others is that the other studies looked at samples of experienced meditators whereas this study involved people who practed meditation for only 8 weeks! The article mentions a control group, but I wasn't clear if people were randomly assigned to either the control or meditation group. I'm really looking forward to reading the original article now! (UPDATE: I've since posted on the original article here.)

To read the Times article, click here.

Integrative Body-Mind Training

A psychologist at the University of Oregon Michael Posner has teamed up with a group of Chinese researchers lead by Dr. Yi-Yuan Tang at Dalian University of Technology. They are studying a form of meditation called Integrative Body-Mind Training (IBMT) developed and adapted by Dr. Tang from traditional Chinese medicine.

IBMT involves mindfulness training, relaxation of muscle groups, and guided imagery, and it is accompanied by music played in the background. It's unclear to me how IBMT differs from mindfulness meditation--with the exception of the addition of background music--but there appears to be significant overlap in these types of meditation.

In a recent study using neuroimaging, changes in brain activity were observed in participants practicing IBMT after 11 hours of training compared to a control group who received only relaxation training. (More than 6 hours appear to be required for changes to be measurable.) Changes were most pronounced in the anterior cingulate, a part of the brain associated with the ability to regulate emotions and behavior.

According to a Science Daily article, IBMT is not available outside of China, so I don't know much about it. As I noted, I'm unclear whether there are any fundamental differences between IBMT and mindfulness meditation. This is a danger of some of the neuroimaging research: so many different types of meditation have been examined using different kinds of equipment that it can be difficult to make sense of the results other than that meditation appears to affect the brain. (Click here for a previous post about a review of the literature, and here for a previous post about some of the problems of the neuroimaging literature.) That said, any attempts at controlled studies of meditation are exciting, and what is unique about this one is that the researchers observed changes after only 11 hours of training! A number of studies draw from either experienced Buddhist meditators or people who have completed an 8-week mindfulness meditation program (e.g., MBSR), so this is a pretty cool finding.

To download and read a PDF of the published scientific article, click here.

To read a Science Daily article about the study, click here.

For the full citation:

Tang, Y. Y., Lu, Q., Geng, X., Stein, E. A., Yang, Y., & Posner, M. I. (2010). Short-term meditation induces white matter changes in the anterior cingulate. Proceedings of the National Academy of Sciences.

Functional Neural Correlates of Mindfulness Meditations in Comparison with Psychotherapy, Pharmacotherapy, and Placebo Effect

In a recent issue of Acta Neuropsychiatrica, Chiesa and colleagues, a group of researchers in Italy, published a review article of neuro-imaging studies. They were interested in comparing neural correlates of mindfulness meditation with those of psychotherapy, pharmacotherapy (e.g., antidepressants), and placebo. The main areas of the brain the researchers focused on were the prefrontal cortex, the anterior cingulate cortex, and the amygdala.

I found the placebo piece of the review particularly interesting as there’s a huge research literature showing placebo effects are powerful enough to be a treatment in themselves. Like psychotherapy, it’s hard to create an adequate placebo substitute for something like meditation, especially as people know more about it today than they did decades ago when this research began.

The authors’ findings suggest that mindfulness meditation may help facilitate a greater flexibility in emotion regulation, and an improved ability to step back from negative mood states by engaging the frontal cortex (higher order functions) in order to dampen amygdala activation (emotion response, especially fear). The authors also found there’s a great deal of overlap in the brain structures activated by mindfulness meditation, psychotherapy, pharmacotherapy, and placebo effects.

They make a preliminary suggestion that mindfulness meditation, psychotherapy, and placebo act through “top down” regulation (i.e., through other processes), whereas antidepressants have a “bottom-up” effect (i.e., more directly). For example, they suggest mindfulness meditation may regulate the amygdala through frontal brain areas whereas antidepressants target the amygdala directly. I found this curious, as Irving Kirsch and others have recently suggested that much of the benefit from antidepressants is through placebo or expectancy effects (here's a short review of this debate). I am not trained as a neuroscientist nor am I an expert in this area of research, so I won’t directly challenge the authors’ conclusions. Nonetheless, I was left uncertain how much of the notion of grouping meditation, psychotherapy, and placebos into one category, and antidepressants in another, is based more on theory than on data.

Nonetheless, I think the authors did a nice job of trying to organize and summarize a growing but somewhat disparate body of research. Additionally, they’ve raised some important questions for other researchers to begin to explore in a more systematic manner. As I blogged about last week, Fletcher and colleagues (2010) recently suggested ways in which a neuroscientific understanding of mindfulness may be refined. This is a really exciting avenue of study, but I agree with the latter authors in that what researchers should really focus on is building our understanding of the neurological underpinnings of mindfulness and meditation in a very deliberate and step-by-step approach.

Full Citation:

Chiesa, A., Brambilla, P., & Serretti, A. (2010). Functional neural correlates of mindfulness meditations in comparison with psychotherapy, pharmacotherapy and placebo effect. Is there a link? Acta Neuropsychiatrica, 22(3), 104-117.

Science of the Mindful Brain

Dan Siegel, MD, author of The Mindful Brain has a short article on Kripalu. He talks about his work and his journey in understanding mindfulness.

The article is available here.

Meditation, Cortical Thickness, and Pain Sensitivity

There’s a small but growing body of research literature showing that meditation practice is associated with greater cortical thickness in the brain (i.e., Grant et al., 2010; Lazar et al., 2005; Pagnoni & Cekic, 2007). All three studies used MRI scans to examine brain structures. In Lazar et al. (2005), a group of Insight meditation practitioners, regions of the brain associated with attention and sensory processing exhibited an increased thickness compared to a control group matched for gender, age, race, and years of education. Interestingly, the average thickness in the prefrontal cortex in 40-50 year-old meditators was similar to the average thickness of 20-30 year-old meditators and controls. This suggests that practice may slow age-related degeneration of brain tissue. Pagnoni & Cekic found a similar pattern in Zen practitioners.

More recently, Grant et al. (2010) examined the relationship between cortical structures and pain sensitivity in meditators. The researcher first compiled a list of 68 meditators willing to participate. In order to have a more homogenous sample, they chose Zen practitioners, who both made up the largest tradition in the list and reported more than 1,000 hours of meditation experience. Of the 19 Zen practitioners, 17 participated; these were matched against 17 non-meditators for age and gender.

A computer controlled increase in temperature, which was designed to create a moderate level of pain, was applied to the inner left calf of each participant. Cortical size was measured using MRI scans.

Zen practitioner exhibited lower pain sensitivity than controls. On average, Zen practitioners required an increase to 50°C in order to report a moderate level of pain; controls required an average of 48°C. Lower pain sensitivity was also related to greater cortical thickness, particularly in the dorsal anterior cingulated cortex, right anterior insula, and bilateral hippocampal formation. Greater thickness in these areas was related to greater meditation experience. Because this was a cross-sectional study and not a true experiment, we can’t be certain that there is a causal relationships between meditation experience, cortical thickness, and pain sensitivity. Taken together, the authors suggest that long-term meditation practice may lead to changes in the brain structures, which in turn may lower sensitivity to physical pain. The full article can be read in the most recent edition of the scientific journal Emotion. Interview excerpts with the first author about this study can be found at Science Daily.

A PDF of the Lazar et al. (2005) article can be found at the first author’s website.

The citations for the articles are:

Grant J.A., Courtemanche J., Duerden, E.G. Duncan G.H., & Rainville, P. (2010). Cortical thickness and pain sensitivity in zen meditators. Emotion, 10(1), 43-53.

Lazar, S. W., Kerr, C. E., Wasserman, R. H., Gray, J. R., Greve, D. N., Treadway, M. T., et al. (2005). Meditation experience is associated with increased cortical thickness. Neuroreport, 16(17), 1893-1997.

Pagnoni, G., & Cekic, M. (2007). Age effects on gray matter volume and attentional performance in Zen meditation. Neurobiology of Aging, 28(10), 1623-1627.