Meditatie als pijnstiller en
tegen teveel aan informatie*
Uit een paar kleine Amerikaanse studies blijkt dat meditatie duidelijk zorgt voor minder gevoeligheid voor pijnen en dat meditatie zorgt voor veranderingen
in de hersenen waardoor men beter kan omgaan met de vaak hectische wereld en minder afgeleid wordt. In de eerste studie lieten wetenschappers enkele tientallen proefpersonen een stoomcursus mediteren volgen. Voor en na de sessies van twintig minuten, drukten de onderzoeksleiders een hitte-element tegen de kuiten van de deelnemers. De deelnemers ervaarden deze pijnprikkel na de meditatie als veel minder (57%) onprettig en minder (40%) intens dan ervoor. De gemiddelde afname van pijngevoeligheid was zelfs groter dan bij het gebruik van sommige pijnstillers. Ook op hersenscans was het effect van de meditatie te zien. Na het mediteren was er volgens de onderzoekers veel minder activiteit waarneembaar in hersendelen die pijn registreren. Delen van het brein die betrokken zijn bij concentratie en verwerking van emoties, werden juist actiever na de sessies.
Uit studies door andere wetenschappers blijkt dat meditatie al binnen acht weken kan leiden tot structurele veranderingen in het menselijk brein. Tijdens de meditatie moesten de deelnemers zich met name concentreren op hun geestelijke gevoelens en lichamelijke sensaties. Voor en na het meditatieprogramma werden er hersenscans van de proefpersonen gemaakt. Na acht weken mediteren, ontstaat er meer grijze hersenmassa in de hippocampus. Dat is een hersengebied dat wordt geassocieerd met geheugen en leervermogen. De dichtheid van de amygdala neemt juist af door meditatie. Als gevolg daarvan ervaren mensen mogelijk minder angst en stress, zo zeggen de wetenschappers. Verder zorgde meditatie voor een betere regeling van alfa-golven in de hersenen, golven die bekend staan dat ze het teveel aan informatie kunnen beperken waardoor men beter kan omgaan daarmee en minder afgeleid wordt. Volgens de onderzoekers is het fascinerend om te zien dat we ons brein en ons welzijn kunnen veranderen door meditatie te beoefenen.
Demystifying Meditation – Brain Imaging Illustrates How Meditation Reduces Pain
Meditation produces powerful pain-relieving effects in the brain, according to new research published in the Journal of Neuroscience.
“This is the first study to show that only a little over an hour of meditation training can dramatically reduce both the experience of pain and pain-related brain activation,” said Fadel Zeidan, Ph.D., lead author of the study and post-doctoral research fellow at Wake Forest Baptist Medical Center.
“We found a big effect – about a 40 percent reduction in pain intensity and a 57 percent reduction in pain unpleasantness. Meditation produced a greater reduction in pain than even morphine or other pain-relieving drugs, which typically reduce pain ratings by about 25 percent.”
For the study, 15 healthy volunteers who had never meditated attended four, 20-minute classes to learn a meditation technique known as focused attention. Focused attention is a form of mindfulness meditation where people are taught to attend to the breath and let go of distracting thoughts and emotions.
Both before and after meditation training, study participants’ brain activity was examined using a special type of imaging -- arterial spin labeling magnetic resonance imaging (ASL MRI) -- that captures longer duration brain processes, such as meditation, better than a standard MRI scan of brain function. During these scans, a pain-inducing heat device was placed on the participants’ right legs. This device heated a small area of their skin to 120° Fahrenheit, a temperature that most people find painful, over a 5-minute period.
The scans taken after meditation training showed that every participant’s pain ratings were reduced, with decreases ranging from 11 to 93 percent, Zeidan said.
At the same time, meditation significantly reduced brain activity in the primary somatosensory cortex, an area that is crucially involved in creating the feeling of where and how intense a painful stimulus is. The scans taken before meditation training showed activity in this area was very high. However, when participants were meditating during the scans, activity in this important pain-processing region could not be detected.
The research also showed that meditation increased brain activity in areas including the anterior cingulate cortex, anterior insula and the orbito-frontal cortex. “These areas all shape how the brain builds an experience of pain from nerve signals that are coming in from the body,” said Robert C. Coghill, Ph.D., senior author of the study and associate professor of neurobiology and anatomy at Wake Forest Baptist.
“Consistent with this function, the more that these areas were activated by meditation the more that pain was reduced. One of the reasons that meditation may have been so effective in blocking pain was that it did not work at just one place in the brain, but instead reduced pain at multiple levels of processing.”
Zeidan and colleagues believe that meditation has great potential for clinical use because so little training was required to produce such dramatic pain-relieving effects. “This study shows that meditation produces real effects in the brain and can provide an effective way for people to substantially reduce their pain without medications,” Zeidan said.
Funding for the study was provided by the Mind and Life Institute in Boulder, Colo., and the Center for Biomolecular Imaging at Wake Forest Baptist.
Meditation May Help the Brain 'Turn Down the Volume' On Distractions
The positive effects of mindfulness meditation on pain and working memory may result from an improved ability to regulate a crucial brain wave called the alpha rhythm. This rhythm is thought to "turn down the volume" on distracting information, which suggests that a key value of meditation may be helping the brain deal with an often-overstimulating world.
Researchers from Massachusetts General Hospital (MGH), Harvard Medical School and the Massachusetts Institute of Technology report that modulation of the alpha rhythm in response to attention-directing cues was faster and significantly more enhanced among study participants who completed an eight-week mindfulness meditation program than in a control group. The report will appear in the journal Brain Research Bulletin and has been released online.
"Mindfulness meditation has been reported to enhance numerous mental abilities, including rapid memory recall," says Catherine Kerr, PhD, of the Martinos Center for Biomedical Imaging at MGH and the Osher Research Center at Harvard Medical School, co-lead author of the report. "Our discovery that mindfulness meditators more quickly adjusted the brain wave that screens out distraction could explain their superior ability to rapidly remember and incorporate new facts."
Brain cells use particular frequencies or waves to regulate the flow of information in much the same way that radio stations broadcast at specific frequencies. One frequency, the alpha rhythm, is particularly active in the cells that process touch, sight and sound in the brain's outmost layer, called the cortex, where it helps to suppress irrelevant or distracting sensations and regulate the flow of sensory information between brain regions.
Previous studies have suggested that attention can be used to regulate the alpha rhythm and, in turn, sensory perception. When an individual anticipates a touch, sight or sound, the focusing of attention toward the expected stimulus induces a lower alpha wave height in cortical cells that would handle the expected sensation, which actually "turns up the volume" of those cells. At the same time the height of the alpha wave in cells that would handle irrelevant or distracting information increases, turning the volume in those regions down. Because mindfulness meditation -- in which practitioners direct nonjudgmental attention to their sensations, feelings and state of mind -- has been associated with improved performance on attention-based tasks, the research team decided to investigate whether individuals trained in the practice also exhibited enhanced regulation of the timing and intensity of alpha rhythms.
The study tested 12 healthy volunteers with no previous experience in meditation. Half completed the eight-week Mindfulness-Based Stress Reduction Program developed at the University of Massachusetts. The other half were asked not to engage in any type of meditation during the study period. Using magnetoencephalography (MEG), an imaging technique that detects the location of brain activity with extreme precision, the researchers measured participants' alpha rhythms before, during and after the eight-week period. Specifically, they measured alpha rhythms in the brain area that processes signals from the left hand while participants were asked to direct their attention to either their left hand or left foot. Participants' abilities to adjust the alpha rhythm in cortical cells associated with the hand, depending on where their attention was directed, were recorded during the milliseconds immediately after they received an attention cue.
Although all participants had showed some attention-related alpha rhythm changes at the beginning of the study, at the end of the eight weeks, those who completed the mindfulness meditation training made faster and significantly more pronounced attention-based adjustments to the alpha rhythm than the non-meditators did. "This result may explain reports that mindfulness meditation decreases pain perception," says Kerr. "Enhanced ability to turn the alpha rhythm up or down could give practitioners' greater ability to regulate pain sensation."
The study also sheds light on how meditation may affect basic brain function, explains Stephanie Jones, PhD, of the Martinos Center, co-lead author of the paper. "Given what we know about how alpha waves arise from electrical currents in sensory cortical cells, these data suggest that mindfulness meditation practitioners can use the mind to enhance regulation of currents in targeted cortical cells. The implications extend far beyond meditation and give us clues about possible ways to help people better regulate a brain rhythm that is dysregulated in attention-deficit hyperactivity disorder and other conditions." Kerr is an instructor in Medicine and Jones an instructor in Pediatrics at Harvard Medical School (HMS).
The senior author of the Brain Research Bulletin report is Christopher Moore, PhD, of Massachusetts Institute of Technology (MIT). Additional co-authors are Qian Wan and Dominique Pritchett of MIT; Anna Wexler, Joel Villaneuva, Jessica Shaw, and Ted Kaptchuk, Osher Research Center at HMS; Sara Lazar, PhD, MGH Psychiatry; Matti Hämäläinen, PhD, Martinos Center for Biomedical Imaging at MGH; Rachel Wasserman, Penn State University; and Ronnie Littenberg, PhD, Women's Mental Health Collective, Cambridge, Mass. The study was supported by grants from the National Institutes of Health and the Osher Research Center at Harvard Medical School.
(Augustus 2011)
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