October 11

The Neuroscience of Mindfulness Meditation

When I think of meditation, the first image that typically comes to mind is that of a monk in flowing orange robes somewhere in the mountains of Tibet. Meditation has gotten a facelift in the last decade in pop culture, thanks in part to best selling books like 10% happier by the television journalist Dan Harris which emphasizes the benefits of meditation while stripping away the orange robes and vows of silence. There seem to be no end to the purported benefits of mindfulness meditation, but at least to me our interest in this ancient practice seemed to come out of nowhere. How did we get here?

 

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Mountainside Meditation [Wikimedia Commons: Tevaprapas]

Exhaustive(ly short) history of meditation

Meditation in its most recognized form was born of Indian traditions, particularly Buddhism. The practice of meditation is used as a tool to still the mind as part of the lifelong quest to transcend the endless cycle of death and rebirth and (optimistically) achieve nirvana. The Zen Buddhist tradition takes meditation a step further and seeks to not only still but also empty the mind. In either case, from the perspective of relatively a-spiritual member of western society the two practices feel extremely similar; ruminating and mindless thought wondering are to be minimized in pursuit of a less scatterbrained and more present sense of being.

While not quite mainstream in American culture, meditation has been around in one form or another for decades. Transcendental Meditation (TM), characterized by repeating a mantra with one’s breath gained worldwide popularity in the 1960s under the promotion of Indian guru Maharishi Mahesh Yogi. Excitement around transcendental meditation was fueled further when Maharishi became the spiritual advisor to The Beatles in 1967. Today TM is one of the most widely practiced meditative traditions in part due to the relative ease of its practice.

Typically considered more challenging, mindfulness meditation is characterized by trying to empty one’s mind through intentional breathing and dismissing natural thoughts that come up. In the late 1970s, Jon Kabat-Zinn, a professor at the University of Massachusetts, began looking at how meditation might reduce stress and pain in patients who had otherwise not responded to treatment. His 8-week stress meditation program consisting of weekly guided meditation sessions and daily meditation at home has produced dramatic results and has been the target of countless interventional treatments and studies. JKZ defines mindfulness as:

[The] … awareness that arises through paying attention, on purpose, in the present moment, non-judgmentally

 

 

East meets West: gray hair is (probably) not a prerequisite for becoming a meditation guru. [left: Wikipedia Commons, right: Personal Website]

Science!

Recent headlines have touted meditation as a panacea, helping improve cognitive function, reduce pain, and boost athletic performance. Early studies looked at how the brains of highly trained meditators (up to 50,000 hours!) differed from non-trained (age-matched) controls in how they respond to distractions while meditating. One consistent finding is that trained meditators show less activity in their amygdala, a region implicated in fear responses, to scary or distracting sounds while meditating. Critically, the strength of this this effect correlates strongly with the amount of training an individual has undertaken, suggesting the meditation itself is leading to the neural changes rather than some confounding differences between the populations (Lewis, 2007; Krala, 2018). Such functional changes suggest that meditation training allows us to suppress our evolutionary ancient limbic structures potentially explain findings of improved attention in practitioners.

Early studies also demonstrated that expert meditators showed less activity in their Default Mode Network providing some of the early neural evidence that this network was activated during mind wandering (Lewis, 2007). The default mode network, which includes the medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC), shows the most activity when the mind is engaged in “mind wandering” or “stimulus-independent thought”. Importantly, since mind wandering is negatively associated with self-reported happiness (Killingsworth, 2010), the ability of experienced meditators to suppress default mode network activity may drive some of the bliss experienced by its practitioners.

With all of these studies there is an important caveat that they are comparing an expert completing an activity with a novice, and many of the changes observed could indeed be related to the ease of the task more than anything else. For example, it was found that soccer (and acting) superstar Neymar exhibited less activity in his foot motor control region when rotating his ankle in a scanner compared with age matched swimmers and less skilled soccer players (Naito, 2014). Controlled studies where experts in other cognitive domains are compared with novices are needed to determine if meditation induced structural changes are indeed “special” to meditation.

Other studies have explored the effectiveness of short term meditation interventions (ranging from 4 days to 8-weeks) on pain perception. In a convincing pair of studies, one group showed that just 4 days of mindfulness meditation training reduced the perception of painful stimuli (heat pad) more than a placebo cream or sham meditation (sham meditation meant participants were given instruction to let their minds wander but were told they were meditating). These effects seemed to be driven by a decrease in activity in the prefrontal cortex, an executive area suggesting perhaps a suppression of conscious awareness of external stimuli. (Zeidan 2015, Zeidan 2011).  

Zeidan2015

Participants who practiced meditation for 4-days reported lower pain perception compared with all other controls. This effect was highly correlated with a reduction in activity in the prefrontal cortex (circled region). Adapted from Zeidan, 2015.

In a more molecular approach, a clever experiment blocking opioid receptors suggests that meditation induced pain suppression may actually be due to the brain producing its own supply of painkillers (Sharon, 2016).These studies are exciting because they suggest a new avenues to tackle pain and stress without the laundry list of side effects associated with pain killers.

Mindfulness meditation has certainly demonstrated value in improving the wellbeing of its practitioners. But whether these effects are unique relative to other forms of meditation of other mindful activities such as running is still an open question. While these questions are sorted out, I’m sure most practitioners of mindfulness meditation will be happy to hedge their bets, after all the benefits seem substantial and the side effects limited. In closing, a very San Diego minded quote reminding us to take things as they come.

You can’t stop the waves but you can learn how to surf. ~Jon Kabat-Zinn.

 

Citations:

Brefczynski-Lewis JA, Lutz A, Schaefer HS, et al. (2007) Neural correlates of attentional expertise in long-term meditation practitioners. PNAS

Tammi R.A. Krala, Brianna S. Schuylera ,et al. (2018) Impact of short- and long-term mindfulness meditation training on amygdala reactivity to emotional stimuli. Neuro Image

Killingsworth MA, Gilbert DT (2010) A wandering mind is an unhappy mind. Science

Naito, E., and Hirose, S. (2014). Efficient foot motor control by Neymar’s brain. Frontiers in Human Neuroscience

Zeidan F, Martucci KT, Kraft RA, et al. (2011) Brain mechanisms supporting the modulation of pain by mindfulness meditation. Journal of Neuroscience

Fadel Zeidan, Nichole M. Emerson, et al. (2015) Mindfulness Meditation-Based Pain Relief Employs Different Neural Mechanisms Than Placebo and Sham Mindfulness Meditation-Induced Analgesia Journal of Neuroscience

Sharon H, Maron-Katz A, Ben Simon E, et al. (2016) Mindfulness meditation modulates pain through endogenous opioids. American Journal of Medicine

 

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