The Science of Meditation

Summary: Altered Traits

Altered Traits (2017) is currently the best book I’m aware of about the scientific research that has been done on meditation. In this summary, I have applied strict standards and only included findings for which the evidence is pretty solid. That makes this a conservative picture of what meditation might be good for, let alone for the fact that the book may have omitted some findings and that the science is in its infancy. Still, none of this stuff is a guarantee, it’s just a fairly safe guess based on the evidence that’s currently available.

So, what will I get if I meditate 20 minutes a day?

Let’s assume you’re practicing diligently and using good technique. Pretty soon, you’ll see a reduction in mind-wandering while you’re trying to focus that will translate into improved performance on tasks such as academic exams. You’ll also get better at tuning out distracting stimuli while you’re trying to focus. You’ll probably get an improvement in “meta-awareness,” the ability to be aware of your own mind states. And if you do an open awareness meditation, you’ll see a reduction in “attentional blink,” the tendency for attention to momentarily go offline the second it spots an important cue.

If compassion meditation is what you’re doing, you’ll probably notice benefits pretty soon. You’re going to get a boost in positive feelings and happiness, and maybe a reduction in self-criticism. Several studies have shown this practice causing people to be more generous and likely to help people in need, something that simply studying or thinking about compassion doesn’t do. It boosts a brain network responsible for love, affiliation, resilience, and positive emotions. This network is distinct from the network for empathy, which causes you to suffer when you see others suffering and leads to burnout.

Definitely, if you have people do breath meditation in an fMRI while you show them disturbing pictures, their amygdala will be less active than if you showed them the pictures while they weren’t meditating. (The amygdala serves in part as the brain’s radar for threat, and can activate the fight-or-flight response.) This has been observed in people with as little as one week of meditation experience. Granted, you don’t always have the luxury of being in the middle of a breath meditation when stressful stimuli pop out at you during daily life. But this proves that implementing a formal meditation technique during a stressful stimulus can cause measurable reductions in your brain’s stress response. So it’s reasonable to suspect that if a stressful stimulus pops up and you begin a formal technique within, say, two seconds, be it breath meditation or mindfulness of the sensations of stress themselves, it could have a comparable effect. So by practicing meditation, you’re developing a tool that you can deploy at a moment’s notice in daily life.

On top of that, there are some strong hints that these stress-reduction effects eventually will stick around even when you’re not meditating, and potentially even as early as eight weeks into practicing. Beside that data is a pile of good studies finding that eight weeks of meditation reduced people’s anxiety and depression symptoms, at least somewhat. To me, it seems like reduced anxiety symptoms are mutually supportive with findings of a lower stress response at baseline. Another rather indirect corroboration of this could be the reduction of inflammation that begins at this stage in meditation, since inflammation is part of the body’s stress response. It should be noted that although inflammation plays a role in many major diseases it is not yet clear how much of an effect the reduction in inflammation found in meditation has in the treatment of these diseases. Similarly, meditation surprisingly seems to increase telomerase, an enzyme that protects DNA and slows cell aging, but we don’t know what the macroscopic ramifications of that are. People with chronic pain definitely say that meditation at this dose helps them, not in treating the biological source of their pain, but in reducing their perceived suffering.

What if I meditate an hour a day and go on intensive retreats, and keep that up over the years?

Most of the benefits in the prior section will become more robust. Your performance on precise concentration tasks will increase in a lasting way. In this range, the more you meditate (or the better you meditate) the more likely you are to see a quicker recovery in your biological markers of stress (especially amygdala activity) after a stressful event, without having to apply a meditation technique. After a few years, a reduction in your baseline “default mode network” activity will likely set in, which is the network in the brain responsible for producing mind-wandering thoughts while you’re at rest, most of which are typically about yourself and your problems.

What if I just meditate once?

Well, your dorsolateral prefrontal cortex will activate to inhibit your default mode network. I bet your amygdala will calm down a bit. You’ll have an afterglow period where both your concentration is enhanced and your attentional blink is reduced. If you do loving-kindness meditation, you’ll probably report feeling happy and socially connected right afterward.

What about the most advanced meditators in the world?

The most experienced subjects ever studied are Tibetan yogis with 12,000-62,000 lifetime hours of practice. The gamma waves in their brains are remarkable. Gamma waves typically occur when multiple brain regions fire in harmony, such as during a creative insight or when imagining a scene involving multiple types of sensory information. They typically last 1/5 of a second and occur in isolated parts of the brain. But when the yogis do compassion and open presence meditation, they can enter within seconds into a state where their gamma activity surges dramatically, is synchronous across the entire brain, and lasts (at least) a full minute. This type of gamma activity had never been seen before in all of neuroscience. What’s more, their gamma activity when not meditating is 25x higher than an average person’s, and advanced meditators have even shown gamma activity while sleeping. When Mingyur Rinpoche, the most experienced among them with 62,000 hours, did loving-kindness meditation in an fMRI, his empathy circuitry was over 7x as active as at baseline, a level never before seen in science. His brain is also aging more slowly than average, and at 41 his brain resembled a typical 33 year old’s.

A standard pain tolerance test consists of a warning cue ten seconds before the pain, a ten-second interval of intense pain, and then a ten-second rest period. For normal people, the brain’s “pain matrix” activates strongly at the warning cue, as if they were already experiencing pain. When the pain hits, the pain matrix activates slightly more, and remains active after the pain subsides. The yogis, however, while practicing open presence meditation, show little response to the warning cue, a major spike in the sensory parts of the pain matrix when the pain hits but only a mild increase in the emotional parts, and a quick recovery after the pain. Later, the yogis did loving-kindness meditation in an fMRI and listened to sounds of people in distress. They showed more activity in the amygdala and premotor areas than average people, indicating increased emotional resonance and preparedness to help, but lower activity in the posterior cingulate cortex and prefrontal cortex, areas involved in self-concern (e.g. “But what will happen to me if I try to help?”).

The studies of these yogis prove that meditation can make dramatic changes to the brain. If huge doses of meditation can produce huge changes, that adds credibility to the idea that smaller doses of meditation can produce real changes, even if those changes are smaller and therefore harder to measure.

What are the brain regions involved with meditation?

The amygdala’s role is to scan our experience for emotionally relevant stimuli and direct our attention to them. Since threats are very emotionally relevant, the amygdala plays a crucial role in detecting threats and activating the fight-or-flight response. You know when you can’t stop thinking about something that’s bothering you? That’s because your amygdala is detecting a threat there and is directing your attention to it. Meditation generally calms the amygdala. But meditating on compassion while you listen to sounds of people suffering actually boosts the amygdala, since their suffering stands out to your attention as salient. Attention is also directed by the reticular activating system, a system in the brain stem that orients us toward novel stimuli, and by the prefrontal cortex, a region in the front of the brain that happens to be the only attention-directing system that is under our voluntary control. When the prefrontal cortex directs attention it can quiet the amygdala, and when the amygdala activates strongly, it can paralyze the prefrontal cortex.The prefrontal cortex is a hotspot in meditation research. The dorsolateral prefrontal cortex activates when you return your attention to your meditation object. The medial prefrontal cortex, along with the posterior cingulate cortex and some other more minor regions, form the default mode network, the network that activates when you’re doing nothing, which produces mind-wandering thoughts that tend to gravitate toward self-centered issues. The dorsolateral prefrontal cortex seems to inhibit the default mode network. By the way, when the posterior cingulate cortex is active during meditation, people report difficulty and distraction, and when it calms down people report ease.

There are separate brain circuits for empathy (“suffering with” someone) and compassion (feelings of love for the suffering person); compassion meditation boosts the latter. The brain’s pain response has two components: physical and emotional; meditation (in high doses at the very least) calms the latter. The insula is mentioned multiple times in the book. I gather that it is a kind of relay center between the body and the brain. And the nucleus accumbens is a site for reward and motivation but also for addiction and compulsion. It can probably be modulated, potentially even shrunk, through meditation.

The bottom line

I can’t honestly say that any of this stuff is a guarantee. I suspect it depends on how well you practice, and what practices you do. And some of these discoveries might get overturned someday. But from this evidence, there’s no denying that meditation is doing something. So go practice.

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