The neuroscience of meditation

Dr. SARA LAZAR is an Associate Researcher in the Psychiatry Department at Massachusetts General Hospital and Assistant Professor in Psychology at Harvard Medical School. The focus of her research is on the neural mechanisms underlying the beneficial effects of yoga and meditation, both in clinical settings and in healthy individuals. Here she speaks about how meditation impacts the brain.

I want to start with a definition of Mindfulness, derived by Jon Kabat-Zinn: purposely paying attention to experiences in the present moment in a non-judgmental way. There is a cartoon that describes it beautifully – one woman is walking in nature, completely oblivious to what’s around her. She’s thinking about the bills, meals, kids, chores, and is not at all aware of her present experience. Another woman is completely tuned in to her surroundings, noticing the trees, the sunlight, perhaps the feel of the warmth of the sun on her face. That’s what Mindfulness is – awareness of the present moment. Neither one of them is meditating. Mindfulness can be done anytime, anywhere.

Anyone can kick a ball. If I ask you to kick a ball down a field and put it through the goalposts, you can do that. But if I put you on that same field with some professional soccer players, and tell you, “Okay, kick the ball down the field into the posts,” that’s much more difficult.

The same thing is true with Mindfulness – anyone can do it, but it’s hard to remember to do it when you’re in the middle of stuff. Just as professional athletes practice their sport so they can play more effectively, we meditate so that we can be more mindful throughout the day. We build that skill.

Mindfulness is purposely paying attention 
to experiences in the present moment 
in a non-judgmental way…
Mindfulness can be done anytime, anywhere.

People have difficulty with the last part of the definition – the non-judgmental. I prefer the word equanimity, because we’re not saying, “Oh, yeah, whatever.” It’s not indifference. We care but we’re not reactive.

There have been thousands of studies demonstrating the benefits of meditation, both for self-reported stress and for biomarkers of stress, like cortisol and inflammation. I’d like to focus on how effective meditation is in reducing symptoms of depression, anxiety, pain, and insomnia. They are standalone conditions, and they are also associated with many other conditions. If someone has a history of heart disease, diabetes, or a stroke, they’ll often have depression, anxiety, pain, or insomnia too.

Importantly, as the Buddha taught, the first goal is spiritual transformation, but there’s more and more evidence that meditation’s good for both reducing symptoms and increasing well-being. People report being happier and more satisfied with life. There are many clinical programs now based on meditation; and the people who do them say, “This practice has changed my life.” That’s what happened to me. I had a sports injury, and started doing yoga as a form of physical therapy. After a few weeks, it completely changed me; I was more relaxed, no longer bothered by the little things that affected me before. My brain had changed. That’s why I started doing this research, to try to understand how yoga and meditation work.

Reduction in Stress

We took people who were going through an eight week secular meditation course called Mindfulness-based Stress Reduction. Compared to the controls, the people in the meditation group had more gray matter in several brain regions after just eight weeks of practice. Those regions were the posterior cingulate, the supra marginal gyrus, and the hippocampus. The posterior cingulate is involved in self-related processes, “How is this relevant to me?” The supra marginal gyrus is involved in perspective taking, and it’s a key component of empathy and directing attention–“Do I pay attention to the inner world or the outer world?” The hippocampus is involved in memory.

Just as professional athletes practice their sport 
so they can play more effectively, 
we meditate so that we can be more mindful 
throughout the day. We build that skill.

These three regions together make up the Default Mode Network. “Default” because if you put someone in an MRI scanner and they’re not doing anything in particular, these regions reliably always turn on, along with two others. When you ask the person to do a task, these three regions turn off. The ideas they put together create the sense of self. These regions were altered by meditation practice.

The posterior cingulate and the hippocampus are destroyed with Alzheimer’s disease. With Alzheimer’s you forget your life and who you are, where as in meditation you’re very present and centered. And these are the regions in which we find changes with just eight weeks of meditation.

Another region that changed was the brainstem, which is involved in regulating the release of neurotransmitters, including serotonin and dopamine, which are very important for mood. These changes correlated with changes in well-being: the more this region changed, the happier and more satisfied people felt. People reported that they were more satisfied with their job, their neighbors, their home, their family, etc. It suggests that there was a change in how they perceived the world.

The amygdala also changed; the amygdala is involved in fear and anxiety, and negative emotions in general. We found that this region became smaller, and the more it decreased, the more stress reduction people reported in just eight weeks. There wasn’t a lot changing in these people’s lives, and yet they were reporting less stress. The neurobiological reason why stress reduced was because the parts of the brain involved in stress were changing.

Pain

There are two components to pain – one is the actual physical sensation of burning, stabbing, pulsing, throbbing, tingling, and the other is the emotional component, “Ouch, that hurts, I don’t like it.” They are controlled by two different parts of the brain that are independent of one another. We also know that there are a lot of ways to control pain, including distraction, expectation, and placebo. All three look more or less the same in the brain.

Normally, when you stub your toe or burn your finger, the signal goes to the spinal cord, and up the spinal cord to the brain. Then the network that includes the insula and the sensory cortex evaluates the sensory component of it. The emotional component is then activated to say, “I don’t like it.” For these three forms of pain control, the front of the brain, the executive control, shuts down the signal – the signal comes in, but it doesn’t go up, so you don’t feel the sensations. If you have chronic pain, but you watch a good movie, or you have a good conversation, you forget your pain. That’s what happens with distraction, you simply don’t feel the pain. But once that interesting conversation or the movie ends, pow, your pain is back. It’s amazing what the brain can do to shut down the system and stop the signal from coming up.

Now, the question we asked was: what about meditation? We recruited a few long-term meditation practitioners and some people who had never meditated for the control group. We put them in the MRI scanner, and applied a very mild electric shock to their hand for forty seconds. We did this in a normal phase and then in a mindful phase. They would be randomly shocked a few times without knowing when it was going to happen. At the end, the subjects had to rate both the intensity and the unpleasantness of their experience. For the control group, there was no difference in intensity between the normal phase and the meditation phase, and this was also true for the Mindfulness practitioners. With unpleasantness, the control group experienced no difference, but there was a very significant decrease in unpleasantness for the Mindfulness practitioners. Although it was just as intense, it didn’t bother them. They were really feeling it, open to it; they were not shutting it down. They were paying attention to it. We see here, neurobiologically, a really beautiful example of equanimity.

After that study, several other researchers did similar studies. They found that the connections between the front of the brain and the sensory cortex were less coupled in the meditation practitioners than the control groups, so that they were better able to decouple their reaction to the pain from the intensity of the pain.

Also, very importantly, that uncoupling was related to the number of years of meditation practice. The more they had practiced, the better they were at separating the “I don’t like it, make it stop” region from the throbbing, painful stabbing, burning sensation. They could separate their emotions from the physical sensations.

This demonstrates how meditation works – it’s a slow, gradual process that changes the brain. This has long lasting consequences for how we experience the world.

Sylvia Boorstein once said, “Life is painful, suffering is optional.” It’s true that we’ll all experience pain at some point in our life, but we can control how we respond to that pain.

“Meditation is not evasion, 
it is a serene encounter with reality.”
—Thich Nhat Hahn

From a talk given at the international Heartfulness conference, “An Integrative Approach to Health and Well-being,” at Kanha Shanti Vanam on December 16, 2022.

Illustrations by ANANYA PATEL