This is Part Two of a three-part series. Find Part One and Part Three here.
Amazing Brain Facts
Your brain weighs about three pounds and is the consistency of soft tofu. It is made of about 1.1 trillion cells. About a hundred billion of these cells are neurons; the others are the support structure of the brain, the white matter, the glial cells, predominantly, that help build myelination around the long axonal fibers of the neurons, which accelerate neurotransmission.
Each of those neurons, on average, has about five thousand connections with other neurons. That creates about five hundred trillion connections, called synapses. These are tiny little junctions between neuron “A” and neuron “B” where they communicate. In most neurons, each time a neuron fires, neurochemicals move across the synapse. (A small fraction of your neurons make direct, electrical connections.)
Each neuron is always either firing, or not. Each firing is a signal, like “green light/red light;” it tells the downstream neuron to fire or not.
So each neuronal firing is like a bit of information in a computer, a zero or a one. Most of the neurons in your brain are firing five to fifty times a second. They are very, very busy.
As a result, this little organ, two percent of body weight, uses twenty to twenty-five percent of the body’s metabolic supplies. Even in the deepest sleep, even in a coma, the brain is busy. It’s like a refrigerator; it’s always on. The brain keeps going so that if you’re suddenly attacked in the wild or you’ve got to deal with something in your cave, kaboom! You’re ready to go.
We can recognize maybe four thoughts per second, if we’re pretty aware. If we get really quiet, we might be able to see eight to ten, at the most. Working memory circuits, which are a key neural substrate of conscious awareness, seem to update about six times a second. That’s roughly how tight the granularity is of discrete thoughts; that is really slow, as far as the brain’s concerned. So what we think of as thought—this slow, congealed, turgid stuff—is just the tip of the iceberg of mental activity.
Neurons often fire in harmony with each other, five to fifty times a second —maybe even eighty or a hundred times in some parts of the brain.
They’re synchronizing with each other, and that’s what produces the rhythmic waves of electrical activity—brainwaves—that are picked up with EEGs. Types of brainwaves are grouped together based on how fast they are; for example, brainwaves that happen 30—80 times a second are called gamma waves. In one study, when experienced Tibetan practitioners meditated, there was a spreading and strengthening pattern of gamma wave activity in the brain: billions of neurons firing in harmony with each other, 30-80 times a second.
Synchronizing microscopic neurons, spread across broad regions of your brain, is like everybody between Barre and Boston clapping in unison, thirty times a second. Wow! And these effects of synchronization and integration are seen outside of formal meditation. In the same study, those Tibetan monks—who have done 30,000 to 50,000 hours of meditation in their lifetimes—have resting state gamma activity that’s greater than people who don’t have so much practice. This suggests that, as we practice more and more, there’s more integration and coherence in the brain—which corresponds to a growing stability and spaciousness, equanimity in other words, in the mind.
Brain and Body Benefits of Meditation
The anterior cingulate cortex (ACC) is a brain region that is ground zero for a lot of very important functions. For one, it’s the part of the brain that manages what’s called “effortful attention.” This means paying attention in a deliberate way. That sounds like meditation. The ACC is the part of the brain we use for mindfulness in all four postures, not just seated, but walking, lying, and standing. It’s also the main source of the focused attention we use for talking, and doing other activities that call for deliberate focus. Your cingulate cortex tends to get thicker to the degree you meditate.
For many people, it’s easy to feel when they feel, or think when they think, but to bring mental clarity into being upset, or to warm up cold cognition with heartfelt emotion, is hard. The capacity to do that is centered in the anterior cingulate cortex. So, for example, doing things like compassion meditation, particularly mingling thoughts and feelings of compassion together, stimulates the ACC and therefore strengthens it; you’re firing those neurons and therefore you’re wiring those neurons.
Another region that gets thicker with meditation is called the insula. If you strengthen a part of the brain through meditation, you get to reap those rewards for other uses. For example, the insula is crucial for one of the three main aspects of empathy: visceral resonance with the feelings of another person (the other two aspects are simulating inside yourself the actions [mirror systems] and the thoughts/wishes/psychodynamics [theory of mind], of others). To the extent that we’re in touch with own inner being, including our gut feelings—and this degree of in-touchness correlates with the activity of the insula—we become more empathic with others.
As we practice, there’s more integration and coherence in the brain, growing stability and spaciousness—equanimity, in other words.
True compassion, true loving kindness, requires empathy. I’ve known people who are sort of generically compassionate, and generically kind, but aren’t actually moved by the inner state of the other person. That’s not the real deal. So it’s foundational to strengthen your empathy. I can tell you from twenty-seven years of marriage, empathy’s a good thing! (And there are, of course, lots of important places for empathy outside of marriage.) Also, if you understand how to be empathic yourself, you understand better how to ask for it from others.
Meditation is probably the most researched mental activity in terms of neural impact.
We know, for example, that meditators have less cortical thinning with aging. As I see more gray hairs on my head every year, I appreciate the fact that one of the great ways to promote mental faculties well into old age is through contemplative practice.
One exploratory study has shown a correlation of about a fifteen percent reduction in Alzheimer’s symptoms if a person has a religious background. (There was only one Buddhist in the sample, and any kind of religious activity counted, but the study is still suggestive.) That reduction of fifteen percent is about as much as the best current medication can do for Alzheimer’s.
In another example, Richard Davidson did a very interesting study with people in a high tech company. He had some of them do daily meditation. After just six weeks, the people who meditated had stronger immune systems. They fought off a flu virus more effectively than people who hadn’t meditated.
So, meditation benefits us through multiple pathways. Parasympathetic activation (“rest- and-digest”)—relaxation, in other words—is very supportive of immune system functioning, whereas sympathetic activation (“fight-or-flight”) suppresses immune function. Chronic stress exposes us to illness to a marked degree. Sleepy meditating is better than no meditation in terms of parasympathetic activation, or dampening sympathetic arousal (wakeful meditation is usually best of all). We can get attached to and even righteous about one specific method, but meditation has a lot of important general effects not specific to any particular method.
Equanimity can break the chain right between feeling tone and craving, like a jumbo scissors.
Another major Richard Davidson finding is that people become increasingly happy as they meditate—positive emotions become more prevalent, broadly defined. There’s a greater asymmetry of activation, left front to right frontal. To illustrate this with stroke patients, people with a stroke in the right frontal region tend to become more mellow. Maybe they can’t walk well, but they’re often relatively serene about it. If they have a stroke in the left frontal region, they’re more likely to be grouchy and grumpy.
Why is that? The left frontal region is involved in dampening, inhibiting negative emotional activity. The right frontal region tends to promote negative emotional activity. In the wild, there’s a lot of survival value to negative emotional activity; right hemisphere activation—which tracks the spatial environment from which most threats originate in the wild—primes you for dealing with threats. In other words, it primes you for aversion, or avoidance behaviors, namely fight, flight, freeze, appease. Maybe sometimes those behaviors are useful. In our evolutionary history, they certainly promoted survival and passing on genes. But today, in different settings and with different aims (like spiritual practice), it’s great to have relatively strong left frontal activation.
This is Part Two of a three-part series. Part One – Mind Changing Brain Changing Mind,
Part Three- Dependent Origination, Brain, & Equanimity
© Rick Hanson, PhD
