In the 1990s, the Dalai Lama invited University of Wisconsin neuroscientist Richard Davidson to study the brains of meditating monks. “You’ve been using the tools of modern neuroscience to mostly study anxiety, depression, and fear, all these negative feelings,” he reportedly said to Davidson. “Why can’t you use these same tools to study qualities like kindness and compassion and equanimity?”
That conversation launched an entire field of study. Suddenly, monks in robes were traveling to spartan labs in the West to take part in neuroimaging tests, and neuroscientists, in turn, began traveling to monasteries. The scientists hoped that studying the ancient contemplative practice, now so popular in the West, might help us understand not just compassion, but the very nature of consciousness.
A few intriguing findings emerged from the work in the early 2000s: Experienced monks seemed to show differences in actual brain structure and neural activity compared with novice meditators. One landmark paper in PNAS, co-authored by Davidson, for example, found that when experienced monks meditated, their brains displayed much higher levels of gamma oscillations—waves of neuronal activity associated with concentration, memory formation, and high-level cognitive functioning—than those of novices. That 2004 study was later challenged on methodological grounds, including sample size, and the use of EEG, which can be a noisy measure of brain activity. But a 2017 study in PLOS ONE seemed to support the earlier finding of higher gamma activity in monks practicing three different meditation traditions. (Some researchers have proposed that gamma is one of the elusive neural coordinates of consciousness.)
Now a lab in Montreal run by psychologist Karim Jerbi has added a new wrinkle to this picture. Jerbi and his colleagues studied 10 monks living at the Santacittarama monastery on the outskirts of Rome and found that the level of gamma oscillations in a meditator’s brain may depend on the type of meditation the monk is practicing. Jerbi’s team also found that different types of meditation may influence a measure of brain activity known as criticality, a state poised between order and randomness. Some researchers argue that neural networks operate at this boundary to maximize information processing. But “brain criticality” is a controversial theory that faces its own methodological limitations and inconsistent experimental findings.
I recently caught up with study author Annalissa Pascarella, a mathematician in Jerbi’s lab, which combines neuroscience with artificial intelligence to study not just meditation but other altered states of consciousness, including psychedelic experiences. Pascarella and I spoke about different styles of meditation, the concept of criticality, and what we know about meditation today, after decades of study.
Tell me about the monks you studied. What are their lives like on a daily basis?
These monks are Buddhist monks from the Theravada Thai forest tradition, which gives priority to meditation, strict monastic discipline, and enlightenment through insight. In the Theravada tradition, monks take part in a three-month winter retreat where they mainly practice meditation. During the retreat, they do two types of meditation in a balanced way: Samatha and Vipassana. Samatha is focused attention meditation, and Vipassana is an open monitoring meditation. After the retreat, they practice meditation at least two hours every day, so these are monks with a lot of hours of practice. On average, they have 15,000 hours of meditation. Some have meditated more than 20,000 hours over the course of their lives.
Can you tell me anything more about how Samatha and Vipassana differ and why that’s important?
Samatha meditation starts with an object of focus, often the breath. Or it could be the flame of a candle. You can also focus attention on parts of your body through body scans. If some distraction arises, you return your focus to the object of attention. Vipassana meditation is more open monitoring, where the meditator engages in non-specific monitoring of experience. That means that you stay attentive to any experience that may arise, but without judging or selecting.
Meditation comes in a broad variety of styles, but over the years, many meditation studies have conflated these different styles. This is one reason why the results of these studies are quite heterogeneous. They’re looking at different forms of practice. Also, some experimental studies use expert meditators while others use novices.
You evaluated the brain activity of these meditating monks according to two measures: criticality and complexity. Why did you choose these dimensions, and what kinds of mental states are they associated with?
Criticality is a concept that derives from physics. It’s typical of a complex system that operates at the boundary of a transition between one phase and another, between order and disorder. Think, for example, about when water becomes ice. This is a phase transition that happens smoothly, and yet there’s a boundary where the state of the system changes from water to ice that’s known as the critical point. Another example is the iron that you put in a magnetic field. All the atoms are eventually magnetized, but there’s a phase of transition from order to disorder.
The “critical brain” hypothesis posits that a healthy brain operates at a critical point where neurodynamics are stable enough to process information in a reliable way but flexible enough to adapt quickly to new information. So a brain that operates at a critical point is highly efficient. A system that’s too orderly adapts poorly while a system that’s too chaotic is dysfunctional. If you think about people under anesthesia, their brains are in an especially orderly phase. On the other hand, the brain dynamics of someone having an epileptic seizure are way too chaotic.
Read more: “The Search for Where Consciousness Lives in the Brain”
What did your study of these monks find?
What we found is that there were some similar patterns between the two forms of meditation, and also some differences. Both types of meditation are characterized by a more complex brain signal, but when we study the distance to criticality, we found a different trend. Samatha seems to stabilize brain activity. This makes sense since during focused attention, you need more stable concentration. This may require a shift from the critical point where the brain is more flexible and responsive.
Vipassana, on the other hand, shifts brain dynamics closer to the critical point—this balance between stability and flexibility—since it requires high sensitivity to the present moment. The findings show that the brain adapts its dynamics to match the specific demands of the practice.
Do your findings challenge what we thought we knew about meditation and the brain?
The study of the relationship between criticality and meditation is quite new. In fact, this is the first study that focuses on how different forms of meditation affect criticality in brain dynamics.
But previous studies had suggested that meditation increases certain kinds of brain waves, such as gamma power, one of the fastest brain waves, which is associated with high level cognitive tasks, memory, and focused mental attention. You found the opposite. Is that correct?
Yes, when you study brain-wave oscillation, you study a spectrum of signals that’s composed of rhythmic, frequency-specific oscillations together with irregular scale-free background noise, or non-periodic waves. When we separated these components out, we found a decrease in gamma oscillation, whereas other studies have found an increase. They likely mistook changes in background noise for rhythmic gamma waves.
A decrease in gamma oscillations reflects reduced mental activity related to processing external stimuli and engaging multiple cognitive processes. This aligns well with the goal of many meditation practices, which aim to cultivate a state of mental calm and inward focus. These decreases were mainly observed in regions of the Default Mode Network, which is typically active during mind-wandering—suggesting that meditation may quiet internal chatter and shift the brain toward a more stable and integrated state of awareness.
You used magnetoencephalography instead of fMRI to study the brains of the monks. Why?
With fMRI you’re imaging how blood travels through the brain as a proxy for neuron activity, which means you can record the activity in a scale of seconds. But magnetoencephalography measures the direct activity of the brain, the electromagnetic field that’s produced by our neurons. This activity happens on the scale of milliseconds, which is important when we’re talking about the firings of neurons. For example, when we look at an image, the first activity in our brains occurs after just 90 milliseconds. That means there are some processes where fMRI can’t capture the signal.
Magnetoencephalography, on the other hand, can capture what happens in the brain in real time in a noninvasive way. It was very comfortable for the monks. They were placed in magnetically sealed rooms alone, one at a time, to diminish the magnetic interference. These rooms are very silent. We put them in these giant helmets that measure the magnetic field.
What are you hoping to learn about criticality and meditation?
Some people still believe that meditation flattens brain dynamics—that it’s similar to what happens when a person is asleep. But criticality tells us that this isn’t the case— that the meditating brain is one that’s very flexible and adaptive. The complexity and criticality frameworks are very helpful for studying brain dynamics through a different lens.
After decades of study, are we certain that meditation is good for the brain?
The evidence tells us that meditation is very good for our brain. I’m very interested in meditation as a practice to manage problems like anxiety and depression, because there’s strong evidence that meditation is good for the cultivation of well-being.
Do you meditate every day?
I try a few minutes of breath meditation every day. 
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