How zapping the brain can supercharge meditation

Life is not just a deluge of bad news. Every day, all sorts of wonderful things are happening. People fall in love. New vaccines are getting closer to saving the roughly 500,000 children who die from malaria each year. And for those of us interested in the science of meditation, which promises a deeper understanding of human psychology and the upper bounds of subjective well-being, the field is entering an incredibly exciting new era.

Research from the early 1990s helped establish the therapeutic potential of mindfulness, while more recent years have seen the investigation of the actual mechanisms that connect meditation to various health benefits. Now, as I’ve previously written, meditation science is going even further, exploring much larger questions that can go well beyond the simple promises of mindfulness-based stress relief.

According to neuroscientist Matthew Sacchet — who runs a bridge project between Harvard Medical School and Massachusetts General Hospital called the Meditation Research Program — today’s new wave of research is characterized by probing the mechanisms that underlie advanced meditation.

This includes a variety of techniques that don’t so much relax the mind as transform it. Advanced practices lead to “states and stages of meditation that unfold with time and mastery,” but can uncover insights that are relevant for consciousness in general, Sacchet told me.

And this isn’t just for Buddhist monks. In addition to shedding light on one of humanity’s most stubbornly puzzling mysteries, deeper insights into the workings of consciousness could help us think more expansively about mental health, and how to cultivate it.

The expanding field is leading cognitive scientists to study a dizzying array of strangely powerful meditative states, from absorptions into rapturous beams of pleasure like the jhānas to temporarily switching consciousness off through a self-induced kind of drug-free general anesthesia known as “cessation.”

But the field still suffers from heavy reliance on data that shows a wealth of correlations, while falling short of demonstrating real causation. Neuroimaging studies that use tools like EEG and fMRI scan a meditator’s brain at a single point in time and give us associations between meditation and the brain’s structure or function.

So far, though, they can’t actually tell us what meditation really does to the brain, or the changes it causes. Maybe people who are drawn to meditation are predisposed to certain patterns of brain activity, and our heap of correlations tells us more about those willing to meditate than anything actually caused by meditation.

Sacchet explained that the neuroscience of meditation has been almost entirely informed by studies that are stuck on the correlation question. That’s why he’s so excited about a new strategy: the possibility of combining meditation research with non-invasive brain stimulation, or “neuromodulation” techniques, which use electrical currents and magnetic fields to fiddle with brain activity in ways that can help isolate the changes that meditation actually causes.

In late August, Sacchet co-authored a review that looked across all the recent research combining neuromodulation with meditation, trying to organize the field and get a sense of where things stand. It’s still early days, but initial signs are promising, and next steps are emerging.

In the land of non-invasive brain stimulation, there are two giants: transcranial magnetic stimulation (TMS), and transcranial electrical stimulation (tES).

During TMS, a power source pulses electrical currents through loops of copper wire, creating a magnetic field along the coil.

Hold the coil right above someone’s head, and the field passes through the scalp like a ghost phasing through a wall. The process either increases or decreases targeted brain activity depending on where you’re aiming the coil, how frequently electrical pulses are being delivered, and the field’s intensity. TMS has been in use for years in the treatment of psychiatric disorders like severe depression.

Meanwhile, tES is a family of techniques that alter brain activity by sending weak electrical currents through electrodes placed on the scalp.

There’s a lot of research on neuromodulation techniques in general, with TMS dating back to 1985, and tES before that. There’s less that looks directly at their combination with meditation. And there’s even fewer studies that focus only on healthy participants, which was an inclusion criteria for Sacchet’s review.

That’s worth dwelling on for a second. Much of the existing research on both meditation and neuromodulation positions them as potential treatments for recognized illnesses, like depression. But a deeper understanding of how advanced meditation and neuromodulation affect well-being could have implications for everyone, not just people currently categorized as mentally ill.

Overall, only six studies met all the criteria for inclusion in Sacchet’s review. Across them, neuromodulation was generally found to enhance outcomes when compared with control groups. Combining tES and mindfulness meditation, for example, improved working memory.

In another study, a single round of tES paired with mindfully walking on a treadmill temporarily reduced anxiety. Another TMS study of 32 participants found that engaging in “self-compassion” practices while receiving TMS pulses to the dorsolateral prefrontal cortex increased self-compassion compared to controls doing the practice without TMS.

Obviously, six studies don’t make a field. But the early experiments are proving a positive safety profile, and more general insights and hypotheses are beginning to emerge.

Why is it that pulsing magnetic fields or zapping particular brain networks seems to amplify meditation’s effects? One idea offered in the review is the neural efficiency hypothesis. If two brains both solve the same puzzle, but one shows less activity in the process, that brain could be considered more efficient, solving the same task with less energy expended. And more efficiency could support higher intelligence.

In the case of brain stimulation plus meditation, it’s like running a marathon while benefiting from a tailwind. Being pushed along in the direction you’re already heading can help you progress faster while expending less energy.

Both fields — neuromodulation and meditation science — are still growing rapidly. As each develops new insights, they can inform new ways of more effectively combining the fields.

For example, a growing heap of studies is establishing that a collection of brain regions known as the default-mode network (DMN) is critical to meditative experiences (psychedelic ones, too). The DMN is associated with self-referential thinking — autobiographical memories, mind wandering, or daydreaming about yourself. Given all the Buddhist talk of the self as some sort of illusion, you might not be surprised to learn that meditation is often linked to a reduction of activity in parts of the DMN. The mind becomes less self-centric.

But neuromodulation research has yet to really take up the study of what happens when you use external means to help along the quieting of the DMN during meditation, creating a very conspicuous next step for the field.

That research is already underway. Meditation teacher Shinzen Young and neuroscientist Jay Sanguinetti work together at the University of Arizona’s Sonication Enhanced Mindful Awareness (SEMA) lab. Not only are they cooking up studies there that target the DMN of meditators, they’re also working on a new generation of neuromodulation technology — transcranial focused ultrasound, or tFUS.

Instead of magnetic fields or electrical currents, tFUS uses very high-frequency sound waves, which offer a roughly tenfold increase over TMS and tES in their precision for targeting specific areas in the brain. In a pilot study published earlier this year, a group of researchers including Sanguinetti and Young showed they could successfully reduce activity in the DMN by shooting tFUS at one of its major hubs, the posterior cingulate cortex. Though participants weren’t meditating during the process, they did report increases in mindfulness and modest reductions in their sense of self.

Now, they’re crowdfunding for what would be the first experiment to combine tFUS with a meditation retreat.

If ultrasound continues on its present trajectory, it’s going to make a really exciting addition to the neuromodulation arsenal. In addition to using these techniques to amplify meditation’s effects, neuroscientists will benefit from a greater ability to carry out what are known as perturbational procedures. That means basically being able to safely, non-invasively turn activity in specific parts of the brain up and down, just to see what happens.

To date, neuroimaging studies have helped build correlations between meditation practices and changes to the brain’s structure and function. More targeted neuromodulation studies, however, will help to actually decipher causality.

“This field has a lot of promise,” said Sacchet, but there’s “a lot of work to be done to do it right.”