Scienceline: Neuroscientists at New York University study longtime meditators to glean insight into how our brains work.
Far from the proverbial mountain top or a quiet shrine, one group of meditators is attempting the ancient practice inside a brain-scanning machine. It is as narrow as a coffin, and they lie inside with foam cubes packed around their heads so that they don’t shift. And even though they wear ear buds to block out noise from the machine, the steady thumping seems to set the mood more for disco dancing than meditating.
This is the unnatural setting in which [1] Zoran Josipovic and [2] David Heeger at New York University have been scanning monks and secular meditators with functional magnetic resonance imaging — or fMRI. The fMRI machine allows the scientists to track the monks’ brain activity based on blood flow as they try to enter a meditative state. The researchers are interested in a special type of meditation in which the practitioners try to merge the external world with their own internal, personal thoughts, explains Josipovic, who is a Tibetan Buddhist as well as research associate in Heeger’s neuroscience lab. Since 2008, the pair has been working to identify if there is a pattern of brain activity that accompanies the experience of “oneness.”
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What they find could help illuminate poorly understood [3] brain disorders such as stress, depression and even Alzheimer’s and autism. These diseases are very different from each other, but they share a common feature: In those afflicted, brain scans reveal strange behavior in the same region of the brain. Zoran and Josipovic believe this part of the brain is associated with internal thoughts, a poorly understood area referred to as the “default network.” It is called default because it seems to activate when people are not doing any particular task.
Average people are conscious of either the external world or their personal world, and they alternate their attention between the two. These worlds push us into and pull us out of our awareness. Imagine how concentrating on a situation in the present, like listening to a friend’s story or solving a math problem, can make you less self-aware — that is the pull of the external world. But then a lapse of focus creeps in, and you begin to wonder if you missed your doctor’s appointment this morning, or what you want to do on vacation next week — and you have felt the push into your inner world.
While neuroscientists have made strides toward understanding the brain activity associated with external tasks, the areas that control self-related thoughts remain shrouded in mystery. Roughly speaking, external or goal-oriented tasks activate regions around the outer part of the brain known as the external network. The default network, on the other hand, is about one-third of the brain nestled inside the external network’s crown. It is an area that is quiet when the external network is active, and active when the external network sits idle. While scientists first thought this area might just be active when the brain had no task to focus on, a growing camp of brain researchers, including Josipovic and Heeger, believe that it is the seat of self-related thinking.
To learn about this mysterious network, they are probing the brains of people who practice a type of meditation called nondualism. Unlike common meditation approaches, such as focusing on an external or imaginary object for a prolonged stretch of time, nondualism trains meditators to watch their own minds. All the while they remain fully aware of their surroundings. “What I think is important here is the use of trained meditators to get at a subjective mental state,” Heeger explains. Because these meditators can control whether they are reflecting on themselves or on external issues, or on both, they can describe their experiences to the researchers after their fMRI. If they achieved a sense of “oneness,” the researchers can look to see if the machine recorded any unique brain activity that could be associated with this mental state.
Stumbling upon the brain’s “resting” network
[4] Dr. Marcus Raichle, a neurologist at the Washington University School of Medicine in St. Louis, Mo, served up the game-changing idea of the default network in 2001 in a study he published in Proceedings of the National Academy of Sciences. By scanning the brains of control subjects who were awake but had no task to do, he noticed areas of the brain that crackled with activity, which he dubbed the default network. His critics rushed to point out that his taskless subjects could be thinking about anything during the scan but, to Raichle, it was exciting just to discover that there was an area of the brain that waxed as the external network’s waned.Experiments in the laboratory of [5] Rafael Malach, a neurobiologist at the Weizmann Institute of Science in Israel, first raised the suspicion that the default network did more than oppose the external network, that it might control self-related thoughts. Malach’s team made the surprising discovery that people’s brains responded in identical ways to certain dramatic scenes in films such as “The Good, the Bad, and the Ugly” and movies by Alfred Hitchcock. But, during other parts of the movies, each viewer had his or her own pattern of brain activity. Malach believes that, during less intense scenes, with less gunshots and bloodshed, people began comparing the action to their own personal experiences, letting their thoughts turn inward. Their brain activity spiked upward in the areas known then as the default network. Now, five years after this “[6] neurocinematics” study, which was published in Science in 2004, Malach says that, “We are [still] very much in the dark about this system.”
FMRI-based experiments usually monitor the brain activity of subjects as they respond to stimuli, whereas the default network tends to activate in the absence of external stimuli. This means that fMRI is an unlikely tool for studying the default network. There are no tests to study the wide range of internal thoughts that could come from this network, such as reflections on the past (do I like the shirt I just bought?), or the future (where will I wear that shirt?) or anticipating other people’s opinions (will my friend think that shirt looks good?). These thoughts often pop into our heads seemingly out of nowhere.
Good luck studying spontaneous thought, says Malach. Still, he commends this approach for illuminating the network, saying that the Western-style studies using fMRI scanning “fit like a glove on Eastern meditation.”
Eastern practices meet Western studies
To learn about the default network and its interplay with the external, Josipovic and Heeger are beginning to piece together a slew of images collected from scanning the brains of Buddhist monks as well as secular meditators from around the Tri-State area. The pair is planning to extend their study to Christian monks, nuns and Jewish contemplatives.
One of the practitioners of nondualism, or “oneness” meditation, in the study is 31-year-old Karma Drodhul. He became a Lama, or leader of Tibetan Buddhist, through spending about seven years in meditation retreats. The brain scans do not prevent Lama Drodhul from entering a state of oneness. “In Buddhism, we are used to meditating through distractions,” he says after a recent fMRI session. “It was fun.”
For each scan session, participants lie with their heads in the [7] fMRI machine, which emits a magnetic field about twice as strong as a hospital MRI. As blood flows to active areas of the brain, it carries oxygen that changes the magnetism of that area. A computer attached to the machine captures a picture of the brain, based on differences in magnetism, about every two seconds. After scanning a participant’s brain, Josipovic typically ends up with hundreds of images. Some of the images reflect the brain activity as subjects see flashing photos of a face or houses or a landscape on a projector screen viewed on a mirror in front of their faces. Each of these types of objects is associated with activation of a different, precise area of the brain, so the resulting images serve as a point of reference for the rest of the images.
Josipovic already has some early revelations about the networks. For normal nonmeditators, Josipovic’s saw the same interplay as other scientists: When the activity of the external network is up, the default is down and vice versa. But the story is different when it comes to experienced meditators. The activity of the two networks for them is not as sharply opposed, perhaps indicating that there is brain activity accompanying the experience of harmony between internal and external perspectives in nondualism meditation.
The default network’s broader implications
Understanding the default network may eventually elucidate information about the mental diseases that seem to target it, including Alzheimer’s, autism and depression. While the activity of the external network is sometimes also affected in these diseases, it is “not nearly as broken,” says [8] Jessica Andrews-Hanna, who recently completed her graduate studies in the laboratory of Randy Buckner at Harvard University on the default networks of aging people.
The diseases that involve the default network are varied but, for all of them, the network does not seem to turn off when it should. Perhaps because it loses that “push-pull” relationship with the external network in patients with severe Alzheimer’s and other cognitive problems, it remains perpetually “on.” Within the default network, activity is disorganized and connections are deteriorated. Its activity also does not seem to wane in studies of autistic people when they perform goal-related tasks, or of depressed people during rest.
All these studies suggest that there could be a striking similarity between the brains of meditators and those of people with dementia or depression. According to Andrews-Hanna, if it’s true that meditators maintain their two networks operating at the same time, their brain scans would be reminiscent of those of the mentally ill. “Presumably, in the meditators’ case, maybe it’s all cognitive; maybe they have the ability to say, ‘Now I want to control these two [networks] together,’” says Andrews-Hanna. “If you can turn the brain regions on and off when you want, that’s great.”
For now, neuroscientists are waiting to learn what Josipovic and Heeger find from their studies of meditators, which they hope will offer unique insight about the default network. The first step is to see if nondual contemplation — combining the external and subjective experiences — does correspond to differences in the default network. If it does, these studies will open up a new way to explore what was before a completely elusive network.
URLs in this post:
[1] Zoran Josipovic: https://psych.nyu.edu/josipovic/
[2] David Heeger: https://www.cns.nyu.edu/~david/
[3] brain disorders: https://www3.interscience.wiley.com/cgi-bin/fulltext/119397609/HTMLSTART
[4] Dr. Marcus Raichle: https://www.nil.wustl.edu/labs/raichle/
[5] Rafael Malach: https://www.weizmann.ac.il/neurobiology/labs/malach/
[6] neurocinematics: https://scienceblogs.com/cortex/2009/05/watching_movies.php
[7] fMRI: https://www.fmri.org/fmri.htm
[8] Jessica Andrews-Hanna: https://www.nmr.mgh.harvard.edu/nexus/members/page52/andrews/andrews.html
[9] tool: https://scienceline.org/2009/05/20/goodier-neuro-brain-waves-currents-flourescence/
[10] lie detection: https://scienceline.org/2008/11/03/ask-intagliata-lie-detection-fmri-brain-scan/
[11] extreme athletes : https://scienceline.org/2009/07/13/health-konkel-extreme-sports-risk-psychology/
