Scanning the brains of trained meditators, like the Buddhist monk pictured here, could help scientists solve mysteries about a major network in our brains. [Credit: Tevaprapas Makklay, P. Read Montague; Wikimedia.org. Compiled by Carina Storrs.]
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 Zoran Josipovic and 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 access a subtle self-reflexive awareness that is free of dualities such as those of self vs. other and internal vs. external, 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.”
What they find could help illuminate poorly understood 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. Josipovic and Heeger 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. These areas are quiet when the external network is active, and active when the external network sits idle. While scientists first thought these areas might just be active when the brain had no task to focus on, a growing camp of brain researchers, including Josipovic and Heeger, believes that they are involved in self-referential processes.
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 while they remain fully aware of their surroundings. In nondual meditation, practitioners are cognizant of awareness which is both the nature of mind and the context of internal and external experiences. “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
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 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 “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.”