How Thinking and Meditating Can Change the Brain
Dalai Lama Helps Scientists Show the Power of the Mind To Sculpt Our
Gray Matter
The Wallstreet Journal Online (wsj.com)
January 19, 2007; Page B1
Although science and religion are often in conflict, the Dalai Lama
takes a different approach. Every year or so the head of Tibetan
Buddhism invites a group of scientists to his home in Dharamsala, in
Northern India, to discuss their work and how Buddhism might
contribute to it.
In 2004 the subject was neuroplasticity, the ability of the brain to
change its structure and function in response to experience. The
following are vignettes adapted from "Train Your Mind, Change Your
Brain," which describes this emerging area of science:
The Dalai Lama, who had watched a brain operation during a visit to
an American medical school over a decade earlier, asked the surgeons
a startling question: Can the mind shape brain matter?
Over the years, he said, neuroscientists had explained to him that
mental experiences reflect chemical and electrical changes in the
brain. When electrical impulses zip through our visual cortex, for
instance, we see; when neurochemicals course through the limbic
system we feel.
But something had always bothered him about this explanation, the
Dalai Lama said. Could it work the other way around? That is, in
addition to the brain giving rise to thoughts and hopes and beliefs
and emotions that add up to this thing we call the mind, maybe the
mind also acts back on the brain to cause physical changes in the
very matter that created it. If so, then pure thought would change
the brain's activity, its circuits or even its structure.
One brain surgeon hardly paused. Physical states give rise to mental
states, he asserted; "downward" causation from the mental to the
physical is not possible. The Dalai Lama let the matter drop. This
wasn't the first time a man of science had dismissed the possibility
that the mind can change the brain. But "I thought then and still
think that there is yet no scientific basis for such a categorical
claim," he later explained. "I am interested in the extent to which
the mind itself, and specific subtle thoughts, may have an influence
upon the brain."
The Dalai Lama had put his finger on an emerging revolution in brain
research. In the last decade of the 20th century, neuroscientists
overthrew the dogma that the adult brain can't change. To the
contrary, its structure and activity can morph in response to
experience, an ability called neuroplasticity. The discovery has led
to promising new treatments for children with dyslexia and for stroke
patients, among others.
But the brain changes that were discovered in the first rounds of the
neuroplasticity revolution reflected input from the outside world.
For instance, certain synthesized speech can alter the auditory
cortex of dyslexic kids in a way that lets their brains hear
previously garbled syllables; intensely practiced movements can alter
the motor cortex of stroke patients and allow them to move once
paralyzed arms or legs.
The kind of change the Dalai Lama asked about was different. It would
come from inside. Something as intangible and insubstantial as a
thought would rewire the brain. To the mandarins of neuroscience, the
very idea seemed as likely as the wings of a butterfly leaving a dent
on an armored tank.
* * *
Neuroscientist Helen Mayberg had not endeared herself to the
pharmaceutical industry by discovering, in 2002, that inert pills --
placebos -- work the same way on the brains of depressed people as
antidepressants do. Activity in the frontal cortex, the seat of
higher thought, increased; activity in limbic regions, which
specialize in emotions, fell. She figured that cognitive-behavioral
therapy, in which patients learn to think about their thoughts
differently, would act by the same mechanism.
At the University of Toronto, Dr. Mayberg, Zindel Segal and their
colleagues first used brain imaging to measure activity in the brains
of depressed adults. Some of these volunteers then received
paroxetine (the generic name of the antidepressant Paxil), while
others underwent 15 to 20 sessions of cognitive-behavior therapy,
learning not to catastrophize. That is, they were taught to break
their habit of interpreting every little setback as a calamity, as
when they conclude from a lousy date that no one will ever love them.
All the patients' depression lifted, regardless of whether their
brains were infused with a powerful drug or with a different way of
thinking. Yet the only "drugs" that the cognitive-therapy group
received were their own thoughts.
The scientists scanned their patients' brains again, expecting that
the changes would be the same no matter which treatment they
received, as Dr. Mayberg had found in her placebo study. But no. "We
were totally dead wrong," she says. Cognitive-behavior therapy muted
overactivity in the frontal cortex, the seat of reasoning, logic,
analysis and higher thought. The antidepressant raised activity
there. Cognitive-behavior therapy raised activity in the limbic
system, the brain's emotion center. The drug lowered activity there.
With cognitive therapy, says Dr. Mayberg, the brain is rewired "to
adopt different thinking circuits."
* * *
Such discoveries of how the mind can change the brain have a spooky
quality that makes you want to cue the "Twilight Zone" theme, but
they rest on a solid foundation of animal studies. Attention, for
instance, seems like one of those ephemeral things that comes and
goes in the mind but has no real physical presence. Yet attention can
alter the layout of the brain as powerfully as a sculptor's knife can
alter a slab of stone.
That was shown dramatically in an experiment with monkeys in 1993.
Scientists at the University of California, San Francisco, rigged up
a device that tapped monkeys' fingers 100 minutes a day every day. As
this bizarre dance was playing on their fingers, the monkeys heard
sounds through headphones. Some of the monkeys were taught: Ignore
the sounds and pay attention to what you feel on your fingers,
because when you tell us it changes we'll reward you with a sip of
juice. Other monkeys were taught: Pay attention to the sound, and if
you indicate when it changes you'll get juice.
After six weeks, the scientists compared the monkeys' brains.
Usually, when a spot on the skin receives unusual amounts of
stimulation, the amount of cortex that processes touch expands. That
was what the scientists found in the monkeys that paid attention to
the taps: The somatosensory region that processes information from
the fingers doubled or tripled. But when the monkeys paid attention
to the sounds, there was no such expansion. Instead, the region of
their auditory cortex that processes the frequency they heard increased.
Through attention, UCSF's Michael Merzenich and a colleague wrote,
"We choose and sculpt how our ever-changing minds will work, we
choose who we will be the next moment in a very real sense, and these
choices are left embossed in physical form on our material selves."
The discovery that neuroplasticity cannot occur without attention has
important implications. If a skill becomes so routine you can do it
on autopilot, practicing it will no longer change the brain. And if
you take up mental exercises to keep your brain young, they will not
be as effective if you become able to do them without paying much
attention.
* * *
Since the 1990s, the Dalai Lama had been lending monks and lamas to
neuroscientists for studies of how meditation alters activity in the
brain. The idea was not to document brain changes during meditation
but to see whether such mental training produces enduring changes in
the brain.
All the Buddhist "adepts" -- experienced meditators -- who lent their
brains to science had practiced meditation for at least 10,000 hours.
One by one, they made their way to the basement lab of Richard
Davidson at the University of Wisconsin, Madison. He and his
colleagues wired them up like latter-day Medusas, a tangle of wires
snaking from their scalps to the electroencephalograph that would
record their brain waves.
Eight Buddhist adepts and 10 volunteers who had had a crash course in
meditation engaged in the form of meditation called nonreferential
compassion. In this state, the meditator focuses on unlimited
compassion and loving kindness toward all living beings.
As the volunteers began meditating, one kind of brain wave grew
exceptionally strong: gamma waves. These, scientists believe, are a
signature of neuronal activity that knits together far-flung circuits
-- consciousness, in a sense. Gamma waves appear when the brain
brings together different features of an object, such as look, feel,
sound and other attributes that lead the brain to its aha moment of,
yup, that's an armadillo.
Some of the novices "showed a slight but significant increase in the
gamma signal," Prof. Davidson explained to the Dalai Lama. But at the
moment the monks switched on compassion meditation, the gamma signal
began rising and kept rising. On its own, that is hardly astounding:
Everything the mind does has a physical correlate, so the gamma waves
(much more intense than in the novice meditators) might just have
been the mark of compassion meditation.
Except for one thing. In between meditations, the gamma signal in the
monks never died down. Even when they were not meditating, their
brains were different from the novices' brains, marked by waves
associated with perception, problem solving and consciousness.
Moreover, the more hours of meditation training a monk had had, the
stronger and more enduring the gamma signal.
It was something Prof. Davidson had been seeking since he trekked
into the hills above Dharamsala to study lamas and monks: evidence
that mental training can create an enduring brain trait.
Prof. Davidson then used fMRI imaging to detect which regions of the
monks' and novices' brains became active during compassion
meditation. The brains of all the subjects showed activity in regions
that monitor one's emotions, plan movements, and generate positive
feelings such as happiness. Regions that keep track of what is self
and what is other became quieter, as if during compassion meditation
the subjects opened their minds and hearts to others.
More interesting were the differences between the monks and the
novices. The monks had much greater activation in brain regions
called the right insula and caudate, a network that underlies empathy
and maternal love. They also had stronger connections from the
frontal regions to the emotion regions, which is the pathway by which
higher thought can control emotions.
In each case, monks with the most hours of meditation showed the most
dramatic brain changes. That was a strong hint that mental training
makes it easier for the brain to turn on circuits that underlie
compassion and empathy.
"This positive state is a skill that can be trained," Prof. Davidson
says. "Our findings clearly indicate that meditation can change the
function of the brain in an enduring way."
