PureInsight | July 8, 2007
[PureInsight.org] As the
spiritual leader of Tibetan Buddhism, the Dalai Lama was intrigued that
scientists had found evidence that some parts of the brain might renew
themselves throughout life. The discovery seemed to fit well with the
Buddhist view that meditation can reshape and expand the mind to foster
happiness and cultivate compassion.
In a November speech, the Dalai Lama made the connection between
neuroscientists' research into brain mechanisms associated with
attention and emotion and Buddhist meditation that is performed to
heighten powers of attention and regulate emotion.
"I feel there might be great potential for collaborative research
between the Buddhist contemplative tradition and neuroscience," he said
at the Society for Neuroscience annual meeting.
Positive Emotion
People have studied the connections between meditation and brain physiology for years.
Can science identify a physical signature of that effort somewhere in the vast landscape of the brain?
Only recently has research been rigorously performed, fueled by two
developments. One is neuroscientist Fred Gage's 1998 discovery,
subsequently confirmed and extended, that new cells can, in fact, grow
in the adult hippocampus, an area of the brain associated with
learning, memory and emotion. It had long been thought that cell growth
stopped in the adult brain. The other is the continual refinement of
technology used to image and measure changes in the brain.
In the early 1990s, American scientist Richard Davidson traveled to
India at the request of the Dalai Lama to meet with Buddhist monks who
devote their lives to meditation. A Harvard-educated researcher at the
University of Wisconsin, Davidson has since brought Buddhist monks to
his lab. There he has hooked them up to an electroencephalograph, or
EEG, that measures changes in the electrical activity of the brain.
Brain cells communicate by producing tiny electrical impulses. During
EEG studies, researchers place several electrodes on a subject's scalp
to detect and record patterns of electrical activity in the brain.
In his studies on monks, Davidson found that electrical activity was
heightened during meditation in an area of the brain called the left
prefrontal cortex, just behind the forehead. Scientists have associated
activity in this region with positive emotions, as opposed to the right
prefrontal cortex, where increases are associated with negative
feelings.
More recently, Davidson has found that longtime Buddhist practitioners
of meditation can induce a heightened pattern of electrical signals
called gamma-band oscillations, associated with concentration and
emotional control, that are not seen in control groups. These changes
are sustained even after meditating.
Thickening the Brain
Sara W. Lazar is a neuroscientist and meditator. You don't often hear
those in the same sentence. But the life of this one-time Ph.D. student
in molecular biology changed course when she discovered yoga and
meditation while recovering from a running injury. That was 12 years
ago and now she is a cutting edge researcher in the field of
neuroscience. She's focusing on the effects of meditation on the brain.
"While in grad school I started practicing yoga and meditation, and
found it to be incredibly helpful. I was less stressed, more focused
and it really changed my perspective on a lot of things. I decided I
would rather do research on meditation than on bacteria so, after I got
my Ph.D., I found a lab that was willing to train me in neuroscience
and let me do a small meditation study."
That lab happened to be in the Psychiatry Department at Massachusetts
General Hospital. The focus of her research is the neurobiology of
meditation. She uses functional magnetic resonance imaging (fMRI) to
investigate the neural correlates of changes in autonomic function
during the practice of meditation. Dr. Lazar goes on to explain, "fMRI
is a special way of using a MRI scanner to look at how the brain works.
Normal MRI takes one really nice picture of your brain, with lots of
details that are easy to see. fMRI is sort of like a movie - it takes
special pictures of blood flow in the brain. The parts of the brain
that are most active at any point will have the most blood flow, so we
take pictures of the person meditating and resting, and then use a
computer to determine where in the brain there is the most blood flow
during meditation compared to rest." Dr. Lazar explains that an MRI
scanner is sort of like an X-ray, but it allows us to take pictures of
the brain.
Unlike Tibetan Buddhist monks, who have devoted their lives to the
practice of meditation and their religion, meditation practitioners in
the U.S. usually meditate just 20 to 60 minutes per day and incorporate
their practice into a daily routine involving career, family, friends,
and other outside interests, according to Lazar. Additionally, many
American meditation students view meditation as a source of
stress-reduction, mental exercise or personal growth, and do not
necessarily incorporate traditional eastern religious elements into
their practice.
Lazar and her colleagues compared the brains of 20 western-style
meditators with 15 people who had no meditation or yoga experience. The
meditators were students of Buddhist "Insight" meditation, which
focuses on the cultivation of a trait called mindfulness, a specific,
non-judgmental awareness of present-moment sensory stimuli. All study
participants laid quietly in the MRI scanner while detailed images were
taken of the structure of their brains.
"We found that brain regions associated with attention and sensory
processing were thicker in meditators than in the non-meditators," says
Lazar. "Also, in one of the regions, the differences in thickness were
most pronounced in older subjects, suggesting that regular practice of
meditation might reduce normal age-related thinning of the brain." This
region is an area of the brain's outer layer or cortex, which is
thought to be involved in integrating emotional and cognitive processes.
"Although numerous studies examining cortical thickness have pointed to
aging and pathology as sources of cortical thinning, there has been
limited work indicating mechanisms promoting cortical thickening," says
Lazar. "Our findings suggest that meditation practice can promote
cortical changes in adults in areas important for cognitive and
emotional processing and well-being."
It is possible that people who naturally have a thicker cortex in areas
associated with awareness and sensory processing are more likely to
practice meditation. However, the pattern of cortical thickening
corresponds well to the specific activities that practitioners of
Insight meditation repeatedly engage in over time: paying attention to
breathing sensation and sensory stimuli, according to Lazar.
Additionally, the observed increases in cortical thickness were
proportional to the amount of time the participant had spent meditating
over their lifetime.
"While additional research needs to be done, our results do suggest
that the observed differences are acquired through extensive practice
of meditation and are not simply due to incidental between-group
differences," says Lazar. "We also believe that other forms of yoga and
meditation would have a similar impact on brain structure."
It shouldn't be surprising that meditation alters part of the brain
physiologically, scientists say. Musicians, linguists and athletes have
thicker brain tissue in areas associated with their strengths and
talents. "It makes sense that if you're using part of your brain a lot,
it's going to get worked out and there's going to be more stuff in that
area to support increased usage," Lazar said. "In a sense, that's all
we're seeing."
In follow-up studies, she plans to study whether the increased thickness is correlated with increased attention and memory.
For the Sleepy
Other researchers from the University of Kentucky examined whether
meditation might involve brain functions similar to sleep. Although
meditation is a form of wakefulness, meditation, like sleep, is also
reported to be relaxing and restorative.
Bruce O'Hara, from the University of Kentucky, has been interested in
whether meditation can reduce the need for sleep. Might meditation be
of value to people with sleep disorders or those whose jobs leave them
sleep-deprived? O'Hara first put subjects to a psychomotor vigilance
test (PVT), which is a simple measure of reaction time. During the
test, subjects press a button as soon as they see an LED clock display
begin to tick. Most alert people push the button after about 200
milliseconds. The test randomly repeats over 10 minutes, and a
subject's results are closely correlated with how sleepy they are,
going into the test.
Each subject, none of whom was an experienced meditator, took the test
after spending 40 minutes in casual conversation, reading, sleeping or
meditating. Only when the subjects meditated prior to the test did
their scores improve.
"It was amazing how consistent it was," O'Hara said. "Twelve out of 12
of our first subjects all improved (on the test) following meditation."
O'Hara also tested subjects who deprived themselves of sleep the night
before. Those who meditated right before the test performed better than
those who did not. O'Hara next examined sleep-deprived subjects who
took a nap right before the test. They actually did worse because it
takes time to fully recover alertness after a nap.
During sleep, neurons fire with more synchrony than during wakefulness.
In the deepest stage of non-REM sleep, the dominant brain wave is
called a delta wave. During meditation, brain cells fire with a
different synchrony that produces alpha waves. The question is: Can
alpha waves be as restorative and therapeutic as delta waves?
In future studies, O'Hara plans to use EEG tests to examine whether a
boost in alpha waves during meditation correlates with a commensurate
drop in delta waves during sleep after meditating. Such a measurement
might provide evidence that meditation does restore the brain in a way
that requires less sleep, he said.
References:
http://www.news.harvard.edu/gazette/daily/2006/01/23-meditation.html
http://www.buddhistchannel.tv/index.php?id=7,2517,0,0,1,0
http://www.sfn.org/index.cfm?pagename=news_111305d
http://www.epochtimes.com/b5/5/11/20/n1126534.htm
