In 2004 psychologist
Richard Davidson used
Buddhist monks to explore the effects of meditation on the
brain. Using electroencephalographic (EEG) recordings, Davidson and
his colleagues compared long-term Buddhist practitioners with students
who had been introduced to the principles of meditation just a week
before the study. The findings were unexpected: the long-term
meditators' brain waves (the electrical oscillations indicative of
neural activity) were in sync at unusually high speed.
Brain
waves, which signify groups of neurons firing in relative harmony,
occur at different speeds. Slow delta waves happen only in dreamless
sleep, and rapid beta waves occur during concentration and mental
effort Gamma waves are the fastest sort, and in normal people they
happen only in very short bursts during REM sleep and, rarely, waking
cognition. The Davidson study was remarkable in that it showed that
long-term meditators are able to produce sustained gamma activity in a
manner that had never been previously observed in a human being. As
such, sustained gamma activity emerged as a sign for at least some
aspects of the meditative state.
If this sustained
gamma rhythm is a trademark of meditation, would it be possible to
induce those gamma waves on demand?
However, before this
can be done, researchers must first find out how exactly gamma
rhythm is produced in the brain. This mechanism is precisely what two
new studies have successfully done: Researchers
at M.I.T and Stanford Universities have managed to induce in mice the
gamma brainwave pattern associated with meditation.
How Science
Defines Meditation
From the perspective of
neuroscience, meditation can be characterised as a series of mental
exercises by which a person strengthens control over the workings of
his or her own brain. The simplest of these practices is focused
attention. During this, the person concentrates on a single object or
experience - for example, their own breathing.
But focused-attention
meditation is fairly
basic compared with the kind of contemplation experienced Buddhists.
Scientists call this form 'open-monitoring meditation'. In this
advanced method the objective is not to focus attention but rather to
use one's brain to monitor the universe of mental experience without
directing attention to any one task. It was this open-monitoring that
Richard Davidson investigated.
Two New Exciting
Studies
The two new studies
rcecently published tested and confirmed the hypothesis that gamma
rhythm results from the activation of fast-spiking
interneurons.
These fast-spiking interneurons get their name because they fire
at a
higher than normal rate and have short, local connections within the
cerebral cortex (the outer layer of gray matter responsible for higher
thoughts). The experimenters utilised a very avant garde technique
called optogenetics. This combinies optical (light-based) and genetic
techniques to investigate the brains of living animals. They developed
viruses that infected only
the fast-spiking interneurons of either the prefrontal cortex or the
barrel cortex (the area that processes sensory input from whiskers) in
mice.
In experiments that
sound like they come from a science fiction book, the virus delivered
an engineered gene that made the target cells sensitive to light. Then
the researchers inserted fine optical fibers into the relevant region
of the mouse cortex, allowing light to be delivered to the infected
neurons and thereby activating only the fast-spiking interneurons. In
essence, this procedure allowed them to switch particular brain cells
on and off with extremely elegant control in both space and time. In
both experiments, selectively stimulating the fast-spiking interneurons
produced gamma oscillations. This confirmed the hypothesis that these
neurons drive the gamma rhythm.
Gamma Technology
Available
This first step in
defining how meditative
states arise in the brain is very exciting. But before you start
searching on-line for shopping sites to buy viruses and genetically
engineerd probes, remember that the sustained gamma activity is a sign
of meditation and not meditation in itself. Before you dismay at not
being able to purchase this on-line, don't put away your credit card
immediately. Gamma-wave-inducing technology IS available. Bill Harris
of Holosynch (website is www.centerpointe.com)
has
spent many years developing audio technologies to get people into
deep states of meditation, including the gamma state. I have used these
CDs myself for several years and can thoroughly recommend them.
Looking to the
Future
Given the
growing body of evidence that suggests that even short-term meditation
improves measures of attention, however, these new experiments provide
an interesting twist to the growing field of cognitive enhancement. If
gamma-wave synchrony is indeed responsible for some of meditation's
beneficial effects on the brain, inducing such rhythms artificially
might result in similarly desirable outcomes. In addition, abnormal
gamma synchronisation is a hallmark of disorders such as autism and
schizophrenia, and it may contribute to altered cognition in these and
other mental illnesses. Thus, developing a technology that could
correct the gamma rhythm could be invaluable for clinical treatment.
