In the recent years there has been a growing interest within the medical community to study the physiological effects of meditation (Venkatesh et al., 1997; Peng et al., 1999; Lazar et al., 2000; Carlson et.al, 2001). Many concepts of meditation have been applied to clinical settings in order to measure its effect on somatic motor function as well as cardiovascular and respiratory function. Also the hermeneutic and phenomenological aspects of meditation are objects of growing interest. Meditation has entered the mainstream of health care as a method of stress and pain reduction. For example, in an early study in 1972, transcendental meditation was shown to affect the human metabolism by lowering the biochemical byproducts of stress, such as lactate (lactic acid), and by decreasing heart rate and blood pressure and inducing favorable brain waves. (Scientific American 226: 84-90 (1972)) The meditative aspects of T'ai Chi Ch'uan and some forms of yoga have also become increasingly popular as means of healthful stress management in recent years.
As a method of stress reduction, meditation is often used in hospitals in cases of chronic or terminal illness to reduce complications associated with increased stress including a depressed immune system. There is a growing consensus in the medical community that mental factors such as stress significantly contribute to a lack of physical health, and there is a growing movement in mainstream science to fund and do research in this area (e.g. the establishment by the NIH in the U.S. of 5 research centers to research the mind-body aspects of disease.) Dr. James Austin, a neurophysiologist at the University of Colorado, reported that Zen meditation rewires the circuitry of the brain in his landmark book Zen and the Brain (Austin, 1999). This has been confirmed using sophisticated imaging techniques which examine the electrical activity of the brain.
Dr. Herbert Benson of the Mind-Body Medical Institute, which is affiliated with Harvard and several Boston hospitals, reports that meditation induces a host of biochemical and physical changes in the body collectively referred to as the "relaxation response" (Lazar et.al, 2003). The relaxation response includes changes in metabolism, heart rate, respiration, blood pressure and brain chemistry. Benson and his team have also done clinical studies at Buddhist monasteries in the Himalayan Mountains. Among other well-known studies within this particular field of interest we find the research of Jon Kabat-Zinn and his colleagues at the University of Massachusetts who have done extensive research on the effects of mindfulness meditation on stress (Kabat-Zinn et.al, 1985; Davidson et.al,2003).
One of the most important invitations to study the clinical effects of meditation comes from The Dalai Lama, the spiritual leader of Tibet. The Dalai Lama has had many dialogues with Western scientists about this subject and it was at the top of the agenda when he visited Massachusetts Institute of Technology in September 2003 for the "Investigating the Mind conference".
Meditation and the Brain
Mindfulness meditation and related techniques are intended to train attention for the sake of provoking insight. Think of it as the opposite of attention deficit disorder. A wider, more flexible attention span makes it easier to be aware of a situation, easier to be objective in emotionally or morally difficult situations, and easier to achieve a state of responsive, creative awareness or "flow".
One theory, presented by Daniel Goleman & Tara Bennett-Goleman, suggests that meditation works because of the relationship between the amygdala, the part of the brain that handles emotions (sometimes referred to as the "emotional brain"), and the neocortex, particularly the prefrontal cortex, which handles reasoning and is also known as the inhibitory centre of the brain.
The neocortex processes information very deeply--so it's smart and flexible, but also very slow. Meanwhile, the amygdala, which is a simpler structure (and older in evolutionary terms), makes rapid guesses about our perceptions, and triggers an appropriate emotional response. These emotional responses are very powerful--often because they are related to our immediate survival needs. In other words, if you're an early human standing on the savannah and a lion jumps out at you, your amygdala will have you running and screaming long before your neocortex can figure out what's happening.
Of course, in making snap judgements, our amygdalas are prone to error, seeing danger where there is none. This is particularly true in contemporary society where social conflicts are far more common than encounters with predators. A basically harmless but emotionally charged situation can trigger our amygdala's fight or flight reflexes before we know what's happening, causing conflict, stress, anxiety, and frustration.
Certain kinds of meditation (also, martial arts, yoga, etc.) train attention to watch the entire experience, so it's possible to catch emotional reflexes before they take over--but at the same time without squashing or denying the emotion (which would only cause additional frustration). The trick is that there is very little time to do this (roughly a quarter of a second) before the amygdala takes over and the person is flooded with emotion. But the idea is that a skilled meditator can quickly reframe fear and anger, and mould them into constructive responses and perhaps even good cheer.
The different roles of the amygdala and prefrontal cortex can be easily observed under the influence of various drugs. Alcohol depresses the brain generally, but the complicated prefrontal cortex is more affected than the comparatively simple and robust amygdala, resulting in lowered inhibitions, decreased attention span, and increased influence of emotions over behaviour. Likewise, the controversial drug ritalin has the opposite effect, because it stimulates activity in the prefrontal cortex.
Some other studies of meditation have linked the practice to increased activity in the left prefrontal cortex, which is associated with concentration, planning, meta-cognition (thinking about thinking), and with positive affect (good feelings). There are similar studies linking depression and anxiety with decreased activity in the same region, and/or with dominant activity in the right prefrontal cortex. Meditation increases activity in the left prefrontal cortex, and the changes are stable over time--even if you stop meditating for a while, the effect lingers.
