The Science of Yoga

creativity.”
    The cottage industry employs similar methods. In his book on writing, Davis recommends postures and types of breathing and awareness meant to quiet the cerebral din and help writers come up with fresh ideas. Doing something as simple as inhaling as long as one exhales, he advises, can become “a quick way to calm the chatter.”
    Science, it turns out, has uncovered at least one biochemical factor that promotes the quieting. It is GABA, the neurotransmitter we visited in the chapter on moods. Remarkably, its calming action has much in common with a much more famous way that artists have slowed their minds in order to aid their explorations.
    Faulkner, Hemingway, Capote, and many other writers and artists in the twentieth century found not only comfort but inspiration in the bottle. The inebriation was so ubiquitous that a book, Hemingway & Bailey’s Bartending Guide to Great American Writers , details the favorite drinks that the literary set imbibed in pursuit of relaxation and compositional fire.
    Alcohol is a depressant that works beautifully to slow the brain. But its side effects are nasty. In the body, ethyl alcohol breaks down into toxins that can promote cancer as well as liver and brain damage, among other troubles.
    Yoga is kinder. Yet its ability to calm the mind—to produce “a retardation of mental functions,” as Behanan put it—shares a common biochemical basis with alcohol. Both do at least part of their mental rejiggering by means of GABA, or gamma-aminobutyric acid. The neurotransmitter slows the firing of neurons, making them less excitable and thus calming the mind. Ethyl alcohol does the trick indirectly. Its binding to neurons produces a chemical environment that increases the power of the inhibitory neurotransmitter.
    By contrast, yoga’s action is direct. The Boston team found that doing yoga caused levels of the potent neurotransmitter to rise, in one case nearly doubling. As many a yoga practitioner can attest, one result is a sense of physical and mental calming, of increased relaxation and reduced anxiety. Perhaps it is also the stuff of poetic inspiration.
    Another factor in thequieting of the mind centers on the differing nature of the brain’s hemispheres. In everyday life, the left side dominates. It excels at logic and language, as well as the din of cerebral chatter. But an emerging body of scientific evidence suggests that yoga can activate the brain’s right hemisphere—the one that tends to govern intuition, creativity, instincts, aesthetics, spatial reasoning, and the sensing and expressing of emotion. So the discipline may act as an inspirational force in part because it shifts the hemispheric balance toward a more artistic frame of mind.
    It has taken decades for scientists to tease the secrets of hemispheric character into the open and learn how the brain’s two halves deal with the world in remarkably different ways. When the Greens did their studies in the 1960s and 1970s, the details were sketchy. But soon thereafter, the field made rapid progress, thanks in no small part to the investigations of Roger Sperry, a neurobiologist at the University of Chicago and the California Institute of Technology. In 1981, he won a Nobel Prize for his trouble.
    Sperry focused on epileptics who had undergone an operation to ease their seizures. It severed the corpus callosum—the bundle of nerves that transmits signals between the brain’s right and left hemispheres. Sperry and colleagues gave these patients special tasks. The surprising results showed that the differing sides of their brains had distinctive forms of consciousness. In effect, Sperry showed that every individual on the planet is endowed with not one but two brains, each pursuing its own particular way of thinking, perceiving, remembering, reasoning, willing, and emoting. His discoveries threw a generation of neuroscientists into uncovering the details of hemispheric specialization.
    Today, the most basic difference between the two halves is considered to be how they process information. The right brain (which controls the body’s left side) does its handiwork in parallel fashion—taking in many streams of information simultaneously from the senses and creating an overall impression of smell and sound, appearance and texture, feeling and sensation. For instance, the right brain dominates an inconspicuous type of sensory activity that yoga seeks to develop—proprioception, or inner knowledge of