The Science of Yoga

while The Relaxation Response was still popular and well on its way to selling millions of copies. For many years, the relaxation paradigm continued to dominate the scientific concept of how yoga worked. The alternative perspective that stressed rare states of continuous arousal—for a variety of reasons—stayed in the shadows.
    As Udupa looked intohormones, Dostálek into brain waves, and Corby into skin conductivity, other scientists were examining a rather curious but poorly understood parallel between yoga and sex—heavy breathing. Dostálek got a glimpse of the similarity when his Bhastrika subjects felt “elation and even exhilaration.” So did Corby when his Tantric meditator soared toward samadhi. But brain waves and skin conductivity were just two of many ways to explore the repercussions of rapid breathing. Indeed, its basic study required no specialized equipment at all. The most fundamental method was just to sit quietly and watch.
    In Human Sexual Response , Masters and Johnson describe fast breathing as an integral part of male and female behavior leading up to sexual climax. The scientists reported rates of more than forty breaths per minute at the height of strong orgasms. Compared to normal rates of relaxed breathing, that is roughly three times as fast.
    The pace of heavy breathing during sex may seem rapid but it is nothing compared to aggressive Bhastrika. Yoga teachers tell beginners to start at one breath per second and work their way up to two breaths per second—or one hundred and twenty breaths per minute. Advanced students are encouraged to take up to four breaths per second. If done without pause, that equals two hundred and forty breaths per minute—a rate five or six times faster than lovers.
    As we saw in chapters 3 and 4, heavy breathing can pose significant risks of injury and even death. But if done in moderation, it can be quite benign. Mild hyperventilation does no permanent damage to the brain or the nervous system but simply contributes to the sense of euphoria that makes both sex and yoga so enjoyable.
    Over the decades, scientists worked hard to explore sexual hyperventilation, usually in the interest of understanding Western sex rather than Eastern asceticism. Still, the overlap was great enough so that some investigators argued that the insights applied to both.
    More recently, a body of emerging research has revealed that fast breathing can not only lower the flow of oxygen to the brain, as we saw in chapter 3, but sharply reduce activity specifically in its outer layers. The findings grow mainly out of the technology of brain scanning. It lets scientists peer deep—going far below the superficial regions that researchers had explored withthe electroencephalograph—to compare the levels of inner and outer activity.
    The scanning unveiled a primal experience that amplified the body’s surges of pleasurable hormones and brain waves.
    In biology, the outer brain is known as the cortex. The term confuses many nonspecialists because it has nothing to do with a core. It’s about edges and coverings. The term derives from the Latin word for “bark,” as in the bark of a tree. The cortex plays important roles in memory, attention, calculation, awareness, thought, empathy, abstract reasoning, language, and sensations, as we saw with the parietal lobe. Right now it is interpreting these words. It also appears to be the seat of consciousness. The area known as the prefrontal cortex (“pre” because it is the most forward part of the brain, way out front, right behind the forehead) is well developed only in primates, especially humans. It controls such higher functions as planning, decision making, and setting priorities.
    Deeper down is the older, more primitive brain. Here lie raw appetite and unfettered passion. The deep structures of the primal brain include the neuroendocrine system, made up of the pineal body, the pituitary gland, and the hypothalamus, with its vigilance area and its control of the autonomic nervous system. Another cluster makes up the limbic system. It wraps around the brain stem and supports such functions as emotion, motivation, homeostasis, and short-term memory.
    The limbic system also controls sex. The amygdala, a limbic body made of two lobes about the size of almonds (its name comes from the Greek word for “almond”), plays major roles in emotion, including aggression and pleasure. As for sexuality, it has the brain’s highest density of