The Brain-Body Connection in Yoga
Communication between the body and the brain occurs every millisecond of our lives, controlling and directing the coordination of each of the 37.2 trillion cells in our body (37,200,000,000 if you like zeroes). Information flows from the internal organs and structures of our torso (primarily the heart, lungs, diaphragm, stomach, pancreas, liver, spleen, kidneys, intestines, adrenals, gonads, and microbiome) up to the brain, giving the brain necessary information about what’s happening in the body. The brain responds to this information and sends information of its own down to the body, largely in the form of electrical messages through the nervous system, hormones, and other substances. The messages often are initiated through thoughts or emotions. For example, emotions such as fear or love will release certain chemicals that correspond with a physical response (sweating, shaking, quickened heartbeat). Thoughts that carry particular qualities, such as kindness, compassion, or forgiveness, also release a chain reaction of electrical messaging, blood flow, and chemical response to the body.
We can think of these communication pathways flowing up and down as top-down and bottom-up information processing. If a message starts in the brain and travels down, then it’s top-down information processing; if it starts in the trunk of the body or even a lower part of the brain that travels to the brain's cortical regions, then it’s called bottom-up processing. Yoga seems effective because it includes strengthening both top-down and bottom-up information flows, perhaps one of the reasons yoga helps create balance, stability, and systemic health. Some examples of bottom-up practices that send messages from the body to the brain stem and then to the pre-frontal cortex are:
Some practices that send messages from the prefrontal cortex to the brain stem and then to the body are:
Conscious behavior shifts
Bottom-up practices have a direct stimulus on blood pressure, respiratory and heart rates, the microbiome, cellular and tissue repair, and immunity, along with the benefits of maintaining a certain amount of flexibility and strength in the body. The influence of postures and breathing, according to both Taylor et al. (2010) and Meuhsam et al. (2017), “exert an influence on the musculoskeletal, cardiovascular and nervous system functions as well as affect the down-regulation of the HPA axis and sympathetic nervous system which then support immune system function and emotional well-being.” The simple act of doing a yoga asana, a physical posture, sends messages through the nervous system to regulate immune function and emotional well-being—a higher-order characteristic of the mind. Taylor further adds that top-down practices “Support regulation of autonomic, neuroendocrine, emotional and behavioral responses to challenge, or, stress perception.” As such, the simple act of meditating on loving-kindness, for example, has a downstream nervous system and endocrine responses, and through the vagus nerve helps to mediate inflammation.
These practices are contained in the term Kriya Yoga, an umbrella for practices that fall under three practices: tapas, svadhyaya, and ishvarapranidhana. Tapas, which means to cook, heat, or ripen, includes asanas, pranayama, diet, sleep, and sexual responsibility and restraint. These practices ripen one’s consciousness and internal states of awareness, preparing the nervous system for more subtle practices. Svadhyaya is the verbal and cognitive practice that includes the repetition of mantras, the study of texts, and self-examination. Svadhyaya helps us understand our current narrative that defines our sense of self and expands, shapes, and transcends those limiting ideas by shifting our perception and refining our intellect. Ishvarapranidhana is the practice of devotion, awe, gratitude, offering, and maintaining a sense of not-knowing. The sense of not-knowing is one of the most liberating attitudes one can adopt, for the need to know everything all the time is limiting. It is an attitude that resists growth and change. We can know some things with certainty, but we cannot know reality with any certainty because reality is beyond the limited comprehensive capacity of the mind, where things like certainty exist.
When we practice any of the branches of yoga, there are wide-ranging effects. Sometimes when we do yoga, we are simply “doing” yoga—but not thinking or sensing what yoga is doing to us. Hopefully, by examining, even in a cursory fashion, some of the ideas about the brain-body connection within the various yoga practices, it can enhance our experience during and after practice. Perhaps it might even give us the tools to use the different yoga techniques in deliberate, purposeful, and careful ways to direct the outcomes in our lives—or those of our students—that we seek.