Those who believe in Yogaⁱ must first believe in Prana
-Gopi Krishna (Krishna, 1993, p. 197).

    To fully understand the mind and the nature of reality, Yogic philosophy carefully describes a system of metaphysical structures to explain both the physical and metaphysical effects of the practices. The basis of Yoga is the concept of prana, or vital energy. Prana is found in all living beings, it is found in all forms of matter, and yet, it is not matter. Prana performs all the functions of the body, manipulating everything from atoms to muscles to drive all bodily functions (Krishna, 1993, p. 20). Prana is in the air and in sunlight; prana is in water and in our food. Yet it is not oxygen, or vitamins; prana is not heat or any chemical or light-ray. Prana manifests as nerve currents but also as electricity, gravitation, breath and thoughts (Vishnu-devananda, 1988, pp. 222-226). The Yogis describe numerous types of prana, each specialized in performing particular functions. Through the practice of yoga, in particular through the practice of pranayama which includes breathing exercises, the Yogi learns to control all types of prana, thereby gaining access to control the body and the mind and most importantly, begin the process of enlightenment.

    There are metaphysical channels in the body whose function is to carry energy to all parts of the body. In Yogic philosophy, such channels are referred to as nadis, each with varied degrees of importance. Three of those channels are of particular interest. The first one, the Ida nadi, found in the left side of the body, dominates all the nadis found in this side of the body: when energy is flowing through Ida, it will also be flowing through smaller channels in the left side of the body (Frawley, 2002, p. 161). The energy that flows through the Ida nadi has cooling and calming properties and is often referred as the female energy. In direct contrast to the Ida, the Pingala nadi dominates the right side of the body. The energy that flows through this channel is heating and stimulating, and is referred to as male energy. Finally, the third and most important Nadiⁱ in the body is the Sushumma nadi, which is in the midline of the body. Unlike the regular flow of energy through the Ida and the Pingala, the energy does not usually flow through the Sushumma, but it requires years of Yoga practice to purify this channel for energy to flow through it and begin a transformative experience.
   
     However, the main goal of Yoga is not to purify the Sushumma nadi or to gain control over prana but to gain insight about reality or enlightenment by experiencing the interconnectedness of the universe. For this to occur, the Yogis believe that a different type of energy, Kundaliniⁱ, must be awakened and — through arduous practice— be moved gradually through energy plexuses found along the central energy channel. These plexuses are referred to as chakras, and they range from the base of the spine to the top of the head. When the Yogi raises the Kundalini energy, it is described as a serpent that rises through the spine, leaving the practitioner in a state of ultimate bliss completely detached from space and time. Thus, we can understand the intricate metaphysical anatomy described by the Yogis as the means to explain how one can achieve such experience through the practice of Yoga.
   
     In addition to the Yoga tradition, many other metaphysical traditions have developed from other cultures. There are many parallels and similarities among these. One example is Kabbalah, a type of Jewish mysticism. One of the most important symbols in Kabbalah is the Tree of Life. This symbol aids in understanding reality by representing humans in the heavens as well as humans in the material world. This tree is composed of ten spheres, which are interconnected by paths thought to be phases of consciousness. Furthermore, the spheres are categorized into three pillars. The left pillar is characterized for being feminine and passive, the right pillar has more male and active characteristics, while the middle pillar does not have a gender assigned to it and is thought to represent equilibrium (Gonzalez-Wippler, 1993, p. 74). It follows that the right pillar could correspond to the Pingala, the left pillar to the Ida, and the middle pillar to the Sushumma nadi. Similarly, Chinese philosophy also has a revealing parallel. The Ying-Yang, one of its most characteristic symbols shows the male and the female principles in perfect balance. Furthermore, the concept of Tao, or middle way or path in Chinese philosophy can be interpreted as the Kabbalah’s middle pillar (Gonzalez-Wippler, 1993, p. 76), or the path of purification of the Sushumma nadi. This recurring theme is also present in Indigenous civilization miles away from Eastern or scientific influences. For instance, in the Popul Vuh, the main Mayan Scripture, there are numerous descriptions of channels and energy as described by the Yogis, such as the air-tube which parallels the Sushumma and twofold air tubes to describe the Ida and Pingala (Avalon, 1974, p. 3). Finally, the Ancient Greek symbol of the Caduceus of  Mercury also has a revealing parallel.  The middle rod in this well known symbol represents the Sushumma nadi, while the two serpents correspond to the Ida and Pingala nadis (Avalon, 1974, p. 21) and the points where the snakes intersect represent the chakras (Burger, 1998, p. 220; Shannahoff-Khalsa D. S., 2007, p. 3).

    From a Western perspective, it is natural to ask if the above converging descriptions of metaphysical anatomy have any foundation in contemporary biology. Even though the “energies” described may have measurable physical counterparts, they are considered to be beyond matter and even beyond the understanding of the masses. Because of this claim, Western science has historically failed to review the empirical claims made by Eastern traditions. Only recently, mainly since the second half of the last century, have scientists began to discover strong parallels between Western science and Eastern metaphysical systems.

Science and Yogic Anatomy

With the spread of Yogic teachings and a variety of demonstrations of actions that seem to defy the laws of medicine and physics (see Rele, 1931), numerous scientists, mostly with Eastern backgrounds, attempted to provide viable explanations for such phenomena. In general, there have been two main approaches. Some scientists claim that all yogic metaphysical anatomy is nothing more than a different understanding of biological anatomy and that the practices of yoga are efficacious means of achieving control over the autonomic nervous system (ANS). Other scientists believe that there are in fact strong connections among body, mind, and metaphysical anatomy, but there is in fact a gap that cannot ever be filled by using the scientific method. Nevertheless they hold that it is worth exploring such connections scientifically. This essay does not take a position on this epistemological issue but explores the conclusions drawn by both groups, whether or not the gap between biological and metaphysical anatomy is ever to be fully comprehended.

Prana, the basis of the yogic metaphysical anatomy, has been interpreted as nerve impulses that flow through the body. This follows the yogic conception quite closely. As Bhole (1989) explains, without nerve impulses no glandular or muscle cells would work, and perception would be impossible since no impulses would reach the brain. The absence of nerve impulses would lead to death, just as the Yogis believed would happen in the absence of prana. In a more comprehensive interpretation, prana has been associated with ionic charges that are essential to the atmosphere and to life. This definition includes the view of prana as nerve impulses because the underlying base of nerve impulses is changes in ionic charges across membranes. Furthermore, it has been observed that the predominance of negative ions (prana) has a stimulating and vitalizing effect on the body, whereas positive ions depress the system (Mukti Bodhananda, 1999, p. 20). From this, pranayama, or the control of prana,
would be the control of nerve impulses of the autonomic nervous system, which in turn control all the main functions of the body (Krishna, 1993). Even though Western Science is not familiar with methods of gaining control of the ANS, this interpretation of prana seems to be acceptable to the Western mind. Given the correlation between the nervous system and the yogic concept of prana, it is natural to explore similar physiological interpretations for the concept of energy channels. Recall that the Ida and Pingala channels act as opposing forces: the Pingala acts as stimulating force while the Ida acts as an inhibiting force. From this, a parallel with the two branches of the ANS becomes apparent: the Ida corresponds to the parasympathetic nervous system while the Pingala corresponds to the sympathetic nervous system. Modern Yogic teachers were clearly aware of such parallel. Swami Sivananda (2005, p. 24), a modern Yoga guru, states that these two energy channels correspond to the left and right sympathetic chains and Swami Vishnu-devananda (1988, p. 230) adds that they are also related to the column of sensory and motor fibers in the spinal column.

Given the interpretation that the Ida and the Pingala are closely related with the nervous tissue on the sides of the spine, it naturally follows that the Sushumma, the most important energy channel, may be interpreted as the nervous tissue within the spine. This is precisely the interpretation given by Swami Sivananda and Swami Kuvalayananda, who believe that the Canalis Centralis (central canal), a small duct within the spinal column, corresponds to the Sushumma nadi (Sivananda, 2005, p. 34 -Kuvalayananda, 2005, p. 53). This importance given to the Sushumma matches the essential role of the spinal column in biological anatomy in sending messages required to perform bodily functions. Furthermore, the chakras, or energy centers, correspond to the plexuses of the sympathetic portion of the ANS (Rele, 1931, p. 24), and are located in the corresponding regions of the spine (e.g. cervical region corresponds to the throat energy center) (Sivananda, 2005, p. 28). However, even though such physiological correspondences exist, Yogic gurus emphasize that the energy channels are more encompassing than just the physiological structures. Thus, to fully understand these energy channels and the corresponding energies that flow through them, an anatomical study will not suffice.

Based on the interpretation of the Sushumma nadi as the central canal in the spinal column, we could interpret the Kundalini energy, which is thought to travel through this nadi, as nervous impulses or fluids traveling along the spine. However, the scenario is much more complex than this, given the transformative powers that the Yogis attribute to the Kundalini energy. Yoga gurus and various scholars explain that the Kundalini is a type of energy that is beyond physiological structures. Dr. Frawley, an expert in Indian Ayurvedic Medicine, states that Kundalini is not a physical force: “it is the concentrated energy of awareness or attention” (Frawley, 2002, p. 142). In the words of psychologist Carl Jung, Kundalini is “something in you, an urge in you, a leading spark” which leads to awakening (Jung, 1999, p. 68). Furthermore, Swami Sivananda and Swami Vishnu Devananda’s did not include any possible physiological correspondences to the Kundalini energy in their guides to Yoga whereas they include numerous physiological correspondences of the nadis. Furthermore, given the Western understanding of the spinal column, an interpretation of the Kundalini as spinal fluids or nervous current within the spine does not explain the Yogi’s understanding of such energy.
Regardless of the presence of a corresponding physiological structure, there is a general consensus that there are marked physiological changes that result from the awakening of the Kundalini energy. For instance, Gopi Krishna states that on the awakening the kundalini, radical changes occur in the working of all the organs in the body (Krishna, 1993, p. 169). Furthermore, he points out that favorable hereditary conditions play a key role in the awakening of Kundalini (Krishna, 1993, p. 141), which suggests a clear interaction between the body and the Kundalini.

There have been other attempts to localize the Kundalini in the physical body. After careful physiological comparisons, Dr. Rele concluded that “Kundalini is the Vagus nerve of modern times, which supplies and controls the nervous plexuses of the sympathetic nervous system” (Rele, 1931). This interpretation of the Kundalini explains the incredible level of control reached by Yogis over the ANS. As Dr. Rele explains, “by stimulating the Vago-sympathetic nerve the Yogi establishes a complete control over the unconscious automatic action of involuntary muscular fibers” (Rele, 1931). However, as Swami Kuvalayananda notes (2005), Dr. Rele did not consult with advanced Yoga students, or carried out any scientific investigation. As he notes in the preface, these conclusions are “possible suggestions only.” Furthermore, this interpretation falls short to explain how control over this nerve can lead to changes in cognition or perception, and most importantly, how it leads to enlightenment. As we will see in further discussions, there is an essential role of the Vagus nerve in Yogic practices, but it is not likely that Vagus nerve control is the source of transformative power of the Kundalini.

Source

Suárez‐Rubio S. From Eastern Metaphysics to Western Psychology: The Brain, the Heart and the Breath. Cornell University (thesis). Ithaca, NY: Cornell University. 2007.