Department of Psychiatry, Cooper University Hospital, and Cooper Medical School of Rowan University, Camden, NJ, USA
Every man can, if he so desires, become the sculptor of his own brain.
— Santiago Ramon y Cajal (1923), neuroscientist and Nobel Prize (1906) winner
The relationship between body (more specifically the brain) and mind is so intimate that it is called as a mind–body unit. The Self and It’s Brain (1977), a famous book by Popper, a philosopher, and Eccles, a neurophysiologist and Noble Prize winner, describes this beautifully. This chapter attempts to integrate neuroscience (specifically, cognitive neuroscience and neuroimaging, neuropsychology), phenomenology, and the spiritual sciences and attempts to foster a multidisciplinary dialogue. Integrative dialogues of this kind are critical to the advancement of a holistic understanding of the human system and its psychological, biological, social, and spiritual dimensions. A comprehensive understanding has the potential to transition from the dualistic Cartesian mind–body framework into a body–mind–beyond mind system.
In the Vedantic (Upanisadic) traditions, the beyond mind entity is referred to as the soul, the highest, purest form of the mind. Holistic and inclusive concepts like these impart insight into bridging the gap between ancient wisdom and modern science. Knowledge of this model is essential for understanding the spiritual sciences. Because of the direct relationship between experiential processes, neural phenomena, and the therapeutic power of understanding this relationship, it is essential that we study the role the brain plays in the manifestations of internal experiences—specifically the meditative experience. There is a need for practical concepts that connect the mind and brain. The concepts will cultivate a better understanding of how our thoughts, language, experiences, and nonverbal behaviors can physically influence our brain and vice versa. Focusing on their clinical utility, these concepts aim to transcend the Cartesian mind–body dualism, which tends to isolate the experiential domains from their biological underpinnings. These following information should be viewed as an attempt at providing integrative insights into the individual’s mental processes in terms of the neural mechanisms that form our experiences, both normal and pathological.
3.1.1 Human Experience Is Tripartite: The One Who Sees (Seer/Self), the Scene (Object/World), and the Interpreting Interface (Mind)
As mentioned in Chap. 2, Samkhya (Rig Vedic) philosophy and Yoga propose a tripartite model of experience. Its three elements are (1) the one who sees/seer/self/subject (the third factor or soul; Sanskrit drashta), (2) the scene/object (Sanskrit drishya, i.e., the world, which is the external projection of the mind), and (3) the instrument that sees the object/the “interface”/the mind (Sanskrit manasa). It is important to note here that the word seeing is not meant in visual sense but in the sense of experiencing). The self sees everything, but it remains in the background, unnoticeable to the ordinary mind because of ignorance (Sanskrit avidya) or lack of wisdom.
3.1.2 The Trilogy in the Human Existence: Body (Brain), Mind, and Soul
Analogous to a computer, the human operating system constructs the experience of objects and the world. There are at least two elements to this operating system: the body (specifically, the brain) and mind. Eastern and Western philosophers agree that there exists another element in addition to the body and mind, more popularly known as the soul. This third factor is the essence of one’s existence. The soul is the bridge between our physical self and the spiritual realm. Experientially, the soul has been regarded as the locus of the deepest levels of experience. The concept of the soul is found not only in ancient Indian scriptures. It is culturally and historically universal. For example, the ancient Chinese referred to two independent consciousnesses, hun and po (Yu 1987; hun, cloud–soul, and po, white–soul). Similarly, the ancient Egyptians believed that a human soul was made up of five parts: the Ren, the Ba, the Ka, the Sheut, and the Ib (Allen 2000).
3.2 Brain: The Most Complex Organ of the Human Body
3.2.1 Facts About the Human Brain
The human brain is about the size of a cantaloupe, weighs about 3 lb, and has average length, width, and height of 17 cm (6.75 in.), 14 cm (5.5 in.), and 9 cm (3.5), respectively. The human brain has 100 billion nerve cells (called neurons). When we add other supporting cells in the brain, this number becomes 1.1 trillion cells (1 trillion = 1012). Although the brain weighs only 2 % of the body’s weight, it consumes approximately 20 % of the body’s supply of oxygen and glucose. The largest section of the brain is the cerebrum, which constitutes 85 % of the brain’s weight. The outer part of the cerebrum is the cortex. The cortex is the thinking apparatus. The inner part of the cerebrum is divided into subcortical structures, including the limbic lobe and basal ganglia, which largely govern feelings and unconscious processes. The human cerebrum is divided into two hemispheres: the left and the right. These hemispheres communicate with each other via the corpus callosum, which consists of some 250 million nerve fibers. Nerve fibers are the thin threadlike structures that transmit nerve signals from the nerves to receptors located in various parts of the body. Each hemisphere can be further divided into four lobes: the frontal (the front of the brain), parietal (the middle and top of the brain), temporal (the middle and bottom of the brain), and occipital (at the back) lobes. Some researchers (Kosslyn and Miller 2013) also propose a functional division of the human forebrain into the top brain and bottom brain. This division is demarcated largely by a groove that separates the frontal and parietal lobes from the temporal lobe below. This groove is referred to as the Sylvian fissure or lateral sulcus (detailed descriptions are provided later in this chapter). The section of the cerebrum that distinguishes humans from other primates is the frontal lobe, more specifically the prefrontal cortex (PFC). The PFC is the bulging portion of the frontal lobe that sits behind the forehead and above the brow. The upper and outer part of the PFC (referred to as the dorsolateral PFC or DLPFC) oversees critical human faculties such as problem solving, organization, maintaining a flexible attitude, and planning for the future. It is not surprising then that the PFC constitutes 30 % of the human’s cortical volume. The frontal lobe is the thinking center of the brain, whereas the limbic areas are the feeling centers of the brain.
Hanging below the cerebrum is the brain stem, which is popularly referred to as the reptilian brain because of its involvement in various bodily reflexes. The brain stem consists of three structures: the midbrain, pons, and medulla. These three structures primarily regulate the body’s vital functions like breathing, heartbeat, and body temperature. From evolutionary perspective, the oldest part of the human brain is the brain stem and the limbic lobe (limbus means a ring). The limbic lobe, the feeling part of the brain, lays buried deep inside the brain and surrounds the most vital centers contained in the brain stem, the breathing and heart centers. One particular region within the temporal lobe is the insula. This is a portion of the cerebral cortex folded deep within the lateral sulcus that separates the temporal lobe from the parietal and frontal lobes. The insula is responsible for storing and registering the visceral emotional representations of our experiences. Functional neuroimaging studies have found that the insula is activated when the individual imagines experiencing pain in response to images of painful events. The insula also plays a crucial role in interoceptive information processing. The insula links our internal experience of bodily functions like heartbeat to evaluative information, thereby generating a subjective representation of one’s own body. This includes a sense of body ownership, as well as social emotions like empathy (Karnath et al. 2005). The insula and the prefrontal cortex (PFC) play a critical role in the meditative experience. The brain communicates our thoughts and feelings to other parts of the body through mediation of a system called the autonomic nervous system: this system has two parts, the sympathetic (excitatory) system and the parasympathetic (calming) system. Within the brain, nerve cells are in constant communication with each other via connections (both physically and chemically) called synapses. On average, each nerve cell has approximately 5,000 connections to other nerve cells. There are two types of synapses: (1) electrical synapses where nerve cells are in physical contact with each other, and (2) chemical synapses, where communication is not transmitted through physical contact, but by the release of chemicals, referred to as neurotransmitters, at nerve endings. A typical nerve cell fires 5–50 times a second. When a nerve cells fires, it sends information signals to other nerve cells communicating whether or not it should fire too.
3.2.2 The Brain as an Important Locus of All Experiences Including the Spiritual Experiences
From an Eastern perspective, the connection between the mind and brain is well accepted. In fact, one of the foundational concepts among Eastern schools of thought is the integration of the mind and body. Tantra, tantric Buddhism (Vajrayana), and qigong propose elaborate energy systems throughout the human body. These various energy systems or flows are believed to support the underlying soul and human functions. These energy systems are called chakras in the Indo-Tibetan tantric system (as discussed in Chap. 1) and qu’ and yin–yang in the Chinese qigong system (Liang et al. 1997). Within these systems, mind–body dynamics are represented more holistically; mind–body interactions cocreate an experience. Our brain has tremendous inductive reasoning power such as the ability to infer complete patterns when perceiving just a small fraction of the pattern. For example, we can recall a person from just a few words or a whole concept from a single phrase. Even an advanced computer cannot match the inductive reasoning power of the human brain. (Further discussion regarding the role the brain plays in our experiences is provided later in this chapter.)
3.2.3 More Recent Research on the Brain: Top Brain and Bottom Brain
Most of us are more familiar with concepts of the left versus right brain. The science indicates that these concepts are oversimplifications. The structures of the brain do not operate independently but as a single interactive system that function in concert. Built upon decades of cognitive neuroscientific research on both the brains of rhesus monkeys and those of human beings, Kosslyn and Miller (2013), in their recent book, Top Brain, Bottom Brain, propose four different cognitive modes on the basis of how the top and bottom portions of their brains function. This mode is supported by the anatomical division of the top and bottom parts of the brain, demarcated largely by the Sylvian fissure. The top brain comprises the entire parietal lobe and the upper, larger portion of the frontal lobe. The bottom brain refers to the smaller remainder of the frontal lobe and the entirety of the occipital and temporal lobes. Kosslyn and Miller describe that the top–brain system uses information on the surrounding environment in determining what actions to execute and goals to achieve. This determination operates in a flexible and adaptable manner that varies with the particular needs of the circumstance.
The bottom–brain system, on the other hand, organizes signals brought to them from the sense organs and simultaneously compares these perceptions with all the information previously stored in one’s memory system. This set of comparative data is used to classify and interpret the object or event, allowing one to convey meaning to the world. While the top-brain system operates mostly on a here and now basis and in an executive or thinking-based mode, the bottom-brain system operates in a visceral, feeling, and meaning-based way. The major implication here is that the top- and bottom-brain systems always work together, albeit in varying extents that depend on the needs and personality of the individual. Kosslyn and Miller further elaborate that depending on the degree to which a person uses the top and bottom systems in various ways (cognitive modes), people can be categorized into four groups: movers, perceivers, stimulators, and adaptors. No one mode is better or worse than the others; rather, each mode contributes something useful. The key is how these cognitive modes interact—both among individuals and within groups of individuals that tend to favor one mode over another. If we can classify persons based on their brains, it must follow that the brain is an important locus for the experiences that shape the personality.
3.3 Concept of the Mind in Yoga
In Yoga, the mind is conceptualized as part of a broader entity, the consciousness. Yogic philosophies consider the mind volatile, needing an anchoring object to hold on to express itself in one’s awareness. As described in Chap. 2, just as we need a reflective surface to experience sunlight, we require five things (objects of mind) in order to perceive the existence and functions of the mind from which our experiences arise. Those five objects of the mind are our thoughts, feelings, sensations or perceptions, memory, and will or impulses. Memory plays a crucial role in construing the experiences and symbolically codifying them in the brain. Increasingly, memories are understood as internal representations within our neural system. Memory is the mechanism in the brain and mind that—according to the philosophies of Abhidhamma and the Yoga Sutras—profoundly influences the other four objects of the mind (i.e., the thoughts, feelings, sensations/perceptions, and will/impulse) to the perception of time in order to hold the experience across time in our minds and brains. Memory binds together the thoughts, feelings, and sensations/perceptions. In addition, memory colors the contents of these three objects of the mind and plants the seeds of will/impulse, the fourth object of the mind, which precipitates our actions.
3.3.1 Mind Is Graded: Lower to Higher
It is important to understand that consciousness in the yogic sense is different from that in the neurological sense. In the yogic sense, consciousness refers to the mind with its various grades or levels. These gradations are classified as the lower level (sensorial mind; Sanskrit manasa), the higher (the intellect; Sanskrit buddhi,), and, finally, the finest grade (the soul or pure experiential realm; Sanskrit atma). This understanding is essential to an understanding of the theories of the mind as described in yogic philosophies. Again we see that unlike the Cartesian perspective, Eastern traditions consider the human body in the context of a body–mind–beyond mind system. The beyond mind entity is the soul or the highest grade of the mind in its purest form. Aurobindo (1999, 2001), twentieth century philosopher, meditator, and proponent of the Integral Yoga, called this as beyond–mind entity or the supramental state. According to yogic philosophies, one’s insight into or knowledge regarding the various levels of Reality depends upon the grade of the mind under which we experience them. The various conditions or grades of the mind and their accompanying levels of knowledge provide us various representations or various levels of expression of the Reality. As described in classical Indian texts like the Yoga Sutras and the Visuddhimagga, meditation is nothing but the incremental process of purifying one’s mind, the interactive interface, until it achieves the highest, purest form (the soul or pure awareness). In this grade of consciousness, the meditator can see in the most vibrant and clearest way.
In the spirit of the body–mind–beyond mind conceptualization, all experience and existence lie within the spectrum of two poles. The somatic–cognitive pole, or the outer self, consists of the body and mind and includes our intellectual, conceptual knowledge regarding ourselves and the world. The other end of the spectrum is the experiential pole, the inner self, manifests within the context of our intuitional, nonconceptual knowledge regarding ourselves and the world. Experiential nature exists in the realm of the beyond mind. Some traditions refer to the inner self as the true self and the outer self as the false self or the projected self. The outer self depends more on the outer world, relying on feedback from the others. In contrast, the inner self is self-directed and thus depends more on the inner world, relying on introspective feedback. Unlike the inner self, the outer self seeks to impress others in order to receive positive feedback. Consequentially, when functioning in the realm of the outer self, one’s happiness is at mercy of others, and thus one experiences more stress and constraints.
In light of psychoanalytic thought, these two selves can be seen as the outer defensive structure and the inner core structure. Because the false self is a façade built on years of fearing retaliation and rejection by others, the individual is under more pressure. Maintenance of the false self requires a high cost, as it consumes all of the individual’s psychic energy. An example of this is the obsessive–compulsive person depleted of his/her psychic energy by maintaining psychological defenses against the experience of anxiety. This may explain why babies, despite their vulnerability and helplessness, appear happy and, furthermore, increase the happiness of others. The baby has simply not lived long enough to build a false self. The true self, on the other hand, is freer because it is more natural, unconditioned, and independent of the world. When one operates as the true self, it costs less. There is no need to expend the energy needed to maintain a façade; the surplus of psychic energy is free to fuel higher deeds such as creativity, altruism, and spirituality. Ancient descriptions of aura surrounding a spiritual person’s head are thought to be the result of this free psychic energy. Within the spectrum of outer self to inner self, spirituality is any factor or intervention that decreases the distance between the outer self and the inner self and promotes harmony between the two. In other words, spirituality is a sort of homecoming. The individual feels settled and, therefore, does not need to fabricate the projected false self. When practicing deeply contemplative methods like meditation, one experiences a process that gradually merges the outer self (i.e., the body and the lower mind) with the inner self (beyond mind or the soul) and, consequentially, the true experience. In order to understand spiritual experiences, we need a framework other than the one we ordinarily use to study non-spiritual experiences. In natural states like sleep or losing oneself in the vastness of nature, we can experience this merger in variable grades that depend upon the quality of the experience. The relaxing effects of sleep or vacationing can explain the stress-reducing effects of these mergers.
3.4 Soul: The Third Entity of Existence and Experience
Yogic philosophies regard the mind as just another sense organ. It is an instrument or partial expression of another finer entity, the soul (Sanskrit Atman, purusha). The soul lies within the experiential realm of one’s consciousness (self-awareness) rather than in the gross or physical realm. The concept of the soul is the foundation of Eastern philosophies. The following discussion provides an example of the presence of another element in one’s existence, different from the body and mind. When one says this is my body, this is my mind, one must be referring to a third entity—the first and second factors being the body and mind, respectively—that is neither the body nor the mind. This third entity is the owner of the body and mind, as suggested by the use of the word my in the phrases my body and my mind. Eastern philosophies assert that the experience of an object in the realm of the soul is the highest level of experience or the real or Absolute experience, while experiencing the same object at the level of the mind is just a relative or incomplete experience. Although the soul is part of the individual (Sanskrit jiva), it can transcend and the whole universe and cosmos become an extension of the self. The soul becomes the universal self, which is limitless unlike the individual self.
Belief in the soul is considered one of the universal elements of human culture (Wilson 1998). The term soul has been described in many different ways. In both Eastern and Western thoughts, the soul is similarly considered to be the immortal part of the human person that has influence over the body. Plato and Aristotle both considered the soul to be the essence of the human being. They never clarified whether or not the soul could exist beyond the body, but we do know that Plato believed the soul included reason, emotions, and desires. St. Augustine, one of the early champions of Christian theology (354 CE–430 CE), described the soul as “a special substance, endowed with reason, adapted to rule the body” (Hill 1990). The present Catechism of the Catholic Church defines the soul as the innermost aspects of humans, that which is of greatest value in them… (1997). Some consider the soul to be related to those attributes that make human beings distinct from other animals. Despite any subtle differences, all of the above definitions suggest that the soul is not the brain or the mind. Still, they admit that there is a deep relationship between them. If the soul has reason, emotion, and desire and is the essence of who we are, then the brain must have some intimate connection to the soul.
3.4.1 Soul and the Pure Awareness (Pure Experience)
In both ancient and modern eras, Eastern philosophers (Buddhaghosha, 430 CE; Aurobindo 1999, 2001) have described the soul as the purest form or the finest grade of the mind or consciousness. In yogic philosophies, the consciousness and mind are often used interchangeably. These philosophies conceptualize the mind in terms of consciousness which is different from consciousness in neurological sense. This consciousness (mind is part of it) exists in graded form: from lower to higher and from crude to fine, and its finest grade is the soul which lies in the realm of direct or pure experience rather than mere intellect. The lower mind (Sanskrit manasa) is considered another sensory apparatus (Sanskrit indriya), just like the other five physical sense organs (touch, vision, smell, etc.). As long as one functions in the realm of the body and lower mind, one is functioning at an intellectual level that is inferior to deeper, experiential one. It is not surprising then that Yoga or meditation, as described in all the original traditions (the Vedas, the Upanishads, Shramana, and Tantra), begins with postures and breathing patterns that involve the gross body. The individual can then transcend the body through meditation and ascend into the subtler realm of the mind. In the Patanjalian tradition, practicing the various stages of samadhi allows one to access the indescribable or the Absolute, the finest or subtlest level of experience. Similar concepts in Buddhist traditions are called the jhanas and sampattis. They are the various access states of the mind as one ascends from the lower mind to higher mind and then beyond the mind.
As described earlier, the ancient Indian scriptural traditions (Upanishads and Visuddhimagga) claim that pure awareness or pure experience is the highest form of consciousness. This highest form has been referred to as soul or God or the Absolute. The body, mind/internal world, and the external world are merely derivatives of this Ultimate One. The highest yogic philosophies claim that both the mind and the physical body are gross material and external manifestations (Sanskrit jada) of that consciousness which is subtle and internal. The internal (i.e., the subtle consciousness or the soul) is the cause and the external (i.e., the gross body, mind, and world) is the effect. Consciousness is expanded energy (as described in Chap. 1, in tantric traditions, this energy is called the cosmic energy or kundalini energy [Sanskrit kundal = coil, spiral]). These concepts present profound psychosomatic implications regarding the body and mind and the intricate dynamics among them. Yoga’s rationale for the deep introspection lies in the fact that by taking control of the internal (the soul), one can also control the external.
Transpersonal psychology, a subdivision of Western psychology, integrates modern psychology with spiritual/meditative psychology. This school of psychology, as its name suggests, bridges (trans = across) the gap between conventional Western psychological schools and the contemplative philosophies of the East, both ancient (e.g., Buddhism) and modern (e.g., Sri Aurobindo’s Integral Yoga). Just as in modern psychology, in which the individual undergoes cognitive and emotional development that includes various stages, the prominent thinkers of the transpersonal movement (e.g., Ken Wilber, Jack Engler, D. T. Suzuki, and Mark Epstein) propose the developmental progression of spiritual development. This development is a multistage model of spiritual development that begins with the physical (gross) realms, followed by the mental (subtle) realms, and ends with the finest stage, the soul. Integrative models like this are not only helpful when studying Eastern philosophies from the perspective of Western psychology, but they also assist in the integration of the valuable insights of both schools. This integration allows for the understanding of a larger audience. For more descriptions, please refer to Wilber et al. (1986).
3.5 Mapping Experiences onto the Brain: The Neural Circuitry
The neural circuitry in our brain governs the crucial elements that constitute our experiences including the meditative experiences. Some of these crucial elements are attention, memory, motivation, engagement, self-observation, and compassion. Experience shapes our behavior and experience is symbolically represented in our brain. Owing to cognitive neuroscience and functional neuroimaging research, we now know that neural circuits can provide neurological explanations for our various behavioral patterns. Having evolved over thousands of years, the various neuronal circuits in the human brain can consider and evaluate multiple variables in a contextual manner before deciding on a course of action. These circuits include not only the ones which can detect the urge to act but also those that postpone the enactment or discharge of our urges and impulses in favor of satisfying higher demands, both from a personal and societal perspectives. These neural circuits have evolved to transcend the narrow focus of the reward system or immediacy of impulse gratification and, instead, function to pursue satisfaction in a manner that is consistent with higher human values.
A critical region in the brain for these higher circuits lies in the prefrontal cortex. This section of the brain facilitates the thinking faculties and allows one to transcend simple reward-driven behavior, typical of less evolved animals. Instead, it allows one to consider all information regarding a situation before the initiation of action. From top to bottom, the human’s prefrontal cortex consists of three critical areas, collectively referred to as the prefrontal pyramid. These regions are as follows: (1) the dorsolateral (i.e., upper outer) prefrontal cortex (DLPFC), which lies on the sides of the front of the frontal lobe; (2) the anterior cingulate cortex (ACC), which lies in the middle of the frontal lobe, almost sandwiched between DLPFC and OFC; and (3) the orbitofrontal cortex (OFC), which lies at the bottom of the frontal lobe of the brain, just above the eyeballs.
3.5.1 Visual Pattern Recognition: The Prototype Process in Mapping Experiences onto the Brain
During information processing of the primate’s brain, one key process is pattern recognition, meaningful recognition of the different patterns of experiences across various domains of information. Pattern recognition forms a symbolic representation of an experience which maps it out on the brain. Although pattern recognition occurs in all sensory modalities, the visual pattern recognition in humans and other primates has been studied the most extensively (Haxby et al. 2001) and, thus, serves as a prototype. The process involves the following six steps in sequence: (1) transmission of the visual input to the occipital cortex; (2) routing the information to the lateral inferior occipital lobe, where a pre–pattern (an intelligent organization of the inputs) is developed; (3) the information is sent to the fusiform gyrus in the ventral temporal lobe, where it is categorized as one of two kinds—face or object; (4) from the fusiform gyrus, the data continue to be transmitted anteriorly: at the temporal pole, the object’s identity is further clarified and integrated with limbic information; (5) simultaneously, data regarding the object are transmitted to the parietal cortex, where the object is placed within three-dimensional space; and (6) the processed information regarding the object is sent to both the entorhinal cortex, where its past significance is determined, and the DLPFC, where its implications for the future are evaluated.
The significance of the human pattern recognition is that it processes all sources of information (i.e., visual, auditory, tactile, etc.) simultaneously. There are two types of interpretive processing: bottom–up (data driven or part-to-whole) and top-down (concept driven or whole-to-part). Information processing system in humans exhibits interaction between the data-driven and concept-driven processes. The arrival of sensory information triggers a series of automatic analyses, beginning with the sensory organs and subsequently through an extensive chain of processing stages. Simultaneously, the context in which the sensory events are embedded triggers expectations based upon past experience. Knowledge, in general, might be defined as expectations that produce concept-driven processing, top-down processes (the dorsal stream), which eventually merge with the bottom-up processes (the ventral stream). For the proper operation of the human information processing system, both the top-down and bottom-up processes must take place simultaneously, each assisting the other when one tries to make sense of the world. An example of this is the act of reading. Reading requires deciphering symbols (i.e., letters), consolidating them into units, and, finally, determining the word. Does one read by deciphering the letters and then constructing the words (bottom-up) or by interpreting the features of the entire word at once (top-down)? Reading is most likely a combination of both bottom-up and top-down processes, the balance of which is determined by what the situation demands. For example, when reading a difficult material, we probably use bottom-up processes. Evidence suggests that there exist multiple streams, some descending to the level of feature analysis, but reading requires quick feature analysis, giving way to a higher order of contextual recognition. This higher order follows that first reading the material engages letter recognition and quickly follows with whole word and phrase recognition (Mather and Wendling 2012). Unfamiliar material is interpreted on the level of morphemes, the smallest grammatical units, while practiced readers tend to maintain the holistic analysis. Reading studies have led to another remarkable discovery: a single printed letter is sometimes read better when it is part of a word than when it stands alone (Wheeler 1970). This author integrates these insights with techniques of mindfulness in his mindfulness-based trataka model (MB-t©, Pradhan 2014) which he uses for the treatment of dyslexia. Trataka is a concentrative meditation (focused attention type) practice of which improves the visual memory (Niranjananada 1993).
3.5.2 The Five Major Groups of Circuits in Our Brain
Considering the complexity of human experience, any attempt to fully describe the experience in terms of neural circuitry would be an oversimplification. Placing ancient wisdom of yogic and meditative philosophies within the framework of modern science and evidence-based medicine could lead to a better understanding of both disciplines, more synergy, and enhancement of their therapeutic potential. With this in mind, the five major neural circuits that play a critical role in the neural mapping of our experiences are as follows:
Executive and evaluative circuits in the prefrontal cortex: The executive circuits are centered in the dorsolateral prefrontal cortex (DLPFC) which is located above and works closely with the risk–reward evaluative circuits. These circuits enable one to function in an ongoing and adaptive manner as demanded by one’s environments, both internal and external.
Risk–reward evaluation circuits: These circuits are located in the orbitofrontal cortex (OFC) and the anterior cingulate cortex (ACC) and include hubs within the amygdala (fear detector) and nucleus accumbens (reward center). These circuits work closely with the autonomic nervous system and the prefrontal executive system. This allows the thinking, feeling, and somatic functions as well as planning dimensions of the risk–reward situation to operate flexibly and appropriately as per the needs of the situations.
Visceral–self circuits (consisting of the insula, cingulated cortex, and brain stem): These circuits contain basic representations of internal states (called interoception) and the visceral self, including those representations that generate discrete bodily states through autonomic and hormonal activation.
Empathy and compassion circuits: These circuits include the ventromedial part of the prefrontal cortex (for mentalizing activities), the insula (for interoceptive awareness), as well as the mirror neuron system (experiential neurons) located in the lower frontal, lower parietal, and upper temporal areas of the brain.
Memory circuits: These circuits engage the hippocampus (explicit/conscious memory), the dorsolateral prefrontal cortex (working/problem-solving memory), the basal ganglia (implicit/unconscious memory), and the amygdala and orbitofrontal cortex (secondary rewards and punishers).
3.5.3 Functions of the Prefrontal Cortical (PFC) Tri-Circuit
The three circuits in the PFC that modulate our complex behavior are located in three chief regions: the dorsolateral prefrontal cortex (DLPFC), the anterior cingulate cortex (ACC), and the orbitofrontal cortex (OFC). These areas are somatotopically mapped and characterized by numerous pathways or channels that run through each region (Mega and Cummings 2001). It is interesting to note that similar descriptions of energy channels (Sanskrit nadis) of the human body are detailed in the ancient Indian Tantric texts (Avalon 1974; Sivananda 1994). The DLPFC is a neural workspace where information needed to evaluate situations, make decisions, solve problems, and plan for the future is gathered. DLPFC constitutes the thinking brain and tends to participate in cognitive circuits, whereas ventral prefrontal areas comprise the feeling brain, as they are significantly linked to emotional circuitry.
The circuit in the anterior cingulate cortex (ACC) is involved primarily in the motivation of goal-directed actions, processing of emotions and the emotion-associated movements, emotional–cognitive integration, and conflict monitoring (Bush et al. 2000). Anytime we consciously exercise our will, we activate our ACC. It transmits emotional motivation to the autonomic, visceromotor, and endocrine systems (Critchley et al. 2003). Because the ACC is central to deliberate and reasoned motivation, it is an important component of reward circuitry. The ACC is not only strategically sandwiched between but also connected by the DLPFC, associated with attention and executive functions, and the OFC, the area that elicits risk evaluation and impulse control. The ACC is closely connected with the DLPFC, which gathers information needed for problem solving, and also with the supplementary motor area of the frontal lobe, the region responsible for planning novel movements. These strategic locations and connections assist the cingulate in receiving cognitive data from the DLPFC (Barbas et al. 2003); facilitate emotional–cognitive integration, generating emotional states appropriate to cognitive contents (Critchley et al. 2003); and convey emotional information to the DLPFC for further cognitive processing. In response to cognitive information, the dorsal ACC triggers the arousal responses of autonomic centers (Critchley et al. 2003).
The ACC is the primary overseer of our attention. It is also the chief neural region associated with the manifestation of targeted and purposeful fulfillment of our actions. It manages our effortful control over various things. It is significant that the ACC works closely with the amygdala, the center for fear learning, which is also associated with motivation. Together, the ACC and the amygdala form a joint system that elicit two forms of motivation: the ACC controls top-down, deliberate, centralized, and reasoned motivation (cool motivation), whereas the amygdala is responsible for bottom-up, reactive, distributed, passionate motivation (warm motivation) (Hanson and Mendius 2009). The ACC and the amygdala modulate each other: in a three-step feedback loop, the amygdala excites the lower part of the ACC, which then excites the upper part of the ACC, which in turn inhibits the amygdala (Lewis and Todd 2007). The other inhibitor of the amygdalar activity is the ventromedial prefrontal cortex (vmPFC). The vmPFC is the mentalizing region of the brain (further described in Chap. 6), and the nerve fibers that arise from it directly inhibit the firing of the amygdala in situations of fear or anxiety. Given its functions, damage to the ACC may result in a lack of motivation and a general state of apathy, in which responses to internal and external stimuli are diminished. Severe damage to the ACC can result in akinetic mutism, a state characterized by little spontaneous movement or speech (Mega and Cummings 2001). Because of its role in reward and motivation, ACC–nucleus accumbens circuitry plays a significant role in addiction. The ACC is not fully developed until 3–6 years of age (Posner and Rothbart 2000), which explains why young children demonstrate less self-control. Around 7 years of age, the child develops the level of cerebral, cognitive, and emotional maturation necessary for meaningful participation in attentional activities like those of meditation.
The third player in the tri-circuit is the orbitofrontal cortex (OFC) which primarily functions to control one’s impulses and promote the pursuit of low-risk rewards that are consistent with one’s internal needs over high-risk ones. The OFC circuit modulates our pursuit of reward within the context of careful considerations of potential consequences. As a result of its connections with the ACC and the autonomic nervous system, the OFC induces anticipatory bodily states that encourage reward seeking, as well as aversive bodily states that reduce the likelihood of risky behavior (Mega and Cummings 2001). From an evolutionary perspective, the OFC modulates behaviors that have significant bearings on the individual’s survival.
The orbitofrontal cortex (OFC) includes distinct medial and lateral areas as well as dorsal and ventral areas (Elliott et al. 2000; Kringelbach 2005). The medial orbitofrontal cortex is active in monitoring associations between stimuli, responses, and outcomes under changing circumstances, whereas the lateral orbitofrontal cortex is active in inhibiting previously rewarded actions that are no longer likely to be rewarded owing to changed conditions. Exhibiting strong links to the thalamus (the sensory relay station), the ACC (the center for conscious motivation and attention), and the autonomic nervous system, which is responsible for fright–fight–flight response, the amygdala rates the emotional importance of any experience. When we reappraise a situation according to the negative and positive emotions associated with our previous memory of it, we activate corresponding punishment and reward circuits: the orbitofrontal circuits for punishment and the ACC and basal ganglia circuits for the reward.
3.5.4 Close Relationship Between the OFC and Amygdala
In the risk–reward evaluation circuits, the OFC and amygdala work together closely. The amygdala, the central alarm system, continuously monitors for opportunities and threats to the individual. The orbitofrontal cortex (OFC) is reciprocally connected to the amygdala; they act in concert to generate emotional states relevant to the pursuit of reward and avoidance of risk (Barbas et al. 2003: experimental work in nonhuman primates). Both the orbitofrontal cortex and the amygdala receive a significant input from all five sensory cortices, as well as from the insula, which again is associated with the visceral elements of our perceptions. The amygdala and OFC, by virtue of their connections to the hypothalamic autonomic centers and other particular subcortical targets, also generate emotional bodily states.
Our brain integrates all of these information into comprehensive and contextual views of external and internal stimuli, making sense of our outer and inner worlds. The amygdala can exert both inhibitory and stimulatory influences on hypothalamic autonomic nuclei. The central nucleus of the amygdala normally inhibits the hypothalamic nuclei, whereas the basolateral nucleus stimulates it. The OFC can suppress as well as activate the autonomic centers: the suppression happens through stimulation of the amygdala’s central nucleus, whereas activation happens through the intercalated cell masses of the amygdala. Stimulation of the autonomic centers occurs when the OFC stimulates the intercalated cell masses of the amygdala, thus diminishing the default inhibitory effect the central nucleus of the amygdala has on the hypothalamic nuclei (Barbas et al. 2003).
Both the OFC and amygdala work closely with the ventromedial prefrontal cortex (vmPFC) which plays a critical role in the evaluation of risk and fear and the suppression of emotional responses to negative emotional stimuli (Hansel and von Kanel 2008). The vmPFC does so by suppressing amygdalar activity and regulating the parasympathetic system. Not surprisingly, patients with vmPFC lesions show diminished emotional responsiveness and also markedly reduced social emotions like compassion, shame, and guilt. The OFC, amygdala, and vmPFC work together to integrate sensory input into comprehensive views of both the external and internal worlds. Imaging studies have shown that orbitofrontal and amygdalar circuits can be modulated through conscious cognitive processes (Ochsner et al. 2002). Deficits in the orbitofrontal–amygdalar circuit can present as impulsivity, social inappropriateness, lack of empathy, lack of respect for social conventions, disregard for rules and consequences, and little response to the threat of personal risk, embarrassment, or punishment (Mega and Cummings 2001).
3.5.5 Frontal Tri-Circuits Modulate the Thalamus (the Sensory Gate) and the Basal Ganglia
The thalamus is a key midline structure of the brain that serves as a gate for all peripheral sensations, with the exception of smell, before these sensations are relayed to their final destination, the sensory cortex. The thalamus also plays an important role in the modulation of sensation, sleepiness and wakefulness, and one’s overall sense of awareness. The basal ganglia, on the other hand, lie at the base of the brain that play an important role in procedural learning and implicit memory, postures and movements, motivation and reward, habitual behavior, and emotion. The basal ganglia consist of the striatum (the caudate nucleus and the putamen together), the globus pallidus, the subthalamic nucleus, the substantia nigra, and the nucleus accumbens (the reward center). All three prefrontal circuits play a crucial role in the modulation of the thalamus via cortico-striato-thalamic projection fibers and the basal ganglia structures.
Below is the general organization of the frontal–thalamic (called cortico-striato-thalamic) circuits:
The thalamus, in turn, connects directly with the frontal cortex via the thalamocortical circuits, completing the loop between the frontal cortex and the thalamus. The common functional element of all the three prefrontal circuits is the modulation of the thalamus by the globus pallidus, both its internal and external parts (Burruss et al. 2000; Mega and Cummings 2001). The thalamic circuitry is tonically inhibited by direct fibers projecting from the internal portion of the globus pallidus (GPi), a key structure of the basal ganglia. Other structures of the basal ganglia and the frontal cortex can reverse this default inhibition of the thalamus that is exerted by the globus pallidus. This select facilitation (reversal of inhibition) of the thalamus is transmitted through three different frontal–thalamic pathways (Feil et al. 2010): the direct (excitatory), the indirect (inhibitory), and the hyper-direct (inhibitory) pathway. The direct pathway disinhibits/stimulates the thalamus via connections that run through the striatum and GPi. On the other hand, the indirect pathway inhibits the thalamus via connections that run through the striatum, the subthalamic nucleus, and the external segment of the globus pallidus (GPe). The hyper-direct pathway is characterized by direct frontal input received by the subthalamic nucleus (bypassing the striatum), which sends excitatory output to the globus pallidus and the substantia nigra, resulting in the inhibition of the thalamus. In this model, the excitatory projections release the neurotransmitter glutamate and the inhibitory projections release gamma-aminobutyric acid (GABA). This information processing model is an example of one of the brain’s facilitative pathways. In a similar manner, the self-excitatory loops that sustain representations of interest in the brain can be selectively activated or facilitated.
3.5.6 A Scenario Illustrating the Functions of the Prefrontal Tri-Circuits
Consider a real-life situation, in which someone mistakes a rope as a snake. In this circumstance, the cognitive uncertainties regarding whether it is really a rope or snake can cause autonomic arousal through the combined action of (1) the amygdala, which after receiving input regarding the danger from the thalamus rings the alarm that induces autonomic arousal, (2) the dorsolateral prefrontal cortex (DLPFC), which represents current cognitive contents including evaluative information concerning the dilemma (snake or rope), and (3) the cingulate gyrus, which generates autonomic tone and body movements consistent with the emotional contents of the situation (Critchley et al. 2003).
In evaluating a situation in order to determine the appropriate behavior, the brain uses the parallel information processing in which the cognitive and emotional centers process information simultaneously rather than sequentially. Because the transmission of information from the thalamus to amygdala is quicker than transmission from the thalamus to neocortex, emotional processing is often completed before cognitive evaluation (LeDoux 1996). The fast (thalamo-amygdalar) pathway activates an act first, think later mode of functioning, on the basis of associative fear memories stored in the amygdala. The slow (thalamo-neocortical) pathway reacts to a stimulus only after the structural dimensions of this stimulus are analyzed. In addition, as demonstrated in Fig. 3.1 below, unconscious emotional learning may be the result of a direct pathway from the thalamus to the amygdala, which does not involve the neocortex (Morris et al. 1998).
Parallel information processing in the limbic and thalamo-cortical circuits in brain
These mechanisms, because of their parallel presentations, may cause conflict among the prefrontal circuits when determining behavior. This can lead to emotional states that elicit approach or withdrawal followed by cognitive assessments that dictate contradictory behavior. The process of restoring balance and mediating the apparent conflict between circuitry and associated hyperarousal (caused by the thalamus and the amygdalar circuits) requires cognitive–emotional reappraisal of the dilemma (e.g., rope or snake) by the ACC and DLPFC. Only then can the individual determine the real situation. If reappraisal is successful, then knowledge-driven action can ensue (e.g., running away or attacking if the object is a snake or ignoring and moving on if it is a rope). While this imbalance appears greater in psychopathological states like depression, anxiety disorders, and addictive and personality disorders, harmonious integration of cognitive and emotional input is often not possible in the average individual’s daily life. Interestingly, in the meditative brain, the act first, think later functional mode is reversed, i.e., a meditative person is inclined to think first, act later. This reversal is likely due to modulations of the prefrontal cortex, anterior cingulated cortex, orbitofrontal cortex, and thalamic activity, in addition to the dampening of limbic–amygdalar hyperarousal. The actions of a meditative individual are governed by cognitive–affective balance rather than just emotions.
3.5.7 Role of Salience and Facilitated Circuits in the Neural Mapping of Experience
In cognitive neuroscience, the term salience refers to the qualities or properties of an item that stand out relative to the neighboring items within one’s field of awareness. Simply put, information’s salience is its pertinence or relative importance to that particular individual in that particular context within which the information was acquired. Salience plays a critical role in making our experiences unique, by means of selective attention and the activity of facilitative neural pathways involved in information processing. Salience affects how our experiences are encoded, organized, and stored in our brain for future use. Salience also plays a crucial role in potentiating a memory and, thus, converting short-term memory into long-term memory (i.e., consolidation). Within the context of incentive salience and the facilitated neural transmission of information, Berridge and Robinson (1998) propose an incentive salience hypothesis and elaborate on the role of dopamine, the pleasure chemical, in the reward and salience system. One significant finding within the large body of salience research (Schultz et al. 1997; Schultz 1998, 2002; Berridge and Robinson 1998, 2003; McClure et al. 2003) demonstrates that dopamine receptor antagonism does not manipulate the appetitive value of rewards, but instead selectively inhibits the initiation of reward-seeking behaviors.
Functional neuroimaging research points to the role of the insula and cingulate gyrus in the development of the (visceral) representations of our experiences. The insula plays a crucial role in processing the information that integrates interoception, the ability to perceive and respond to stimuli from one’s own body/organs (e.g., feeling one’s stomach rambling, timing one’s own heartbeat) with emotional salience. This integration generates a subjective representation of the body and bodily self-awareness like one’s sense of body ownership (Karnath et al. 2005). In addition to the insula and the cingulate gyrus, the orbitofrontal and amygdala assist in determining the salience of objects within our awareness by rating their emotional significance. The amygdala projects to the same sites in the orbitofrontal cortex that receive direct sensory input; this arrangement may allow the orbitofrontal cortex to extract the emotional significance of sensory events (Barbas et al. 2003). Both the amygdala and the orbitofrontal cortex ignore neutral sensory input, that which bears no implications of risk or reward, and function to cease response to any input lacking motivational value (Barbas et al. 2003). Thus, motivation plays a critical role in our experience of practice and learning like those of Yoga–meditation. When learning and practicing Yoga–meditation, the proper motivation can reinforce the experience via activity of the facilitative pathways. These pathways not only reinforce learning but also assist in maintaining representations of the experience within the brain, allowing one to own the experience.
3.5.8 The Main Players in the Meditative Brain
The cognitive and emotional processes associated with meditative practices are mediated by interactions among the neural circuitry that govern our various experiences. Harmonious integration of cognition and emotions often is not an easy task even in the healthiest and normal individuals, and the imbalance is even greater in psychopathological processes. With recent advances in the cognitive neurosciences, these neural circuits provide us with answers for so many questions which were unanswered before. Research has demonstrated that the key brain areas in experiences like the meditative experience are the prefrontal circuit triad, thalamus, amygdala, hippocampus, and the basal ganglia system. In the meditative process, close interactions between these key brain areas, i.e., the prefrontal pyramid, thalamus, and amygdala, need more elaboration.
The Prefrontal Pyramid and the Tri-Circuits
The evolutionary significance of the prefrontal tri-circuits lies in their crucial role in supporting the adaptive and non-impulsive behavior by making it possible for the individual to consider many variables before responding to a stimulus. The prefrontal pyramid is functionally conceptualized as a top-down system of self–awareness and consists of, from top to bottom, the prefrontal cortex (PFC, mostly its dorsolateral, medial, and ventromedial areas), anterior cingulate cortex (ACC), and orbitofrontal cortex (OFC). Cognitive considerations are generated in the lateral prefrontal cortices.
The dorsolateral prefrontal cortex (DLPFC), being on the top, potentiates executive function and working memory (Wheeler et al. 1997; Johnson et al. 2002). DLPFC with the help from the right parietal cortex which provides data to define the person in space and time by placing the body in the three physical dimensions (temporal–spatial orientation) is capable of integrating the full range of sensory, affective, and memory data. In addition, DLPFC has the ability to project individuals both backward and forward in time and thus generates a coherent self with temporal continuity (Wheeler et al. 1997). Thus, the right parietal lobe provides the temporal–spatial orientation, whereas the DLPFC allows for its presence in consciousness (by working memory, attention) and its manipulation based on the needs of the situation (by problem-solving abilities). The ACC and medial PFC (mPFC) play crucial roles in the meditative process, especially in the aspects of flexible monitoring of attention, cognitive reappraisal, and affect regulation. The ACC and mPFC make use of internal cues like emotions and incentives to regulate attention and action in changing circumstances that call for continual decision making and self-regulation. The ACC bridges emotion and attention: the ventral portions (affective region) register emotional salience of situations and regulate emotions, whereas the dorsal part (cognitive region) modulates attention and executive functions in cognitively demanding situations (Bush et al. 2000). The mPFC is the area of the brain that registers our gut feelings about various people, situations, or the various somatic states based on our past experiences in similar situations. It is active in ambiguous and conflict-laden situations and not only keeps track of situations and actions that are potentially rewarding or punishing but also continually keeps updating this information on the moment-to-moment basis. Thus, in the prefrontal tri-circuits, the dorsolateral prefrontal cortex (DLPFC) plays important role in flexible monitoring of one’s attention during the meditative process. In contrast, the medial prefrontal cortex complements the anterior cingulate in flexibly responding to changing circumstances that call for self-regulation (Frith and Frith 1999) and is consistently activated during self-reflective endeavors (Johnson et al. 2002). Meditation entails such self-reflection and introspection.
Although a small structure in the brain, the amygdala plays important role in meditative experiences. The amygdala rates the emotional importance of any experience including the meditative experience, selectively directs the attention of the meditator to the meditation object based on its emotional salience to the meditator, and, in addition, serves as a gate to the hippocampal memory circuits for emotional experiences. The ventromedial prefrontal cortex (vmPFC) is a special area in the medial prefrontal cortex that also includes a portion of the anterior cingulate cortex and inhibits the firing of the central nucleus of the amygdala in response to emotional situations. The amygdala in conjunction with the orbitofrontal cortex plays a crucial role in motivating an individual for practice and learning, both of which are crucial in the experience of meditation as well.
3.6 Experience is Representational and Knowledge (Insight) Changes These Representations
As previously mentioned, the mind, the creator of our experiences, is a bundle of five components: thoughts, feelings, perceptions, memory, and will. From a neural perspective, a thought most likely results from the momentary pattern of stimulation that simultaneously involves much of the nervous system. Consciousness is described as the ongoing stream of awareness of one’s surroundings or sequential thoughts (Guyton 1987, p. 232–233). The stimulated areas of the brain determine the general nature of the thought, as well as associate specific qualities to it like feelings of pleasure, pain, etc. From the pattern of stimulation involving various neural regions and specific localizations within the brain associated with the thoughts, discrete patterns of sensations or perceptions arise that assist in forming an experience. Sensations arise from the activity of receptors in and on the skin and other sense organs, in addition to various nerve fibers that transmit these sensations to the appropriate neural regions. Perceptions, on the other hand, result from the operation of neural cells that lie beyond the first synapse in the sensory cortex (Kolb and Whishaw 1990). Although sensations can be objective, the perception of experiences is highly subjective and personal, as it is founded on the basis of prior memory of similar kinds of experiences. Sensation occurs on the bodily level and tends to be objective, whereas perceptions are essentially within the mind and are subjective, representational elements of the experience.
An experience has multiple dimensions. Experience is coded in the brain as representations. According to visual information processing research (Talbot 1991, p. 163), less than 50 % of what we see actually stems from the information entering our eyes; the other 50 % is formed from our expectations and memories regarding how the world appears and operates. The meanings attributed to human experiences are largely representational and, thus, based largely on perceptions and memories and only partly on objective data provided by the sense organs. Both conscious and unconscious representations of an object will cause activation of corresponding circuitry in the brain. In general, meaning is defined in terms of its functional significance to the individual. The meaning attributed to the physical and emotional sensations aroused when observing others (or objects) is an amalgam of actual observations and the internal transformation or representations (i.e., memories of these objects). As Wexler (2006), a psychiatrist and researcher from Yale University, puts it: “… we develop an internal neuropsychological representation of the world that forms the neuronal basis for all our habits, beliefs and overarching ideologies…” The power to manipulate these representations lies in knowing how to access those representations and change them so that they are more comparable to Reality. Aurobindo, a twentieth century Indian philosopher and proponent of Integral Yoga, has described something similar to Wexler’s theory. Aurobindo (2001, p. 1) states: “… it is not by ‘thinking out’ the entire Reality, but by a change of ‘consciousness’ that one can pass from the ignorance to the Knowledge—the Knowledge by which we become what we know.”
3.6.1 Knowledge, Direct Experience, and Reality: Three Synonyms in Yoga
Scriptural descriptions of yogic philosophies often use the following terms interchangeably: true knowledge, direct experience, and Reality. The yogic philosophies claim pure knowledge or pure/direct experience provides the yogi (i.e., one who practices Yoga) access to the Reality of things based on the various levels of insights the yogi has obtained through meditation and from direct experience. Using a ladder analogy of insight, the yogi develops higher, more comprehensive views (insights) about the landscape (realities) when they climb atop the higher rungs of the ladder. Similarly, when one ascends the Empire State Building, their perspective of New York City becomes increasingly panoramic or holistic. The different levels of knowledge are equivalent to perceiving things from different levels of Reality. In yogic philosophies, pure knowledge, referred to as real knowledge or pure awareness, Truth, or wisdom, is obtained through insight that results from deeply contemplative practices like meditation. In meditative traditions, knowledge of the Reality (Sanskrit jnana; Pali nana, panna) is referred to as insight and forms the essence of mindfulness/insight meditation (vipassana in Buddhism or Samyama in Patanjali’s Yoga Sutras).
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