|Dynamic change of awareness . . .
|Dynamic change of awareness during mind-body techniques—neural correlates and physiology
The physiological and neuroscientific study of consciousness presents one of the greatest challenges today. This article presents a description of the physiological and psychological changes that take place through the practice of mind–body techniques based on empirical research and practitioner responses. Neural correlates of expanding awareness during the relaxation response are described as the autonomic nervous system shifts from a sympathetic dominant to a parasympathetic dominant state. Understanding the mind-body response in this way makes possible further clinical neuro-physiological research and brings the study of consciousness closer to a unified model. This article presents a review of current research to illustrate the neural correlates and plasticity of brain to accommodate the changes in consciousness.
EMOTIONS AND LIMBIC SYSTEM
In 1884 William James first proposed the idea that physiological and behavioral responses precede a subjective experience of emotions that are marked by “distinct bodily expressions” (Friedman 2010). Today the emotion-specific autonomic nervous system is an important area for research. This construct of autonomic specificity continues to influence the number of core theoretical issues in affective science, such as the existence of the structure of affective space, the cognition-emotion relationship and the function of emotions (Friedman 2010). In review articles on electrical autonomic correlates of emotions, a consistent relationship between the autonomic state and emotions has been observed (Beauregard et al 2001, Sequeira et al 2009).
The limbic system is not the only neural element involved with emotions (Ressler 2010). The emotions activate the autonomic nervous system as well, and peripheral input leads to preparation of the body in acquiring a reward or avoiding a punishment. This model is related to the following: a) how attention progresses along networks within working memory, b) how a single, unified concept is formed, c) how value-based and cognitive-based concepts are formed, and d) how a stream of consciousness is put together and driven forward. These concepts are integrated into a scenario of the orchestration of the conscious experience and behavior by subcortical limbic system structures interacting with the cortex (Ressler 2010).
Any concept of consciousness is linked to the brainstem. The ascending reticular system (ARAS) projects from the lowest level of the mesencephalic formation reticularis in the brainstem to the thalamus. The thalamus further connects to the hypothalamus, cortex, basal forebrain, and limbic system. Interruptions of ARAS can impair consciousness (Jellinger 2009). Its activity with higher centers is tied to several states of consciousness, a) hyperalertness, b) alertness, c) somnolence or lethargy, d) obtundation with tendency to sleep, e) stupor, f) coma and dreaming. Although the brain is a key area of consciousness, the connections of the brain stem with the heart, lungs, and viscera are vital to the level of consciousness (Jellinger 2009). Alterations to the autonomic nervous system are transmitted to the entire body. Similarly, a change in emotions brings about a corresponding change in autonomic response (Lang & McTeague 2009). Monitoring of electrodermal activity in relation to the brain was found to be a useful tool in monitoring emotional states. The emotions affect the thinking process and cause somatic changes that vary depending upon the extent of the response of mind and body (Lang & McTeague 2009).
MODELING SPATIAL AWARENESS DURING THE MIND-BODY RESPONSE
Normally, we are aware of our physical bodies when we are walking, swimming, dancing etc. The mind-body response involves the interrelationship between one's physical health and the state of one's mind. The tactile consciousness and general spatial information cannot be separated completely (Aspell et al 2009, Gallace & Spence 2008). Those who practice a mind-body technique, such as pranayama, may experience bodily awareness that merges with awareness outside the body (Mehling et al 2011). This experience may be described as a state of inner and/or outer awareness. Our proposed visual model utilizes pranayama (the ancient Indian art of breath control, here simplified to techniques of slow, deep breathing, see figures 1-3) to achieve a better understanding of how pranayama may induce relaxation and the concomitant harmonization of internal and external space.
Meditation and pranayama can be thought of as tools that can be used to make an assessment of internal and external space. The physiological response from deep breathing leads to an autonomic shift from sympathetic to parasympathetic dominance (Jerath et al 2006). The spatial aspect of mind may be dynamically changed from an agitated to a calmer state. This change can be induced by synchronization of hemodynamic changes to slower heart and breathing rates with brain activity. Awareness of the mental transformation to a state of increasing calm can lead a pranayama practitioner to an experience of inner and outer space via increase of self-awareness through practice. Therefore, pranayama and meditation can be windows to the mind and brain.
It is well known that deep, slow breathing leads to detectable changes in our sympathetic nervous system and cutaneous blood vessels (Baron et al 1996, Pilowsky 1995). This was observed in both normal healthy subjects and those who have had sympathotectomy, a surgical procedure where the autonomic ganglion is removed (Baron et al 1996). The muscle vasoconstriction, sudomotor, and pilo-erection of skin that occurs during deep inspiration can be detected based on respiratory patterns (Pilowsky 1995). In a study where skin sympathetic activity was measured by microneurography, bursts of activity associated with irregular respiration were noticed (Habler & Janig 1995, Iwase 2009). The deep, slow breathing leads to inhibitory signals and hyperpolarizing action potentials that affect the brain, heart muscles, and skin with physiological changes that an experienced pranayama practitioner may be able to observe (Matsumoto 1996).
Our proposed visual model that represents dynamic changes of awareness during practice of a slow deep breathing includes visualization of internal and external space (see Figure 1). The internal space within the self cannot be ordinarily (Stage 1, see Figure 1.A) differentiated from outer awareness (Yu et al 2011). Subjects who were trained to practice Yoga Ujjai respiration (pranayama, four to six breaths a minute) increased respiratory sensations (Villien et al 2005). They could also discriminate digital, tactile, mechanical pressure and sound pressure (auditory) stimulation (Villien et al 2005). Irregular, shallow breathing is thought to promote sympathetic tone (Dolan 2007, Pilowsky 1995), while deep, slow breathing leads to a potent parasympathetic dominant response (Iwase 2009). Normally, the sympathetic tone decreases to 2% of respiratory cycle at the end of inspiration and increases to 25% or 30% total at the end of inspiration (St Croix et al 1999). During pranayama, the increased length of inspiration decreases sympathetic tone (Jerath et al 2006). Therefore, over twenty minutes of pranayama, the body undergoes a change to parasympathetic dominance (Jain et al 2005, Pramanik et al 2009); see Figure 1.D-4.D.
NEUROPROCESSING OF INTERNAL AND EXTERNAL SPACE
The brain senses internal and external space simultaneously and pranayama practice may help to expand our awareness to increase comprehension (Roy & Llinas 2008). The visual spatial memory has been extensively studied. It is known that when objects disappear from view, we can still bring them to mind, at least for a brief period of time, because we can represent those objects in visual short term memory (VSTM) (Astle et al 2010, Cowan 2001). The defining characteristic is topographic, that is, it preserves a spatial organization from the original perception, such as a panoramic view of sky or an object close by. The meditator has a sense of increased interior “space.” This endogenous space may expand during pranayama. The space of the body schema, such as the lungs, expands, as does the sense of interiority. At the same time, the perceived boundaries of the body become more fluid, as the perspective changes from the body as perceived from the outside, to the body as perceived from within (see Figure 1.A-D).
The awareness of pranayama-induced respiratory sensations is illustrated in our model (Figure 2). Piloerection, a form of tactile sensation, (Halata 1993), occurs with deep breathing and allows a practitioner of pranayama to be aware of the external borders of the whole body (Figure 2.B). In stage 2, when a practitioner focuses his/her attention with eyes closed to the face and body, the difference in both internal and external space can be better differentiated. When pranayama is practiced over a twenty-minute period (Figure 3.A), the awareness of bodily space decreases, while the cerebral consciousness expands. In a study conducted to observe the cognitive performance by unilateral forced nostril breathing, external spatial task performance was significantly enhanced (Jella & Shannahoff-Khalsa 1993).
fMRI AND OTHER IMAGING FINDINGS
Functional MRI studies were conducted to compare the different activations of neural structures when an individual sees an external object or imagines the object with eyes closed. In a study where widespread areas in the brain were activated (including bilateral cortical activation), an object imagined was associated with the visual cortex. This represents automatic orientation in a smaller area in the visual cortex (Mayer et al 2004). This suggests that there is more synchronization of neurons in the brain when an article is imagined surrounded by a larger space within the mind. During pranayama, or other meditation practices, one may perceive an empty space within the mind without the object. This process may lead a long-time practitioner of pranayama to experience expansion of endogenous space (internal calmness) during the practice.
Imaging shows increased blood flow in frontal lobes and decreased blood flow in parietal lobes after focused meditation (Newberg et al 2010). A study conducted with mindfulness-based stress reduction on patients with social anxiety disorder reported that during the breath-focused attention task, subjects showed (a) decreased negative emotional experiences, (b) reduced amygdala activity, and (c) increased activity in brain regions implicated in attentional deployment (Goldin & Gross 2010). Another study conducted by Lazar et al. analyzed subjects that practiced Kundalini meditation daily over a 4-year period. Physiological changes were associated with Kundalini meditation after slow deep breathing, immediately after which the respiration rate slowed down from 12 to 16 breaths per minute to 4 per minute, and the heart rate increased. Other changes observed were increases in oxygen saturation, decreases in CO2, and decreases in global fMRI signal activation. These changes showed that focused meditation activated neural structures involved in attention (frontal and parietal cortex) and arousal/autonomic control (pregenual anterior cingulate, amygdala, midbrain, and hypothalamus). Activation of the putamen, precentral and postcentral gyri and hippocampus/parahippocampus, was shown to be associated with the meditative state. The results suggest that meditation has an effect on the autonomic nervous system by means of activating specific neural structures (Lazar et al 2000).
Another example is seen in ChunDoSunBup Qi-training. Compared to the resting state before Qi-training, subjects reported less anxiety, their activation coefficients decreased, and alpha wave activity increased significantly during sound exercise and meditation in the occipital regions. This may be because the Default Mode Network (DMN) activity increased during meditation possibly via reduced limbic activity and increased respiratory activity causing increasing DMN (Birn et al 2008, Lazar et al 2000). These results suggest that this type of meditation may reduce activation of the visual cortex and its influence on the thalamus and other functions of the brain. Results of this practice include decreased anxiety levels and modulation of psychological, neurological, and physiological functioning (Lee et al 1997).
Current research illustrates how the neural correlates and plasticity of brain accommodate changes in consciousness. In order to adequately model changes in consciousness during meditation, the interactions between the body, the mind, and the surroundings must be taken into account. Merely locating consciousness within the brain will not account for the dynamic interactions that occur within the body’s various systems as it interacts with the environment. To our vision, external space, brain, heart, limbs, and viscera may appear separate, but our consciousness that includes all of these elements operates in a unified manner. This remarkable synthesizing aspect of consciousness has slowly progressed towards a general theory of consciousness to date. Neural correlates of expanding awareness during the relaxation response describe how the autonomic nervous system shifts from a sympathetic dominant to a parasympathetic dominant state. Understanding the mind-body response, physiological and psychological changes that take place through the practice of mind–body techniques based on empirical research and practitioner responses, makes possible further clinical neuro-physiological research and brings the study of consciousness closer to a unified model. Further research is needed to define tangible parameters that may standardize the notions of self, mind, and consciousness.