Individual Effects
The Issue: Isn't transcendental consciousness just a metaphysical concept?
The Evidence:
Transcendental consciousness has been a metaphysical concept for centuries, because there was no practical technology for reliably producing it. With the availability of Maharishi’s Transcendental Meditation program, taught worldwide in a standardized format, it has now been studied in many laboratories.
Wallace was the first to measure the physiology of transcendental consciousness. 1-3 He found that the physiological pattern characteristic of transcendental consciousness indicated that it is a fourth major state of consciousness, which is physiologically distinct from the first three major states, waking, dreaming, and sleep. 4 A meta-analysis of 31 studies found that during TM practice the respiration rate, heart rate, basal skin conductance, and plasma lactate levels decreased more during the practice than during ordinary rest. 5 A review by Alexander, et al. distinguished transcendental consciousness from waking, dreaming, and sleep on 20 psychophysiological parameters. 6
Wallace found that transcendental consciousness is more than just a state of physiological relaxation, as produced by relaxation techniques, but also has a 'restful alertness' component. 1-3 Restful alertness is indicated by a number of parameters: increased alpha EEG power, particularly in the frontal, executive control areas of the cerebral cortex; 1 2 7-11 increased cerebral blood flow; 12-14 increased arginine vasopressin; 15 and shorter P300 latencies and reaction times in visual tasks following meditation. 16 17
Contrary to hypotheses that meditation merely produces relaxation, skin conductance, an unambiguous marker of sympathetic nervous system activity, increases at the onset of the transcendental consciousness period.18 This is interpreted as corresponding to the subjective experience of heightened inner awareness during transcendental consciousness. Generally, however, the level of skin conductance is lower during the Transcendental Meditation technique than during ordinary rest, indicating that on average the meditation period is one of deep relaxation.1 2 5 19-21
The early research averaged the physiological changes during the entire meditation period, which obscured the dynamics of the process. Several subsequent studies focused on the objective correlates of specific periods of transcendental consciousness during the TM technique. They found that specific periods of self-reported transcendental consciousness are correlated with slowing of the breath by 40% or even virtual respiratory suspension for up to a minute without compensatory breathing afterwards. 18 21-24 Such patterns do not occur in resting controls during deliberate breath holding.
Kesterson and Clinch report that the reduction in respiration during the breath slowing is not due to a reduction in metabolic rate, as was previously thought, 2 but rather due to a significant drop in the respiratory exchange ratio (the ratio of the amount of carbon dioxide produced by the body to the amount of oxygen consumed). This indicates a significant fall in CO2 elimination during the slowing of breathing. They calculated, however, that the amount of CO2 retention in the body is relatively small. They also found that the fall of CO2 elimination covaries with decreases in alveolar ventilation. Before and during meditation, breathing slowed first followed by a reduction in CO2 elimination. After meditation, a rise in CO2 elimination was followed by a rise in the respiratory rate. They found that the respiratory "suspension" was not actually a complete cessation of breathing, but rather a continual slight inspiration of many small breaths.25
It appears from these data that transcendental consciousness is not primarily an a metabolic event of the bodily tissue, but rather is a brain-mediated event. The slowing of breathing during the Transcendental Meditation technique does not seem to be initiated by a fall in metabolic rate or oxygen consumption, but rather by events in the brain, principally the frontal cortex. The oxygen consumed by the body during meditation appears to be completely appropriate for maintaining the necessary muscle activity for holding the body in a sitting upright position, whether one is meditating or just resting ordinarily with eyes closed. Kesterson and Clinch found that when one lies down, and fewer muscles are used, then less oxygen is consumed than either during sitting meditating or sitting with eyes close. However, it is not completely clear that this is always the case, because an independent study from the University of Alberta, Canada, found a significantly greater drop in metabolic rate during TM (15.5%) than during supine rest (3.5%, p < .001), even though the initial baseline level was somewhat lower for TM than rest supine (257 ml/min compared to 275 ml/min, respectively). This study also found that whereas TM decreased the volume of air being breathed (tidal volume), resting supine increased it. 26
In any case, the respiratory slowing during the Transcendental Meditation technique appears to be part of the orienting response, which is mediated by the brain, particularly the executive frontal areas, where TM has its greatest effect. It is well known that part of the orienting response is slowing of breath rate when one's attention becomes absorbed into novelty or into something one is really interested in. 27 The function of this is believed to enhance perception. As one becomes absorbed into the more blissful, subtler areas of thought, and eventually transcends into unbounded bliss consciousness, the breathing naturally slows. It should be noted that unlike some other meditation techniques in which breathing is intentionally controlled or attended to, there is no controlling of the breath or paying attention to it during the Transcendental Meditation technique. Any changes in breathing during TM are completely natural and spontaneous. Breathing slows during the Transcendental Meditation technique because attention becomes completely absorbed in the process, not because one is controlling the breath.
As breathing slows down, the carbon dioxide level in the body begins to rise. Usually, slight rises in carbon dioxide stimulate reflexive mechanisms in the brainstem to cause the ventilation rate to increase. But during Transcendental Meditation, the adsorption in bliss appears to override these reflexive mechanisms. This is not harmful to the body, because the amount of carbon dioxide retained is actually very small.25 It appears to be similar to one not noticing some discomfort in the body while they are absorbed in deep meditation.
It is interesting to note that this reduced responsiveness to carbon dioxide levels during deep meditation may be an indication of increased "equanimity", traditionally said to be a quality that develops with regular practice of the Transcendental Meditation program. The traditional literature on meditation says that as one grows in enlightenment, one gains "equanimity in pleasure and pain, victory and defeat". In enlightenment, one is said to spontaneously perform at a very high level, but to be even minded with regard to the results of action. In a recent neuroimaging study, we found that over a period of four months, Transcendental Meditation practice reduced the brain's reactivity to pain, although the subjects continue to perceive pain just as acutely as before. 28 Several other studies relating to this quality of equanimity are discussed in the section on enlightenment.
One of the changes in the brain that appears to be correlated with increased bliss during transcendental consciousness is increased EEG coherence. 18 23 29 30 During periods of marked slowing of the breath and transcendental consciousness, EEG coherence increases across all frequencies and cortical areas compared to periods immediately before and after. 18 23 Such patterns do not occur in resting controls during deliberate breath holding. EEG power and coherence are particularly evident in the 6-10 Hz band peaks, with large individual differences in peak frequencies and scalp locations. 24 Coherence increases both bilaterally between the hemispheres in frontal cortical area, as well as between anterior and posterior regions. 10 21 31 EEG coherence distinguished the meditative state from non-meditating periods better than EEG power.21
High EEG coherence indicates a higher level of communication among brain areas. 31 One indication of this is that the brain’s registration of novel experiences (P300) is faster during meditation. 32 It makes sense, then, that high EEG coherence has been correlated with experiences of transcendental consciousness, greater creativity, increased flexibility of concept learning, principled moral reasoning, and more rapid recovery of the H-reflex. 30 33-35
Travis and Wallace found that the changes to slowing of breath and increased EEG coherence occur within the first minute of meditation. They speculated that this rapid shift in physiological function in the first minute suggests a neural switch in the pre-frontal area, which inhibits specific and nonspecific to thalamocortical circuits, which induces the restfully alert state. They suggest that the resulting restfully alert state might be sustained by a basal ganglia-corticothalamic threshold regulation mechanism automatically maintaining lower levels of cortical excitability. 21
The evidence indicates that the state of increased EEG coherence seen during the Transcendental Meditation program becomes a trait of increased coherence outside of meditation and during tasks. 36 37 Dillbeck found that resting EEG coherence increased after two weeks of TM practice. 36 Travis et al. found higher EEG coherence during a reaction time test in subjects experiencing stabilized transcendental consciousness compared to controls. This study also provided evidence that the stabilized subjects’ brains were less bound to preconceived cognitive commitments than controls, 37 which has also been demonstrated by cognitive research. 38
Recent research compared "self-referral" subjects, who identify their "self" with transcendental consciousness, an abstract sense of self underlying thoughts and feelings, with object- referral subjects, who define themselves in concrete cognitive and behavioral terms. The self - referral subjects had higher frontal EEG coherence, higher EEG alpha (which is related to restful alertness), lower EEG gamma (which is related to active thinking), and a more efficient cortical response to task than the object - referral subjects. 39
The distinctive phenomenological and physiological characteristics of transcendental consciousness have been reviewed by Travis and Pearson.40
References
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