Neurophysiology of Meditation
Retd. Chief Technical Examiner To The Govt. Of Kerala, Kerala, India
By simple definition, meditation is engagement in contemplation, especially of a spiritual or
devotional nature. To elaborate further, meditation is an attempt to concentrate mind on a single
form or an idea or an aspect of divinity at the exclusion of all other forms, thoughts, and ideas.
The mind is focused inwards, and this effort of concentration acts as a stimulus to gain access
to knowledge of 'object of meditation'. The aspirant makes an attempt to minimize perceptions
through senses - inputs through special senses like touch, sight, hearing, etc. - by detaching
mind from sense organs in the brain. This helps in controlling restlessness of mind, in
inner contemplation. The mind, as if, is made still. Meditation may be, therefore, taken as a
'passive' activity! But is it really so?
Tremendous changes observed in the human brain and nervous system during mediation run
contrary to this belief of 'passivity' attached to meditation. Unprecedented progress and research
in neurobiology, investigative neurology, and study of neurotransmitters in the last two decades
has given a great fillip to the study of neuro-physiology of Meditation and Yoga. Altered State of
Consciousness can be brought about by hypnosis, drugs (e. g. LSD), sleep, etc., but here we
are trying to study a state specific science of altered consciousness brought about by
We shall attempt to review the progress in neurobiology in the recent years. An attempt is made
to throw light on this new and fascinating subject. The terms used are technical, but, as far as
possible, an attempt is made to simplify the description.
This attempt to explain the neurophysiology of meditation is purely hypothetical.
Meditation and Changes in Neurophysiology:
One of the ways to control physiological reactions to psychological stimuli is meditation, Yoga,
Zen Buddhism etc. The scientists take Transcendental Meditation (TM) as the uniform
technique, and base their observations on the study of the subjects engaged in this form of
meditation. In summing up the results the scientists have come to conclusion that the effect of
meditation is a "wakeful, hypo-metabolic state."
They have found that:
1) Yogis could slow both heart rate and rate of respiration.
2) Yogis could slow the rate of metabolism as confirmed by decreased oxygen consumption and
3) Electro-Encephalo-Gram (EEG - recording of brain activity) in Yogis showed changes of
calmness in the form of "alpha rhythm" during both eyes closed and eyes open recordings.
4) Their skin resistance to electric stimulation was increased (indicating increased tolerance to
Our usual 'defense-alarm' reaction to emotional and physical stress is in the form of "fright,
flight, and fight" mediated through over-secretion of certain neuro-transmitters and
neuro-modulators, namely adrenaline and dopamine by way of stimulation of sympathetic
nervous system. Under the influence of these chemicals and hormones, we reflexively become
panicky or aggressive, our blood pressure rises. Thus stress and anxiety is the end result if we
allow our natural age-old sympathetic reactions to act and to come to surface. We try to run
away, become fearful, or fight the situation. But today these 'defensce-alarm' reactions have no
place in our lives. Rather, they should be replaced by more calm and serene reactions of
equanimity and fearlessness. The need is to just 'face the brute, and it will go away'. Such
desirable reactions of non-aggression and peaceful attitude are generated by Yoga and
EEG Studies on Yogis and The Zen Meditations:
Yogis practicing Raja-Yoga claim that during the state of samadhi they are oblivious to the
internal and external stimuli, and they enjoy a calm ecstasy during that state. A study was
undertaken to record the electrical activity of their brain during this state by means of a regular
and useful test known as electroencephalography EEG. Physiological and experimental studies
have demonstrated that the basis of conscious state of brain, among other things, is due to
activation of "reticular system" in the brain-stem in response to internal and external stimuli.
These stimuli bring about various changes during sleeping and wakeful states of the organism
and these can be studied by EEG.
The study was carried out on four subjects during the state of concentration and meditation.
Effects of external stimuli, like a loud gong, strong light, thermal simulation, and vibrations were
studied. The results were compiled and analyzed. It was observed that two Yogis could keep
their hands immersed in extremely cold water for about 50 minutes (raised pain threshold).
During state of meditation, all of them showed persistent "alpha activity" in their EEG with
increased amplitude wave pattern, both during 'eyes closed' and 'eyes open' recording. It was
observed that these alpha activities could not be blocked by various sensory stimuli during
meditation. It was also observed that those, who had well-marked "alpha activity" in
their resting EEG showed greater aptitude and zeal for maintaining the practice of
Yoga. Similar observations and results were obtained when EEGs were recorded in persons
adept in Zen Meditative technique. Can we say that only those persons who exhibit such
recording of "alpha wave rhythm" in their EEG are fit for Yoga? and be designated as right
candidates for meditation and Yoga practices? (Such experiments are indeed very few and the
number of yogis examined is also very small. Therefore, scientifically and statistically these
observations have only a tentative importance. Further research is definitely called for, albeit it
will have its own limitations.)
Discussion and Conclusion
Neurotransmitters and Neuro-modulators: These are chemical substances released at the
Neuronal Synapses (nerve junctions). They act by altering electrical membrane potential by
opening up channels that permit diffusion of Sodium, Potassium, and Calcium ions in and out of
the nerve cell. They not only transmit the message from one cell to another, but also selectively
facilitate some information while inhibiting the other. Moreover, the action of Calcium ions
permits transfer of electrical events into molecular changes that can alter functions of the nerve
cells permanently, i.e. change cellular function to subserve a memory or learning response.
Neuro-modulators affect the neuro-transmitters by influencing neuronal plasticity, growth, or
differentiation. Different types of receptors, as present in different regions of brain, can account
for the complex and multiple effects of medication, meditation, concentration, and
contemplation. This may be effected through actions of specific type of neuro-transmitter and
For example, a sub-type of glutamate receptor appears to mediate the function of brain
plasticity, a process considered important in learning and memory.
Acetylcholine helps in memory, motivation, perception and cognition. It is also involved in
attention and arousal functions of ascending reticular system. Decrease in the levels of this
neuro-modulator leads to loss of memory, senile dementia - Alzheimer's disease.
Excess of serotonin, another important neuro-modulator, leads to hallucinations, as seen in LSD
consumption, which causes increase in serotonin level. This discovery called attention to the
correlation between behavior and variation in brain serotonin content. Selective depletion of
serotonin, in animals, causes prolonged wakefulness. It also plays important role in circadian
rhythm and sleep cycle.
Other neurotransmitters and modulators like nor-epinephrine cause changes in mood - excess
leading to elation, and deficiency causing nervous depression. It also controls food intake,
regulates temperature, and hormonal secretions.
Excess of dopamine level is responsible for schizophrenia and psychosis.
Nerve growth factor is a hormone like peptide that is responsible for the growth and maintenance
of various brain structures.
The plausible hypothesis to explain the altered state of consciousness brought about by
intense and prolonged mediation may be constructed as follows:
The evolutionary process adds higher centers to the primitive nervous system. These higher
centers have inhibitory influence, in other words they suppress the functions of lower
Thus, the brain stem is controlled by the higher limbic system, and the limbic system in turn is
controlled by still higher neo-cortex. The neuro-modulators with their influence on various
neuro-transmitters effectively bring about this inhibitory modifications and inter-relations among
various brain centers (hierarchy).
For instance, involuntary movements like tremors and chorea are suppressed by basal ganglia
through the action of dopamine and acetylcholine synergy. Any imbalance in these
neuro-modulators causes involuntary movements like chorea, tremors (Parkinson's Disease
etc.). Similarly, loss of cortical control over the motor neurons of spinal cord leads to
exaggerated muscle and tendon jerks due loss of inhibitory control of the higher motor cortex.
Neo-cortex keeps all the involuntary movements, hyper-reflexivity, rage, aggression, and similar
animal tendencies under check so that it can effectively pursue its own highly developed
activities of logic, memory, reason, language, calculations, judgement, and concepts, etc.
Conscious, willful, imaginative functions are therefore, normal state of awareness of the human
When meditation acts as a constant repetitive stimulus, certain qualitative and quantitative
permanent changes develop in the nervous system. The neuro-transmitters and
neuro-modulators may stimulate growth of dormant or latent neurons to develop a
center (or centers) which on the evolutionary ladder is/are still higher than the present day cerebral cortex.
The brain may develop new connections and plasticity resulting in the capacity to think, to
rationalize, and react in a different way to the sensory input than what is expected by present
day physiologists. For want of name, we may label such higher center as 'God Module'. This
higher center will exert inhibitory control over the present day neo-cortex, and thereby, over the
mind as a whole (consciousness, reasoning, conceptual thinking, willing, feeling, and doing,
etc.)! The consciousness and all mental activities will hence be suppressed. The person will
reach a state beyond mind itself - transcendental awareness!
"The spiritual ascent is from the least evolved state of consciousness to near perfect state, after
which the mind itself will cease to be, and there will remain only non-dual experience."