Yoga, rebirth and Science

I consider myself fortunate to be born in India, the great land of Rishis. I am proud to be a part of Vedic heritage. I am a physician, a scientist by profession, but I consider the knowledge of Sanskrit language and Vedic literature and an attempt to follow such path as shown by our sages, a privilege. Our sanskriti, or culture has been a slave of various invaders over last 2000 yrs.  Some serious attempts have been to destroy everything that we have our literature, temples, social customs etc. over 1000 yrs.  I am proud to say that despite this repeated mutiny, it has survived. There must be some strength and resilience in in our religion, culture, values and social structure. This is not the case in many parts of world, where most of the original culture and values have largely been replaced by what was brought in by the invaders.

Today, in USA, there is hardly any significant town which does not have a yoga center. Western individuals have modified the yoga to its needs. Some call it a Christian yoga, others stress that it originated from Buddha religion and yet others simply follow what is being taught to them in health clubs, place of work etc. as long as it makes them feel healthier, relieves stress, improves sleep etc.

Besides self-realization and relief of stress, the ultimate goal of human life is salvation. After death, the soul can be reborn or get salvation, a state where the soul stays for an extended period of time before rebirth. So, the phenomenon of rebirth is really intertwined with yoga and meditation.

So I will speak on two subjects, the Yoga and Rebirth. I will try to explain what the modern science has to say about these two subjects and whether this all makes sense.

Phenomenon of rebirth

Swami ji has quoted mantras from the Rg veda, Yajur Veda and Atharva veda which essentially mean that “the seeker is praying for an auspicious and meaningful birth in a life full of good fortune, good conduct, usefulness to the self, family and society”. Swami ji further stated while explaining the meaning of a mantra from Atharva veda that a person who lived his/her life righteously gets a good rebirth and vice versa. After leaving the body (death), the soul first stays in the ether, followed by water, medicinal plants and then the vital breath. It then enters in the semen and then enters the ovum. Then fertilization and Zygote formation accours leading to subsequent fetal development in mother and finally the birth.  This concept of father being the first parent comes with a total surprise and shock to most people.

Sage patanjali describes in his Yoga Darshan’s 2nd chapter of Sadhan-pad from 3rd to 9th suktas, that there are 5 types of “Kleshas” or unhappinesses.
These are Avidya, Asmita, Raga, Dwesha and finally Abhinivesh. The last one is the fear of death, which is essentially a universal phenomenon. One who understands the eternal truth that the soul is immortal, and fully surrenders to God, “Ishwar Pranidhan” and obeys the universal laws of humanity can become free from the unhappiness’s.

Now I will describe what some researchers have concluded or at least have pondered on this issue of “life after and before life”. One of my readings has been a book called “life after life” by Dr. Raymond Moody. He did his PHD in philosophy from university of Virginia in 1969. He taught philosophy at a university in North Carolina and then went to medical school and became a psychiatrist. As a practicing psychiatrist, he stumbled on this subject of people narrating their near death experiences. He became interested in the subject of life after death and since then has written several books.  He has not concluded by any certainty that there is a phenomenon of rebirth. He did not package it in to a religion either.

In his book, he has systematically summarized the near death different experiences of different people from different cultural, social backgrounds, all ages, both sexes and different levels of education and professional backgrounds. Here are his observations.

He has put the experiences of people in 3 categories.

  1. People who were resuscitated after they were thought to be dead by conventional medical wisdom, which means, lack of response, no pulse, BP, heartbeat, respiration, dilated pupils and a falling body temperature.
  2. Persons who came close to death by accidents or illnesses.
  3. Dying people who narrated their feelings to people around them, who in turn described these to Dr. Moody

Here is the common sequence of happenings.

  1. First- person heard a loud noise or a ringing or buzzing,
  2. Then he/she felt himself/herself moving through a very dark space or a tunnel of various shapes,
  3. Then suddenly found himself/herself outside his/hers own body and actually observed the body lying there.
  4. Initial feeling was neither of happiness nor unhappiness and then there was an intense feeling of joy, love and peace.
  5. The person saw a very bright glow of light and felt that there was a person of sort(not a physical form), a being he/she had never seen before and some also saw their friends and relatives who had long passed away.

The dark tunnel which is described above has been described as deep and dark. There was no fear. This was a wonderful worry free experience.

About watching one’s own body:  This was a floating sensation, person being not upset about seeing one’s own body from distance. Some people felt that they were pure conscious beings in that state. Some people felt that in that state, they could see anywhere, anything through the time, space and person.

About meeting others, the person could hear them; communicate with them, but not in the words as we normally use to communicate with people.

Presence of a very powerful, completely loving being was felt by people as well.

There came a point in these people’s experiences that as they were moving through this boat or tunnel, the feeling of joy was so intense that they did not want to go back in to the body. It almost seemed that on the other side where his/her friends/relatives/the being of light was, there was a border. The person could not go beyond that border. The person was being pushed back towards the tunnel, towards their own body. It makes sense, that they did not cross that border as these people were alive and able to tell their stories. Those who did cross that border obviously could not come back to life to tell their stories.

Anyway, I cannot summarize the whole book here in detail, but it seemed to me that these experiences are almost identical to what our sages have experienced in the state of deep meditation, the separation, the joy, the union with Supreme Being etc. I am thoroughly convinced that the Upanishads and other such texts were the results of real experiences of our sages including Swami Dayanand Saraswati. Of course the basis of all knowledge is the Holy Vedas.

The scientific research seems to be proving the phenomenon of rebirth.


Meditation and yoga and scientific research

First, I would like to go over my understanding of the structure and function of brain, especially as it relates to its involvement  in thought process, emotions, reactions, sleep, wakefulness, fear, happiness, unhappiness etc. Also, I would like to explain the positive changes that occur in brain with meditation.

We all know that one of the benefits of pranayama is better oxygenation. This is achieved by better ventilation in lungs resulting in more oxygen in the blood and better dissociation of oxygen at a tissue level with better availability of oxygen to the body.


Recently there has been some interesting research in the field of meditation. You will be happy to know that there is even a center of spirituality and mind in some universities in USA and the examples are university of Pennsylvania, Harward, Yale and MIT.  SPECT, fMRI and EEG scans have been done people who have been meditating for many years in resting state and while meditating. Under the leadership Andrew Newberg professor of nuclear medicine, SPECT scan has been done in these long term meditators in resting state and during active meditation. The main finding has been that of more activity in frontal lobe and less activity in parietal lobe during meditation. To under more changes, we need to first understand the brain structure and function .

The top part of brain is called the cortex. The parts of brain which constantly interact with the cortex are called, limbic system, thalamus, hypothalamus, other nuclei of the brain, brain stem and the reticular system.

Pertaining to this talk, I will focus on the following.

  1. Frontal lobe could be called the AAA or attention association area

Deals with will-power, focus of attention/energy and concentration. Prefrontal area is the brain’s top executive. It organizes responses to complex problems, guides behavior with verbal skills and houses networking memory.

  1. Connected to the limbic system and helps to mediate attention, emotion, and memory
  2. Parietal lobe. It is also called OAA or the orientation association area. . Sensory input from the body goes in to this part of the brain.

Deals with orientation in space, provides distinction between self and the world and is the seat of mind and ego

Any change in this, can create an out of body feeling and distorted experience of space and time

  1. Limbic system. It is involved in instinctive behaviors, deep seated emotions, memory and basic impulses such as sex, anger, pleasure and general survival. It also forms the link between centers of higher consciousness in the cerebral cortex and brain stem. This eventually regulates body functions. Parts of limbic system are: Cingulate gyrus, parahippocampal gyrus, Hippocampus, amygdala, hypothalamus, thalamus, mammillary bodies and other deeper more central brain structures. Limbic system is hard wired with sensory and motor cortex and has a role in expectation, reward and decision making. Cingulate Gyrus: It coordinates Sensory Input With Emotions Emotional Responses to Pain and Regulates Aggressive Behavior. It gets deactivated during meditation.Hippocampus is heavily involved in memory and space orientation. Damage to this part can prevent a person from forming new memories. This is specially so for memories of particular events. As far as space memory is concerned, it is confined to this Hippocampus only. Amygdala is involved in very special memories, at times called emotional memory. This also is involved in managing our reactions to fear. Mammillary bodies are small lumps of nerve cells which relay signals to thalamus, contributing to alertness and memory formation. Hypothalamus is a part of brain located at the base and it produces some chemicals which have a very important role in conscious behavior, emotions, instincts and automatic control of body systems and processes. This is mainly through what is called a hypothalamic, pituitary adrenal axis.

Memory. While we are on this subject, I would like to briefly mention the various parts of brain involved in the memory. Frontal cortex is involved heavily in short term memory. Visual memory is located in occipital cortex. As mentioned above Hippocampus is involved in memory of facts and events. Procedural memory or how to do things appears to involve cerebellum, basal ganglia and motor cortex.  Localization of a particular function to one side of brain has been questioned recently.

  1. reticular system. Through our senses, information of various types is being fed constantly to our brain through our nerves. This information travels back and forth to our brains through the brain stem in a series of long nerve pathways called the reticular system. This plays an important role in regulating our autonomic nervous system. There are various centers in the brain stem, which control and regulate our digestive, respiratory, circulatory, urinary and sexual functions. Reticular system constitutes an arousal mechanism that keeps the brain alert and keeps us awake. Information from the reticular system goes to part of brain called thalamus and then on the brain.

One can now understand how a modification of sensory input through the reticular system to various parts of   brain through Yoga/meditation can tone down and better regulate and control various body functions. Many of our responses to stimuli of various types are at subconscious level while some other involves a conscious action.

Now the scanning studies in people who are long term meditators.

The SPECT scan (single photon emission CT) showed that base line blood flow is higher in long term meditators in most of the brain and even the thickness of the grey matter is more. During meditation, there is deactivation of posterior parietal lobe leading to detachment from the outside world   and the increased activation of frontal lobe leads to intense concentration. Deactivation of cingulate gyrus might explain the feeling of happiness and a sense of well-being while meditating. So one can say that the command center of brain shifts from parietal to frontal lobe leading to higher level of consciousness and a sense of happiness.


Brain waves and Meditation

There are 4 types of brain waves.


Beta waves– low amplitude, high frequency and occur when the brain is working on a goal oriented task. The frequency of beta waves ranges from 15 to 40 cycles a second. Beta waves are characteristics of a strongly engaged mind. A person in active conversation would be in beta. A debater would be in high beta. A person making a speech, or a teacher, or a talk show host would all be in beta when they are engaged in their work. These are minimal during meditation.

Alpha waves-alpha represents non-arousal. Alpha brainwaves are slower and higher in amplitude. Their frequency ranges from 9 to 14 cycles per second. A person who has completed a task and sits down to rest is often in an alpha state. A person who takes time out to reflect or meditate is usually in an alpha state. A person who takes a break from a conference and walks in the garden is often in an alpha state. These are common in the posterior parts of brain during meditation.


Theta waves– The next state, theta brainwaves, are typically of even greater amplitude and slower frequency. This frequency range is normally between 5 and 8 cycles a second. A person who has taken time off from a task and begins to daydream is often in a theta brainwave state, and when in theta, they are prone to a flow of ideas. The ideation that can take place during the theta state is often free flow and occurs without censorship or guilt. It is typically a very positive mental state. These are the waves which occur during meditation in the prefrontal cortex.

Delta waves– high amplitude, low frequency and occur more during sleep. This indicates that sleep is distinct from meditation.  Their frequency ranges   around 1.5 to 4 cycles per second. They never go down to zero because that would mean that you were brain dead. But, deep dreamless sleep would take you down to the lowest frequency. Typically, 2 to 3 cycles a second.


When we go to bed and read for a few minutes before attempting sleep, we are likely to be in low beta. When we put the book down, turn off the lights and close our eyes, our brainwaves will descend from beta, to alpha, to theta and finally, when we fall asleep, to delta.


It is a well-known fact that humans dream in 90 minute cycles. When the delta brainwave frequencies increase into the frequency of theta brainwaves, active dreaming takes place and often becomes more experiential to the person. Typically, when this occurs there is rapid eye movement, which is characteristic of active dreaming. This is called REM, and is a well-known phenomenon.


When an individual awakes from a deep sleep in preparation for getting up, their brainwave frequencies will increase through the different specific stages of brainwave activity. That is, they will increase from delta to theta and then to alpha and finally, when the alarm goes off, into beta. If that individual hits the snooze alarm button they will drop in frequency to a non-aroused state, or even into theta, or sometimes fall back to sleep in delta.

Brain Size and Meditation

Meditators showed significantly larger volumes of the regions which regulate emotions.These are: hippocampus, prefrontal cortex, thalamus, inferior temporal gyrus and Rt. Insula. Also there was a study done on age effects on gray matter volume and attention performance in Zen meditation and it was found that there was no decline in the putamen grey matter volume with aging in people who are long term meditators.


So, it appears that meditation provides stress relief, relaxation, better focus in what we do, better control of thalamic and hypothalamic activity, resulting in better function of entire body, specially the cardiovascular and neuro-endocrine function. Anatomically and functionally, there seems to be more circulation to the desired area, desired brain waves and even slowdown of aging of brain and higher brain volume in desired areas.

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