Human body has five sheaths or layers.
Annamaya Kosa, Of Food,
Pranamaya Kosa,of Vital Breath,
Vijnanamaya Kosa, of Knowledge,
Manomaya Kosa , of Mind and
These five layers surround the Atman,the individual self.
Annamaya Kosa is made up of the essence of Food, not food itself.
The food we eat gets digested and its essence. called the Rasa and it sustains the body.
Food determines our thoughts and dispositions-read my post on this under Hinduism.
We become what we eat for we think because of what we eat and we become what we think.( Bhagavad Gita)
Prana is the subtle breath, not actual air.
It is the subtle quality of air.
Breath regulation is taught is Yoga;people mistake control of air.
Breath has three aspects,
It is Puraka when inhaled(through the left nostril)
It is also called the Ida Nadi.
Rechaka is drawn through the right nostril, Pingala Nadi.
When retained in the lungs it is Kumbhaka.
The ratio of Pranayama, of breath control is 1:4:3-Puraka:Kumbhaka:Rechakam.
Mind is the other layer.
Thought waves determine what we think and what we think decide what we are and what we become.
Through right food and right breath control, right mental disposition can be attained.
Vijnana or Knowledge is another layer, made of two types of knowledge.
Para Vidya, Knowledge of the Reality, which is eternal, correct .
The other one is Apara Knowledge, of the mundane kind, Science and other empirical knowledge.
The term Vijnana is used to distinguish from the correct knowledge, Vidya.
All these constitute the attributes of the soul to enable perception and understanding.
By careful and correct practice soul can evolve higher.
When a human being is about to die,of natural causes, ears give out first-loses the power of hearing .
Then eyesight goes.
Speech then fails.
Body becomes getting cold from feet upwards.
When life breath leaves from the left nostril,enters the lungs for last time, it comes out in a long sigh and is life is gone.
This is a description of the process of death in Hindu scriptures.
Even after life has gone out -the Annamaya, Pranamaya are gone-vijnana maya remains for twelve days after death.
It also leaves after the twelfth day ceremony called Sabindekaranam is performed.
Annamaya Kosa is Eternal, remains even after death.
The remnants of the Vijnana is now detected and scientifically proved in the form of electrical signature in the Brain.
Whether and how the dying brain is capable of generating conscious activity has been vigorously debated.
But in this week’s PNAS Early Edition, a U-M study shows shortly after clinical death, in which the heart stops beating and blood stops flowing to the brain, rats display brain activity patterns characteristic of conscious perception.
“This study, performed in animals, is the first dealing with what happens to the neuropsychological state of the dying brain,” says lead study author Jimo Borjigin, Ph.D., associate professor of molecular and integrative physiologyand associate professor of neurology at the University of Michigan Medical School.
“It will form the foundation for future human studies investigating mental experiences occurring in the dying brain, including seeing light during cardiac arrest,” she says.
Approximately 20 percent of cardiac arrest survivors report having had a near-death experience. These visions and perceptions have been called “realer than real,” according to previous research, but it remains unclear whether the brain is capable of such activity after cardiac arrest.
“We reasoned that if near-death experience stems from brain activity, neural correlates of consciousness should be identifiable in humans or animals even after the cessation of cerebral blood flow,” she says.
Researchers analyzed the recordings of brain activity called electroencephalograms (EEGs) from nine anesthetized rats undergoing experimentally induced cardiac arrest.