As per the theory of evolution, man is the most highly evolved being. In the human body the brain is of prime importance. The brain is a most complex structure and has varied functions. Many mysteries of the brain have been unravelled by neurophysiology, but there is one part of the brain which has still remained an enigma. It is the prefrontal areas of the frontal lobes of the cerebral cortex. This is the foremost part of the brain situated just behind the forehead.
According to the process of evolution the brain is divided into an old part and a newly developed part. The prefrontal areas are the most recent development of the new brain. These areas are not found in the lower animals. They are present in a developed form only in the human brain. All these years this part of the brain was called the 'silent area' because nothing was known about its functions. No clinically discernible neurological loss could be detected with a lesion in the prefrontal areas. An operative procedure called lobotomy was tried in the earlier part of this century for the cure of a mental disease known as schizophrenia. In this operation the prefrontal areas were disconnected from the rest of the brain. The person used to live without his mental illness but with hardly any human qualities. He used to be a vegetative being.
The prefrontal areas were supposed to be the seat of intelligence. Yet, efforts to show that the prefrontal cortex is more important in higher intellectual functions than other portions of the brain have not been successful. In fact, destruction of the general interpretive area of Wernicke, situated in the temporal lobe of the dominant (usually the left) hemisphere of the brain causes infinitely more harm to the intellect than does the destruction of both the prefrontal areas.
Research on the prefrontal areas is difficult, because:
But by non-invasive techniques, like measuring the blood flow, it has been shown that even the resting blood flow in the prefrontal cortex is higher than that in other cerebral areas. The brain constitutes only 2% of the body weight, yet it receives 20% of the entire circulating blood volume. The cerebral cortex is the neuronal mass comprising 75% of the brain of which the prefrontal areas constitute quite a major portion., Thus, even when the prefrontal areas are not obviously involved in any activity, they are receiving a large amount of blood, which means they have some higher, important function. It has also been shown that the blood flow in the prefrontal areas increases with minor attempts at concentration such as listening to digits and reciting them in a reverse order or sorting out geometric figures according to shape, size and colour. If meditation has been preceded by pranayama, the cerebral blood flow is still more increased, as shown by the physiology of pranayama.
The functions of the prefrontal areas so far deduced are as follows:
Meditation is the sheet-anchor of all the yogic practices. There may be various ways but they all lead through meditation. There are many methods of meditation, such as mantra japa, ajapa japa, siddha yoga, 'transcendental' meditation, kundalini yoga, vipassana, etc. But the main principle in all of them is 'concentration' in the early stages, followed by simple 'awareness' at the final level.
One may reach the levels of concentration and drawing in of senses, i.e. pratyahara, through the physical processes of asana, pranayama, mudra and bandha in hatha yoga and kriya yoga. One may concentrate on visual symbols like a point, a flame, a lotus, a chakra, a yantra, an image of ishta, or the visual image of Om. Another may use an auditory or verbal japa of Om or any other mantra as used in mantra japa. A third may use sound as in nada yoga, or the act of breathing as in ajapa japa, to gain similar effects of concentration and pratyahara. One may concentrate on an emotion like the love of a deity in bhakti yoga, or a thought or idea in dhyana yoga. Even in the symbol-less meditation of vipassana of Buddha, the idea of impermanence is used for concentration. Instead of a communicable symbol like Om or an image, the sensations over the human body as a whole are used for concentration in vipassana.
While learning the physiological functions of the prefrontal areas of the frontal lobes of the: human cerebral cortex, we have noticed these main functions:
We have also seen that even simple acts needing some concentration increase the blood flow of the prefrontal areas. Meditation which is concentration in its purest form must be increasing the blood flow tremendously and exercising the prefrontal areas, thus developing them to a still higher level of performance and evolution.
At the beginning of the practice of meditation we associate some other cerebral centre along with the prefrontal areas. If we use a visual symbol we are employing the visual cortical centre along with the prefrontal areas: Similarly with all other methods of meditation, we are employing the corresponding cortical centres.
Blood flow measurement studies have shown that the blood flow in the corresponding areas also increases along with that of the prefrontal areas. These studies have not yet been done on the various meditative practices but on simple mental exercises like counting and reciting or visual sorting acts. They are worth a trial on the meditative practices.
In mantra japa the Brocka's area of speech is used. In laya yoga, the auditory area is utilised. In bhakti yoga, the limbic area dealing with emotions is involved. In dhyana yoga we bring into use the Wernicke's general interpretive area concerned with verbal reasoning. In vipassana we use the sensory cortex, while in ajapa japa we employ the motor cortex while watching the act of breathing. Whatever other centre we may use, we are employing the prefrontal areas to the maximum as concentration is the main feature of elementary meditation, and concentration is the function of the prefrontal areas.
As we progress further and further in meditation, we gradually do away with these extra centres, until finally we remain only with prefrontal areas in tune. This is the stage of savikalpa samadhi.
We do away with the visual symbols of point, flame, Om, swastika, ishta, lotus, chakra and mantra. We dispense with the auditory symbols of laya yoga and Om, and hear the anahata sound, which is nothing but the awareness of the sensation of sound by the prefrontal areas. We do away with the verbal symbols of various mantras. We do not remain concerned about the body sensations of vipassana or the motor act of breathing. We go beyond the emotions of bhakti yoga, and the processes of reasoning of gyana yoga. We remain only with awareness, with the prefrontal areas.
So many functions of the prefrontal areas are still remaining an enigma and are likely to remain so for reasons given above. When subjective ideas get involved in a scientific experiment, it no longer remains an experiment but becomes a personal, subjective experience. This phenomenon has started happening even in the natural sciences of subatomic physics. No wonder that it should crop up when we are dealing with the human mind.
But, even from the list of functions of the prefrontal areas so far known, one can deduce the achievements possible after the development of prefrontal areas through meditation.
Control of reactions to external stimuli is obviously possible. The highest levels of abstract thinking must have been achieved by the rishis through meditation. No wonder they have reached Himalayan heights of imagination and intuition to solve the mysteries of the universe, as expounded in the Upanishads. Social behaviour is influenced. Tranquility of mind is gained. The meaning of life is understood.
Through the practice of meditation we accelerate the process of evolution, whose current phase appears to be the development of the prefrontal areas of the human brain. This could be the arousal of super-consciousness.
The merging of the individual consciousness with the cosmic consciousness as envisaged in nirvikalpa and other higher states of samadhi may be beyond the domain of just human neuro-physiology.
This article is an attempt to correlate the contemporary knowledge of the human neurophysiology to the practice of meditation. New scientific knowledge may be added. At the same time, it is noted that meditation is more of the nature of an experience than an experiment. This experience is worth a trial even without knowing the 'How?' of it. Through meditation we transcend the mind. Thus meditation has still some qualities not yet understandable through our present knowledge of neuro-physiology. Hence, the final advice would be to follow the various techniques of meditation, and without expecting any result, practise with diligence and accept the experience that one may attain.