The physiological mechanism of meditation

1. The brain

The activity of consciousness is bound up with the activity of the brain. We use the words "bound up with" to suggest a close connection but not an identity. This means that the activities of consciousness both depend on the brain and can be independent of it. If the brain is injured, a person's consciousness is immediately disturbed, because consciousness is bound up with the brain. However, at death the spirit leaves the body and consciousness leaves the brain, yet that consciousness continues to function, because consciousness can be independent of the brain. Precisely because of this two-sided nature, we must not regard the brain as the whole of consciousness, or of meditation. To study meditation solely on the basis of the brain would still be one-sided. But not to know anything about the brain would also be a shortcoming. Science is still working hard to understand the human brain. Many functions of the brain are being discovered gradually. First, when consciousness is active, the brain is active; conversely, when consciousness is still, the brain is less active. There are some substances capable of inhibiting the brain that make it less active, creating a temporary feeling of calm. Opium is one of them. However, these substances all have side effects, such as dependence (addiction), loss of resistance, decline of morality, and so on.

Meditation is the work of reducing brain activity using only one's own consciousness. Meditation can be defined as using consciousness to quieten consciousness, without outside means.

The brain has many nerve centres with different and complex functions, but they are in close contact with one another. Brain cells transmit signals to one another both by chemical molecules and by brain waves. Today there are machines that measure brain waves. For the time being, people divide the brain into the main parts: the brain stem, the medulla, the thalamus, the cortex (part of the cerebrum), the cerebrum and the cerebellum.

The brain also contains endocrine glands such as the pineal gland and the pituitary gland, which control the activity of other endocrine glands in the body below, such as the thyroid, the adrenals, the sex glands and so on. Blood carries nutrients up to feed the brain, such as glucose, protein, oxygen and vitamins. The pressure of the blood on the brain is also a very important matter. Insufficient blood pressure also reduces the brain's capacity. High blood pressure is also dangerous, risking a stroke with unpredictable consequences.

2. Two opposing nervous systems

a. The vegetative (autonomic) and the animal (somatic) nervous systems

The animal nervous system is the nervous system that acts according to the will of the subject (the person). It includes sensations, reflexes, thinking, emotions and creativity, and transmits commands to the body below. There are regions of the brain that tend to act continuously, and conversely there are regions of the brain whose function is to inhibit that activity. This has great significance for a person who practises meditation and wants to gradually reduce the activity of thoughts.

The vegetative nervous system is the automatic nervous system, independent of the subject's will, which controls respiration, digestion, circulation and other deep, hidden mental processes.

However, there are also activities that mix the two, for example the breath, which is automatic but can also be adjusted at will. The breath is the intermediary between the two nervous systems, so using the breath to practise meditation is the optimal method.

When one enters deep concentration, one begins to be able to control even the vegetative nervous system. There are meditation masters and ascetics who can slow their heartbeat at will.

b. The sympathetic and parasympathetic nervous systems

These two nervous systems belong to the vegetative nervous system. The sympathetic system heightens the activity of the muscles and the endocrine glands, and also drives the flow of ideas. Conversely, the parasympathetic system inhibits those activities, which also means calming the flow of delusive thoughts.

The difference, however, is that although a person practising meditation must reduce thoughts, they must still maintain constant alertness. This is a state that has not yet been studied in the physiology of the brain.

3. Avoiding chain stimulation of the brain

Normally, deep within, the neurons (brain cells) maintain their own activity by continuously stimulating one another, back and forth. Signals keep travelling and spreading throughout the brain. The data stored in the brain stimulates the brain to be active. The instinct to keep one's own activity going is regarded as the ego.

Then, throughout life, outside data continues to be added, which also stimulates the brain to keep acting.

Then our own deliberate activities, such as thinking, imagining, creating, daydreaming, anger, greed and so on, also stimulate the neurons to spread signals as a habit. Therefore, to help the mind abiding in meditation be stable, we must avoid causing the initial stimulations such as anger, greed and selfishness. We must also erase the habit of letting our thoughts wander, so that the neurons no longer have the habit of excitation.

Negative ideas such as greed, anger and selfishness cause excitation to spread through the brain, while positive ideas such as altruism, gentleness and sacrifice help to inhibit, that is, help the brain to be less active.

4. The effect of daily life

The serotonin secreted from the brain stem, which becomes the sleep chemical, is also a substance that helps the brain be less excited in ordinary life. If one has insomnia or sleeps little, less serotonin is released, which also makes the brain excited, that is, tense. Therefore we must value sleep and must not force ourselves to stay awake to work except when unavoidable. One should go to bed at a regular hour in order to fall asleep easily. When sleeping, one must intend to sleep deeply. Thoughts of loving-kindness and compassion also help sleep be better. However, too much sleep also weakens the frontal lobe, which is responsible for alertness.

Food holds an important place in influencing the brain's activity. There are many substances that excite the neurons excessively, such as alcohol, tobacco, synthetic drugs, some chemical medicines, some spices and certain kinds of food. We must carefully pay attention to this in life so as to learn from experience.

Physical activity of the hands and feet is beneficial for calming the activation of the neurons. Therefore one should keep up some elementary manual labour even if one works mostly with the head. Physical exercise is very good for inhibiting the brain. However, excessive rivalry in sports competition stimulates the brain to pointless excitement.

Pastimes such as playing chess use a great deal of the brain's energy and keep the brain constantly stimulated. Noisy, crowded entertainments also stimulate the brain pointlessly.

However, sincere charitable activities that are quiet, humble and dedicated help the brain be more alert and calmer.

Question: Describe concrete personal experiences of the influence of daily life on meditative concentration.