________________
67
Perceiving Touching/Pain, Seeing and Hearing
by imitating the action of enkephalin in stimulating the nerve-cells that switch off the responses to traumatic stimuli, including the subjective phenomena of pain. This is the brain's program for reducing pain. However, in extreme cases, where the brain is not able to reduce or regulate pain, it just gives up and resorts to withdraw itself, resulting in "unconsciousness" or fainting. Once again we see how actively the brain regulates everything that is allowed to enter it, even pain.
G. Pleasure and Pain
Some of these central regions are not concerned with pain but are pleasure centres. We do not yet know enough to be able to say whether the pain-inhibiting sets of cells are identical with these that produce pleasure. Is pleasure to be regarded as the absence of pain, or possibly vice versa ? Do our programs seek to maximize pleasure or minimize pain, or both? The important point is that there are bere what we might call the reference systems that set the course of the whole living control system. Their operation largely determines the ends or aims of the animal or man. These brain regions and the programs they produce are determined by vedniya karman, heredity, and, no doubt, modified by experience. These controls are there to provide the objectives that we seek for in life. It is not too much to say that these systems largely determine what human beings do. But human life is not simple. Other types of program intervene, as it were, on top of these fundamental ones of pleasure and pain that are produced by the actions of the reticular and reward centres. So evidently there are activities in this part of the brain that regulate what we commonly call emotional feelings.
H. Surgical Relief of Pain
Discoveries about the central grey matter have been used in the relief of human pain. Intractable pains are said to be relieved by lesions in the medial part of the thalamus, or by cutting the cingulum bundle, which connects the frontal cortex to the hippocampus. It is clear in any case that there is no one single 'centre for pain' in the brain. The cerebral system does have distinct parts, but many of them interact for the performance of each program of action. Pain is the result of a disordered operation of a program for exploring the world in the immediate neighborhood of the
