Can Man Learn to Use The Other Half of His Brain?

"I have taken all knowledge to be my province," wrote Francis Bacon. And in 1592, when most of today's complex sciences had not even been conceived, he was neither idly boasting nor wildly exaggerating. But among the many things that Bacon did not know was that despite his encyclopedic knowledge and the amazing breadth and power of his intellect, he was using little more than half his brain. Not until one short century ago did neurologists learn that one half of the brain--nearly always the left, especially in right-handed people--controls the movements of the opposite side of the body and the all-important human attribute of language and its associated skills.

Two tantalizing questions are now bugging medical science: Can man learn to take more knowledge for his province by putting more of his brain to active use? What parts of the brain are responsible for controlling various movements, functions and faculties, from aimless thumb-twiddling to Boolean algebra? To the first question, there is still no answer. And neurologists have not yet agreed on a detailed mapping of brain areas and brain functions.

Old Bark & New. What is generally agreed is that the most primitive emotions and reactions, such as hunger and sex drives, are experienced in the hypothalamus (see diagram). In general, the higher the functions, the higher their seats in the brain--rising through the thalami and their branches, and the basal ganglia, to the paleocortex ("old bark"), which man shares with the higher animals.

But man's brain differs from the animals' in having a huge neocortex, a thick new bark containing billions of nerve cells. Each half of the cortex is divided into four main lobes: frontal (behind the forehead), temporal (inside the temple), parietal (under the crown), and occipital (at the back of the head). Animals do not speak, write, or think abstractly, and presumably both halves of their brains are equally active. At birth, the human brain is little different from an animal's. A newborn infant who has suffered severe damage to the left side of the brain may have almost half of his brain removed and grow up intellectually normal: the right hemisphere learns to do most of the things that a whole brain can do.

But in the normally developing right-handed child, the left hemisphere becomes dominant. As he learns to understand words and to talk, it contains his most specialized language center. This is nearly always true even in a left-handed child. And in the 85% of people who develop right-handedness, the left hemisphere controls the most essentially human of physical movements--writing and using tools.

While mapping with the help of electronic stimulation has pinpointed some parts of the brain primarily responsible for controlling individual parts of the body as small as the tongue, fingers, or even eyelids, there is evidence of much overlap and feedback. Speech obviously demands control of movements of different parts of the mouth--but not until after the speaker has decided what words he wants to say. So both motor control and intellectual processes are involved.

A Million Strokes. If medical scientists had to rely on the study of healthy people to find out how the brain works, they would know even less about it than they do. But an accident in a brain artery is one of the most dramatic and disabling illnesses that can befall a man. And in the U.S., it is one of the most common. Each year, a million or more Americans suffer strokes and other forms of brain damage, with 200,000 deaths resulting. From the study and treatment of stroke victims, researchers are learning the implications of using half a brain, and what can be done when that half is damaged.

What happens in a stroke (which doctors call a cerebrovascular accident or CVA) seems superficially simple: a shutdown of any kind in one of the arteries in the neck or head cuts off the essential supply of blood and oxygen to part of the brain, which then "dies." For unlike cells in flesh, or even in bone, which go on multiplying until near the end of life, brain cells have virtually no power to reproduce themselves. Medicine can only rely on whatever self-healing capacity the damaged brain area has--or find some way to stimulate another part of the brain to take over the functions of the damaged part.

The carotid arteries that channel blood through the neck to the brain are almost as subject to atherosclerotic disease with advancing age as are the coronaries. They may simply be narrowed, so that less blood gets through. They may be almost closed by a fatty plaque, so that a clot forms there and clogs an artery. About 85% of strokes are caused by arterial shutdowns; about 10% by hemorrhage (bleeding through a burst blood vessel in the brain, usually in victims of high blood pressure), and 5% by traveling clots in the bloodstream.

In a typical case, a man in his 50s awakes one morning to find that he cannot move his right side. He is not in pain. He has had no warning. When the average man tries to tell his wife about his difficulty in moving, he finds that he cannot talk, or can only mumble slurred syllables that make no sense. At this point, he feels a panic of anxiety--which may be as big a problem to him and his doctors in the months to come as the physical damage wrought by the stroke.

Forgotten Fall? There is little that doctors can do immediately, beyond getting the patient and his family quieted down, and keeping his room full of fresh air. The patient should have his skull X-rayed to be sure that he has not fractured it in a forgotten fall. And he should have a spinal tap to detect infection or bleeding into the spinal fluid.

In some cases, the next thing to do is inject radiopaque dye into the patient's arm or neck arteries and take an arteriogram, a rapid-fire series of X rays. (Two per second is the standard speed; six per second is now possible, and 60 per second may be soon.) These may show precisely where the clot has done its damage; they can give general guidance to the doctors and therapists who will have to work with the patient later.

A right-handed man with a left-hemisphere stroke is so frustrated by physical helplessness and speechlessness that he has a powerful motive to do the repetitive exercises that will help him to recover. The older the patient, usually, the less powerful this motive. How much of his improvement over a period of months is due to a partial resumption of function by damaged but not quite dead brain cells, and how much is due to other parts of the brain taking over the lost functions, is not known. The number of detailed differences between individual cases is so nearly infinite, says New York University's Professor Clark Randt, that medical science is turning to computers for the answers. But so far it does not have enough data to feed into the machines.

Like a Pricked Bubble. Even among victims of strokes on the dominant side of the brain, says Psychologist Leonard Diller of New York's Institute of Physical Medicine and Rehabilitation, there are two drastically different effects, depending on the severity of the brain damage. ''One type," he says, "is like a pricked bubble--after you've pricked it, the bubble isn't there any more. The personality seems to have vanished. The second seems unchanged in basic type, but less efficient."

Behavior changes are often paradoxical. Many patients with one-side paralysis tend to cry. Dr. Diller asks, "Are you sad?" and is told, "Yes, I'm sad because I can't stop crying." The doctor goes on: "Are you crying because you're sad?" The patient replies: "No, I'm not sad." Dr. Diller tells such a patient that when he feels a crying spell coming on, he should grip his wheelchair tightly with his good hand. By some unexplained crossover within the brain, the motor activity of the muscles is often a satisfactory substitute for crying. These crossovers and feedbacks between physical movements and processes that appear to be purely mental are as subtle as they are mysterious. At the Philadelphia Rehabilitation Center, Therapist Glenn J. Doman treats partly paralyzed patients by training them to "capture" reflex movements by a conscious effort. An obvious one is the knee jerk. The therapist provokes this by hitting the knee with a little rubber mallet. The nerve impulses involved travel only as far as the spinal cord, and the patient cannot make the movement of his own volition. But after willing himself to do it often enough, the patient contributes some movement of his own. The clincher comes when the therapist swings the hammer and does not hit the right spot, but the knee jerks anyway. Somehow, nerve-muscle control has been extended from the spinal cord to the brain itself.

The type and severity of paralysis vary with the location of the clot which has caused the stroke. If it is in the anterior cerebral artery, the leg on the opposite side will be more severely affected. But most strokes affect the middle cerebral artery, so the arm is more handicapped than the leg. This is why 90% of stroke victims learn to walk again, while only 10% to 20% regain full use of the right arm--though almost 50% of those under 45, even with severe impairment, could probably do so with proper training.

Blunted Senses. The power of speech, and the ability to write and walk, are measurable. Far more elusive, says Dr. Diller, are the variations in loss of memory. Usually, it is knowledge of recent and current events that seems to vanish. But it may be the memory of colors, or dates, or shapes, or perhaps most significant, of emotionally important events. Even the senses present puzzling problems. Vision may become poorer, but so subtly that the beset patient does not recognize his difficulty. Or he may be depressed by a general decline in his responsiveness to sensory stimuli, or by a partial failure of his mental computer to pull together the stimuli received through different senses.

A stroke on the nondominant side of the brain may produce effects even more baffling and variegated than damage on the brain's dominant side. If, as is usually the case, it happens on the right side of the brain in a right-handed patient, his language skills are unimpaired. He can still write; he can reset his wrist watch. After a mild right-side stroke, the patient may have no paralysis, but only what neurologists call "silent impairment"--a vague depression, believed to result from a blunting of sensory awareness, and in judgment of spatial relations. He does not become overanxious. But he is likely to complain endlessly about his food or the hospital routine. And the dulling of his sensitivity may make him careless of toilet habits. Worst of all, this patient, with supposedly less crippling damage, lacks the strong motive to retrain himself that speechlessness provides.

Only the most severely paralyzing strokes have a physical effect on the patient's sexual powers. But a simple stroke of moderate severity on either side of the brain is almost certain to exert indirect effects. Desire is likely to be reduced because the patient is depressed. This and other emotional disturbances can drastically reduce sexual competence even when there is no obvious physical impairment. And since intercourse causes a dramatic rise in blood pressure, it carries the risk of provoking hemorrhagic strokes in weakened arteries, especially if blood pressure is already high.

In the Neck. After a brain artery shutdown, neurologists and neurosurgeons can do little but provide guide lines for rehab specialists. Prevention of strokes is still a vision of the future. But any measures that slow down atherosclerosis will prevent almost as many strokes as coronary attacks. Meanwhile, neurologists are working with surgeons to see what can be done about narrowed arteries in the neck, where the surgeon can get at them. From 5% to 20% of strokes (doctors differ widely about the proportion) occur not in the brain but in the carotid arteries in the neck. Houston's Dr. Michael E. DeBakey has pioneered with a series of operations to restore full blood flow through a narrowed carotid--by installing a bypass, or cutting out the narrowed stretch, or putting in a patch graft to widen the artery. But evaluation of stroke victims' recovery is so difficult that no fewer than 22 medical centers are now doing DeBakey operations and comparing the results with the fate of unoperated patients. It will be a few years before medicine has a collective verdict.

An ingenious gadget, forbiddingly named the ophthalmodynamometer, has recently been devised to help in diagnosis. If blood flow through the internal ophthalmic artery is cut off, the eye on that side loses its vision. The doctor presses against the eyeball with the ophthalmodynamometer until the patient reports that he cannot see out of that eye. The instrument registers the pressure at which vision was cut off. This in turn indicates the pressure in the internal carotid artery and shows whether that vessel is dangerously narrowed. If it is, a DeBakey operation may prove to be the answer.

Among the oddest of many unexplained effects of strokes is that a patient's perception of the vertical is tilted. But whether it is tilted to right or left depends on which side of his brain has been injured. With paralysis on the left side, a right-handed man sees a bar of light as vertical when its top is actually tilted to the left--about 40DEG. Paralysis on the right side tilts the apparent vertical to the right, but only about half as far.

Total Organization. From their work with children, neurologists are confident that establishment of dominance by one of the brain's hemispheres is desirable and even necessary. A truly ambidextrous child is likely to have early difficulties with speech and other intellectual functions. From their work with stroke victims, most of them elderly, the neurologists are equally convinced that too much hemisphere dominance is bad. As yet, they have no idea how to strike a better balance. Researchers working with children at the Philadelphia Rehabilitation Center have labeled their system "neurological organization." The child is given every chance and encouragement to do by himself the simple things for which his damaged brain gives him the necessary control. Beyond that, he is helped to do things that are one stage too difficult for him to do alone. By the mysteries of feedback, repeated physical movements made with the therapist's help enable the brain to develop control so that the child can make the movements unaided.

It is still a question how far such principles can be extended to young, normal brains. Educators following the doctrine of Italian Physician Maria Montessori hold that children can do higher mathematics by the age of eight if they are encouraged to work to the limits of what they believe their own capacities to be.

"Men fear thought," says Bertrand Russell, "as they fear nothing else on earth--more than ruin, more even than death." But in every age since the pyramid builders', there have been a few exceptional men who would willingly risk death for the enjoyment of thinking. Whether Socrates had as high an I.Q. as Shakespeare or Descartes, Schweitzer or Einstein, will never be known. What is certain is that all such men used their brains as energetically as they knew how. Today, man may have no greater brain capacity than the ancients, but he has revolutionary ideas about how to exploit it.

From all-out education, it is but a step to "complete neurological organization," in which the individual will be guided to exploit the potentials of both his brain hemispheres, instead of leaving one of them largely dormant. This is the aim of neurologists, educators and other researchers, who are now organizing a group of Institutes for the Achievement of Human Potential. If they succeed, they will produce the Bacons of the 20th century --equally at home in computer theory and the kitchen garden, in the nucleus of the atom and all recorded literature.

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