Richard M. Restak, M.D.

Introduction to  THE BRAIN

                         Weighing less than sixteen hundred grams (three pounds), the human brain in its natural state resembles nothing so much as a soft, wrinkled walnut. Yet despite this inauspicious appearance, the human brain can store more information than all the libraries in the world. It is also responsible for our most primitive urges, our loftiest ideals, the way we think, even the reason why, on occasion, we sometimes don't think, but act instead. The workings of an organ capable of creating Hamlet, the Bill of Rights, and Hiroshima remain deeply mysterious. How is it constructed? How did it develop! If we learn more about the brain, can we learn more about ourselves? Indeed, are we anything other than our brain?

            Some of these questions remain unanswered; others ("Is the brain the mind?") may remain forever unanswerable. But in recent years neuroscience has been making some remarkable advances. On the basis of what is now known, neuroscientists have begun to suspect that our very humanity may someday be defined by the chemical and electrical activities within our brains. But most of us recoil at the idea that our hopes, our dreams, our lusts, and our ambitions may someday be defined in terms familiar only to the neurochemist and the neurophysiologist. Our mind, our free will, our creativity--surely these things attest to the presence of something more than the gnarled mass of cells we call the brain.

            In this book, based on the Public Television series The Brain, we will explore these questions and try to give you some feeling for the outer limits of our present knowledge about the brain, as well as what we can reasonably expect in the near and distant future. Since the brain poses such a formidable challenge, neuroscientists are exploring it in a number of different ways. For one thing, they are hard at work plotting the connections between and among neurons, the brain's basic unit. But since there are between ten billion and a hundred billion neurons (no one knows precisely how many), it is obvious that a mere "wiring diagram" will not supply all the answers we seek.

            Neurons communicate with each other through electrical and chemical messages. These messages can now be decoded. But as neuroscientists decipher them, they encounter the brain as paradox: those same neuroscientists are using their own brains to understand the brain. In a very literal sense, the brain is seeking to understand itself. This is a much more urgent goal than, say, learning about our most distant galaxies or peering into the subatomic world of particle physics. None of those inquiries can be satisfactorily answered until we understand how we understand. Just as our knowledge of other people is based on our knowledge of ourselves, "reality" is limited by our knowledge of the physical basis of all understanding, the human brain.

            Here are some of the most exciting areas of brain research in the mid-1980s.

          Vision and Movement.  We humans are capable of prodigious feats of strength and power. Witness the hands of a championship boxer as they curl into fists and within split seconds land on an opponent's body with bone-shattering impact. The brain that directs this activity can also "program" movements of exquisite delicacy: the pirouette of a prima ballerina, the ever-so-brief contact between a piano keyboard and the fingertips of the concert pianist.

            Every day each one of us carries out movements of incredible complexity. Even something as "simple" as walking engages our brains in a precise electrical and chemical repertoire. Each muscle must come into action at a specific moment. If the sequence is altered even slightly, we literally fall all over ourselves.

            From the study of patients with "movement disorders" we learn a great deal about normal movement. The goal! To develop treatments for many of the nation's elderly who are afflicted with Parkinson's disease, a disorder that imprisons the affected person within the confines of a body that will no longer move as it should. From these studies neuroscientists are also discovering ways of improving athletic performance and reducing muscular tension, which leads to athletic injuries and permanent disability.

            Is the eye like a camera! How is the complexity of the outer world suitably recorded and transformed within the brain~ Neuroscientists are answering these questions by research directed along several fronts. In one of the most promising, electrodes are being implanted within cells along the brain's visual pathway. These electrical activity recordings reveal a system of incredible complexity. Even slight variations in the contour of an object within a person's visual field may bring into play a totally new population of brain cells. Research on vision and movement may make a philosophical contribution to such subjects as free will and the difference between instinctual and voluntary behavior.

            The Brain's Underlying Rhythms.  No living creature lives in a vacuum, and we are no exceptions. Our bodies are constantly influenced by cycles of day and night, seasons, tides, magnetic and gravitational forces, and, some claim, even such environmental forces as lunar phases. The human brain responds to these cycles by mirroring them with cycles of its own: sleep and waking, the ebb and flow of hormones, periodicities in our levels of alertness and competence. Even our emotions follow cycles that, when they go awry, can result in forms of mental illness. Neuroscientists are currently exploring how all these "biological clocks" are constituted, what winds them up, and how they run down.

            Madness.  Investigations by neuroscientists reveal that many forms of mental illness may result from alterations in normal brain functioning. A psychosis is often accompanied by shifts in neurotransmitter balances or changes in the brain's electrical patterns, which, when the patient improves, return to a normal pattern. Can mental illness be explained on the basis of changes within the brain? Neuroscientists are at the point where answers to such questions may soon be possible.

            The Neuronal Basis for Learning and Memory.  Brain research is raising the astonishing possibility that at the molecular level we may operate very similarly to such humble creatures as the sea slug. In all living organisms,  memories may be stored within the brain according to their importance for survival. An animal "remembers" its predator and withdraws at the first sign of its enemy's approach. Memories are also laid down in tandem with the intensity of emotional experiences. As children, we don't have to be told more than once not to put our hands on a hot stove.

            The Electrical and Chemical Brain.  The lightning of a sudden thunderstorm has its terrifying equivalent in the human brain--an epileptic seizure. Even a slight electrical malfunction in the brain can make normal life almost impossible. This is the problem that many of the nation's two million epileptics face daily. From investigations into the brains of epileptics, neuroscientists are learning what it is within our healthy brains that limits electrical discharges and protects us from epileptic attacks.

            Specialization Within the Brain. There is firm evidence that parts of the brain are at their best when engaged in certain activities. For instance, the left hemisphere is generally concerned with language and verbal reasoning, while the right hemisphere is more involved with spatial perceptions and emotions. But none of these rules is etched in granite. In fact, the number of exceptions is prompting neuroscientists to reevaluate their preconceptions about what goes on within the brain.

            Endorphins: "the natural high." How does the brain respond when we're injured. There is evidence that it produces several chemicals, which provide pain relief during times of extreme physical and even mental stress. These endorphins ("morphine-like substances") have their own receptors in the brain. By using their knowledge of endorphins, neuroscientists are developing pain killers that may be able to relieve pain without leading to addiction. Researchers also hope that their studies may lead to understanding what happens when a person becomes "hooked" on a drug, which in turn may make new, more effective, treatment possible.

            Brain Activity Mapping. The brain uses glucose (sugar) and oxygen according to its activity at a given moment. Reading this sentence results in increased glucose and oxygen consumption in the visual cortex. Closing your eyes and thinking about turning the page sparks an increase in metabolic activity in the frontal areas of the brain. Since the advent of radioactive tracers (special procedures capable of tracking molecules of radioactively tagged glucose), brain activity maps have become possible. Maps can also be plotted for electrical impulses in the brain and, in the near future, for the brain's magnetic fields. We are fast approaching a time when it will be possible to observe physical changes within the brain in "real time," from moment to moment. But despite these advances, considerable disagreement exists among neuroscientists on whether it will ever be possible to ·equate a "disordered thought" with a "disordered molecule. ''

            Consciousness.  No one really knows what consciousness is. Its nature is perhaps the greatest mystery of the human brain. Neuroscientists are now attempting to solve this enigma by concentrating on what happens within the brain during altered states. For instance, although insomnia has claimed victims through the ages, neuroscientists have only recently learned of the complicated interplay of forces that must proceed exactly according to schedule if we expect to have a good night's sleep. Research on people with multiple personalities provides another avenue for under- standing the brain's role in consciousness. Does a person with several different personalities exhibit distinctive pat- terns of brain activity for whichever personality is dominant at the time! If they do, then many of our concepts about who we are may have to be changed. Imagine the social and legal consequences.  If a multiple personality commits a crime in one state of consciousness, how can that person be held responsible at a later time when another personality may be in command!

            Although many other areas of brain research will be discussed throughout this book, the above topics convey some sense of how broad our canvas will be.