- The Washington Times - Sunday, December 9, 2001

By Richard Restak
Joseph Henry Press, $35, 193 pages, illus.

While human behavior in general provides scant evidence that we recently completed "the Decade of the Brain," as a presidential proclamation dubbed the 1990s, an army of scientific researchers hard at work during those years succeeded in uncovering many new details of the working of the human body's most mysterious and most significant organ. Richard Restak's "The Secret Life of the Brain," the companion volume to a forthcoming five-part PBS television series, describes many of those findings. Dr. Restak, a psychiatrist who practices in Washington and who is a professor of neurology at George Washington University, has written more than 15 books on the brain, and this clearly written and richly illustrated volume demonstrates both his mastery of an incredibly complex topic and his continuing ability to find new things to say about it.
The book discusses the differences in the structure and operation of the brain at five stages in human development: infancy, childhood, adolescence, adulthood and old age. Its main emphasis is on the astonishing degree of plasticity the brain continues to demonstrate at every age. Until comparatively recently, the conventional wisdom was that the brain continued developing until early adulthood, after which its original, and fixed, complement of nerve cells (neurons) began to die off and brain function entered into a continuing and inexorable decline. Now, however, it has been discovered that the number of connections between neurons, the key to the brain's operation, continues to increase as long as the brain is presented with new learning tasks, which the normal brain can accomplish throughout life.
Dr. Restak begins with a description of the devices that allow brain researchers to look inside the folded blob of seemingly impenetrable grey and white matter that constitutes the brain. While early students of the brain had to rely for their insights on such fortuitous, if unfortunate occurrences as the 1848 accident that shot a 13 lb. rod through the head of a railroad foreman Phineas Gage, leaving a permanent observation hole in his skull, today's brain scientists have an array of high-tech, non-invasive techniques that allow them to peek into the depths of the brain and observe it at work.
CAT and MRI scanners use, respectively, X-rays and nuclear magnetic resonance imaging to provide ever more detailed knowledge of the structure of brain tissue, while functional (fMRI) scanners and PET (positron emission tomography) scanners show where metabolic activity is occurring in the brain as it performs different tasks. Two other techniques, EEG (electroencephalography) and MEG (magnetoencephalography) can observe electrical and magnetic activity occurring in the brain.
Prenatal development of the brain, Dr. Restak shows, is an astonishing process of growth that culminates in a newborn baby whose brain already possesses virtually all the 100 billion neurons that will serve it for the rest of its life, artfully arranged so that each one can form an average of about 10,000 appropriately chosen connections with other neurons that will give it the ability to soak up information from its surroundings and react appropriately.
While still in the womb, connections between neurons that are vital for vision and hearing form before there is anything to see or hear, and before the still-forming eyes and ears are able to perceive light or sound.
Dr. Restak's discussion is illuminated and humanized by numerous interviews with scientists on the frontline of research and examples of how brain malfunctions affect real people. For each stage of the brain's development, he describes some of the things that can go wrong, and how we are learning to set them right. For example, babies born with cataracts in their eyes will never be able to see normally unless the problem is corrected within a month or two after birth. Once this window of opportunity closes, the nerve circuitry of the visual system will never be able to correct itself.
Another important topic that will be news to many is that the medical marvels that now allow premature infants to survive from much earlier stages than ever before may have lifelong negative effects on the brain because the bright, noisy and generally invasive environment of the intensive care unity used to keep the infants alive overloads their sensory capacity. A few hospitals are now attempting to correct this situation by providing more individualized attention for preemies that shields them from excessive light and noise and keeps them close to their mothers most of the time.
The infant's brain is primed for learning by exposure to all kinds of environmental stimuli, which cause new connections to form within the brain and encourage the pruning away of other connections that are unnecessary. For example, while babies up to six- or seven-months old are capable of learning to speak any language, by 11 months they are unable to recognize subtle distinctions between slightly different sounds that do not occur in the languages they hear around them. Native Japanese speakers, for example, find it difficult or impossible to distinguish between the sounds of "l" and "r" , which are not differentiated in Japanese, but if they are exposed as babies to both English and Japanese, they have no problem.
Researchers have devoted much effort to discover how children learn to read, a rather complex skill, and what dysfunctions of the brain cause dyslexia.
They now believe that it may involve disturbances in widespread areas throughout the brain. One intriguing corner of this subject involves the study of hyperlexic children, who may possess reading skills approaching adult levels even before they are able to speak, and often do not begin speaking until well after the normal age for children.
Recent research quoted by Dr. Restak shows that when a child becomes an adolescent, there is a new spurt of nerve cell growth and subsequent pruning that resembles the rapid changes that occur in the first 18 months of life. Many of the problems associated with adolescence, Dr. Restak says, occur because different parts of the brain do not mature at the same rate. The limbic areas associated with emotion mature earlier than the parts involved in judgment and reasoning, a discrepancy which may explain in part why many adolescents demonstrate impulsiveness, emotional volatility and a disregard for consequences.
Lack of self-control expresses itself in a small fraction of children and adolescents as attention hyperactivity disorder (ADHD), which can be controlled by drugs such as Ritalin that increase the level of the brain chemical dopamine. Opponents of the use of Ritalin argue that it is simply a substitute for illegal drugs that have similar effects. Dr. Restak explains the mechanism that leads to drug addiction: Dopamine levels surge in "pleasure circuits" within the brain, leading to a pleasurable experience more intense than that produced by normal means of gratification, and "hijacking the brain" away from the real world.
In his chapter on the adult brain, Dr. Restak discusses advances in the treatment of depression, and how damage to specific areas of the brain can render people incapable of feeling emotions and empathizing with others. His final chapter discusses the brain in old age, when learning takes longer, working memory becomes more limited, long term memory becomes less reliable, and distractions become harder to ignore. The good news is that vocabulary, verbal skills and abstract thinking do not deteriorate and, when combined with accumulated experience, give old people better judgment and more wisdom than they had earlier.
This is not true if they fall victim to Alzheimer's disease. According to the most popular theory today, Alzheimer's is caused by a build-up of amyloid protein, a gummy substance that sticks to neurons and eventually destroys them. Some believe that anti-inflammatory drugs and antioxidants may help combat this scourge, while others advocate a lifestyle including exercise, curiosity, reducing stress, sleeping enough, and healthy eating habits.
Armed with many new nuggets of information about the brain, the reader will come away from the book echoing Dr. Restak's conclusion that it "will continue to challenge, puzzle and fascinate."

Jeffrey Marsh has written widely on scientific topics ranging from nuclear strategy to social policy.

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