With a 1999 introduction by Alan Jacobs, editor...

For turn-of-the-century scientists, the new technique would lead to a fundamental change in how the brain was conceptualized. It became abundantly clear that the brain was composed of diverse cellular elements. Like many advances in science, this one was not without debate. Golgi held the view that the vast numbers of nerve cells with their many branching processes were an unbroken chain of physically interconnected cells that formed a grand network. Cajal, on the other hand, was convinced that the nerve cells were discrete entities separated from each other. Cajal was correct in presaging the existence of synapses between nerve cells, but proof would have to await the invention of the electron microscope. Nevertheless, for many students of neuroscience, Cajal's observations and explanations of the organization, development, and function of the nervous system were prophetical.

It is now 90 years later, we are in the middle of the last decade of the twentieth century, the Decade of the Brain, and 1996 is the fiftieth anniversary of the National Institute of Mental Health. As we close out this century and enter the twenty-first, research of the brain will be devoted to answering a most complex question: How do the cells of the nervous system produce behavior and cognition, store memory, and execute other complex phenomena?

The brain, and in particular, the human brain, has been called the last frontier of biomedical sciences because of its enormous complexity. The average brain cell is both like and unlike every other cell of the body. The little bag of tricks the liver cell uses for daily housekeeping is similar to that of the nerve cell. However, nerve cells have evolved these tricks for their own specialized functions.

Unlike the liver, which is composed of a relatively homogenous population of cells, the brain has a multitude of diversity. The organization of this second edition of "The Neuroscience of Mental Health" reflects this diversity. The nine chapters comprising this volume address the following areas:

• Neural Development
• Functional Organization of the Central Nervous System
• Neurotransmission
• Neural Regulation of Behavior
• Cognitive Neuroscience and Neural Plasticity
• Neuropsychopharmacology
• Neuroimmunology and Neurovirology
• Advanced Technologies for Neuroscience
• Neural Basis of Psychopathology

These chapters are offered to both the casual reader and the serious student of modern neurobiology as an attempt to capture the state of the art in each of these areas of research. A paradox of sorts will become apparent in the scientific content of each chapter. This paradox is rooted in the tremendous diversity across each of the subdisciplines, yet each chapter is linked to the others by a fundamental commonality. Indeed, discoveries in one area of neuroscience rapidly find applications and open new areas of understanding across widely divergent scientific and clinical investigations. For example, the concept of plasticity first encountered in chapter 1 in the presentation of neural development is a recurring theme throughout this treatise.

Plasticity, or the ability to change, is one of the underlying principles of the nervous system - it is not only a phenomenon of the embryonic brain, it is a dynamic process operating at all levels of organization throughout the life of the organism. Rooted in the mechanisms of plasticity are molecular elements that also happen to be the fundamental elements of neurotransmission - a discussion of one cannot take place without a discussion of the other. Likewise, any conversation on how drugs affect the brain and behavior (neuropsychopharmacology) requires the language of neurotransmission, because many drugs work by affecting neurotransmission. Perhaps the most exciting, and as yet least understood, example of plasticity in the brain is learning.

The diversity and the commonality linking seemingly disparate fields is the basis of one important insight into the future direction of neuroscience research. When the first edition of this book was published 10 years ago, it was possible for researchers to identify themselves along scientific disciplinary lines. For example, one might be a psychologist, an anatomist, a molecular biologist, a psychiatrist, a biochemist, or a pharmacologist. Now and into the future, investigators of the brain must be integrative across once-distinct disciplines. The nature of the questions demands multidisciplinary answers.

One only needs to read the chapter on neuroirnmunology and neurovirology to see the complex integration between brain function, mental state, and the physical state of the body. We can no longer conceptualize the brain in isolation from other organs and organ systems. Of even greater importance is the need to Integrate the biology of the brain with some of its major functions, behavior and cognitive function.

A reading of this book will provide an overview of the kind of basic and applied research that has advanced our understanding and treatment of mental disorders. Indeed, progress in basic neuroscience research is of benefit to a wide variety of human disorders from mental illness to neurological problems. It is particularly gratifying to see how the past 50 years of NIMH support for basic neuroscience has resulted in pivotal contributions to our understanding and treatment of many of the mental disorders. Numerous specific examples can be cited, but perhaps the most profound observation lies in the fact that our advances in basic neuroscience have profoundly changed how we think about mental disorders. Both the specialist and nonspecialist now appreciate the biological basis for diseases of the mind. As new insight is brought to bear on the relationship between the workings of nerve cells, behavior, and the environment, progress in the next 10 years will doubtless be even greater.

*This article was originally published in The Neuroscience of Mental Health, NIMH Publication No. 95-4000, 1995, pp. 1-3.

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