The welcome fourth edition of Principles of Neural Science follows the third edition by 9 years. Although this may not seem like a long time, the task of covering the scientific advances of this period is onerous, given the tremendous growth in neurosciences, particularly molecular biology. This text does an admirable job of presenting these scientific advances despite their magnitude. The overall goals of this edition echo those of its predecessors and include the following key inquiries: 1) How does the brain develop? 2) How do nerve cells communicate? 3) How do various patterns of interconnections give rise to different perceptions and motor acts? 4) How is communication between neurons modified by experience? and, lastly, 5) How is neural communication modified by disease?

Molecular neuroscience has always had a presence in previous editions; however, the current edition has an even greater molecular emphasis, which has superseded the original emphasis on cellular structure and function. This expansion of molecular topics has been incorporated throughout the various topics because there are now strategies to study molecular mechanisms from neural growth and differentiation, to cellular signaling, to the pathogenesis of disease. Perhaps the most difficult task of all is to tie these seemingly technical mechanisms and molecules into human experience, behavior, and consciousness. As the editors aptly state in the preface, the understanding of consciousness, or the attempt to "know thyself," is the greatest challenge to the modern neuroscientist. The frontier of consciousness is an exciting territory that is more accessible now than ever before with the tools of molecular neurobiology, as clearly outlined in this edition. It is an exciting time to be a student of neuroscience, and this text reflects that promise and excitement.

Delineating each addition to the 63 chapters covering new developments, techniques, and knowledge in neuroscience would require excessive space. Generally speaking, the progression of the chapters has remained the same, with relevant additions made to each to deal with new developments. Most of these additions, as already noted, fall into the molecular arena. A new chapter, "Genes and Behavior," is presented in part 1 and provides the foundation for genetic topics in subsequent chapters. The "Genes and Behavior" overview describes very cogently the multiple avenues for exploration of the genetic determinants of behavior, including single gene allele determinants of normal variations in behavior, as well as the effects of mutations, deletions, and other defects in manifest behaviors. This introduction does an exceptional job of setting the stage for the remainder of the text. The broad scope of this text is exemplified in the introduction as it overviews genetic findings in worms, Drosophila, and mice, bridging these findings with studies of complex behavioral and psychiatric disturbances such as bipolar affective disorder and schizophrenia.

As in the previous editions, each chapter presents highly concentrated scientific information in a very digestible and reader-friendly way. Particularly for the reader who is not a neuroscientist, the beauty of this text is that it makes no assumptions. Each new term and symbol is clearly defined, and each chapter thoroughly covers the pivotal historical studies leading to present-day research in each area. The visual appeal of the text is another great strength. Nearly every page has a relevant image, diagram, table, or figure. Rendering the information to memory is much easier with this visual tactic; the editors were clearly using their knowledge of learning and memory in their design.

Each chapter addresses a different aspect or functional modality of neuroscience, but there is ample attention to focusing the reader back to the overarching theme of how all aspects work together to create a functioning nervous system. There are frequent cross-references within the text to other relevant aspects of the topic at hand. For example, in chapter 8, "Local Signaling," at the point where the ionic current flow in myelinated fibers is discussed, the reader is referred to chapter 35 for a discussion of demyelinating diseases and their effects on behavior.

Overall, Principles of Neural Science continues to be a mainstay reference for the field. The enhancements in the fourth edition include a greater molecular focus as well as more attention to higher cortical function and consciousness. The latter is particularly intriguing, since increasingly sophisticated technologies have allowed the exploration of abstract cognitive processes in a more quantitative way. The psychiatrist reader will also appreciate the thorough coverage of the major axis I disorders in terms of their proposed genetic features and neurobiological bases as well as the neural underpinnings of psychopharmacological interventions. Again, for all readers, it is an exciting time to be a student of neuroscience. To comprehend the magnitude of the advances seen in this decade of neural research, students are precisely what we must continue to be, regardless of our station.