A mental A to Z

If psychology is the science of mental life.., then neuropsychology is the scientific study of the relationship between the brain and mental life." So runs the definition of the topic of this dictionary given in its own pages. Faced then with the broad, controversial and often uncharted territory that neuropsychology is expected to cover, a comprehensive reference book would seem to be needed desperately and, at the same time, almost impossible to produce. The three authors of this dictionary have shown admirably that such a feat can be pulled off after all. The more one flicks through their book, the more one is surprised at and stimulated by the choice of entries and depth of coverage.

It must have been far from easy thinking up and selecting all the appropriate topics, summarised in one or two words, that give a comprehensive guide to the issue thrown up in the scientific struggle to relate "mental life" to the physical "brain". Perhaps the entries on the brain side are the most obvious and least problematic. Obvious inclusions are macrobrain systems and structures, damage to which is well known to be associated with specific disorders. Hence "limbic system", "basal ganglia", "cerebellum", "brain stem", "striate cortex" and "temporal lobe" all receive appropriate attention. However the entries are far from mere anatomical definitions. Each brain region commands a summary of between 500 and 5,000 words written by an expert with a set of up-to-date references. These effective essays cover not only the anatomy, but thephysiology, neurochemistry and pathology in each case. A pre-clinical student embarking on neuroscience would find these entries an invaluable and fast way of accessing the essential wood from among the trees of the conventional textbook.

A less expected type of entry, and indeed a very brave and welcome one, is that covering topics that are both frighteningly large as well as so obvious that they might have been excluded. "Brain" is a good example. In a mere seven pages Robert Dotty gives us a Cook's Tour, starting with the suggestion of Alkmaion of Croton in 500bc that the brain plays a role in perception and ending with the nature of the link between mind and brain. On the way there are classic illustrations of the pioneering work on brain cells by the Spanish anatomist Cajal a century ago, as well as an overview of how those cells communicate with each other and how they are organised into brain regions, which are in turn associated with certain functions. Anyone interested in the brain who had read nothing previously, could do far worse than read this. Similarly, Michael Morgan's entry on "neurotransmitters", the chemical messengers between neurons, is elegant, exhaustive and concise. All the essential facts are there: the criteria for definition which are so hard to find in ordinary textbooks; a list of the types of transmitters along with their functional significance -again a feature frequently diluted among the many pages of pharmacology books, as well as a discussion on the actions of drugs. The information that many people may want quickly and unambiguously, will be there to hand.

The other side of the neuropsychological coin, "mental life", must have been particularly challenging to divide into stand-alone modules. Not only are mental disorders covered but, more surprising perhaps, are entries on phenomena such as "sleep" and "ageing". In both cases the contributions of, respectively, Elio Lugaresi and Gerald Goldstein with Paul Nussbaum distil what one might hope to find in a textbook, but for which one would normally have had to work hard at farming different chapters. It is exciting and thought provoking to find not just facts but also theories which bring the reader to the very boundary of the subject.

The range of disorders of the physical brain through to those with more emphasis on the disruptions in mental life predictably account for many of the entries. As well as the most familiar dysfunctions the more baffling conditions, blindsight, face recognition and vegetative state, also receive detailed treatment. There is even an extended entry on that most puzzling aspect of mental life, "consciousness". Geoffrey Underwood concentrates mainly on the relation between consciousness and cognitive skills and attention. However this psychological perspective is complemented by a piece by Mario Bunge on the "mind-body problem". How refreshing to have the frequently convoluted and sophistic arguments of philosophers of mind summarised into ten broad views, five monist and five dualist. While such attempts at an overview of the question might make card-carrying philosophers grind their teeth, for those of us in the biomedical areas, with a lay interest in these theoretical questions, such a contribution is just what is needed.

Overall, this book is just what is needed for all those striving to keep up with a field that has boundaries seeping even beyond the conventional multidisciplinary terrain of anatomy, biochemistry, physiology and psychology into philosophy, sociology, and the chemistry and physics of advanced imaging techniques. As the editors admit, the title is actually a misnomer. True, many of the 8,000 entries are less than 500 words long, but many are considerably lengthier. It is an effective encyclopedia of brain-mind phenomena, complete with tables, photographs and line illustrations.

The Blackwell Dictionary of Neuropsychology does indeed contain, as stated in the preface, just the answer to the sort of question the hard-pressed professional would want to know quickly but would normally spend a frustrating few hours trying to track down. At the same time, for the student or the enthusiastic general reader, dipping into this book will yield rich and satisfying returns.

Susan Greenfield is professor of pharmacology, University of Oxford.