Mechanisms of Cortical Development.by David J Price and David J WillshawOxford University Press, Oxford, UK.328 pages, £69.50ISSN 0‐19‐262427‐X
Single author, or as in this case, dual author textbooks are becoming rare in today's world of increasing specialization and explosion of factual knowledge. The big advantage of this type of book is that the reader gets a unified view of a field. This is difficult to achieve in multi‐authored books, which even with the most diligent editors are likely to be a mosaic with gaps and style changes. However, the uniformity of single/dual authors may be at the cost of detail and accuracy when they stray from their areas of expertise.
David Price and David Willshaw join a select group of distinguished authors who have shown their breadth of expertise by providing specialist monographs on topics as diverse as ‘Secretory Mechanisms of the Gastro‐Intestinal Tract’ and ‘Human Baro‐reflexes in Health and Disease’. Those interested in the development of the cerebral cortex should be grateful to the authors for providing a largely up‐to‐date book that seeks to explain what is known today about the fundamental mechanisms that underlie the development of the mammalian neocortex. The scope is broad indeed, covering topics at the cellular and molecular levels including: the early development of the telencephalon, its molecular regulation, axon guidance and the control of cortical connections. The general coverage of the monograph makes it useful not only to the non‐expert who wants an entry into or update on the field, but the wide range of the book makes it also of benefit to experts, who want a view of related aspects in the context of their own work.
The introduction mentions future challenges, which helps to establish the scope of the volume. The authors make the case that understanding the mechanisms of cortical development will have a great impact on our ability to comprehend and eventually treat neurological disorders. They make the conscious (sic) decision, however, not to deal with the nature of consciousness on the grounds that it is not directly observable, but can only be inferred from behaviour—a view that may not be shared by cognitive neurobiologists. The one concession to this view of neurobiology is in the last chapter, which deals very briefly with face perception and language, both of which require consciousness.
Much of the authors' description of cortical development is based on what is known about the mouse. They reason that future use of molecular biology techniques and studies of mutant mice will substantially increase our understanding of human neurological disorders. As the authors demonstrate, this is already bearing fruit in understanding the earliest stages of neural tube development and the etiology of certain neurological disorders. But proper understanding of human conditions requires knowledge of development of the human neocortex; a short summary of the information available would have been helpful.
Consideration of a wider range of species would have helped other sections of the book as well. Results from Richard Mark‘s group in Canberra working on marsupials could contribute to the discussion on whether a period of ’waiting‘ of thalamocortical afferents in the subplate region precedes their growth into the compact immature cortical plate. Similarly, there is still some controversy about the fate of subplate neurons: do they die in all species or do they die in some and fade away in others? I am not sure that many developmental ’neocorticologists' would accept the statement that the neuroepithelium provides the only source of all neurons for the neocortex, whereas the subventricular zone just produces astrocytes and oligodendroglia.
One of the things a non‐expert looks for in a general text is some guidance on the value of experimental evidence and pitfalls for the uninitiated to watch out for. This is well done in some sections, particularly in those dealing with molecular genetics. In others, a bit more background would have been helpful. For example the authors mention in several places that studies which identify nuclei with DNA breaks were the first evidence that in the early neocortex programmed cell death occurs in as many as 50–70% of neuroepithelial cells on some gestational days. Here, a consideration that breaks in DNA are an inevitable indication of apoptosis would have been useful. Is there evidence that in rapidly dividing tissues such as the neuroepithelium, such breaks inevitably lead to cell death? Several reviews published in 1999 are substantially more up to date on the general aspects of cell death (apoptosis) than is covered in chapter 6. Particularly striking is the fact that the authors did not mention caspases in this context.
It is always a difficult task in a book of this scope to make appropriate choices about references and there is a lack of balance in some areas. Considerable prominence is given to the ‘Oxford School’ of visual cortex development, where a more even‐handed account would have given more space to the later work of Hubel and Wiesel, and of others. The section on barrel formation gives little inkling of the intellectual dominance of Hendrik Van der Loos in this field. His idea of how the periphery determines development of the somatosensory cortex is in one of the references cited, but it is not clearly expressed in the text. Later papers that develop the idea further and provide compelling experimental evidence are not cited at all.
Two useful features of the monograph are the extensive bibliography, which would have been even more useful as a searchable CD, and a glossary of terms and abbreviations. The latter is a bit uneven and contains at least one unacceptable error: horseradish peroxidase is not ‘an electrondense enzyme.’ Its reaction product is electrondense.
Although this monograph involved a great deal of work for the authors in the preparation, its presentation carries with it sepia‐tinted reminders of books from the 1950s. After more than 50 years and 48 publications, perhaps the Physiological Society should review its policy on monographs. In this one, almost all of the illustrations are line drawings, many inaccurate or unclear. Some sources are incorrect or missing. The Physiological Society has already done a good job of modernizing its Journal of Physiology. Perhaps the same effort should be put into their monographs. The authors' text deserves better visual support and a much wider audience would be reached.
- Copyright © 2000 European Molecular Biology Organization
The author is professor of physiology at the University of Tasmania. E‐mail: