Book review Electric Fields of the Brain. The Neurophysics of EEG, second ed. Paul L. Nunez, Ramesh Srinivasan. Oxford University Press, Oxford (2005). 611 pages, ISBN: 0-19-505038-7 A usual problem found by physicians or neuroscientists working with EEG or evoked potentials is the difficulty in finding a text that explains in an accessible way the physics that underlies the electrical phenomena being recorded. Also, physicists and engineers working on EEG analysis need to understand some basic principles of brain physiol- ogy. This book tries to accomplish both roles; its central goal is to explain how fundamental physical principles apply to EEG, and to bridge communication gaps between complementary scientific fields. The authors, biomedical engineers, have tried to make an easy accessible book for non-experts in either engineering, physics or mathematics, avoiding an excessive use of formulae in the text (most of them are in the appendixes) and using easy comparisons with real-life phenomena whenever possible. As the authors point out in the text ‘‘presenting equations at medical con- ferences has been compared to showing X-rate movies in church’’. This book is the second edition of Electrical Fields of the Brain: The Neurophysics of EEG. Compared with the 1981 edition, the central goal remains unchanged but the text has been revised, updated and made easier to read. Some topics regarding brain dynamics have also been reduced. The book is structured in three main blocks. The first two chapters are a kind of introduction to the rest of the book, and can be recommended for anyone interested in EEG; the first one introduces the reader to the relation- ship between neuronal discharges and EEG recordings, while the second discusses many usual both new and old ‘‘fallacies’’ in EEG, including discussion on reference electrodes, dipole modelling, advantages and disadvantag- es of MEG, etc. The authors strongly fight the vision of EEG as a so-called epiphenomenon apparently meaning a measure peripheral to genuine scientific interest, and defend scalp EEG as a tool that provides very large-scale and robust measures of neocortical dynamics, as opposed to intracraneal recordings that provide small scale mea- sures (the information obtained is different, but not neces- sarily better or larger). Both chapters are imaginative and fun to read while scientifically sound, a recommended reading for anyone interested in EEG and evoked poten- tials. Chapters 3–8 discuss in more detail some of the con- cepts introduced in the first two chapters (electromagnetic fields and their relationship to EEG generation, recording strategies and high-resolution EEG); chapters 3–6, dealing with the behaviour of potentials and currents sources in homogeneous, inhomogenous and isotropic mediums may be difficult to follow for readers without a good maths and physics knowledge. The last three chapters are more specialized in dynamic EEG signal analysis, and include some examples of studies directly carried our by the two authors. The book finally includes a series of large appendixes where most mathematical procedures are detailed.The book has the advantages and disadvan- tages of not being a multiauthor book. The content is very homogeneous, with clear objectives at each chapter and a constant line of thought. On the other hand, the authors mainly deal with the aspects of EEG signal anal- ysis in which they feel comfortable. Laplacian derivatives, ‘‘dural imaging’’ and dipole models are dealt in detail, but there is no reference to distributed sources estimates like LORETA or DICS, for example. Only coherence esti- mates are discussed regarding relationships between corti- cal areas; the description of other alternative techniques (phase synchronization, PLV) would be a welcome addi- tion. Other analysis tools for oscillatory activity like time-frequency transforms (wavelets, Gabor), or process- ing techniques like independent component analysis are neither dealt with in detail. Also, in future editions, the text might benefit from the inclusion of a chapter dedicated to non-linear dynamics of EEG (complexity, self-organising systems, etc.). As the authors point out, there has traditionally been a ‘‘gap’’ between physicists and engineers dealing with the physical basis of electrical brain activity on one hand, and clinicians and cognitive scientists interpreting EEG sig- nals on the other. This book tries to fill this gap, making electromagnetic fields of the brain and their analysis easily understandable by non-experts in the field, while simulta- neously keeping a high scientific level that can also be inter- esting for expert researchers. In summary, Electric Fields of the Brain is an excellent book that should be in the book- shelves of any professional interested in EEG or brain dynamics. doi:10.1016/j.clinph.2006.06.001 www.elsevier.com/locate/clinph Clinical Neurophysiology 117 (2006) 2109–2110