It is now about 10 years since the first edition of Nerve Cells and Nervous Systems was published. There have been many important advances across the whole field of neuro- science since 1990 and it was obvious that the first edition had become much less useful than when it was published. Hence this new edition. I have attempted to keep to the aims of the first edition by presenting the general principles of neuroscience in the context of experimental evidence. As with the first edition, the selection of material to include, or exclude, has been difficult and invariably reflects my personal biases. I hope that not too many readers will be disappointed with the selections. I have unashamedly retained material, and, in particular, illustrations where I think they remain of importance to an understanding of the field and to its historical development. As before, I have attempted as reasonable a coverage as possible within the confines of a book that should be easy to carry around, to handle and, I hope, to read. The book should be useful for anyone studying the nervous system at both undergraduate and immediate postgraduate levels. In particular, under- graduates reading neuroscience or any course containing a neuroscience component, such as physiology, pharmacology, biomedical sciences or psychology, as well as medicine and veterinary medicine should find the book helpful.