The main aim of this book is to raise and clear up the intriguing problems of noise and chaos in the nervous system. What functional role do fluctuations in neural systems play? Are there chaotic processes in the brain? What is the neural code, and how robust is it towards noise? Are there mechanisms that can control noise and chaos?The book provides an introduction to this new and hot field of research, and at the same time brings the reader to the forefront of scientific inquiry. It is intended primarily for biologists involved in theoretical treatment and for physicists with an interest in biology, but the overview character of the articles makes it also well suited for a broader readership.