Gene transfer technology is a powerful tool for increasing our understandingof brain functions. It is also the basis of gene therapy, which is now technically possible for the correction of many human diseases, including several disorders of the nervous (and muscular) system such as Alzheimer's disease, Parkinson's disease, and dystrophy. This volume, which contains the proceedings of a symposium of the Fondation Ipsen, provides a unique view of the state of the art on different transgenes, vectors, target cells, and clinical applications related to the nervous system.