As currently understood, neuromodulation comprises not only electrical and magnetic stimulation but also chemical and genetic manipulations. The fact that adverse events induced by some of these treatments are largely reversible has sparked great interest in the development of new applications and targets for neuromodulatory treatments. As the number of indications and studies increases, so does research in associated fields. This chapter provides a brief introduction and discusses the overall contents of this volume of the International Review of Neurobiology.