Glial cells play an essential role in initiating and controlling our behaviours, playing a major role in communication between brain cells. They share certain properties with neurons, including the ability to use information from the environment to formulate behaviors. Understanding these cells is key to explaining human movement, emotion, and thoughts. Moreover, glial cells provide a panoply of new therapeutic targets for the treatment of neuropsychiatric disorders. This book is the ‘brain’ child of two scientist physicians: Pierre Magistretti, a leading expert in cerebral metabolism and glial cell biology, and Yves Agid, an expert in the treatment of nervous system diseases and a researcher in the field of neurodegenerative diseases. This book provides many examples of the decisive role glial cells play in the functioning of the human brain, as well as in neurological and psychiatric pathologies. The result is a revolution in our understanding of the brain and a beacon of hope in the treatment of neuropsychiatric disorders.