For the 6th edition of this text, the authors have added a new chapter on memory and learning and have reorganized the material on catecholamines into separate chapters on norepinephrine and epinephrine and dopamine. In addition, they have included much new information on G proteins and second messengers, excitatory amino acid receptors, and other timely issues. The book is aimed at students and professionals at many different levels: undergraduates studying psychopharmacology or neurobiology, medical students, graduate students in pharmacology and neuroscience, neuroscientists and residents and practitioners in neurology and psychiatry.