In the past two decades, there have been astonishing advances in our understanding of the neurobiological basis and nature of drug addiction. We now know the initial molecular sites of action, at identified receptors, of virtually all of the major drugs of abuse including cocaine, heroin, and amphetamine, as well as legal drugs such as nicotine and alcohol. We also understand the main components of a 'reward system' and its connections to major brain regions involved in motivation and emotion, such as the amygdala, hippocampus, and prefrontal cortex. The Neurobiology of Addiction describes...