What we have learned about addiction from animal models of drug self-administration.

Self-administration of addictive drugs in laboratory animals has been widely used for decades as a tool for studying behavioral, neurobiological, and genetic factors in addiction. From such studies has come an enormous amount of information on brain mechanisms involved in addiction, on vulnerability factors in the addictive process, and on possible pharmacotherapeutic treatments for addiction. Modifications of the laboratory animal self-administration paradigm--including progressive ratio break-point models and the "reinstatement" model of relapse to drug-seeking behavior--are currently increasing our knowledge of incentive motivational factors in addiction and of the mechanisms underlying relapse to drug self-administration behavior.