ABSTRACT
Autoradiographic studies in laboratory animals have been useful in identifying brain areas that contribute to the behavioral and physiological effects of psychoactive compounds. Local functional changes could reflect direct receptor interactions as well as indirect effects of afferents. These and other invasive procedures, such as intracranial injections and selective lesioning, have provided valuable information about anatomical circuits in brain that contribute to the behavioral effects of psychoactive drugs. Psychoactive drugs that support compulsive self-administration behavior in vulnerable individuals share the property of producing a positive affective state. Although the drugs that fall into this category belong to different chemical classes and have many other behavioral effects that are not shared, these drugs generally have been linked to alterations in brain dopamine systems. The concept of an affective continuum allows interpretation of evidence relating to effects of drugs that produce negative affect as further indirect support for the view that a reduction of brain metabolism contributes to drug-induced reward in humans.
