The behavioral neuroscience laboratory of Prof. James R. Stellar studies the brain mechanisms of mammalian reward processes using rats as an animal model of the behavioral, neuroanatomical, and neurochemical systems at work in humans. A chief behavioral technique is electrical self-stimulation of medial forebrain bundle using psychophysical threshold methods to generate a quantitative measure of reward function. This method can be applied to scale the hedonic effects of drugs of abuse and look for anti-cocaine compounds. Other behavioral techniques include intracranial drug self-administration of amphetamine and nicotine, food reward, and general behavioral activation (locomotion, sniffing, rearing, etc.). A recent effort is to develop and validate an animal model of drug craving (as distinct from drug reward). Anatomically and neurochemically, the laboratory focuses on the nucleus accumbens, its subdivision into core, shell, and rostral pole regions, as well as subdivisions of the shell itself into 5 separate subregions. In addition, the connections to other brain structures such as the medial prefrontal cortex, ventral pallidum and the ventral tegmental area are of key interest in examining the effects of psychostimulant drugs of abuse in a behavioral sensitization paradigm. Behavioral sensitization is a phenomenon by which repeated exposure to psychostimulants results in an augmented response to a subsequent challenge. This augmented response is believed to underlie the initial components to addiction, craving, as well as schizophrenic symptomology. A second focus is on the hypothalamus and the directly stimulated self-stimulation reward-relevant fibers that run in the medial forebrain bundle. Functional significance of these anatomical distinctions is studied by excitotoxic, knife-cut, and electrolytic lesion, as well as by direct infusion (or self-infusion) of drugs of abuse. Additional techniques used to study the anatomy of drug addiction directly are immunocytochemistry and retrograde tracing.