Cocaine sensitization and dopamine mediation of cue effects in rodents, monkeys, and humans: areas of agreement, disagreement, and implications for addiction.

BACKGROUND: Sensitization of mesocorticolimbic dopamine projections has been a valuable model of neurobiological adaptation to chronic exposure to cocaine and other psychostimulants. DISCUSSIONS: In addition to providing an explanation of exaggerated responses to drugs that might explain their increased ability to serve as reinforcers, sensitization has also been incorporated into influential theories of how drug associated cues can acquire increased salience and incentive motivation. However, almost all of the work exploring behavioral and neurochemical sensitization has been conducted in rodents. Importantly, the relatively small amount of work conducted in human and nonhuman primates differs from the rodent work in some important regards. This review will examine areas of convergence and divergence between the rodent and primate literature on sensitization and the ability of drug associated environmental cues to elicit dopamine release. The implications of this comparison for expanding addiction research beyond dopaminergic mechanisms in the striatum/nucleus accumbens will be considered.