Abstract
Drug addiction can be viewed as a form of neural plasticity—drug—induced neural plasticity. This is because most features of addiction develop gradually and progressively in response to repeated exposure to a drug of abuse and can persist for a long time, perhaps even a lifetime, after discontinuation of drug administration. Within this context of neural plasticity, studies of drug addiction offer a unique opportunity to establish the biological basis of a complex and clinically relevant behavioral abnormality. This derives from the fact that many aspects of addiction can be reproduced with increasing accuracy in laboratory animals. The availability of animal models, in turn, has made it possible to identify specific regions of the brain that mediate behavioral aspects of addiction. Identification of these discrete brain regions has made it possible to begin the process of identifying the molecular and cellular basis of addiction mediated via these regions. This situation for drug addiction contrasts markedly with that for most other model systems of neural plasticity, for which behavioral, let alone clinical, correlates are not readily apparent. It also contrasts with many other neuropsychiatric abnormalities, for example, schizophrenia and depression, for which animal models are much less straight forward and much more difficult to interpret. Advances made in the field of drug addiction have the potential of providing insight into the types of mechanisms underlying other forms of neural plasticity and even, per haps, other neuropsychiatric abnormalities. The goal of this review is to describe recent progress in under standing the molecular basis of addictive states. The Neuroscientist 1:212-220, 1995