Figure 1.

Depiction of the temporal relationship of associative learning of drug-seeking behavior with inhibitory learning during subsequent extinction of the drug-seeking behavior. The initial phase of addiction involves associative learning processes in which drug-taking becomes linked through classic Pavlovian conditioning with drug-related cues (e.g., drug paraphernalia or drug-taking environment). With repeated pairing, this association results in formation of a persistent “drug memory.” This memory trace remains long after discontinuation of drug-taking. The extinction of drug-seeking by pairing unreinforced exposure of drug-related cues, does not result in the deletion of the original drug memory, but instead involves the formation of a new inhibitory “extinction memory.” While this new memory provides inhibitory drive over drug-seeking behavior in the short term, the original drug-memory remains, which may explain the high rate of relapse following behavioral extinction therapies.