plasticity, the neural circuit adaptations that underlie drug-induced behavioral changes will involve drug-induced synaptic changes. Indeed, converging evidence from many studies suggests that addictive drugs modify synaptic transmission in the mesocorticolimbic DA system by hijacking mechanisms normally used for adaptive forms of experience-dependent synaptic plasticity; hence the term “drug-evoked synaptic plasticity”. However, the term should not imply that drug exposure alone is necessarily sufficient to elicit synaptic plasticity. On the contrary, many forms of drug-evoked synaptic plasticity appear to depend on the context in which the drug has been experienced, presumably because the final synaptic adaptation will depend both on the molecular action of the drug and the pattern of neural activity in the brain at the time the drug is experienced. It is also important to note that a single drug experience is certainly not sufficient to induce addiction. However, the synaptic and neural circuit adaptations caused by a drug experience often persist and lay the foundation upon which further drug-induced adaptations occur.
