At the core of drug addiction are the conditioned responses to stimuli associated with the drug that develop in habitual users — such as objects that are used to administer the drugs, people who procure the drug or emotional states that in the past were either relieved or triggered by the use of the drug — that then drive the desire for drug taking and that are important contributors to relapse. Imaging studies have evaluated these conditioned responses by exposing addicted people to drug-related cues, for example, by showing them drug-related pictures. Here, we first review studies that compared the PFC response to cue exposure in addicted individuals and controls (Supplementary information S3 (table)), and then we discuss studies that explored the effect of abstinence, expectation and cognitive interventions on the PFC responses to drug-related cues (Supplementary information S4 (table)). We predict that in addicted individuals, PFC responses to drug-related cues mimic the responses to the drug itself, owing to conditioning, and that intervention causes a reduction of the drug-cue conditioned responses in the PFC.
