Glossary of terms
| Behavioral Term | Definition |
|---|---|
| Conditioned place preference | A Pavlovian conditioning procedure in which one distinct context is paired with noncontingent drug injections while another context is paired with vehicle injections. During subsequent drug-free tests, increased preference for the drug context serves as a measure of the drug’s reinforcing effects. |
| Craving | An affective state described as an urge for drug; it can be induced in human drug users by exposure to the self-administered drug, drug cues and contexts, or stress. |
| Cue-induced reinstatement | An experimental condition in which laboratory animals are first trained to self-administer a drug or non–drug reinforcer, and each reinforcer delivery is temporally paired with a discrete cue (e.g., tone or light). Operant responses are then extinguished in the absence of the reinforcer and the cue. During reinstatement testing, exposure to the cue, which is earned contingently during testing, reinstates responding. |
| Discrete cue | An experimental condition in which an environmental cue (e.g., light, tone) is contingently paired with the reinforcer delivery. |
| Discriminative cue | An experimental condition in which an environmental cue (e.g., light, tone) predicts the availability of a reinforcer. |
| Drug-induced reinstatement | Resumption of drug seeking after extinction following noncontingent priming injections of the self-administered drug or related drugs immediately prior to the test session. |
| Drug self-administration | An operant procedure in which laboratory animals lever press (or nose poke) for drug injections or oral drug delivery. Most (but not all) drugs self-administered by humans are self-administered by rodents and nonhuman primates. |
| Early abstinence | The beginning of abstinence phase when people with substance use disorders experience somatic withdrawal symptoms. In studies using rat models, this term refers to the first several days after cessation of drug self-administration. |
| Extinction | The decrease in the frequency or intensity of learned responses after the removal of the unconditioned stimulus (e.g., drug) that has reinforced the learning. In studies on incubation of drug craving and relapse after forced or voluntary abstinence, extinction responding (in the presence of the drug-paired contextual and discrete cues) is the operational measure of drug seeking. |
| Forced abstinence | Experimental conditions in which abstinence after drug self-administration is imposed by the experimenter. In animal models, forced abstinence can be achieved by (1) extinction training in the drug self-administration context or a nondrug context or (2) keeping the experimental animals in their home cage during the abstinence period. |
| Incubation of drug craving | A hypothetical psychologic process inferred from the findings of time-dependent increases in nonreinforced drug seeking after cessation of drug self-administration in rodents. |
| Intermittent-access drug self-administration | A drug self-administration procedure in which the drug is repeatedly available for short periods that are separated by long timeout periods (typically 12 cycles of 5-min drug access, 25-min timeout). Exposure to this procedure induces binge-like self-administration behavior and spiking brain drug levels. |
| Long-access drug self-administration | A drug self-administration procedure in which the drug is continuously available for extended daily sessions (6 h/day or more). This procedure results in escalation of drug intake and high and stable drug concentrations in the brain. |
| Reinstatement of drug seeking | Postextinction resumption of operant behavior that had previously been maintained by a drug. Reinstatement is induced by a drug priming injection, stressors, contexts previously paired with drug self-administration, or response-contingent presentation of drug-associated cues. |
| Relapse | Resumption of drug-taking behavior during self-imposed (voluntary) or forced abstinence in humans and laboratory animals. |
| Sex | Characterization of an individual as female or male from biologic and morphologic features. |
| Short-access drug self-administration | A drug self-administration procedure in which the drug is continuously available during short daily sessions (3 h/day or less). |
| Stress-induced reinstatement | Resumption of drug seeking after extinction following exposure to environmental or pharmacological stressors. |
| Voluntary abstinence | Experimental conditions in which the self-administered drug is available in the self-administration chamber but the laboratory animal either stops or significantly decreases drug self-administration behavior. In animal models, voluntary abstinence can be achieved by introducing 1) mild foot shock punishment after the drug-reinforced operant response, 2) an electric barrier that delivers mild shock near the drug-paired lever, 3) mutually exclusive alternative palatable food reward, and 4) mutually exclusive alternative social reward. |