Table 1

Glossary of terminology

Active lever. Responses on this lever lead to drug infusions during drug self-administration training. During extinction training and tests for reinstatement, responses on this lever are not reinforced by the drug and serve as a measure of “drug seeking”.
Between-session reinstatement procedure.A procedure in which drug self-administration training, extinction training, and tests for reinstatement of drug seeking are conducted on separate daily sessions.
Between-within session reinstatement procedure. A procedure in which drug self-administration training is conducted over days, and then extinction training and tests for reinstatement of drug seeking are examined on the same day following different periods of drug withdrawal.
CPP procedure. A classical conditioning procedure used to study the conditioned reinforcing effects of drugs or nondrug reinforcers. During training, one portion of a test chamber is associated with injections of a drug and another portion is associated with injections of a vehicle. During testing for CPP, conducted in a drug-free state, the subject is allowed to choose between the drug-paired and the vehicle-paired environment. An increase in preference for the drug-paired context serves as a measure of the conditioned reinforcing effects of the drug.
Conditioned reinforcer. A previously neutral stimulus (e.g., tone, light) that acquired reinforcing effects through its prior association with a primary or unconditioned reinforcer (e.g., food, drug).
Contextual drug cue. A diffuse set of “background” stimuli (e.g., operant chamber fan, time of day) in the drug self-administration context that becomes associated with the availability and the effects of the drug following repeated daily training sessions.
Cross-reinstatement. Reinstatement of drug seeking, following extinction of the drug-reinforced behavior by drugs that are different from the self-administered drug.
Discrete conditioned drug cue. A neutral stimulus (e.g., cue light, tone, sound of infusion pump) that becomes a conditioned reinforcer following repeated pairing with drug infusions and effects during self-administration training.
Discriminative drug cue. An environmental stimulus that after discrimination training sets the occasion for drug self-administration behavior (rendering the behavior more likely). During training, this stimulus termed the S+ (or SD) is presented just before the drug becomes available or throughout the period of self-administration; a different stimulus, termed the S (or SΔ), is presented when the drug is not available either on alternate days or sessions.
Drug self-administration procedure. In this procedure, laboratory animals typically lever press for drug injections. The premise of this procedure is that psychoactive drugs control behavior by functioning as positive reinforcers. A high concordance exists between drugs self-administered by laboratory animals and those abused by humans.
Extinction. In the terminology of operant conditioning, extinction refers to discontinuing the reinforcement (e.g., food, drug) of a response (e.g., lever press). In the terminology of classical conditioning, extinction refers to the presentation of a conditioned stimulus(i), previously paired with a given unconditioned stimulus (e.g., food, drug), in the absence of the primary reinforcer. In studies of cue-induced reinstatement, extinction may refer to lever pressing in the absence of both the drug and the conditioned cues that had previously been paired with drug injections.
FR schedule of reinforcement. A reinforcement schedule in which the reinforcer (e.g., drug, food) is delivered following an invariant number of responses.
Inactive lever. Responses on this lever do not lead to the delivery of drugs during self-administration training. In reinstatement studies, responses on this lever during testing are thought to measure nonspecific activity and/or response generalization.
Negative reinforcer. A stimulus is defined as a negative reinforcer if its removal or postponement, following a response, increases or maintains the likelihood of a response.
Positive reinforcer. A stimulus is defined as a positive reinforcer in operant conditioning if its presentation, following a response, increases or maintains the likelihood of the response.
Primary reinforcer (or unconditioned reinforcer). Any stimulus that has reinforcing effects without the need for any explicit conditioning operation.
Predictive validity. A measure of how well a manipulation in the model predicts an analogous manipulation in the modeled condition.
Rate-dependent effects of drugs.Refers to the observation that the effects of drugs on operant responding are related to the rate of the response in the absence of the drug. Typically low rates of responding increase proportionally more than higher rates following drug administration; the very high response rates are often decreased by drug administration.
Reinstatement. In the learning literature reinstatement refers to the recovery of a learned response (e.g., lever-pressing behavior) that occurs when a subject is exposed noncontingently to the unconditioned stimulus (e.g., food) after extinction. In studies of reinstatement of drug seeking, reinstatement typically refers to the resumption of drug seeking after extinction following exposure to drugs, drug cues, or stressors.
Relapse. The term commonly used in the clinical literature to describe the resumption of drug-taking behavior following drug-free periods.
Renewal. Recovery of extinguished behavior that can occur when the context is changed after extinction, when the subject returns to the learning environment after extinction in a different environment. In studies of reinstatement of drug seeking, rats are trained to lever press for a drug in one environmental context, the lever-pressing behavior is extinguished in a different context, and renewal of drug seeking occurs when rats return to the original drug self-administration context.
Second-order schedule of reinforcement. A complex schedule of reinforcement in which completion of the response requirements of one schedule (often referred to as the unit schedule) is treated as a unitary response that is reinforced according to another schedule. Often a stimulus is briefly presented at the completion of the unit schedule requirements, and this stimulus can acquire conditioned reinforcing effects.
Within-session reinstatement procedure. A procedure in which drug self-administration training, extinction training, and tests for reinstatement are conducted on the same day.
  • Sources: Bouton and Swartzentruber, 1991; Catania, 1992;Stolerman, 1992.