Assessment of drug state dimensionality via drug-drug training and stimulus generalization testing

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a concurrent fixed-interval (FI) FI schedule of food presentation on which, after pentobarbital administration, responses on one key were reinforced with food under an FI 60-s component and responses on the other key were reinforced under an FI 240-s component. After saline administration, the schedule contingencies on the two keys were reversed. After both pentobarbital and saline, pigeons responded more frequently on the key on which responses had been programmed to produce the reinforcer under the FI 60 component of the concurrent schedule. The schedule was changed to concurrent FI 150 FI 150 s for drug-substitution tests. In each bird, increasing doses of pentobarbital, ethanol, and chlordiazepoxide produced increases in the proportion of responses on the key on which responses had been reinforced under the FI 60 component after pentobarbital administration during training sessions. The proportion of responses on that key was slightly lower for ethanol than for chlordiazepoxide and pentobarbital. At a dose of pentobarbital higher than the training dose, responding decreased on the key that had been reinforced under the FI 60 component during training sessions. Phencyclidine produced less responding on the key programmed under the FI 60-s component than did pentobarbital. Methamphetamine produced responding primarily on the key on which responses had been reinforced under the FI 60-s component after saline administration.

mentioning

confidence: 99%

Drug Discrimination Under a Concurrent Fixed‐interval Fixed‐interval Schedule

McMillan

Hardwick

1997

“…These studies have shown that the schedule of reinforcement is an important determinant Among the schedules used in drug-discrimination studies, the fixed-ratio (FR) schedule has been used most frequently (Colpaert, 1987). Other reinforcement schedules that have been used include fixed-interval (FI) schedules (Krimmer, McGuire, & Barry, 1984;Kubena & Barry, 1969), variable-interval (VI) schedules (Gouvier, Akins, & Trapold, 1984), tandem VI FR schedules (Witkin, Carter, & Dykstra, 1980), and second-order FR (FR) color-tracking schedules (McMillan, Cole-Fullenwider, Hardwick, & Wenger, 1982). Although a variety of schedules have been used to investigate the stimulus effects of drugs, the manner in which different reinforcement contingencies produce differential effects on drugdiscrimination behavior has not been explored systematically.…”

mentioning

confidence: 99%

Effects of Schedule of Reinforcement on a Pentobarbital Discrimination in Rats

Snodgrass

McMillan

1991

The purpose of this study was to determine the effects of the schedule of reinforcement on a pentobarbital discrimination in rats. Five rats were trained to discriminate 10 mg/kg pentobarbital from saline under a multiple fixed-interval 180-s fixed-ratio 20 schedule of reinforcement. During both saline and pentobarbital training sessions, subjects emitted a higher percentage of correct responses under the fixed-ratio component as compared to the fixed-interval component of the multiple schedule. Determination of the pentobarbital dose-response curve under the fixed-ratio component resulted in a steep curve characterized by responding on the saline lever at low doses and on the drug lever at higher doses. Under the fixed-interval component, a graded dose-effect curve was produced, with considerable responding on both levers after intermediate doses of pentobarbital. The administration of phencyclidine and MK-801 resulted in an intermediate level of drug-lever responding for some subjects. Administration of d-amphetamine resulted in saline (nondrug) appropriate responding. The results of this study demonstrate that the schedule of reinforcement is a determinant of drug stimulus control, just as it is a determinant of other drug effects.

“…The general finding has been that drug-discrimination generalization gradients are quantal when responding is maintained under FR schedules and are graded when responding is maintained under fixed-interval (FI) and variable-interval (VI) schedules of reinforcement. These effects occur under simple FI schedules (Massey, McMillan, & Wessinger, 1992), simple FR schedules (Colpaert, 1987;Massey et al, 1992), VI schedules (Gouvier, Akins, & Trapold, 1984), second-order FR schedules (McMillan, Cole-Fullenwider, Hardwick, & Wenger, 1982), multiple FR FI schedules Snodgrass & McMillan, 1991), concurrent FR FR schedules (McMillan & Li, 1999a), concurrent FI FI schedules , and concurrent VI VI schedules .…”

mentioning

confidence: 99%

Drug Discrimination Under Concurrent Variable‐ratio Variable‐ratio Schedules

McMillan¹,

Hardwick²,

Li³

2002

Pigeons were trained to discriminate 5 mg/kg pentobarbital from saline under concurrent variable-ratio (VR) VR schedules, in which responses on the pentobarbital-biased lever were reinforced under the VR schedule with the smaller response requirements when pentobarbital was given before the session, and responses on the saline-biased key were reinforced under the VR schedule with the larger response requirements. When saline was administered before the session, the reinforcement contingencies associated with the two response keys were reversed. When responding stabilized under concurrent VR 20 VR 30, concurrent VR 10 VR 40, or concurrent VR 5 VR 50 schedules, pigeons responded almost exclusively on the key on which fewer responses were required to produce the reinforcer. When other doses of pentobarbital and other drugs were substituted for the training dose, low doses of all drugs produced responding on the saline-biased key. Higher doses of pentobarbital and chlordiazepoxide produced responding only on the pentobarbital-biased key, whereas higher doses of ethanol and phencyclidine produced responding only on this key less often. d-Amphetamine produced responding primarily on the saline-biased key. When drugs generalized to pentobarbital, the shape of the generalization curve under concurrent VR VR schedules was more often graded than quantal in shape. Thus, drug discrimination can be established under concurrent VR VR schedules, but the shapes of drug-discrimination dose-response curves under concurrent VR VR schedules more closely resemble those seen under interval schedules than those seen under fixed-ratio schedules. Graded dose-response curves under concurrent VR VR schedules may relate to probability matching and difficulty in discriminating differences in reinforcement frequency.