The effect of drugs on the acquisition of stimulus control in a conditioned suppression procedure.
Psychopharmacology 1985 DOI: 10.1007/bf00427327 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Peer reviewed |
|---|---|
| Population | Rats |
| Interventions | Cocaine Diazepam Lisuride Mescaline 5-methoxy-N N-dimethyltryptamine Amphetamine Pentobarbital Morphine Atropine Scopolamine Clonazepam Chlorpromazine BC-105 Saline |
| Dose | LSD: 0.2 and 0.32 mg/kg; cocaine: 20 mg/kg; diazepam: 2.5 mg/kg; lisuride: 0.08 mg/kg; mescaline: 20 mg/kg; 5-methoxy-N,N-dimethyltryptamine: 4 mg/kg; amphetamine: 4 mg/kg; pentobarbital: 15 mg/kg; morphine: 4 mg/kg; atropine: 10 mg/kg; scopolamine: 1 mg/kg; clonazepam: 0.5 mg/kg; chlorpromazine: 4 mg/kg; BC-105: 6 mg/kg |
| Key findings | In rats, a tone previously paired with shock suppressed lever pressing, and this suppression was eliminated or attenuated by several psychoactive drugs including LSD, cocaine, diazepam, mescaline, and others, while some drugs had no effect. The authors suggest that drug-induced stimuli may overshadow external stimuli during classical conditioning and that drugs can alter behavior without affecting motor control. |
Abstract
Rats were trained to press a lever under a variable-interval (VI) schedule of water reinforcement. After stable responding had developed, a 4.5-KHz tone (CS) was conditioned classically to a 2.5-mA electric shock (US) in groups of animals which had been given various psychoactive drugs or saline. Twenty-four hours later, a stimulus generalization test was conducted in the absence of drug; during this session, tones that varied in frequency around 4.5 KHz were presented while the animals were responding under the VI schedule. In animals conditioned under saline, all tones (non-differentially) suppressed responding which, however, recovered gradually over time. This suppressive effect was eliminated by lysergic acid diethylamide (LSD; 0.2 and 0.32 mg/kg), cocaine (20 mg/kg), diazepam (2.5 mg/kg), lisuride (0.08 mg/kg), mescaline (20 mg/kg) and 5-methoxy-N,N-dimethyltryptamine (4 mg/kg), and was attenuated by amphetamine (4 mg/kg), pentobarbital (15 mg/kg) and morphine (4 mg/kg). Atropine (10 mg/kg), scopolamine (1 mg/kg), clonazepam (0.5 mg/kg), and chlorpromazine (4 mg/kg) did not alter the suppressive effect of the tone. The serotonin antagonist BC-105 (6 mg/kg) reversed the effect of 0.2 mg/kg of LSD. These results suggest (1) that drug-induced stimuli may "overshadow" other (e.g., external) stimuli during classical conditioning and, (2) that drugs might affect behavior by altering processes (stimulus control or others) that do not simultaneously involve response or motor control.