Anticonflict effects of buspirone and chlordiazepoxide in pigeons under a concurrent schedule with punishment and a changeover response.

A procedure was developed with pigeons to extend the experimental analysis of punished behavior and the effects of anxiolytic drugs. Under this procedure the completion of a fixed-ratio requirement on a changeover key switched between two variable-interval schedules of reinforcement that were programmed on a second response key. Under one schedule, correlated with a green keylight, key pecks produced only food; under the second schedule, correlated with a red keylight, key pecks produced both food and electric shock. Pigeons were switched into the component with shock if they did not enter that component within 5 min. Parameter values of the variable-interval schedules were manipulated systematically and the effects of two clinically active anxiolytic drugs, buspirone and chlordiazepoxide, were examined. Responding was suppressed during the component with shock (punishment) and, under non-drug conditions, pigeons infrequently switched into the punishment component; changeover responses occurred rapidly when switched into the punishment component. Both buspirone (0.1-3.0 mg/kg) and chlordiazepoxide (3.0-30 mg/kg) increased punished responding at doses that had little effect on unpunished responding; d-amphetamine (0.3-5.6 mg/kg), which was studied only under one parameter of the variable-interval schedule, produced greater decreases in rates of punished responding than in unpunished responding.(ABSTRACT TRUNCATED AT 250 WORDS)