Influence of Changes in Adrenergic and Cholinergic Activity upon Acquisition of Operant Discrimination in Albino Rats

Abstract

The effect of adrenergic and cholinergic drugs upon two discrete-trial fixed-interval reinforcement schedules that generate either high or low rates of unreinforced (S^Δ) responding was investigated. Amphetamine and scopolamine decreased high S^Δ rates while having no effect on low S^Δ rates. Withdrawal of amphetamine after acquisition under the drug led to a dramatic increase in S^Δ rates under both reinforcement schedules. Alpha methyl-p-tyrosine reduced high S^Δ rates, while pilocarpine had no effect on behavior. These results suggest that the similarities between the behavioral effects of amphetamine and scopolamine on appetitive schedules may primarily reflect their motivational properties. Furthermore, these data indicate that withdrawal from chronic amphetamine administration can produce dramatic alterations in response rate even in cases where the acquisition of behavior is unaltered by chronic drug treatment.