Behavioral CRs elicited by a lithium- or an amphetamine-paired contextual test chamber

Abstract

The behavioral CRs elicited by a drug-paired contextual cue in rats were measured in a series of experiments. The first three experiments measured the pattern of CRs elicited by a lithiumand an amphetamine-paired CS chamber. The final experiment measured the pattern of URs elicited by lithium or amphetamine when administered in the same chamber. The suppression of grooming-related activities (body washing, face washing, and/or scratching) appeared as a nonspecific effect of both drug USs that was capable of becoming conditioned to the contextual chamber cue. A number of other behaviors differed among conditions, which provides evidence that contextual cue-drug associations are drug-specific. Of the behaviors that differed between the two US drug conditions, lithium CRs showed evidence of behavioral activation (enhanced rearing and limb flicking), but amphetamine CRs showed evidence of behavioral suppression (line crossing, rearing, and shaking). The UR patterns shared some similar and some dissimilar elements of the CR patterns elicited by the CS chamber for both lithium and amphetamine; in fact, by the activity and rearing measures, the URs and CRs were opposite in direction. The results exclusively supported neither stimulus substitution nor conditioned compensatory response accounts of Pavlovian conditioning; instead, each process appears to have accounted for different components of the overall CR pattern.