Glucocorticoid receptor agonist enhances pavlovian appetitive conditioning but disrupts outcome-specific associations.

A Pavlovian-instrumental transfer design was used to investigate the impact of the glucocorticoid receptor agonist dexamethasone (dex) on Pavlovian associations involving the sensory and motivational aspects of rewards. Rats were trained with 2 lever responses, R1 and R2, for different rewards, Outcome (O)1 and O2. In separate Pavlovian training sessions. Stimulus A was paired with O1 and Stimulus B with O2. Administration of dex after A-O1 sessions enhanced A-O1 associations measured in extinction, relative to B-O2 pairings that were followed by saline. In lever-press transfer tests, presentation of Stimuli A or B enhanced general responding to the same degree. However, outcome-specific transfer (selectively greater enhancement of R1 during A and R2 during B) was abolished for Stimulus A. This suggests that memory enhancement by posttraining dex is simultaneously detrimental to processing of outcome-specific sensory information. (c) 2003 APA