BENZODIAZEPINE-INDUCED OUTCOME REVALUATION AND THE MOTIVATIONAL CONTROL OF INSTRUMENTAL ACTION IN RATS

It has been argued that the control of instrumental action by motivati onal states is indirect, being mediated by the effects these states ha ve on the incentive value of the instrumental outcome (A. Dickinson & B. W. Balleine, 1994). In this study, the benzodiazepine agonist midaz olam was found to control instrumental action in a similar manner. Mid azolam (1 mg/kg) increased rewarded instrumental performance in rats t rained undeprived but only elevated performance in extinction when rat s were reexposed to the instrumental outcome under midazolam before th e test. This effect of reexposure under midazolam did not transfer to a test conducted under food deprivation, suggesting that it was not pr oduced by drug-induced hunger. Finally, in animals trained hungry, mid azolam was found to block outcome devaluation induced by a reduction i n food deprivation, indicating that midazolam and food deprivation aff ect outcome value via a common substrate.