A SELECTIVE ROLE FOR CORTICOSTERONE IN CONTEXTUAL-FEAR CONDITIONING

The contribution of corticosterone to contextual- and auditory-cue fea r conditioning was examined. Adrenalectomized rats showed reduced cont extual-fear conditioning when tested 24 hr after conditioning; however , neither immediate contextual- nor auditory-cue fear conditioning was impaired. Contextual-fear conditioning in adrenalectomized rats with corticosterone replacement during the 4-day interval separating surger y and conditioning matched the level of controls. Moreover, rats expos ed to the context prior to adrenalectomy showed normal long-term conte xtual-fear conditioning. Corticosterone replacement administered after the conditioning episode also negated the effects of adrenalectomy. T hus, corticosterone's role in fear conditioning is selective: It appea rs to contribute to the neural processes that support the consolidatio n of a long-term memory representation of the context.