Glucocorticoid hormones (GCs) are known to strengthen the consolidation of long-term memory of emotionally arousing experiencies.  Particularly, fear memories are consolidated in a robust manner which hampers the possibility of the subjects to discriminate. This phenomenon is related to the amount of glucocorticoids released during emotionally arousing experiences. Currently, the information regarding the role of GCs in memory discrimination and generalization is scarce.

The aim of this study is to determine the involvement of GCs on memory accuracy in a cued fear conditioning task. As it has been reported an impairing effect of high doses of GCs on memory processes, we hypothesize that GCs promote memory generalization.

We used male Wistar rats to standardize the cued fear conditioning task using two tones of different frequencies. A low frequency tone (500 Hz) paired to a footshock in the last two seconds of its duration (0.4 mA or 0.2 mA, CS+) is presented in three trials during training, while a high frequency tone (1500 kHz, CS-) is presented randomly in three trials during retention without the unconditioned stimulus ; subjects were injected with vehicle or CORT in a dose of 1 or 3 mg/kg either 60 m before the retention or right after training.

Results showed that the high, but not the low dose of corticosterone administered after training, causes an increase of the freezing response to the CS- ; these data indicate a generalized response when subjects are trained with a high intensity footshock, however, when they are trained with a low intensity footshock, an enhancing effect in discrimination between stimulus is observed.

Our data indicates that highly arousing experiences are modulated by GCs promoting generalization, whereas neutral experiences are enhanced allowing for discrimination.

Glucocorticoids, memory, discrimination, generalization