Stressful and emotionally arousing experiences create strong memories that seem to lose specificity over time. It is uncertain, however, how the stress system contributes to the phenomenon of time-dependent fear generalization. Here, we investigated whether post-training corticosterone (CORT-HBC) injections, given after different training intensities, affect contextual fear memory specificity at several time points. We trained male Wistar rats on the contextual fear conditioning (CFC) task using two footshock intensities (mild CFC, 3 footshocks of 0.3 mA, or moderate CFC, 3x 0.6 mA) and immediately after the training session we administered CORT-HBC systemically. We first tested the animals in a novel context and then in the training context at different intervals following training (2, 14, 28 or 42 days). By measuring freezing in the novel context and then contrasting freezing times shown in both contexts, we inferred contextual fear generalization for each rat, classifying them into Generalizers or Discriminators. Following mild CFC training, the glucocorticoid injection promoted an accurate contextual memory at the recent time point (2 days), and increase the contextual memory accuracy 28 days after training. In contrast, after the moderate CFC training, CORT-HBC facilitated contextual generalization at 14 days, compared to the control group that maintained contextual discrimination at this timepoint. For this training intensity, however, CORT-HBC did not have any effect on recent memory specificity. These findings indicate that treatment with CORT-HBC immediately after the encoding of mild or moderately arousing experiences may differentially modulate memory consolidation and time-dependent fear generalization.

压力和情绪激动的经历会产生强烈的记忆，随着时间的推移似乎会失去特异性。然而，尚不确定压力系统如何促成时间依赖性恐惧泛化现象。在这里，我们调查了在不同训练强度后给予的训练后皮质酮 (CORT-HBC) 注射是否会影响几个时间点的情境恐惧记忆特异性。我们使用两种电击强度（轻度 CFC，3 次 0.3 mA 或中度 CFC，3x 0.6 mA）对雄性 Wistar 大鼠进行情境恐惧条件反射 (CFC) 任务训练，并在训练后立即系统地管理 CORT-HBC。我们首先在新的环境中测试动物，然后在训练后的不同时间间隔（2、14、28 或 42 天）在训练环境中进行测试。通过测量新环境中的冻结，然后对比两种情况下显示的冻结时间，我们推断出每只大鼠的上下文恐惧泛化，将它们分类为泛化器或鉴别器。在轻度 CFC 训练后，糖皮质激素注射促进了最近时间点（2 天）的准确上下文记忆，并在训练后 28 天提高了上下文记忆的准确性。相比之下，在中度 CFC 训练后，CORT-HBC 在 14 天时促进了上下文泛化，而对照组在此时间点保持上下文歧视。然而，对于这种训练强度，CORT-HBC 对最近的记忆特异性没有任何影响。