BG University Hospital Bergmannsheil, Department of Neurology, Ruhr University Bochum, Germany.
Department of Cognitive Psychology, Faculty of Psychology, Ruhr University Bochum, Germany.
Neurobiol Learn Mem. 2023 Nov;205:107844. doi: 10.1016/j.nlm.2023.107844. Epub 2023 Oct 20.
Conditioned responding gradually stops during successful extinction learning. The renewal effect is defined as the recovery of a extinguished conditioned response when the context of extinction is different from acquisition. The stress hormone cortisol is known to have an influence on extinction memory and associative learning. Different effects of cortisol on behaviour and brain activity have been observed with respect to stress timing, duration, and intensity. However, the influence of cortisol prior to the initial encoding of stimulus-outcome associations on extinction learning, renewal and its behavioural and neurobiological correlates is still largely unknown. In our study, 60 human participants received 20 mg cortisol or placebo and then learned, extinguished, and recalled the associations between food stimuli presented in distinct contexts and different outcomes in three subsequent task phases. Learning performance during acquisition and extinction phases was equally good for both treatment groups. In the cortisol group, significantly more participants showed renewal compared to placebo. In the subgroup of participants with renewal, cortisol treated participants showed significantly better extinction learning performance compared to placebo. Participants showing renewal had in general difficulties with recalling extinction memory, but in contrast to placebo, the cortisol group exhibited a context-dependent impairment of extinction memory recall. Imaging analyses revealed that cortisol decreased activation in the hippocampus during acquisition. The cortisol group also showed reduced dorsolateral prefrontal cortex activation when extinction learning took place in a different context, but enhanced activation in inferior frontal gyrus during extinction learning without context change. During recall, cortisol decreased ventromedial prefrontal cortex activation. Taken together, our findings illustrate cortisol as a potent modulator of extinction learning and recall of extinction memory which also promotes renewal.
条件反射在成功的消退学习过程中逐渐停止。恢复效应被定义为当消退的情境与获得的情境不同时，已消退的条件反应的恢复。应激激素皮质醇已知对消退记忆和联想学习有影响。皮质醇对行为和大脑活动的影响因应激的时间、持续时间和强度而异。然而，皮质醇在刺激-结果关联的初始编码之前对消退学习、恢复及其行为和神经生物学相关性的影响在很大程度上仍然未知。在我们的研究中，60 名人类参与者接受了 20 毫克皮质醇或安慰剂，然后在三个后续任务阶段学习、消退和回忆在不同情境下呈现的食物刺激与不同结果之间的关联。在获得和消退阶段，两组治疗组的学习表现同样出色。在皮质醇组中，与安慰剂组相比，有更多的参与者表现出恢复。在有恢复的参与者亚组中，皮质醇治疗的参与者与安慰剂相比，表现出更好的消退学习表现。表现出恢复的参与者通常难以回忆起消退记忆，但与安慰剂组不同的是，皮质醇组表现出与情境相关的消退记忆回忆障碍。成像分析显示，皮质醇在获得过程中降低了海马体的激活。当在不同的情境中进行消退学习时，皮质醇组也表现出背外侧前额叶皮层的激活减少，但在没有情境变化的消退学习期间，下额前回的激活增强。在回忆过程中，皮质醇降低了腹内侧前额叶皮层的激活。总的来说，我们的发现说明了皮质醇作为消退学习和消退记忆回忆的有效调节剂，它也促进了恢复。
