Institute for Neuroscience, University of Texas at Austin, Austin, TX, USA; Center for Learning and Memory, Department of Neuroscience, University of Texas at Austin, Austin, TX, USA.
Department of Psychology, University of California, Los Angeles, Los Angeles, CA, USA.
Curr Biol. 2022 Jan 24;32(2):304-314.e5. doi: 10.1016/j.cub.2021.11.004. Epub 2021 Nov 22.
Neurobiological research in rodents has revealed that competing experiences of fear and extinction are stored as distinct memory traces in the brain. This divided organization is adaptive for mitigating overgeneralization of fear to related stimuli that are learned to be safe while also maintaining threat associations for unsafe stimuli. The mechanisms involved in organizing these competing memories in the human brain remain unclear. Here, we used a hybrid form of Pavlovian conditioning with an episodic memory component to identify overlapping multivariate patterns of fMRI activity associated with the formation and retrieval of fear versus extinction. In healthy adults, distinct regions of the medial prefrontal cortex (PFC) and hippocampus showed selective reactivation of fear versus extinction memories based on the temporal context in which these memories were encoded. This dissociation was absent in participants with posttraumatic stress disorder (PTSD) symptoms. The divided neural organization of fear and extinction may support flexible retrieval of context-appropriate emotional memories, while their disorganization may promote overgeneralization and increased fear relapse in affective disorders.
啮齿动物的神经生物学研究表明，恐惧和消退的竞争经验在大脑中被储存为不同的记忆痕迹。这种分裂的组织对于减轻对相关刺激的过度泛化是适应的，这些刺激已经被学习为安全的，同时也保持了对不安全刺激的威胁关联。在人类大脑中组织这些竞争记忆的机制尚不清楚。在这里，我们使用一种具有情节记忆成分的混合形式的条件反射来识别与恐惧与消退的形成和检索相关联的 fMRI 活动的重叠多变量模式。在健康成年人中，内侧前额叶皮层（PFC）和海马体的不同区域根据这些记忆被编码的时间背景，选择性地重新激活恐惧与消退记忆。在有创伤后应激障碍（PTSD）症状的参与者中，这种分离是不存在的。恐惧和消退的分裂神经组织可能支持灵活检索上下文适当的情绪记忆，而它们的组织紊乱可能促进情感障碍中的过度泛化和恐惧复发。
