Departments of Psychology, Psychiatry & Biobehavioral Sciences, and Integrative Center for Learning and Memory, University of California, Los Angeles, California 90095.
Evelyn F. McKnight Brain Institute and.
J Neurosci. 2014 Jun 18;34(25):8462-6. doi: 10.1523/JNEUROSCI.3624-13.2014.
Although the circuit mediating contextual fear conditioning has been extensively described, the precise contribution that specific anatomical nodes make to behavior has not been fully elucidated. To clarify the roles of the dorsal hippocampus (DH), basolateral amygdala (BLA), and medial prefrontal cortex (mPFC) in contextual fear conditioning, activity within these regions was mapped using cellular compartment analysis of temporal activity using fluorescence in situ hybridization (catFISH) for Arc mRNA. Rats were delay-fear conditioned or immediately shocked (controls) and thereafter reexposed to the shocked context to test for fear memory recall. Subsequent catFISH analyses revealed that in the DH, cells were preferentially reactivated during the context test, regardless of whether animals had been fear conditioned or immediately shocked, suggesting that the DH encodes spatial information specifically, rather then the emotional valence of an environment. In direct contrast, neuronal ensembles in the BLA were only reactivated at test if animals had been fear conditioned, suggesting that the amygdala specifically tracks the emotional properties of a context. Interestingly, Arc expression in the mPFC was consistent with both amygdala- and hippocampus-like patterns, supporting a role for the mPFC in both fear and contextual processing. Collectively, these data provide crucial insight into the region-specific behavior of neuronal ensembles during contextual fear conditioning and demonstrate a dissociable role for the hippocampus and amygdala in processing the contextual and emotional properties of a fear memory.
虽然介导情境恐惧条件反射的回路已经被广泛描述，但特定解剖节点对行为的确切贡献尚未完全阐明。为了阐明背侧海马体（DH）、基底外侧杏仁核（BLA）和内侧前额叶皮层（mPFC）在情境恐惧条件反射中的作用，使用荧光原位杂交（catFISH）对 Arc mRNA 的时间活动进行细胞区室分析，对这些区域的活动进行了映射。大鼠接受延迟恐惧条件反射或立即电击（对照），然后重新暴露于受电击的环境中，以测试恐惧记忆的回忆。随后的 catFISH 分析表明，在 DH 中，无论动物是否接受过恐惧条件反射或立即受到电击，细胞在情境测试中都会优先被重新激活，这表明 DH 专门编码空间信息，而不是环境的情绪效价。与此形成鲜明对比的是，只有在动物接受过恐惧条件反射时，BLA 中的神经元集合才会在测试中被重新激活，这表明杏仁核专门跟踪环境的情绪特征。有趣的是，mPFC 中的 Arc 表达与杏仁核和海马体相似的模式一致，支持 mPFC 在恐惧和情境处理中都有作用。总的来说，这些数据提供了关于情境恐惧条件反射过程中神经元集合的区域特异性行为的重要见解，并证明了海马体和杏仁核对处理恐惧记忆的情境和情绪特征的分离作用。
