Faculty of Medicine, Memorial University of Newfoundland, St. John's, NF, Canada.
Front Neural Circuits. 2024 Feb 27;18:1371130. doi: 10.3389/fncir.2024.1371130. eCollection 2024.
Hippocampal networks required for associative memory formation are involved in cue- and context-dependent threat conditioning. The hippocampus is functionally heterogeneous at its dorsal and ventral poles, and recent investigations have focused on the specific roles required from each sub-region for associative conditioning. Cumulative evidence suggests that contextual and emotional information is processed by the dorsal and ventral hippocampus, respectively. However, it is not well understood how these two divisions engage in threat conditioning with cues of different sensory modalities. Here, we compare the involvement of the dorsal and ventral hippocampus in two types of threat conditioning: olfactory and auditory. Our results suggest that the dorsal hippocampus encodes contextual information and is activated upon recall of an olfactory threat memory only if contextual cues are relevant to the threat. Overnight habituation to the context eliminates dorsal hippocampal activation, implying that this area does not directly support cue-dependent threat conditioning. The ventral hippocampus is activated upon recall of olfactory, but not auditory, threat memory regardless of habituation duration. Concurrent activation of the piriform cortex is consistent with its direct connection with the ventral hippocampus. Together, our study suggests a unique role of the ventral hippocampus in olfactory threat conditioning.
参与联想记忆形成的海马体网络参与线索和上下文相关的威胁条件作用。海马体在其背侧和腹侧两极具有不同的功能，最近的研究集中在每个亚区对联想条件作用的具体作用。累积的证据表明，上下文和情绪信息分别由背侧和腹侧海马体处理。然而，尚不清楚这两个分区如何在不同感觉模态的线索下参与威胁条件作用。在这里，我们比较了背侧和腹侧海马体在两种类型的威胁条件作用中的参与情况：嗅觉和听觉。我们的结果表明，背侧海马体编码上下文信息，并且仅在与威胁相关的情况下，才会在回忆嗅觉威胁记忆时被激活。对上下文的夜间习惯化会消除背侧海马体的激活，这意味着该区域不会直接支持线索依赖性的威胁条件作用。腹侧海马体在回忆嗅觉威胁记忆时被激活，而与听觉无关，无论习惯化持续时间如何。梨状皮层的并发激活与其与腹侧海马体的直接连接一致。总之，我们的研究表明腹侧海马体在嗅觉威胁条件作用中具有独特的作用。
