The acquisition of active avoidance (AA) behavior is typically aided by the presence of two signals—the warning signal, which predicts the future occurrence of an aversive event (e.g., shocks), and the safety signal, which is presented upon successful avoidance of oncoming shocks. While the warning signal could be conceived to act as a Pavlovian fear cue, and is likely mediated by brain areas that underlie Pavlovian fear cue conditioning, the neural substrates underlying safety signaling are less clear, largely due to the unavailability of AA tasks that are devoid of an explicit warning signal. The present study sought to investigate the role of the ventral hippocampus (VH) in safety signaled AA performance acquired without an explicit warning signal, using a novel discrete trial paradigm. Adult male Long Evans rats were divided into two groups and trained to acquire AA responses with, or without a safety signal. Analysis of the acquisition and stable state performance data revealed that the availability of a safety signal alone did not improve the acquisition or performance of AA responses. Furthermore, post‐training, reversible VH inactivation did not impact stable state avoidance behavior. However, extinction of avoidance responses was facilitated in the group trained with a safety signal, and this effect was further potentiated by VH inactivation. Additional elevated plus maze (EPM), light–dark box, and locomotor tests demonstrated that VH inactivation reduced anxiety without affecting locomotor activity. Taken together, these results demonstrate the importance of VH in the extinction of persistent pathological avoidance behavior when safety is signaled.

中文翻译：

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在存在安全信号的情况下，腹侧海马体失活增强了主动回避反应的消失，但使离散试验操作性主动回避表现完好无损。

主动回避 (AA) 行为的获得通常由两个信号的存在来辅助——警告信号，它预测未来会发生厌恶事件（例如，冲击），以及安全信号，它在成功避免发生即将到来的冲击。虽然警告信号可以被认为是巴甫洛夫恐惧线索，并且很可能由巴甫洛夫恐惧线索条件下的大脑区域介导，但安全信号背后的神经基质不太清楚，主要是由于缺乏 AA 任务的不可用明确的警告信号。本研究试图调查腹侧海马 (VH) 在没有明确警告信号的情况下获得的安全信号 AA 性能中的作用，使用新的离散试验范式。成年雄性 Long Evans 大鼠被分成两组，并接受训练以在有或没有安全信号的情况下获得 AA 反应。对采集和稳定状态性能数据的分析表明，仅提供安全信号并不能改善 AA 响应的采集或性能。此外，训练后可逆的 VH 失活不会影响稳定状态回避行为。然而，在接受安全信号训练的组中，回避反应的消失得到了促进，并且 VH 失活进一步加强了这种效果。额外的高架十字迷宫 (EPM)、明暗盒和运动测试表明，VH 失活可在不影响运动活动的情况下减少焦虑。综合起来，