Recent work indicates that the bed nucleus of the stria terminalis (BNST) is critically involved in the regulation of conditioned fear responses to unpredictable threats. Here we examined whether the involvement of the BNST in contextual fear conditioning in male rats depends on the imminence of shock after placement in the conditioning chamber. Specifically, we hypothesized that the BNST supports contextual freezing after conditioning with delayed, but not imminent, footshock (relative to placement in the context). Rats were implanted with cannulae targeting the BNST and underwent a contextual fear conditioning procedure in which a single footshock unconditioned stimulus (US) was delivered either 1 min or 9 min after the rat was placed in the context; the rats received a total of four identical conditioning sessions over two days, all with equivalent exposure to the context. Contexts associated with either imminent or delayed US onsets produced distinct patterns of freezing and shock-induced activity but freezing in each case was context-dependent. Reversible inactivation of the BNST reduced the expression of contextual freezing in the context paired with delayed (9 min), but not imminent (1 min), footshock onset. Implications of these data are discussed in the light of recent conceptualizations of BNST function, as well as for anxiety behaviors.

中文翻译：

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威胁的紧迫性决定了终纹床核在情境恐惧中的作用。


最近的研究表明，终纹床核（BNST）在调节对不可预测威胁的条件性恐惧反应方面发挥着重要作用。在这里，我们检查了 BNST 在雄性大鼠情境恐惧调节中的参与是否取决于放置在调节室中后休克的迫近。具体来说，我们假设 BNST 支持在延迟但不是迫在眉睫的足部电击（相对于在上下文中的放置）进行调节后的上下文冻结。大鼠被植入针对 BNST 的插管，并接受情境恐惧调节程序，其中在将大鼠置于情境中 1 分钟或 9 分钟后，发出单次足部电击非条件刺激 (US)；两天内，老鼠总共接受了四次相同的调节训练，所有训练都具有相同的环境暴露程度。与即将发生或延迟的美国发病相关的背景会产生不同的冻结和休克诱发活动模式，但每种情况下的冻结都取决于具体情况。 BNST 的可逆失活减少了与延迟（9 分钟）但不立即（1 分钟）的足部电击发作相匹配的背景冻结的表达。根据最近 BNST 功能以及焦虑行为的概念化讨论了这些数据的含义。