Norepinephrine (NE) plays a central role in the acquisition of aversive learning via actions in the lateral nucleus of the amygdala (LA) [1, 2]. However, the function of NE in expression of aversively-conditioned responses has not been established. Given the role of the central nucleus of the amygdala (CeA) in the expression of such behaviors [3-5], and the presence of NE axons projections in this brain nucleus [6], we assessed the effects of NE activity in the CeA on behavioral expression using receptor-specific pharmacology and cell- and projection-specific chemogenetic manipulations. We found that inhibition and activation of locus coeruleus (LC) neurons decreases and increases freezing to aversively conditioned cues, respectively. We then show that locally inhibiting or activating LC terminals in CeA is sufficient to achieve this bidirectional modulation of defensive reactions. These findings support the hypothesis that LC projections to CeA are critical for the expression of defensive responses elicited by conditioned threats.

中文翻译：

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脑干中央杏仁核回路是对已知威胁的防御反应的基础。

去甲肾上腺素 (NE) 通过杏仁核外侧核 (LA) [1, 2] 的作用在获得厌恶性学习中起核心作用。然而，NE 在表达厌恶性条件反应中的功能尚未确定。鉴于杏仁核中央核 (CeA) 在此类行为表达中的作用 [3-5]，以及该脑核中 NE 轴突投射的存在 [6]，我们评估了 NE 活动在 CeA 中的影响使用受体特异性药理学和细胞和投射特异性化学遗传学操作对行为表达进行研究。我们发现蓝斑 (LC) 神经元的抑制和激活分别减少和增加对厌恶条件线索的冻结。然后我们表明，局部抑制或激活 CeA 中的 LC 末端足以实现这种防御反应的双向调节。这些发现支持这样的假设，即 LC 对 CeA 的预测对于条件性威胁引发的防御反应的表达至关重要。