The ability to predict the occurrence of an aversive outcome based on available cues requires associative learning and plastic changes in the amygdala. When the predictive cue and aversive shock outcome are separated in time as in trace fear conditioning, additional circuitry is needed, including the prelimbic (PL) area of the prefrontal cortex. We have previously shown that neuronal firing in the PL during the trace interval separating the cue and shock is required for trace cued fear memory formation, but whether this mnemonic signal is conveyed to the amygdala is unknown. Here we show in males that silencing PL activity during the trace interval reduces Arc protein in the basolateral amygdala (BLA) of trace-conditioned rats. Then, using pathway-specific optogenetic and chemogenetic silencing, we show a role for direct PL-BLA communication in trace cued fear learning under weak training conditions, but not standard training. These results suggest that PL input to the BLA may serve to promote cued learning when the cue-shock relationship is most ambiguous and that other trace fear circuitry can compensate for the loss of this connection with additional training. This also highlights the challenge to studying how emotional memories are formed and stored within a distributed network and suggests that the function of individual connections within such a network may best be determined using weak training conditions.

中文翻译：

---

足底杏仁核的前期输入有助于在弱训练条件下获得痕迹的恐惧记忆。

根据可用线索预测厌恶结果发生的能力需要杏仁核的联想学习和可塑性变化。当预测性提示和厌恶性休克结果如在痕迹恐惧调节中那样及时分开时，则需要额外的电路，包括前额叶皮层的前缘（PL）区域。先前我们已经表明，在跟踪提示和电击分离的跟踪间隔期间，PL的神经元放电是跟踪暗示的恐惧记忆形成所必需的，但是该记忆信号是否传递到杏仁核尚不清楚。在这里，我们在雄性中显示，在痕量间隔内沉默PL活性会降低痕量条件大鼠基底外侧杏仁核（BLA）中的Arc蛋白。然后，使用特定于途径的光遗传和化学遗传沉默，我们在弱训练条件下（但不是标准训练）在跟踪线索恐惧学习中显示了直接PL-BLA交流的作用。这些结果表明，当提示-电击关系最模糊时，向BLA的PL输入可能有助于促进提示学习，并且其他跟踪恐惧电路可以通过额外的训练来弥补这种联系的丧失。这也凸显了研究情绪记忆如何在分布式网络中形成和存储的挑战，并建议最好使用弱训练条件来确定这种网络中各个连接的功能。这些结果表明，当提示-电击关系最模糊时，向BLA的PL输入可能有助于促进提示学习，并且其他跟踪恐惧电路可以通过额外的训练来弥补这种联系的丧失。这也凸显了研究情绪记忆如何在分布式网络中形成和存储的挑战，并建议使用弱训练条件可以最好地确定这种网络中各个连接的功能。这些结果表明，当提示-电击关系最模糊时，向BLA的PL输入可能有助于促进提示学习，并且其他跟踪恐惧电路可以通过额外的训练来弥补这种联系的丧失。这也凸显了研究情绪记忆如何在分布式网络中形成和存储的挑战，并建议最好使用弱训练条件来确定此类网络中各个连接的功能。