Hippocampal Functional Organization in Fear Memory

众所周知，内嗅皮层（EC）是情景记忆形成所必需的海马输入的主要来源之一。然而，情景记忆中的多模态因素是如何在欧共体中被处理的还不是很清楚。在本研究中，我们调查了个别EC子区域在情景记忆中的贡献，以确定EC子区域可能的功能分离。我们对处于正迷宫中的条件动物有两种不同类型的刺激——空间或物体，这两种刺激在MEC和LEC中进行处理，而光遗传学抑制MEC/LEC。完成行为学实验，统计分析行为学和组织学数据。在弱足震条件下（0.3mA）， LEC抑制动物（n=6）对电击物体的回避显著低于对照组（n=7; p < 0.005）。MEC抑制动物（n=8）对电击臂的回避也相对低于对照组（n=7; p = 0.06）。在足部强电击（1mA）条件下，LEC抑制动物（n=6）和对照组（n=8）对电击物体的回避均超过90%，但LEC抑制动物对电击物体和未电击物体的回避时间均显著长于对照组（p < 0.05）。在原位恐惧条件反射中，MEC抑制动物（n=7）比对照组动物更倾向于避开与被电击手臂相邻的未电击手臂（n=4; p = 0.07）。这些结果表明，东皮层子区域处理特定地点/物体的信息，并将这些信息与恐惧记忆联系起来。

It is well known that the entorhinal cortex (EC) is one of the main sources of inputs to the hippocampus necessary for the formation of episodic memory. However, how multimodal factors in episodic memory are processed in the EC is not well understood. In the present study, we investigated individual EC sub-regional contributions in episodic memory to determine a possible functional dissociation of EC sub-regions. We fear conditioned animals on a plus maze with two different types of stimuli - spatial or object, which is processed in MEC and LEC, while optogenetically inhibiting MEC/LEC. I finished behavioral experiments and statistically analyzed behavioral and histological data.In weak foot-shock condition (0.3mA), LEC inhibited animals (n=6) showed significantly lower avoidance toward shocked object than control animals (n=7; p < 0.005). Avoidance toward the shocked arm of MEC inhibited animals (n=8) was also comparatively lower than controls (n=7; p = 0.06). In strong foot-shock condition (1mA), LEC inhibited (n=6) as well as control (n=8) animals showed over 90% avoidance toward shock object, however, LEC inhibited animals avoided not only the shocked but also no-shocked object significantly longer than controls (p < 0.05). In place fear conditioning, MEC inhibited animals (n=7) tended to avoid the no-shocked arm, which is adjacent to the shocked arm, longer than control animals (n=4; p = 0.07). These results suggest that EC sub-regions process information about specific place/object as well as associate the information with fear memory.