Issa John B, Radvansky Brad A, Xuan Feng, Dombeck Daniel A
Department of Neurobiology, Northwestern University, Evanston, IL 60608, USA.
bioRxiv. 2023 Oct 10:2023.10.09.561557. doi: 10.1101/2023.10.09.561557.
During goal-directed navigation, "what" information, which describes the experiences occurring in periods surrounding a reward, can be combined with spatial "where" information to guide behavior and form episodic memories. This integrative process is thought to occur in the hippocampus, which receives spatial information from the medial entorhinal cortex (MEC); however, the source of the "what" information and how it is represented is largely unknown. Here, by establishing a novel imaging method, we show that the lateral entorhinal cortex (LEC) of mice represents key experiential epochs during a reward-based navigation task. We discover a population of neurons that signals goal approach and a separate population of neurons that signals goal departure. A third population of neurons signals reward consumption. When reward location is moved, these populations immediately shift their respective representations of each experiential epoch relative to reward, while optogenetic inhibition of LEC disrupts learning of the new reward location. Together, these results indicate the LEC provides a stable code of experiential epochs surrounding and including reward consumption, providing reward-centric information to contextualize the spatial information carried by the MEC. Such parallel representations are well-suited for generating episodic memories of rewarding experiences and guiding flexible and efficient goal-directed navigation.
在目标导向导航过程中,描述奖励前后时期所发生经历的“什么”信息,可以与空间“哪里”信息相结合,以指导行为并形成情景记忆。这种整合过程被认为发生在海马体中,海马体从内侧内嗅皮质(MEC)接收空间信息;然而,“什么”信息的来源及其表征方式在很大程度上尚不清楚。在这里,通过建立一种新的成像方法,我们表明小鼠的外侧内嗅皮质(LEC)在基于奖励的导航任务中代表关键的体验时期。我们发现一群神经元发出接近目标的信号,另一群独立的神经元发出离开目标的信号。第三群神经元发出奖励消耗的信号。当奖励位置移动时,这些群体相对于奖励立即改变它们各自对每个体验时期的表征,而对LEC的光遗传学抑制会破坏对新奖励位置的学习。总之,这些结果表明LEC提供了围绕并包括奖励消耗的体验时期的稳定编码,为MEC携带的空间信息提供以奖励为中心的信息,使其具有背景意义。这种并行表征非常适合生成奖励体验的情景记忆,并指导灵活高效的目标导向导航。