Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York 12208
Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York 12208.
J Neurosci. 2023 May 3;43(18):3353-3364. doi: 10.1523/JNEUROSCI.1939-22.2023. Epub 2023 Mar 28.
Adapting flexibly to changing circumstances is guided by memory of past choices, their outcomes in similar circumstances, and a method for choosing among potential actions. The hippocampus (HPC) is needed to remember episodes, and the prefrontal cortex (PFC) helps guide memory retrieval. Single-unit activity in the HPC and PFC correlates with such cognitive functions. Previous work recorded CA1 and mPFC activity as male rats performed a spatial reversal task in a plus maze that requires both structures, found that PFC activity helps reactivate HPC representations of pending goal choices but did not describe frontotemporal interactions after choices. We describe these interactions after choices here. CA1 activity tracked both current goal location and the past starting location of single trials; PFC activity tracked current goal location better than past start location. CA1 and PFC reciprocally modulated representations of each other both before and after goal choices. After choices, CA1 activity predicted changes in PFC activity in subsequent trials, and the magnitude of this prediction correlated with faster learning. In contrast, PFC start arm activity more strongly modulated CA1 activity after choices correlated with slower learning. Together, the results suggest post-choice HPC activity conveys retrospective signals to the PFC, which combines different paths to common goals into rules. In subsequent trials, prechoice mPFC activity modulates prospective CA1 signals informing goal selection. HPC and PFC activity supports cognitive flexibility in changing circumstances. HPC signals represent behavioral episodes that link the start, choice, and goal of paths. PFC signals represent rules that guide goal-directed actions. Although prior studies described HPC-PFC interactions preceding decisions in the plus maze, post-decision interactions were not investigated. Here, we show post-choice HPC and PFC activity distinguished the start and goal of paths, and CA1 signaled the past start of each trial more accurately than mPFC. Postchoice CA1 activity modulated subsequent PFC activity, so rewarded actions were more likely to occur. Together, the results show that in changing circumstances, HPC retrospective codes modulate subsequent PFC coding, which in turn modulates HPC prospective codes that predict choices.
灵活适应变化的环境受到对过去选择的记忆、在类似环境下的结果以及在潜在行动之间进行选择的方法的指导。海马体（HPC）用于记忆情节，而前额叶皮层（PFC）有助于指导记忆检索。HPC 和 PFC 中的单个单元活动与这些认知功能相关。以前的工作记录了雄性大鼠在一个需要这两个结构的正字迷宫中执行空间反转任务时的 CA1 和 mPFC 活动，发现 PFC 活动有助于重新激活 HPC 对即将到来的目标选择的表示，但没有描述选择后的额颞叶相互作用。我们在这里描述了这些相互作用。CA1 活动跟踪当前目标位置和单个试验的过去起始位置；PFC 活动比过去的起始位置更能跟踪当前目标位置。CA1 和 PFC 在目标选择前后相互调节对方的表示。选择后，CA1 活动预测随后试验中 PFC 活动的变化，并且该预测的幅度与更快的学习相关。相比之下，选择后，PFC 起始臂活动更强烈地调节 CA1 活动，与较慢的学习相关。总的来说，结果表明选择后的 HPC 活动将回溯信号传递给 PFC，PFC 将不同的路径组合到共同的目标中形成规则。在随后的试验中，预选择 mPFC 活动调节前瞻性 CA1 信号，告知目标选择。HPC 和 PFC 活动支持在不断变化的环境中的认知灵活性。HPC 信号代表将路径的起点、选择和目标联系起来的行为情节。PFC 信号代表指导目标导向行动的规则。尽管先前的研究描述了在正字迷宫中做出决定之前的 HPC-PFC 相互作用，但没有研究决定后的相互作用。在这里，我们表明选择后的 HPC 和 PFC 活动区分了路径的起点和终点，并且 CA1 比 mPFC 更准确地表示每个试验的过去起点。选择后的 CA1 活动调节随后的 PFC 活动，因此奖励动作更有可能发生。总的来说，结果表明，在不断变化的环境中，HPC 的回溯代码调节随后的 PFC 编码，反过来又调节预测选择的 HPC 前瞻性代码。
