Behavioral data of animals in three cohorts.

Hippocampus is known to be important for episodic memories. Measuring of hippocampal neural ensembles is therefore important for observing hippocampal cognitive processes such as pattern completion. Previous studies on pattern completion had a limitation because the activities of CA3 were not simultaneously observed with the activities of the entorhinal cortex that project to the CA3. In addition, in previous research and modelling, distinct concepts such as pattern completion and pattern convergence have not been considered separately. Here, I used a molecular analysis technique that enables comparison of neural ensembles that evoked two successive events and evaluated neural ensembles in the hippocampal CA3 region and entorhinal cortex. By comparing neural ensembles in hippocampus and entorhinal cortex, I could obtain evidence that suggests pattern completion occurring in the CA3 region was induced by the partial input from EC. Use of the molecular-based ensemble measurement allows measuring two or more brain regions simultaneously, which can lead to insights into the cognitive functions of neural circuits.海马体（hippocampus）已知对情景记忆至关重要。因此，对海马体神经集群（neural ensembles）的检测，对于观测海马体的认知过程（如模式完成（pattern completion））具有重要意义。过往针对模式完成的研究存在一项局限：无法同步记录CA3亚区的神经活动，以及向CA3投射的内嗅皮层（entorhinal cortex）的神经活动。此外，在既往研究与建模工作中，模式完成与模式会聚（pattern convergence）这类截然不同的概念并未被单独区分考量。本研究采用了一种可对诱发连续两次事件的神经集群进行比较分析的分子分析技术，并对海马CA3亚区与内嗅皮层的神经集群进行了评估。通过对比海马体与内嗅皮层的神经集群活动，本研究获得了证据，表明CA3亚区的模式完成是由内嗅皮层（EC）的部分输入所诱发。基于分子的集群检测技术可同时记录两个及以上脑区的活动，这将为深入解析神经环路的认知功能提供新的研究视角。