Complementary population codes in the dorsal and ventral hippocampus during associative learning

Memories are multifaceted and layered, incorporating external stimuli and internal states, and at multiple levels of resolution. Although the hippocampus is essential for memory, it remains unclear if distinct aspects of experience are encoded within different hippocampal subnetworks during learning. By tracking the same dCA1 or vCA1 neurons across cue-outcome learning, we find detailed and externally based (stimulus identity) representations in dCA1, and broad and internally based (stimulus relevance) signals in vCA1 that emerge with learning. These dorsoventral differences were observed regardless of cue modality or outcome valence, and representations within each region were largely stable for days after learning. These results identify how the hippocampus encodes associative memories, and show that hippocampal ensembles not only link experiences, but also imbue relationships with meaning and highlight behaviorally relevant information. Together, these complementary dynamics across hippocampal subnetworks allow for rich, diverse representation of experiences. ### Competing Interest Statement The authors have declared no competing interest.