Hippocampo-cortical circuits for selective memory encoding, routing, and replay

Traditionally considered a homogeneous cell type, hippocampal pyramidal cells have been recently shown to be highly diverse. However, how this cellular diversity relates to the different hippocampal network computations that support memory-guided behavior is not yet known. We show that the anatomical identity of pyramidal cells is a major organizing principle of CA1 assembly dynamics, the emergence of memory replay, and cortical projection patterns in rats. Segregated pyramidal cell subpopulations encoded trajectory and choice-specific information or tracked changes in reward configuration respectively, and their activity was selectively read out by different cortical targets. Furthermore, distinct hippocampo-cortical assemblies coordinated the reactivation of complementary memory representations. These findings reveal the existence of specialized hippocampo-cortical subcircuits and provide a cellular mechanism that supports the computational flexibility and memory capacities of these structures. [Display omitted] •Superficial CA1 pyramidal cells are the main contributors to memory replay•CA1 superficial cells encode spatial context and future choices and project to MEC•CA1 deep cells track reward configuration and project to PFC•Hippocampo-cortical assemblies reactivate complementary memory representations Harvey et al. show the existence of segregated hippocampo-cortical subcircuits that support the selective encoding, routing, and replay of complementary memory representations. These results highlight the contribution of pyramidal cell diversity to the flexible computational capabilities of the hippocampus during learning and memory.