CRC 1315/2: Role of heterogeneous pyramidal cell populations and specific connectivity motifs in pattern completion and replay of memory sequences (SP A01)

Hippocampal sharp wave/ripple complexes (SWRs) are short (50–100 ms) episodes of coordinated network activity arising in the hippocampal CA3 area (Buzsáki, 1989). They mediate the consolidation of explicit memories, and their disruption impairs memory (Girardeau et al., 2009) whereas their prolongation enhances memory (Fernández-Ruiz et al., 2019). However, the mechanisms governing the occurrence of these episodes remain obscure. To better understand their dynamics, we will focus on the role of heterogeneity between pyramidal-cell populations and specific connectivitymotifs in pattern completion and replay of memory sequences. We will analyze the differential embedding of CA3 pyramids during SWRs, assess their specific connectivities, manipulate subsets of neurons using optogenetics in vitro and in vivo, and develop computational network models of SWRs that can be numerically simulated and analyzed mathematically. This work will considerably extend our understanding of sharp-wave models, which were established in our joint experimental-theoretical work in the previous funding period.