Subiculum as a Generator of Sharp Wave-Ripples in the Rodent Hippocampus

Abstract

Sharp waves ripples (SWRs) represent synchronous discharges of hippocampal neurons and are believed to play a major role in memory consolidation. A large body of evidence suggests that SWRs are exclusively generated in the CA3-CA2 network. In contrast, here we provide several lines of evidence showing that the subiculum can function as a secondary SWRs generator. SWRs with subicular origin propagate forward into the entorhinal cortex as well as backward into the hippocampus proper. Our findings suggest that the output structures of the hippocampus are not only passively facilitating the transfer of SWRs to the cortex but they can actively contribute to SWRs genesis. We hypothesize that SWRs with subicular origin may be important for the consolidation of information conveyed to the hippocampus via the temporoammonic pathway.