On how the dentate gyrus contributes to memory discrimination

SummaryThe dentate gyrus (DG) is crucial for behaviorally discriminating similar spatial memories, predicting that dentate gyrus place cells change (\"remap\") spatial tuning (\"place fields\") for memory discrimination. This prediction was never tested, although DG place cells remap across similar environments without memory tasks. We confirm this prior finding, then demonstrate that DG place fields do not remap across spatial tasks that require DG-dependent memory discrimination. Instead of remapping, place-discriminating discharge is observed transiently amongst DG place cells, particularly where memory discrimination is most necessary. The DG network signals memory discrimination by expressing distinctive sub-second network patterns of co-firing amongst principal cells at memory discrimination sites. This is accompanied by increased coupling of discharge from excitatory principal cells and inhibitory interneurons. Instead of remapping, these findings identify that memory discrimination is signaled by sub-second patterns of correlated discharge within the dentate network.\n\neTOC blurbvan Dijk and Fenton report that dentate gyrus place cells signal memory discrimination not by remapping, but by variable sub-second patterns of coordinated place cell network discharge and enhanced discharge coupling between excitatory and inhibitory neurons, at sites of memory discrimination.\n\nHighlightsO_LIDentate gyrus-dependent memory discrimination does not require place cell remapping\nC_LIO_LIDentate neural correlates of pattern discrimination are transient, lasting seconds\nC_LIO_LISub-second dentate network discharge correlations signal memory discrimination\nC_LIO_LIDentate excitatory-inhibitory coupling is increased at memory discrimination sites\nC_LI