Reactivation of memory-encoding dentate gyrus neurons during memory consolidation is associated with subregion-specific, learning- and sleep-mediated biosynthetic changes [spatial RNA expression level]
Post-learning sleep plays an important role in hippocampal memory processing, including contextual fear memory (CFM) consolidation. Here, we used targeted recombination in activated populations (TRAP) to label context-encoding engram neurons in the hippocampal dentate gyrus (DG) and assessed reactivation of these neurons during post-learning sleep. We find that post-learning sleep deprivation (SD), which impairs CFM consolidation, selectively disrupts reactivation in inferior blade DG engram neurons. This change was linked to more general suppression of neuronal activity markers in the inferior, but not superior, DG blade by SD. To further characterize how learning and subsequent sleep or SD affect these (and other) hippocampal subregions, we used subregion-specific spatial profiling of transcripts and proteins. We found that transcriptomic responses to sleep loss differed greatly between hippocampal regions CA1, CA3, and DG inferior blade, superior blade, and hilus. Critically, learning-driven transcriptomic changes, measured 6 h following contextual fear learning, were limited to the two DG blades, differed dramatically between the blades, and were absent from all other regions. Similarly, protein abundance in these hippocampal subregions were differentially impacted by sleep vs. SD and by prior learning, with the majority of alterations to protein expression restricted to DG. Together, these data suggest that the DG plays an essential role in the consolidation of hippocampal memories, and that the effects of sleep and sleep loss on the brain are highly subregion-specific, even within the DG itself. Overall design: This dataset contains RNA expression levels from spatially resolved regions of interest (ROIs) of mice that received CFC+sleep, CFC+SD, No_CFC+Sleep (Home Cage+Sleep), and No_CFC+SD (Home Cage+SD). ROIs were collected from both hemispheres of the brain, including 5 different subregions of the brain (CA1, CA3, DG-superior blade, DG-inferior blade, and DG-hilus).