Extended Data Fig. 1: Reactivated cells play a key role in encoding prior experience. | Nature Neuroscience

Extended Data Fig. 1: Reactivated cells play a key role in encoding prior experience.

From: Mapping the epigenomic and transcriptomic interplay during memory formation and recall in the hippocampal engram ensemble

Extended Data Fig. 1

a, Schematic of the Targeted Recombination in Active Populations (TRAP), which requires two transgenes, one that expresses CreERT2 from an activity-dependent Arc promoter (ArcCreERT2) and one that allows expression of the eYFP reporter, in a Cre- dependent manner. Administration of TAM to TRAP mice results in a permanent eYFP label in the initially activated Arc neurons. Without TAM, CreERT2 is retained in the cytoplasm of active neurons in which it is expressed, so no recombination can occur. b, Representative images and co-localization analysis between endogenous Arc protein (Cyan) and the Arc:eYFP reporter (Magenta), 1.5 h after the FS. Upper panel shows images from the whole hippocampus and lower panel images shows neurons from the DG. Magenta arrows—neurons with only Arc:eYFP reporter signal, Cyan arrows—neurons with only endogenous Arc signal, White arrows—neurons with signal from both populations. Analysis was performed using IMARIS module (co-localization tools) and revealed an average of 84% overlap between the two populations. Scale bar, 100 μm. n = 3 mice /5 slices per animal, boxplot indicates the mean, interquartile range and the minimum and maximum. c, Contextual fear conditioning (CFC) freezing test. Percentage of the time freezing levels were measured during habituation (Day 0, Pre-FS) and during the re-exposure (Day 5) to the fear-inducing cue. n = 30 mice, boxplot indicates the mean, interquartile range and the minimum and maximum, two-sided unpaired Student’s t-test, t = 15.63, df=16, ****P < 0.0001. d, Representative images of Activated -late and Reactivated neurons in the hippocampus in two experimental groups; CFC with (TAM) or without (NO-TAM) tamoxifen administration. Scale bar, 100 μm. e, Contextual fear conditioning (CFC) freezing test. Percentage of the time freezing levels were measured during the re-exposure to the fear inducing cue (A-A) and during the exposure to a novel neutral environment (context B). n = 15 mice, boxplot indicates the mean, interquartile range and the minimum and maximum, two-sided unpaired Student’s t-test, t = 8.506, df=14, ****P < 0.0001. f, Representative images of Activated -late and Reactivated neurons from the DG in the A-A’ or A-B group.

Back to article page