Fig. 6: Inhibitory synaptic plasticity during memory consolidation carves selective engrams.
From: Dynamic and selective engrams emerge with memory consolidation
a, Schematic of simulation protocol with blockage of inhibitory synaptic plasticity during consolidation. b–d, Means and 99% confidence intervals are shown. n = 10 trials. Color denotes stimulus as in Fig. 1c. b, Firing rate of engram cells averaged across all cue presentations during recall in a as a function of consolidation time (Methods). Dashed line indicates threshold ζthr = 10 Hz for engram cell activation. c, Memory recall in a as a function of consolidation time. d, Discrimination index between recall evoked by cues of the training stimulus and individual novel stimuli in a as a function of consolidation time (Methods). e, Schematic of experimental protocol with chemogenetic inhibition of DG CCK+ interneurons. f,g, Means and 99% confidence intervals are shown. f, Freezing levels during memory recall in e as a function of delay time. Top, control group. Bottom, CCK+ inhibition group. Two-sided Wilcoxon signed-rank test between freezing in the training and neutral contexts. Control, n = 9 mice per group. CCK+ inhibition, n = 9 mice per group. g, Discrimination index between freezing levels in the training and neutral contexts in f. Two-sided one-sample Wilcoxon signed-rank test against discrimination = 0. Control, n = 9 mice per group. CCK+ inhibition, n = 9 mice per group. h, Schematic of experimental protocol to measure the plasticity of DG CCK+ efferent synapses onto Cal-Light-labeled EGFP+ neurons using slice recordings. Ephys, electrophysiology. i,j, Means and s.e.m. are shown. i, oIPSCs recorded in h. Left, representative traces showing oIPSCs recorded in neighboring EGFP+ and EGFP− neurons. Right, comparison of oIPSC amplitudes between EGFP+ and EGFP− neurons. Two-way repeated-measures ANOVA with Greenhouse–Geisser correction. For EGFP+ versus EGFP−, n = 12 neurons per group from three mice. j, oIPSCs recorded in the control (mCh) and CCK+ inhibition (hM4Di-mCh) groups in h. Left, representative traces showing oIPSCs recorded in neighboring EGFP+ and EGFP− neurons. Right, comparison of normalized oIPSC amplitudes between EGFP+ and EGFP− neurons. Paired t-test. mCh group, n = 12 neurons per group from three mice. hM4Di-mCh group, n = 10 neurons per group from three mice. f,g,i,j, *P < 0.05; NS, not significant. For detailed statistical test results, see Supplementary Table 1.
