Remote fear memory recall reactivates a larger CeA Fos engram than contextual memory recall. (A–C) Stereotaxic plate drawings of CeA rostro–caudal subregions (gray; left), along with representative examples of reactivated neurons (tdTomato+ and Fos-ir; i.e., dual-labeled) and corresponding summary distribution plots from context-TRAPed (middle) and fear-TRAPed (right) mice (n = 5 group) in the rostral (A), middle (B), and caudal (C) CeA subregions. Scale bars (context images: middle, left), 200 µm. (D) Average density of reactivated counts in each CeA subregion in context-TRAPed (squares) and fear-TRAPed (circles) mice. (###) P = 0.0007 context versus fear group. Two-way ANOVA with Sidak's posttest. (E) Average density of reactivation counts in rostral, middle, and caudal subregions of the CeAC and CeAML in context-TRAPed (white) and fear-TRAPed (yellow) mice. (**) P = 0.0030 fear group, CeAC versus CeAML; (###) P = 0.0003 CeAC, context versus fear group; (ϕ) P = 0.0200 fear group between rostro–caudal subregions. Three-way ANOVA with Tukey's posttest. Data are mean ± SEM. (F) Correlation between the amount of time spent freezing during memory recall and dual-labeled counts in context (squares) and fear (circles) groups in the entire CeA (left), CeAC (middle), and CeAML (right). (G) Correlation between the amount of time spent freezing during memory recall and the percent of tdTomato+ or Fos+ neurons that are dual-labeled in context (squares) and fear (circles) groups in the CeA. Least squares regression lines are shown along with corresponding Pearson's coefficients (r). Fisher's z-transformation was applied to compute r′ values comparing the strength of correlations between groups for the entire CeA and its CeAC and CeAML subdivisions (see Supplemental Table S2).
