Arc protein expression peaks 2 h after behavior and overlaps with d4EGFP expression in Arc-d4EGFP-BAC mice. A, Parasagittal AOB sections from resident mice perfused 0, 30, 60, 120, or 240 min after behavior, stained for both Arc protein and d4EGFP. The ICL is indicated by white dotted lines, and posterior AOB is shown. Scale bar, 100 μm. B, Arc protein and d4EGFP expression in negative control mice that were perfused after 0 or 60 min in the behavioral setup but were not exposed to a BALB/cJ intruder (left two panels). Arc protein and d4EGFP expression in a resident mouse that was exposed to soiled BALB/cJ bedding only in the behavioral setup then was perfused 60 min later. Scale bar, 50 μm. C, Quantification of Arc immunostaining across conditions. One-way ANOVA, F(7,11) = 18.64, p < 0.0001. D, Quantification of d4EGFP immunostaining across conditions. One-way ANOVA, F(7,11) = 13.07, p = 0.0002. For C and D: *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001, compared with the 0 min controls (19 sections across 11 mice; ANOVA corrected for multiple comparisons using Dunnett's method). E, Time course of d4EGFP expression in a single acute live slice visualized using two-photon microscopy. Each image is a maximum z-projection of a 200 μm slice. Dissection occurred 1 h after behavior. Scale bar, 100 μm. ctrl, Control.