Figure 2.

Memory of what. Mice perform urine marking when exposed to the same environment in which they had previously encountered a female. A, Quantification of urine markings of CD-1 male mice exposed to a female during the experience trial (Same Arena), not exposed to a female during the experience trial (No Female), or exposed to a female mouse during the experience trial but placed in a different arena during the recall trial (Different Arena). B, CD-1 male mice preferred the female's location during the experience (Exp) trial and during the 24 h recall trial performed in the same arena used during the experience trial. **p < 0.01 (Dunn's multiple comparisons after Kruskal–Wallis test) compared with the Same Arena group; ⁺⁺p < 0.01 (Wilcoxon signed-rank test) compared with chance level (depicted with a dashed line).