Fig. 2.

dCA2 is necessary in the initial stages of social memory formation. a Protocol for experiment examining effect of IP injection of CNO 24 h prior to the direct interaction test. Both WT and Amigo2-Cre littermates were injected in dCA2 with AAV-DIO-hM4Di-IRES-mCitrine. b WT controls and Amigo2-Cre mice showed normal decrease in social exploration time during trial 2 (WT: n = 9, t(8) = 2.815, P = 0.0227, paired t test; Cre: n = 6, t(5) = 2.790, P = 0.0384, paired t test). The groups did not differ significantly (two-way ANOVA: treatment × trial F(1,13) = 0.08127, P = 0.7801). c No difference was found in percent reduction in social exploration time in trial 2 compared to trial 1 between groups (unpaired t test: t(13) = 0.1591, P = 0.8760). d Protocol for a direct interaction test with 24 h intertrial interval. WT and Amigo2-Cre littermates were injected in dCA2 with AAV-DIO-hM4Di-IRES-mCitrine. Trial 1 was performed 30 min after IP injection of CNO and trial 2 was performed 24 h later. e WT but not Amigo2-Cre mice displayed decreased social exploration during trial 2 relative to trial 1 (WT: n = 11, P = 0.0040, Sidak’s multiple comparisons test; Cre: n = 11, P = 0.9578, Sidak’s multiple comparisons test). The groups differed significantly (two-way ANOVA: treatment × trial F(1,20) = 5.394, P = 0.0309). f Percent reduction in social exploration time was lower in Amigo2-Cre than WT groups (unpaired t test: t(20) = 2.558, P = 0.0187). Results in b and e show mean ± s.e.m. Box-whiskers plots in c and f present median (center line), extension from the 25th to 75th percentiles (box) and minimal and maximal values (whiskers). *P < 0.05; **P < 0.01; ns, P > 0.05