Male, but not female, Tg26 mice show impaired hippocampal basal synaptic transmission andlong‐term potentiation (LTP). Input–output (IO) responses from male (a) and female (d) Tg26 and littermate WT mice (n = 6 per each group). IO responses were significantly reduced in male Tg26 mice, but not in female Tg26 mice as compared to their respective WT controls. *P < 0.05 as compared to WT; repeated measures two‐way ANOVA with Tukey's HSD correction. LTP induced by high frequency tetanization from male (b) and female (e) mice. LTP was significantly impaired in male Tg26 mice as compared to WT mice, but normal in female Tg26 mice. *P < 0.05 as compared to WT, repeated measures two‐way ANOVA with Tukey's HSD correction. Average of fEPSP slopes from 0 to 5 min and 45–60 min post‐tetanization from male (c) and female (f) mice. *P < 0.05 as compared to WT 45–60 min; two‐way ANOVA with Tukey's HSD correction