FIGURE 1.

Impaired contextual fear memory in male, but not female, Tg26 mice. Male (a) and female (c) Tg26 and littermate WT mice were put through a delay fear conditioning paradigm consisting of discrete cues (80 dB white noise and dim house light) that were temporally paired with a foot‐shock (0.7 mA, 1 sec) and diffuse contextual cues (standard test chamber with Simple Green scent) present throughout the conditioning session. Over the 5 cue‐shock pairings mice displayed an increased freezing (fear) response following the shock. Fear memory was assessed in the male (b) and female (d) mice 24 h after the conditioning. Male Tg26 mice show normal baseline and cue‐freezing (fear) in an altered context, but reduced fear in the context that was paired with foot‐shock. *P < 0.05 as compared to WT, n = 10 for male WT, n = 9 for male Tg26, n = 14 for female WT and n = 12 for female Tg26 mice; two‐way ANOVA with Bonferroni's correction. Cue‐freezing behaviour was measured for 2 min during presentation of the shock‐associated cues (80 dB white noise and dim house light) in a contextually altered test chamber. Data are expressed as per cent time the animal spends freezing. No differences in contextual‐ and cued‐fear memories were observed between female WT and Tg26 mice