FIGURE 1.

Locomotor activity (A) and anxiety-like behavior (B) in the open field test are not altered by ⁵⁶Fe irradiation; however females (N = 29) moved more than males (N = 28) (**P < 0.01). (C) 3Gy irradiated females and 2Gy irradiated males did not show novel object recognition (P > 0.05, novel object vs. the two familiar objects, PLSD); however, all other groups of mice did explored the novel object more than the two familiar ones (*P < 0.05). (D) Diagram of the fear conditioning paradigm. (E and F) Males showed more contextual and cued freezing than females in the fear conditioning test (effect of sex, F(1,40) = 21.58; P < 0.001). In contextual freezing (E), both males and females showed greater freezing to the 0.35 and 0.90 mA shock intensity compared to the no-shock group (*P < 0.05, ***P < 0.001, no shock group vs. 0.35 and 0.90 mA, respectively). (G) 3Gy irradiated females showed deficits in contextual fear conditioning (P < 0.05 vs. sham-irradiated females). (H) Cued fear conditioning was not impaired by irradiation. (For A–C and G–H, N = 6–8 mice/sex/dose).