Figure 4

Enhancements in Schaffer collateral-CA1 LTP and spatial learning 12 months after exposure to ⁵⁶Fe particle radiation (a, b) Time course and magnitude (inset bar graph) of LTP in slices from mice exposed to 10 cGy, 50 cGy, or 100 cGy radiation, compared to sham-irradiated controls (0 cGy). After a 15 min baseline, LTP was elicited by two high-frequency TBS stimulus trains (arrows), and magnitude of LTP between 35 and 40 min post TBS (perforated box) was compared across doses in (a) male mice, One-way RM ANOVA, F(1.73,17.31) = 3137.0, P < 0.001, Tukey’s post hoc test: 0 cGy vs. 10 cGy, P < 0.0001; 0 cGy vs. 50 cGy, P < 0.0001; 0 cGy vs. 100 cGy, P < 0.0001, 10 cGy vs. 50 cGy, P < 0.0001, 10 cGy vs. 100 cGy, P < 0.0001, 50 cGy vs. 100 cGy, P < 0.0001 and (b) female mice, One-way RM ANOVA, F(2.48,24.77) = 449.1, P < 0.0001, Tukey’s post hoc test: 0 cGy vs. 10 cGy, P < 0.0001; 0 cGy vs. 50 cGy, P < 0.0001; 0 cGy vs. 100 cGy, P < 0.0001, 10 cGy vs. 50 cGy, P < 0.0001, 10 cGy vs. 100 cGy, P < 0.0001, 50 cGy vs. 100 cGy, P < 0.0001. *P < 0.05 compared to 0 cGy, n = 12–16 slices per dose per sex. (c, d) Learning curves, including pretraining, training days 1–3, and conflict training days 1–2, are shown for (c) male mice Two-way RM ANOVA, dose: F(3,16) = 2.78, P = 0.08; trial: F(1.933,30.93) = 54.98, P < 0.0001; interaction: F(15,80) = 1.31, P = 0.21, Tukey’s post hoc test: Training Day 1, 0 cGy vs. 50 cGy, P = 0.008, 0 cGy vs. 100 cGy, P = 0.045, Training Day 2, 0 cGy vs. 50 cGy, P = 0.019 and (d) female mice Two-way RM ANOVA, dose: F(3,16) = 2.57, P = 0.09; trial: F(2.445,39.12) = 47.93, P < 0.0001; interaction: F(15,80) = 1.23, P = 0.266, Tukey’s post hoc test: Training Day 2, 0 cGy vs. 50 cGy, P = 0.021, Training Day 3, 0 cGy vs. 50 cGy, P = 0.044, Conflict Day 2, 0 cGy vs. 100 cGy, P = 0.038, as a function of normalized number of entries into the stationary shock zone (Errors). *P < 0.05, n = 5 mice per dose per sex. Each point represents mean errors normalized to pre-training entries ± SEM.