Fig. 1

Passive avoidance task performance. a On day 6 (D6) post-TBI, mice were placed into the light chamber, and a foot shock was given once they entered into the dark chamber. From D7 to 3 months (3 M) post-TBI, the mice were placed into the light chamber, and the duration of time spent before entering into the dark chamber is reported. No foot shock was given on post-shock days. The experiment was repeated again from 6 M to 8 M post-TBI, where a foot shock was given on the first day of 6 M only. The duration of time spent before the mice entered into the dark chamber is reported. A longer duration indicates stronger fear memory. b The cumulative fear response was reported as the AUC from (a). c The duration in the light chamber on post-shock days was used to fit the Ebbinghaus saving function M = θt^-ψ to model the extinction of fear memory, where θ is the initial memory and ψ is the rate of extinction. d Initial memory at D1 post-shock was evaluated from (c) by inputting t = 1. e The rate of extinction ψ from (c) is reported. Data are expressed as mean ± SE. Omnibus statistical results are provided below each panel. In (a), asterisks represent significant post hoc differences between APP/PS1-TBI and APP/PS1-Sham (* p < 0.05, ** p < 0.01, *** p < 0.001). Ampersand represents significant post hoc differences between APP/PS1-TBI and WT-TBI (^& p < 0.05). In (b), (d) and (e), asterisks represent significant post hoc differences between marked groups (* p < 0.05, ** p < 0.01, *** p < 0.001). n = 8–13 per genotype per injury per time point