A. Average speed of locomotion on apparatus during Barnes Maze habituation task. B. Latency to full entry to escape hole by day, average of four trials per day for each of four consecutive days. C. Latency to first approach to escape hole by day, average of four trials per day for each of four consecutive days. D. Delay to complete escape after first approach to escape hole, average of four trials per day for each of four consecutive days (excludes all mice that did not make an approach to the escape hole during the trial). Three-way ANOVA with Tukey’s multiple comparisons test: &, APOE3 Ctrl vs. APOE3 Doxo; +, APOE3 Ctrl vs. APOE4 Ctrl; #, APOE3 Ctrl vs. APOE4 Doxo; $, APOE3 Doxo vs. APOE4 Ctrl; %, APOE3 Doxo vs. APOE4 Doxo; *, APOE4 Ctrl vs. APOE4 Doxo; @, All APOE3 vs. all APOE4. * p<.05, ** p<.01, ***p<.001, ****p<.0001.