FIG. 5.

The effect of repetitive mild TBI (rmTBI) on gross motor function, spatial learning, and memory in post-natal day 18 rats that underwent either sham insult or mTBI on three consecutive occasions 24 h apart. Before surgery, balancing ability (A) or inclined platform performance (B) did not differ among groups. After surgery, there was no effect of rmTBI on beam balance performance (A); rmTBI group performed better than the sham group on inclined plane (B) on days 2 and 3 (n = 12–18/group, mean ± standard error of the mean (SEM), *p < 0.05 vs. S-S-S). (C) Both rmTBI and sham groups began at a similar level in the Morris water maze, and there was no difference between the two groups during acquisition on days 11–15. (D) Analysis of the time to hidden platform of the last acquisition day (day 15) and retesting day (day 61) showed that injured rats tended to take longer to find the hidden platform compared with sham rats (n = 9–12/group, mean ± SEM, p = 0.0685). (E) Rats exposed to rmTBI spent significantly less time exploring the novel object versus rats exposed to sham insults on day 18 (n = 12–18/group, mean ± SEM, *p < 0.05 vs. S-S-S).