Figure 2.

mTBIs do not produce long-term deficits in ambulatory activity, gait, or learning and memory. Ambulatory activity was assessed with a photobeam home cage monitoring system immediately following the 4-m/s impact for 5 d continuously. Activity was assessed for 4 h immediately after the treatment in 5-min bins (A). To assess sleep wake cycles, the activity was monitored 24 h before treatment and continuously for 6 d in 1-h bins (B). The dashed line indicates the time of treatment (sham vs impact). Open field behavior was assessed 24 h post-sham or mTBI (4 m/s) treatment to test for overall activity and anxiety. There was no significant difference in total distance traveled (C), time spent in the center (D), and time spent in the border regions (E). Novel object recognition was used to test for short-term learning and memory 48 h post-treatment. Animals were placed into the open field arena containing two objects and allowed to explore the objects for 5 min. Animals were removed and the arena, objects were cleaned, one identical object and one novel object were placed back into the arena, and the same animals was allowed to explore the objects for another 5 min. The time spent with each object was quantified (F). Using the Noldus CatWalk gait analysis system we quantified the footprint area (G), swing duration (H), and stride length (I) for each individual foot 72 h post-treatment. Contextual trace fear conditioning was also used to assess for hippocampal dysfunction. 24 h post-treatment animals were placed within the behavioral box and given a 30-s tone followed by a 20-s delay and a 0.6-mA foot shock for 2 s. This was repeated five times to learn the association. On day 2, the animals were put into a modified chamber and given the 30-s tone without the foot shock. Freezing was assessed during the 30-s tone (J) and the 20-s delay (K). On day 3, the animals were placed into the original context for 8 min. The percentage of the time freezing during that 8-min trial was quantified (L).