Exercise-induced improvement in cognitive performance after fimbria-fornix transection depends on the timing of exercise administration.

Background: Exercise after brain injury holds major therapeutic potentials, but it is still uncertain whether such an intervention should take place during the critical time window of intrinsic repair mechanisms.

Objective: To assess the effects of acute or delayed voluntary exercise in running wheels on post-injury allocentric place learning in an 8-arm radial maze.

Methods: Forty-eight pre-shaped male rats underwent fimbria-fornix transection (FF) or control surgery (Sham). The animals were divided into six groups: FF group with no access to exercise (FF/NE); FF group starting exercise 1day post-surgery (FF/E+1); FF group starting exercise 8days post-surgery (FF/E+8); FF group starting exercise 21days post-surgery (FF/E+21); Sham group with no access to exercise (Sham/NE), and Sham group starting exercise 1day post-surgery (Sham/E+1). After 7days of exercise 6h/day, all animals underwent 28 place learning acquisition sessions.

Results: The FF/E+21 group showed an enhanced acquisition of the task compared to FF/NE. The FF/E+1 and FF/E+8 groups also showed an enhanced task acquisition relative to FF/NE, however with a slower acquisition than the FF/E+21 group.

Conclusion: The data underscores the link between exercise and functional recovery after brain injury and emphasizes the importance of optimal timing of this intervention.