Abstract
The relation between traumatic brain injury (TBI) and memory dysfunction is well established, yet imprecise. Here, we investigate whether mild TBI causes a specific deficit in spatial episodic memory. Fifty-eight (29 TBI, 29 sham) mice were run in a spatial recognition task. To determine which phase of memory might be affected in our task, we assessed rodent performance at three different delay times (3 min, 1 h, and 24 h). We found that sham and TBI mice performed equally well at 3 min, but TBI mice had significantly impaired spatial recognition memory after a delay time of 1 h. Neither sham nor injured mice remembered the test object locations after a 24-h delay. In addition, the TBI-specific impairment was accompanied by a decrease in exploratory behavior during the first 3 mins of the initial exposure to the test objects. These memory and exploratory behavioral deficits were linked as branched-chain amino acid (BCAA) dietary therapy restored both memory performance and normal exploratory behavior. Our findings 1) support the use of BCAA therapy as a potential treatment for mild TBI and 2) suggest that poor memory performance post-TBI is associated with a deficit in exploratory behavior that is likely to underlie the encoding needed for memory formation.