FIG. 10.

r-mTBI results in social deficits. Mice were assessed for motor and social behavior related to functions of cortical regions under the impact site at bregma and corresponding areas of the corpus callosum. (A and B) The motor task used a running wheel sequence as shown by the pattern of wheel rungs (A) across a 3-week time line. Mice were first provided training wheels (TW; regular rung pattern) to stabilize baseline running behavior for 1 week preceding r-sham/r-mTBI (days −7 to 0). After r-sham/r-mTBI, mice were provided complex wheels (CW; nonuniform rung spacing) for 1 week (days 0–7). Mice must learn to adapt to the complex rung pattern to master this motor skill. The second week (days 8–14) on the complex wheels assesses the velocity plateau as a measure of bilateral sensorimotor coordination. The cohorts (n = 12 per condition) did not show differences in any phase on the training or complex wheel after r-mTBI (B). (C) A three-chamber sociability test was used to test social behavior at 3 weeks after r-mTBI. The r-sham mice spent the majority of time interacting with the carrier containing a stranger mouse rather than the empty carrier. The r-mTBI mice showed a significant reduction in social approach behaviors. The r-mTBI mice spent less time interacting with the unfamiliar mouse, as compared to the behavior of r-sham. Values are mean ± standard error of the mean; n = 12; ***p < 0.001. Max, maximum; r-mTBI, repetitive mild traumatic brain injury; r-sham, repetitive sham.