A comparison of different models with motor dysfunction after traumatic brain injury in adult rats

The aim of this study was to evaluate the validity of the model that could produce reproducible and persistent motor weakness and define the accurate tasks and testing parameters for longitudinal assessment of neurological deficits after traumatic brain injury (TBI). We compared the effects of two rat models that suffered different controlled cortical impact (CCI) injury, as well as extensive motor cortex resection model, on behavior recovery and brain morphology. Behavioral tests including the skilled reaching task, limb-use asymmetry test and the grasping test were employed to evaluate neurofunctional recovery from pre- to 12 weeks after the injury. The results demonstrated that all the rats in four groups showed spontaneous functional improvement with the past of time after surgery, especially in rats with mild and moderate CCI injury. At the end of the experiment, the animals' performance reached preoperative base lines on reaching task and limb-use asymmetry test in mild and moderate groups, while severe motor weakness could be observed in rats with severe CCI injury, as well as rats with extended motor cortex resection. Overall, the results of this study indicated that both models with severe CCI injury and extended resection of the motor cortex developed reproducible and long-lasting motor weakness, comparable in severity and duration and identified skilled reaching task, as well as limb-use asymmetry test, as sensitive assessments for slight neurological deficits after brain injury. This will help to provide the basis for further research of the processes after the TBI and development of novel therapies.