Behavioural Effects of Concussion History and their Underlying Neural Mechanisms in Elite and Non-Elite Athletes

Purpose: Rule-based visually guided movements, in which cognitive-motor integration is required, are essential for tasks in our daily lives and in sport performance. The frontoparietal-cerebellar network is essential for adequate performance on these visuomotor tasks. The purpose of these dissertation projects was to investigate the limits of our motor system, in both those with healthy brain states and those with a previous concussion, including those with persistent symptoms or post-concussion syndrome. Furthermore, we sought to better understand the effects of concussion and its association with motor performance by examining structural differences in the brain between those with post-concussion syndrome and healthy individuals. Methods: We tested elite athletes with a history of concussion, females with post-concussion syndrome, and healthy control participants on a visually-guided reaching task requiring cognitive-motor integration. Additionally, we examined structural correlates, including white matter integrity, cortical thickness and volume, and cerebellar lobule volume, in those with persistent symptoms compared to healthy controls. Results: Overall, the results of the included studies added to the body of literature in understanding visually-guided reaching and the underlying neural correlates for skilled performance. When looking at the effects of concussion, the cerebellum appears vulnerable, which may be due to its anatomical location and reciprocal relationship with the cortex. Finally, the results suggest that there may be neurological compensatory mechanisms following concussive injury, with elite athletes able to better compensate due to their existing neural efficiency. Conclusion: The results of these studies add to our understanding of the effects of concussion on the motor system, specifically in rule-based visually-guided reaching. These findings may help to improve current rehabilitation and return to play procedures following concussive injury.