LONG-LASTING EFFECTS OF MTBI ON OCULOMOTOR ABILITY AND NEUROMUSCULAR CONTROL

Abstract

Concussions result in short-lived to long-lasting neurological function impairment and disturbances, typically undetectable by standard neuroimaging protocols, which can persist for several months post-trauma. Eye-tracking and virtual reality can be a powerful tool in the assessment of short- and long-term concussed individuals. However, it needs a clear and concise methodology. When acting as an optical flow-induced perturbation of balance metrics and combined with electroencephalographic data, it can differentiate between a non-concussed fatigue state and a concussive state. Furthermore, when employed as a secondary cognitive task, it elicits neural modulations and postural control perturbations that can detect concussion-related impairments up to eight years post-trauma. In this dissertation we sought to (i) develop a virtual reality environment that implements known eye-tracking methodologies and validate its accuracy in differentiating between non-concussed and concussed cohorts, (ii) investigate the presence of neural signatures that could differentiate between a concussive state and a fatigue state, and (iii) determine if long-lasting oculomotor and peripheral muscle control impairments could be reliably detected in a concussed cohort several years post-trauma. Our overarching hypotheses were that (i) eye-tracking metrics observed in a virtual reality environment can differentiate between non- concussed and concussed cohorts, (ii) spectral power of cortical activations are different between non-concussed participants in a fatigued state and concussed participants, and (iii) oculomotor impairments and corticomuscular correlates of balance metrics can be detected in a concussed several months post-trauma. Our findings support the majority of the initial proposed investigation. We detected corticomuscular coherence and postural control differences capable of differentiating between non-concussed and long-term concussed participants, established a link between corticomuscular coherence and postural control adaptations observed in the concussed group, determined some limitations of virtual reality paradigms in concussion assessment.