Multimodal Functional Neuroimaging of Oculomotor Deficits in Athletes with Concussion.
Open Access
- Author:
- Zhang, Kai
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 24, 2014
- Committee Members:
- Semyon Slobounov, Dissertation Advisor/Co-Advisor
Semyon Slobounov, Committee Chair/Co-Chair
Karl Maxim Newell, Committee Member
Frank Gerard Hillary, Committee Member
Wayne Joseph Sebastianelli, Committee Member
David E Conroy, Committee Member - Keywords:
- Concussion
Neuroimaging
fMRI
DMN
Graph Theory - Abstract:
- In the pursuit of development of better diagnostic and assessment tools of concussion, the most common sports-related injury, this study explores the potential of combining brain imaging and oculomotor measures. Based on the increasing evidence that concussion can disrupt multiple brain functional networks, including the oculomotor control network, a series of classic saccadic and smooth pursuit tasks are adopted during functional magnetic resonance imaging (fMRI) scans. The behavioral/neurological testing sessions contain reflexive saccades, anti-saccades, memory-guided saccades, self-paced saccades, sinusoidal smooth pursuit, circular and random smooth pursuit. Nine concussed athletes and nine age and sex matched healthy subjects are recruited for this study. Among them, Seven were tested twice around 7 days and 30 days post injury, and 2 patients missed the second test. Both behavioral/neurological and imaging (fMRI) data revealed differential results between the healthy controls and concussed patients. Concussed patients have longer latency time in the saccadic tasks, worse position errors and fewer number of self-paced saccades compared to control subjects. Marginal trends of longer pursuit lag and greater end position errors are observed in concussion group. Specifically, at day 7: Firstly, concussion group had additional brain regions and larger activation sites as evidenced by fMRI images. Moreover, functional connectivity analysis on the default mode network (DMN) deactivation demonstrated failure of complete deactivation in concussed subjects. Additionally, graph theory analysis revealed disrupted whole brain network properties in concussed subjects. At day 30: Most of neurological measures returned to those observed in normal controls. However, fMRI patterns of the antisaccades task remained to be abnormal, that appeared to be matched with the relatively worse behavioral results. It can be concluded that concussed patients have persistent oculomotor deficits far beyond 7 days post-injury and compromised neural network, even though after they were clinically cleared for return to sports activities. Our findings are consistent with “compensatory” hypothesis that latent brain resources may allow the concussed patients to reach a comparable level performance. That is being said, their behavioral results cannot match those of healthy controls, especially during anti-saccades and self-paced saccades oculomotor tasks. Therefore, collective examination of saccadic task and brain functional connectivity analysis have the potential to be considered as a sensitive assessing tool for assessment of concussion in acute and sub-acute phases of injury.