Functional neuroimaging of acute oculomotor deficits in concussed athletes

Brian Johnson, Kai Zhang, Mark Hallett, Semyon Slobounov

In the pursuit to better understand the neural underpinnings of oculomotor deficits following concussion we performed a battery of oculomotor tests while performing simultaneous functional magnetic resonance imaging (fMRI). Based on the increasing evidence that concussion can disrupt multiple brain functional networks, including the oculomotor control networks, a series of classic saccadic and smooth pursuit tasks were implemented. Nine concussed athletes were tested within seven days of injury along with nine age and sex matched healthy normal volunteers. Both behavioral and fMRI data revealed differential results between the concussed and normal volunteer groups. Concussed subjects displayed longer latency time in the saccadic tasks, worse position errors, and fewer numbers of self-paced saccades compared to normal volunteer subjects. Furthermore, the concussed group showed recruitment of additional brain regions and larger activation sites as evidenced by fMRI. As a potential diagnostic and management tool for concussion, oculomotor testing shows promise, and here we try to understand the reasons for this disrupted performance with the aide of advanced neuroimaging tools.