Abstract
Attention impairment may provide a cohesive neurobiological explanation for clusters of clinical symptoms that occur after a concussion; therefore, objective quantification of attention is needed. Visually tracking a moving target is an attention-dependent sensorimotor function, and eye movement can be recorded easily and objectively to quantify performance. Our previous work suggested the utility of gaze-target synchronization metrics of a predictive visual tracking task in concussion screening and recovery monitoring. Another objectively quantifiable performance measure frequently suggested for concussion screening is simple visuo-manual reaction time (simple reaction time, SRT). Here, we used visual tracking and SRT tasks to assess changes between pre- and within-2-week post-concussion performances and explore their relationships to post-concussion symptomatology. Athletes participating in organized competitive sports were recruited. Visual tracking and SRT records were collected from the recruited athlete pool as baseline measures over a 4-year period. When athletes experienced a concussion, they were re-assessed within 2 weeks of their injury. We present the data from a total of 29 concussed athletes. Post-concussion symptom burden was assessed with the Rivermead Post-Concussion Symptoms Questionnaire and subscales of the Brain Injury Screening Questionnaire. Post-concussion changes in visual tracking and SRT performance were examined using a paired t-test. Correlations of changes in visual tracking and SRT performance to symptom burden were examined using Pearson's coefficients. Post-concussion changes in visual tracking performance were not consistent among the athletes. However, changes in several visual tracking metrics had moderate to strong correlations to symptom scales (r up to 0.68). On the other hand, while post-concussion SRT performance was reduced (p < 0.01), the changes in the performance metrics were not meaningfully correlated to symptomatology (r ≤ 0.33). Results suggest that visual tracking performance metrics reflect clinical symptoms when assessed within 2 weeks of concussion. Evaluation of concussion requires assessments in multiple domains because the clinical profiles are heterogeneous. While most individuals show recovery within a week of injury, others experience prolonged recovery periods. Visual tracking performance metrics may serve as a biomarker of debilitating symptoms of concussion implicating attention as a root cause of such pathologies.
Highlights
Cognitive abilities are often compromised after a concussion, with attention dysfunction being a common sequela [1, 2]
Attention impairment may provide a cohesive neurobiological explanation for clusters of clinical symptoms that occur after a concussion [3,4,5]
To characterize the stability of the gaze on the target, we evaluated the variability of gaze position error along axes orthogonal and parallel to target movement
Summary
Cognitive abilities are often compromised after a concussion, with attention dysfunction being a common sequela [1, 2]. Attention impairment may provide a cohesive neurobiological explanation for clusters of clinical symptoms that occur after a concussion [3,4,5] For these reasons, objective quantification of attention is needed. Because the visual and motor processing delay of ≈100 ms [8, 13] would preclude visual interception of the target if one was to react to the visual input of the target, accurate and precise synchronization must be achieved through shaping anticipatory eye movement Such shaping is likely to take place with contributions of the fronto-parietal cortical regions and the cerebellum [14], which are important foci of attention processing. A predictive visual tracking task would be a useful test paradigm to provide attentional bases for concussion screening and recovery monitoring with objective sensorimotor synchronization metrics [5, 18, 22]
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