Pupil size during an antisaccade task at acute and sub-acute stages of concussion recovery


The antisaccade task (i.e., saccade mirror-symmetrical to a target) is an effective tool for the identification and management of executive dysfunction following a sport-related concussion (SRC). Convergent evidence shows that persons with a SRC exhibit impaired antisaccade kinematic metrics during the acute and chronic stages of SRC recovery, and perhaps most notably, such deficits persist even when clinical signs of concussion resolve. It remains unclear whether these behavioural deficits are related to the executive demands of response execution (i.e., attentional fluctuations or concussive symptoms) or response preparation (i.e., neural recruitment and activation). Therefore, the current study employed pupillometry measures of the antisaccade task in persons with a SRC – and their aged- and sex-matched controls – during the early (?12 days post-SRC) (i.e. initial assessment) and later stages (14-30 days post-SRC) (i.e. follow-up assessment) of their recovery. Notably, task-evoked pupil dilations (i.e. TEPDs) provide a neural correlate of top-down inhibitory control and saccade preparation, and therefore provide a means to dissociate preparatory impairments from other factors influencing executive control. At the initial assessment, the SRC group exhibited longer antisaccade RTs (p=0.001) and larger TEPDs (p<0.01) than the control group. At the follow-up assessment, the SRC group showed improved antisaccade RTs (p<0.02) and sustained larger TEPDs (p<0.03). Accordingly, persistent executive dysfunction following a SRC is related to inefficient preparatory activity. Thus, concomitant pupillometry and antisaccade metrics provide an index of both cognitive and autonomic function that may serve to provide effective biomarkers for concussion diagnosis and management.

Acknowledgments: Funded by NSERC.