Exploring oculomotor functions in a pilot study with healthy controls: Insights from eye-tracking and fMRI.

Eye-tracking techniques have gained widespread application in various fields including research on the visual system, neurosciences, psychology, and human-computer interaction, with emerging clinical implications. In this preliminary phase of our study, we introduce a pilot test of innovative virtual reality technology designed for tracking head and eye movements among healthy individuals. This tool was developed to assess the presence of mild traumatic brain injury (mTBI), given the frequent association of oculomotor function deficits with such injuries. Alongside eye-tracking, we also integrated fMRI due to the complementary nature of these techniques, offering insights into both neural activation patterns and behavioural responses, thereby providing a comprehensive understanding of oculomotor function. We used fMRI with tasks evaluating oculomotor functions: Smooth Pursuit (SP), Saccades, Anti-Saccades, and Optokinetic Nystagmus (OKN). Prior to the scanning, the testing with a system of VR goggles with integrated eye and head tracking was used where subjects performed the same tasks as those used in fMRI. 31 healthy adult controls (HCs) were tested with the purpose of identifying brain regions associated with these tasks and collecting preliminary norms for later comparison with concussed subjects. HCs' fMRI results showed following peak activation regions: SP-cuneus, superior parietal lobule, paracentral lobule, inferior parietal lobule (IPL), cerebellartonsil (CT); Saccades-middle frontal gyrus (MFG), postcentral gyrus, medial frontal gyrus; Anti-saccades-precuneus, IPL, MFG; OKN-middle temporal gyrus, ACC, postcentral gyrus, MFG, CT. These results demonstrated brain regions associated with the performance on oculomotor tasks in healthy controls and most of the highlighted areas are corresponding with those affected in concussion. This suggests that the involvement of brain areas susceptible to mTBI in implementing oculomotor evaluation, taken together with commonly reported oculomotor difficulties post-concussion, may lead to finding objective biomarkers using eye-tracking tasks.

Assessment of Oculomotor Functions as a Biomarker in Mild Traumatic Brain Injury.

Mild traumatic brain injury (mTBI), or concussion, is a major public health problem, and ambiguity still exists regarding its diagnosis. While functional magnetic resonance imaging (fMRI) has been identified as a helpful screening tool for concussion, its limited accessibility in clinical or field settings necessitates a more efficient alternative. Oculomotor function deficit is an often-reported pathology in mTBI. Due to the neuroanatomical overlap between eye-movement circuitry and mTBI pathophysiology, visual deficits are expected. In this study, we investigate the possibility of using an oculomotor assessment tool for finding biomarkers in concussion. We used fMRI with tasks evaluating oculomotor functions: smooth pursuit (SP), saccades, anti-saccades, and optokinetic nystagmus (OKN). Before the scanning, the testing with a system of virtual reality goggles with integrated eye- and head-tracking was used where subjects performed the same tasks as those used in fMRI. Twenty-nine concussed symptomatic adults (CSA) within 1-month postconcussion and 29 age- and sex-matched healthy controls (HCS) were tested to examine blood oxygen level-dependent (BOLD) fMRI alterations associated with performances in oculomotor function after mTBI and evaluate the efficacy of the oculomotor assessment in detecting oculomotor and gaze deficits following mTBI. Comparing CSA with HCS, significant differences were observed in anti-saccades and OKN performance. CSA group exhibited elevated %BOLD signal change on each task compared with HCS: in the superior frontal gyrus during the smooth pursuit, inferior frontal gyrus during the saccades, putamen and dorsolateral prefrontal cortex (DLPFC) during the anti-saccades, and lingual gyrus and IFG during the OKN. Key findings include the following: (1) oculomotor deficits in concussed subjects compared with controls, (2) abnormal activation patterns in areas related to the regulation and control of oculomotor movements, suggesting concussion-induced disruptions, and (3) the potential of oculomotor assessment as a promising approach for mTBI biomarkers, with anti-saccades and OKN identified as the most sensitive tasks.