Effect of cognitive load on eye-target synchronization during smooth pursuit eye movement

In mild traumatic brain injury (mTBI), the fiber tracts that connect the frontal cortex with the cerebellum may suffer shear damage, leading to attention deficits and performance variability. This damage also disrupts the enhancement of eye-target synchronization that can be affected by cognitive load when subjects are tested using a concurrent eye-tracking test and word-recall test. We investigated the effect of cognitive load on eye-target synchronization in normal and mTBI patients using the nonlinear dynamical technique of stochastic phase synchronization. Results demonstrate that eye-target synchronization was negatively affected by cognitive load in mTBI subjects. In contrast, eye-target synchronization improved under intermediate cognitive load in young (≤ 40 years old) normal subjects.

Research Highlights
► Phase synchronization methods can be used to assess eye tracking performance.
► Cognitive load increases smooth pursuit eye tracking performance in normal subjects.
► In mild traumatic brain-injured subjects, this effect is reversed.
► Shear damage to fiber tracts connecting cerebellum and frontal cortex may be implicated.
► Eye-target synchronization is significantly better in the horizontal direction.