Uncover the connection between eye tracking and manual control : evidence from both visuomotor experts and patients at high risk for neurodegenerative movement disorders

Abstract

Seamless coordination between eye and hand movement control is critical for a wide variety of real-world visuomotor control tasks such as catching a ball, driving, and music-reading etc. In this thesis, I studied the functional integration between eye and hand movements control with two special populations: visuomotor experts (i.e., professional baseball players and avid action gamers) and visuomotor impaired patients with REM sleep behavior disorder (RBD). We previously found that after playing an action game for only five hours, participants improved significantly in their manual control ability underlying essential daily life visuomotor tasks such as driving (Chapter 1). Here we proposed that long-term challenging experiences in visuomotor control affect not only manual control ability but also the link between eye and hand movements control. We tested professional baseball players (Chapter 2) and avid action gamers (Chapter 3) with an eye tracking task in which participants visually tracked unpredictable step-ramp motion and a manual control task in which participants used a joystick to center a randomly-moving target. While the superiority of eye tracking ability was only observed in the professional baseball players but not the action gamers, both groups of visuomotor experts showed superior manual control abilities as well as a tight coupling between eye and hand movements control which was absent in the demographically-matched controls. Furthermore, eye tracking performance predicts real-world batting for more-experienced but not less-experienced baseball players, suggesting that real-world batting develops within visuomotor limits. To directly examine the eye-hand coordination ability of visuomotor experts, we tested baseball players and action gamers (Chapter 4) with an oculo-manual control task in which participants smoothly tracked a moving cyan target with their eyes while using their dominant hands to move a high-precision mouse to vertically align a red Gaussian cursor with the cyan target. We found that both baseball players and action gamers showed better eye and hand tracking performance than the demographically-matched controls, suggesting challenging visuomotor experiences indeed enhance eye-hand coordination ability. In Chapter 5, we systematically examined the fundamental eye tracking and manual control abilities in RBD patients who are at substantial risk of developing neurodegenerative disorders such as Parkinson’s disease (PD). We found that RBD patients showed impairments in eye tracking, manual control, and the link between eye tracking and manual control compared with healthy controls. Furthermore, RBD patients’ manual control performance is associated with their clinical motor symptoms of PD, and their eye tracking ability corresponds to an early predictive marker (i.e., tonic electromyographic abnormalities) of PD, suggesting that both eye tracking and manual control abilities may serve as potential prodromal behavioral markers that can be used for the early detection of neurodegenerative disorder. The findings in this thesis give insights to the underlying neural circuits serving the functional integration between eye and hand movements control and the progression of the sensorimotor impairment in patients with neurodegenerative disorders. Furthermore, empirical evidences of enhanced eye-hand coordination found in visuomotor experts pave the way for future development of effective assessment and intervention program for patients with movement disorders.