Cognitive-motor interaction during virtual reality trail making

There is great interest in ecological virtual reality (VR-) based adaptations of traditional pen-and-paper neuropsychological tests. Such adaptations are designed to measure the same cognitive construct(s) as the original test but may also evaluate interactions between such constructs and other functions (e.g., motor), as occurs in daily life. Here we report on translation of the pen-and-paper Color Trails Test (CTT) to a VR-based head-mount device (HMD) implementation. Trails A is a measure of sustained attention, while Trails B measures divided attention. Participants were twenty-seven young (28.02±3.98 years) and twenty-nine middle-aged (55.41±6.60 years) healthy individuals. For young and middle-aged participants, respectively, mean VR-CTT Trails A completion times were 61.77 and 86.70 sec. Mean VR-CTT Trails B completion times were 113.25 and 154.00 sec, respectively. These completion times were significantly longer than those obtained for the pen-and-paper version (p<.001). The middle-aged group had longer completion times than young adults for both test formats (p<.001), with VR-CTT Trails B separating among the groups better than the corresponding pen-and-paper measure (p<.05). Supporting construct validity, completion times were correlated between pen-and-paper and VR-based versions (Trails A: r=.63; Trails B: r=.60, p's<.001). VR-CTT motor performance was evaluated by quantifying the deviation of the actual reaching trajectories from the hand trajectories predicted by the minimal jerk model. For both age groups, deviations were greater for Trails B relative to Trails A (p<.001), consistent with a potential effect of divided attention on motor planning and execution. In sum, our VR-based HMD implementation of the CTT assesses similar cognitive constructs to the original pen-and-paper test (construct validity). Further, as suggested by longer completion times and substantial impact of cognitive demands upon motor performance, this VR-CTT affords enhanced ecological validity and added value by capturing cognitive-motor interactions associated with planning and execution of voluntary reaching movements during the task. We believe that such VR-based adaptations lie at the frontier of neuropsychological testing and will ultimately offer novel insights into our understanding of multimodal human function in the real world.