Multimodal immersive trail making – virtual reality paradigm to study cognitive-motor interactions

Background: Neuropsychological tests of executive function have limited real-world predictive and functional relevance. An emerging solution for this limitation is to adapt the tests for implementation in virtual reality (VR). We thus developed two VR-based versions of the classic Color-Trails Test (CTT), a well-validated pencil-and-paper executive function test assessing sustained (Trails A) and divided (Trails B) attention - one for a large-scale VR system (DOME-CTT) and the other for a portable head-mount display VR system (HMD-CTT). We then evaluated construct validity, test-retest reliability, and age-related discriminant validity of the VR-based versions and explored effects on motor function. Methods: Healthy adults (n=147) in three age groups (young: n=50; middle-aged: n=80; older: n=17) participated. All participants were administered the original CTT, some completing the DOME-CTT (14 young, 29 middle-aged) and the rest completing the HMD-CTT. Primary outcomes were Trails A and B completion times (tA, tB). Spatiotemporal characteristics of upper-limb reaching movements during VR test performance were reconstructed from motion capture data. Statistics included correlations and repeated measures analysis of variance. Results: Construct validity was substantiated by moderate correlations between the 9gold standard9 pencil-and-paper CTT and the VR adaptations (DOME-CTT: tA 0.58, tB 0.71; HMD-CTT: tA 0.62, tB 0.69). VR versions showed relatively high test-retest reliability (intraclass correlation; VR: tA 0.60-0.75, tB 0.59-0.89; original: tA 0.75-0.85, tB 0.77-0.80) and discriminant validity (area under the curve; VR: tA 0.70-0.92, tB 0.71-0.92; original: tA 0.73-0.95, tB 0.77-0.95). VR completion times were longer than for the original pencil-and-paper test; completion times were longer with advanced age. Compared with Trails A, Trails B target-to-target VR hand trajectories were characterized by delayed, more erratic acceleration and deceleration, consistent with the greater executive function demands of divided vs. sustained attention; acceleration onset later for older participants. Conclusions: The present study demonstrates the feasibility and validity of converting a neuropsychological test from two-dimensional pencil-and-paper to three-dimensional VR-based format while preserving core neuropsychological task features. Findings on the spatiotemporal morphology of motor planning/execution during the cognitive tasks may lead to multimodal analysis methods that enrich the ecological validity of VR-based neuropsychological testing, representing a novel paradigm for studying cognitive-motor interactions.