Eyes-closed finger-tapping task for assessing visual dependence in temporal motor control in Parkinson’s disease

Abstract

Impaired motor automaticity in Parkinson’s disease (PD) may increase reliance on visual feedback, but its role in stabilizing repetitive movements remains unclear. To quantify the effect of eye closure on finger tapping and identify performance features reflecting visual dependence in PD. Forty-five individuals with PD (74.0 ± 6.6 years; 21 women) and 20 age-matched healthy controls (HC; 74.6 ± 5.5 years; 13 women) performed 10-s index finger–to–thumb tapping under eyes-open and eyes-closed conditions. A wearable device recorded metacarpophalangeal flexion–extension angles at 1 kHz, with 30-Hz low-pass filtering. Six metrics were computed: the mean and variability of amplitude, velocity, and inter-peak interval. Eye-closure effects were estimated as r = ln(closed/open) and analyzed using a linear mixed-effects model with group, side, age, and sex as fixed effects and subject as a random intercept. A nominal group effect was observed only for interval variability ( p  = 0.0337), whereas no group effects were observed for the other metrics. Eye closure was associated with a numerical increase in interval variability in the PD group ( r  > 0) and a numerical decrease in the HC group (r < 0); however, the corresponding within-group comparisons did not reach statistical significance (PD: p  = 0.077; HC: p  = 0.081). The opposing numerical changes in tapping-interval variability in the PD and HC groups raise the possibility that visual input may contribute differently to temporal stability during repetitive movements in the two groups, warranting further investigation.