Eyes-closed finger-tapping task for assessing visual dependence in temporal motor control in Parkinson's disease
Kazuhide Seo1, Masayuki Hara2, Masahito Miki2
1Department of Neurology, Saitama Medical University, Saitama, Japan.
Background:
Impaired motor automaticity in Parkinson's disease (PD) may increase reliance on visual feedback, but its role in stabilizing repetitive movements remains unclear.
Objective:
To quantify the effect of eye closure on finger tapping and identify performance features reflecting visual dependence in PD.
Methods:
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.
Results:
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).
Conclusion:
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.
