Attentional Resource Associated With Visual Feedback on a Postural Dual Task in Parkinson’s Disease

Abstract

Background Restricted attentional resource and central processing in patients with Parkinson’s disease (PD) may reduce the benefit of visual feedback in a dual task. Objectives Using brain event-related potentials (ERPs), this study aims to investigate the neural mechanisms of posture visual feedback and supraposture visual feedback during performing of a posture-motor dual task. Methods Eighteen patients with PD and 18 healthy controls stood on a mobile platform (postural task) and executed a manual force-matching task (suprapostural task) concurrently with provided visual feedback of platform movement (posture-feedback condition) or force output (force-feedback condition). The platform movement, force-matching performance, and ERPs (P1, N1, and P2 waves) were recorded. Results Both PD and control groups had superior force accuracy in the force-feedback condition. Decreased postural sway by posture-feedback was observed in healthy controls but not in PD. Force-feedback led to a greater frontal area N1 peak in PD group but smaller N1 peaks in control group. In addition, force-feedback led to smaller P2 peaks of the frontal and sensorimotor areas among PD patients but greater P2 peaks of the sensorimotor and parietal-occipital areas among healthy controls. However, P1 modulations was present only in healthy controls. Conclusions Force-feedback had positive effect on force accuracy in both PD and healthy individuals; however, the beneficial effect of posture-feedback on posture balance is not observed in PD. These findings are the first to suggest that PD could recruit more attentional resources in dual-task preparation to enhance suprapostural accuracy and avoid degrading postural stability by supraposture visual feedback.

Additional visual information on postural control mechanisms in Parkinson's disease: a pilot study

“…Our results were opposite to our expectations and went against, in part, the predictions of our first hypothesis. Individuals with PD increased the COP velocity when they received the VF compared to the OE condition corroborating with previous study that also observed that PD did not use the real-time VF to reduce their sway 31 . There is a two-fold explanation for the increased postural sway in our study: a difficulty in integrating the information provided by the VF 9,32 or a delay in the sensory integration as reported in previous study 13 .…”

“…It is possible to relate this with increased muscle contraction, hypertonicity, or rigidity 37 , due to the task instruction to stay as still as possible, influencing more the peripheral postural control mechanisms 38 . Overall, these findings corroborate with the information that individuals with PD have difficulty to use the additional visual information to improve postural stability 31,33 . Future studies should investigate whether individuals with more advanced PD and with different clinical characteristic (e.g., freezing of gait) have different responses to VF of the COP.…”

“…It is possible that an overload in supraspinal postural control mechanisms 31 had cause a delay to integrate the information provided by the VF and then compensatory effects are required by the peripheral postural control mechanisms. A delay in compensating the postural changes in different visual conditions has been reported 12 .…”