Abstract
In Parkinson's disease (PD) self-directed movement, such as walking, is often found to be impaired while goal directed movement, such as catching a ball, stays relatively unaltered. This dichotomy is most clearly observed when sensory cueing techniques are used to deliver patterns of sound and/or light which in turn act as an external guide that improves gait performance. In this study we developed visual cues that could be presented in an immersive, interactive virtual reality (VR) environment. By controlling how the visual cues (black footprints) were presented, we created different forms of spatial and temporal information. By presenting the black footprints at a pre-specified distance apart we could recreate different step lengths (spatial cues) and by controlling when the black footprints changed color to red, we could convey information about the timing of the foot placement (temporal cues). A group of healthy controls (HC; N = 10) and a group of idiopathic PD patients (PD, N = 12) were asked to walk using visual cues that were tailored to their own gait performance [two spatial conditions (115% [N] and 130% [L] of an individual's baseline step length) and three different temporal conditions (spatial only condition [NT], 100 and 125% baseline step cadence)]. Both groups were found to be able to match their gait performance (step length and step cadence) to the information presented in all the visual cue conditions apart from the 125% step cadence conditions. In all conditions the PD group showed reduced levels of gait variability (p < 0.05) while the HC group did not decrease. For step velocity there was a significant increase in the temporal conditions, the spatial conditions and of the interaction between the two for both groups of participants (p < 0.05). The coefficient of variation of step length, cadence, and velocity were all significantly reduced for the PD group compared to the HC group. In conclusion, our results show how virtual footsteps presented in an immersive, interactive VR environment can significantly improve gait performance in participants with Parkinson's disease.
Highlights
The loss of dopamine-generating neurons in the basal-ganglia as well as dysfunctional activation of the supplementary motor area, anterior cingulate cortex, and left putamen lead to problems with self-paced movement in people suffering from Parkinson Disease (PD) [1]
With respect to step cadence, the t-tests revealed that both groups adhered (HC: 1.81 ± 0.22 Hz; Parkinson’s disease (PD): 1.69 ± 0.31 Hz) to the 100% condition (HC: 1.77 Hz; PD: 1.59 Hz), but neither of the groups fully adapted to the 125% condition [healthy control (HC): t(19) = −3.84, p = 0.001, 1.94 ± 0.34 Hz; PD: t(23) = −3.02, p = 0.006, 1.80 ± 0.30 Hz], indicating that the imposed cadence (HC: 2.21 Hz; PD: 1.99 Hz) in this condition was too fast to use as a guide to improve gait performance
For step velocity (Figure 3C) increased values were obtained for all conditions in the PD group, while in the HC group only the N-NT condition did not induce a significant increase in velocity which would be expected given the closeness of the cue to the baseline condition
Summary
The loss of dopamine-generating neurons in the basal-ganglia as well as dysfunctional activation of the supplementary motor area, anterior cingulate cortex, and left putamen lead to problems with self-paced movement in people suffering from Parkinson Disease (PD) [1]. Both automated and self-paced movements are impaired by the disease, the ability to control goal-directed or externally cued movements stays relatively unaltered [2, 3]. It suggests that in these instances where sensory information is available (e.g., visual or auditory) there is a change in the neural mechanisms employed to control movement, effectively bypassing defective basal ganglia circuitry [10]
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