Visual cues added to a virtual environment paradigm do not improve motor arrests in Parkinson’s disease

Abstract

Objective. Elucidating how cueing alleviates freezing of gait (FOG) in Parkinson's disease (PD) would enable the development of more effective, personalized cueing strategies. Here, we aimed to validate a visual cueing virtual environment (VE) paradigm for future use in e.g. neuroimaging studies and behavioral studies on motor timing and scaling in PD patients with FOG. Approach. We included 20 PD patients with FOG and 16 age-matched healthy control subjects. Supine participants were confronted with a VE displaying either no cues, bars or staircases. They navigated forward using alternate suppression of foot pedals. Motor arrests (as proxy for FOG), and measures of motor timing and scaling were compared across the three VE conditions for both groups. Main results. VE cues (bars and staircases) did not reduce motor arrests in PD patients and healthy control subjects. The VE cues did reduce pedal amplitude in healthy control subjects, without effects on other motor parameters. Conclusion. We could not validate a visual cueing VE paradigm to study FOG. The VE cues possibly failed to convey the necessary spatial and temporal information to support motor timing and scaling. We discuss avenues for future research.

Gait-modifying effects of augmented-reality cueing in people with Parkinson’s disease

“…Second, our study clearly showed that gait parameters like gait speed and step length could be modulated with AR cues relative to one’s baseline gait pattern. This is encouraging considering earlier research with AR cues showing limited effects on various gait parameters ( 19 , 23 – 25 , 28 , 48 ). AR cues, when delivered through state-of-the-art AR headsets which have a sufficiently large vertical AR-FOV size, may thus be used to improve Parkinsonian gait.…”

“…It is, however, unknown whether participants processed spatial information of the footprints in the air, on the ground, or both. The action-relevance, an important factor for effective cueing ( 47 ), of such step-length cues in the air is probably much lower [i.e., as the spatial information conveyed by the cues is not directly specifying the actual foot-placement locations ( 48 )] than when participants can directly step onto stepping targets on the ground, for which existing visuolocomotor control mechanisms can be utilized ( 49 – 52 ). The second additional benefit that we explored was adding mud sounds to dinosaur footprints to augment steps.…”