Abstract
BackgroundRecent research has argued that removal of relevant sensory information during the planning and control of simple, self-paced walking can result in increased demand on central processing resources in Parkinson’s disease (PD). However, little is known about more complex gait tasks that require planning of gait adaptations to cross over an obstacle in PD.MethodsIn order to understand the interaction between availability of visual information relevant for self-motion and cognitive load, the current study evaluated PD participants and healthy controls while walking toward and stepping over an obstacle in three visual feedback conditions: (i) no visual restrictions; (ii) vision of the obstacle and their lower limbs while in complete darkness; (iii) vision of the obstacle only while in complete darkness; as well as two conditions including a cognitive load (with a dual task versus without a dual task). Each walk trial was divided into an early and late phase to examine changes associated with planning of step adjustments when approaching the obstacle.ResultsInteractions between visual feedback and dual task conditions during the obstacle approach were not significant. Patients with PD had greater deceleration and step time variability in the late phase of the obstacle approach phase while walking in both dark conditions compared to control participants. Additionally, participants with PD had a greater number of obstacle contacts when vision of their lower limbs was not available specifically during the dual task condition. Dual task performance was worse in PD compared to healthy control participants, but notably only while walking in the dark regardless of visual feedback.ConclusionsThese results suggest that reducing visual feedback while approaching an obstacle shifts processing to somatosensory feedback to guide movement which imposes a greater demand on planning resources. These results are key to fully understanding why trips and falls occur in those with PD.
Highlights
Recent research has argued that removal of relevant sensory information during the planning and control of simple, self-paced walking can result in increased demand on central processing resources in Parkinson’s disease (PD)
Main effects of group (F1,31 = 5.39; p = 0.021) (PD were more variable than healthy controls (HC)), and phase (F1,31 = 14.14; p = 0.001) were found for step time variability
Main effects of group (F1,31 = 10.07; p = 0.003) (PD patients were more variable than healthy controls), and phase (F1,31 = 32.52; p < 0.001) were identified for step-length variability; no interactions were significant
Summary
Recent research has argued that removal of relevant sensory information during the planning and control of simple, self-paced walking can result in increased demand on central processing resources in Parkinson’s disease (PD). Pieruccini-Faria et al BMC Neurology (2014) 14:250 position, aided in updating proprioceptive feedback for a motor plan Together, these studies suggest that patients with PD are more dependent on visual feedback to update their sense of self-motion and body position compared to healthy control participants during gait. These studies suggest that patients with PD are more dependent on visual feedback to update their sense of self-motion and body position compared to healthy control participants during gait This dependence on vision may be important for estimating the distance between their body and targets/ obstacles that they have planned to negotiate in their environment. This study suggested that visual feedback of self-motion may be important for accurate planning (decreasing accidental obstacle contacts) for obstacle crossing, measures of gait control during the obstacle approach were not evaluated. Little is known about the influence of reduced visual feedback on gait control in individuals with PD when the demand for planning resources increases (i.e. walking toward an obstacle)
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