Gaze and motor behavior of people with PD during obstacle circumvention

Abstract

The aim of this study was to analyze the motor and visual strategies used when walking around (circumvention) an obstacle in patients with Parkinson's disease (PD), in addition to the effects of dopaminergic medication on these strategies. To answer the study question, people with PD (15) and neurologically healthy individuals (15 − CG) performed the task of obstacle circumvention during walking (5 trials of unobstructed walking and obstacle circumvention). The following parameters were analyzed: body clearance (longer mediolateral distance during obstacle circumvention of the center of mass-CoM-to the obstacle), horizontal distance (distance of the CoM at the beginning of obstacle circumvention to the obstacle), circumvention strategy ("lead-out" or "lead-in" strategy), spatial-temporal of each step, and number of fixations, the mean duration of the fixations and time of fixations according to areas of interest. In addition, the variability of each parameter was calculated. The results indicated that people with PD and the CG presented similar obstacle circumvention strategies (no differences between groups for body clearance, horizontal distance to obstacle, or obstacle circumvention strategy), but the groups used different adjustments to perform these strategies (people with PD performed adjustments during both the approach and circumvention steps and presented greater visual dependence on the obstacle; the CG adjusted only the final step before obstacle circumvention). Moreover, without dopaminergic medication, people with PD reduced body clearance and increased the use of a "lead-out" strategy, variability in spatial-temporal parameters, and dependency on obstacle information, increasing the risk of contact with the obstacle during circumvention.

Obstacle circumvention and eye coordination during walking to least and most affected side in people with Parkinson’s disease

“…The aim of this study was to investigate the effects on body clearance, spatial-temporal adjustments, and gaze behavior of obstacle circumvention to the least and most affected side in people with PD, under and without the effects of dopaminergic medication, and compare these effects with neurologically healthy individuals. People with PD and the control group presented similar strategies to circumvent an obstacle (both used "lead-in" and "lead-out" strategies, began obstacle circumvention at a similar horizontal body clearance to the obstacle, and had similar mediolateral body clearance from the obstacle), which corroborated with our previous study [2]. However, the groups performed different spatial-temporal and gaze adjustments to circumvent the obstacle.…”

“…In addition, participants were instructed to return to the starting line. The obstacle was cylindrical (0.35 m diameter) and 1.30 m high [2]. The obstacle was positioned in the middle of the pathway, allowing a similar space on both sides (∼1.60 m) and 4 m from the starting point.…”

“…The former task requires that the individual detects the obstacle's position and edges, performs precise motor actions, and adjusts their movement around it, allowing adequate personal space (body clearance) at the point of moving past the obstacle to ensure safe navigation [1]. During obstacle circumvention, both people with Parkinson's disease (PD) and neurologically healthy individuals decrease step length and step velocity compared to unobstructed walking [2]. In addition, people with PD increase gait variability and duration of gaze fixations on the obstacle and ground when walking with obstacle circumvention, and reduce body clearance without effects from dopaminergic medication [2].…”

“…During obstacle circumvention, both people with Parkinson's disease (PD) and neurologically healthy individuals decrease step length and step velocity compared to unobstructed walking [2]. In addition, people with PD increase gait variability and duration of gaze fixations on the obstacle and ground when walking with obstacle circumvention, and reduce body clearance without effects from dopaminergic medication [2].…”