Constraining eye movement in individuals with Parkinson’s disease during walking turns

Abstract

Walking and turning is a movement that places individuals with Parkinson's disease (PD) at increased risk for fall-related injury. However, turning is an essential movement in activities of daily living, making up to 45 % of the total steps taken in a given day. Hypotheses regarding how turning is controlled suggest an essential role of anticipatory eye movements to provide feedforward information for body coordination. However, little research has investigated control of turning in individuals with PD with specific consideration for eye movements. The purpose of this study was to examine eye movement behavior and body segment coordination in individuals with PD during walking turns. Three experimental groups, a group of individuals with PD, a group of healthy young adults (YAC), and a group of healthy older adults (OAC), performed walking and turning tasks under two visual conditions: free gaze and fixed gaze. Whole-body motion capture and eye tracking characterized body segment coordination and eye movement behavior during walking trials. Statistical analysis revealed significant main effects of group (PD, YAC, and OAC) and visual condition (free and fixed gaze) on timing of segment rotation and horizontal eye movement. Within group comparisons, revealed timing of eye and head movement was significantly different between the free and fixed gaze conditions for YAC (p < 0.001) and OAC (p < 0.05), but not for the PD group (p > 0.05). In addition, while intersegment timings (reflecting segment coordination) were significantly different for YAC and OAC during free gaze (p < 0.05), they were not significantly different in PD. These results suggest individuals with PD do not make anticipatory eye and head movements ahead of turning and that this may result in altered segment coordination during turning. As such, eye movements may be an important addition to training programs for those with PD, possibly promoting better coordination during turning and potentially reducing the risk of falls.

Neural circuits mediating visual stabilization during active motion in zebrafish

“…More than that, there is evidence that the disorder of body movement system leads to the constraining eye movement in patients with Parkinson's disease (Ambati et al, 2016), which implies a common or interactive system to control eye and body movement simultaneously (Srivastava et al, 2018). The current study may also shed lights on the potential clinical anchor points of the disorders in locomotion-eye coordination with zebrafish model (Huang and Neuhauss, 2008).…”

Visual Cues Promote Head First Strategies During Walking Turns in Individuals With Parkinson's Disease

“…However, individuals with Parkinson's disease, unlike neurotypical young adults, do not anticipate a turn by moving their eyes and head in the direction of the turn. Instead, individuals with PD maintain the eyes straight ahead until the onset of the turn and use an "enbloc" turning strategy (Ambati et al, 2016). These observations suggest that en-bloc segment coordination may result from a lack of anticipatory redirection of the eyes.…”

“…The turn movement was defined by the ipsilateral foot contact (IFC1) prior to change in direction (onset) to the ipsilateral foot contact (IFC2) following the change in direction (completion), as used in previous work (Patla et al, 1999;Ambati et al, 2016). Refer to Supplementary Figure 1 in supplementary files for further definition.…”

“…Time of turn onset was then estimated as the local minima of each segment's yaw angular velocity prior to reaching maximum angular velocity during the turning motion. Segment onsets were referenced with respect to IFC1 by subtracting each segment onset time from IFC1 time (milliseconds) as per previously published work (Patla et al, 1999;Hollands et al, 2002;Ambati et al, 2016). Intersegment timing, differences between when adjacent segments initiated rotation, were examined by comparing the onset of the inferior segment to that of the superior segment.…”

“…Turning while walking is defined as having a robust cranio-caudal segment sequence resulting in a head first turning strategy (Spildooren et al, 2017) or steering synergy (Patla et al, 1999;Ambati et al, 2016). This strategy requires independent control of the segments, increasing the complexity of control by the CNS, but also allows individuals to respond to perturbations (Assaiante and Amblard, 1995).…”