Optic flow in a virtual environment can impact on locomotor steering post stroke

Persons with a chronic stroke often manifest mobility deficits that may in part be related to altered visuomotor control. Specifically, the ability to use optic flow, which reflects self-motion, may be compromised after a stroke. We evaluated the locomotor behavior of 6 subjects with chronic stroke as they walked overground while viewing a virtual room displayed in a head-mounted display. The subjects were asked to walk straight in the virtual environment (VE). At 1.5m of forward walking, the room was slowly rotated up to 40° towards the paretic or non-paretic side, or remained centered (0°). In order to maintain a straight trajectory or a small net heading error in the VE, subjects could rotate their head, with or without modifying their walking trajectory. The responses of subjects were varied in terms of strategies and accuracy, leading to a wide range of net heading errors, in the VE. While there was no precise biomarker of excellent performance, the two individuals with the poorest performance had a history of visuospatial neglect. walking, steering, vision, stroke, hemiparetic, gait, visual motion, neglect