Stroke affects locomotor steering responses to changing optic flow directions.

Area of Science:

• Neuroscience
• Biomechanics
• Rehabilitation Science

Background:

• Stroke survivors often experience impaired walking and steering.
• Altered visual motion perception may contribute to these motor deficits.

Purpose of the Study:

• To investigate heading control during walking in stroke patients using virtual environments.
• To analyze responses to translational optic flows (OFs) from various directions.

Main Methods:

• 10 stroke patients and 11 healthy controls walked in a virtual environment (VE) with helmet-mounted display.
• Participants navigated with optic flow (OF) stimuli from five different focus of expansion (FOE) locations.
• Center of mass (CoM) trajectory, heading direction, and body reorientation were measured.

Main Results:

• Healthy individuals adjusted their path opposite to the FOE, with greater deviations at eccentric locations.
• Stroke patients showed deficits in steering, including lack of CoM corrections, heading errors, or veering to the nonparetic side.
• Both groups exhibited small CoM corrections leading to significant virtual heading errors.

Conclusions:

• Stroke impacts the control of locomotion heading in response to optic flow.
• Altered heading perception and/or sensory-motor integration issues are probable causes.
• This impaired response to optic flow may underlie post-stroke steering difficulties.