School of Physical and Occupational Therapy, McGill University and Jewish Rehabilitation Hospital (Feil & Oberfeld/CRIR) Research Center, Montréal, Canada.
Neurorehabil Neural Repair. 2010 Jun;24(5):457-68. doi: 10.1177/1545968309355985. Epub 2010 Jan 12.
Stroke patients manifest steering difficulties during walking, which may arise from an altered perception of visual motion.
To examine the ability of stroke patients to control their heading direction while walking in a virtual environment (VE) describing translational optic flows (OFs) expanding from different directions.
The authors evaluated 10 stroke patients and 11 healthy people while they were walking overground and visualizing a VE in a helmet-mounted display. Participants were instructed to walk straight in the VE and were randomly exposed to an OF having a focus of expansion (FOE) located in 5 possible locations (0 degrees, +/-20 degrees, and +/-40 degrees to the right or left). The body's center of mass (CoM) trajectory, heading direction, and horizontal body reorientation were recorded with a Vicon-512 system.
Healthy participants veered opposite to the FOE location in the physical world, with larger deviations occurring at the most eccentric FOE locations. Stroke patients displayed altered steering behaviors characterized either by an absence of CoM trajectory corrections, multiple errors in the heading direction, or systematic veering to the nonparetic side. Both groups displayed relatively small CoM trajectory corrections that led to large virtual heading errors.
The control of heading of locomotion in response to different OF directions is affected by stroke. An altered perception of heading direction and/or a poor integration of sensory and motor information are likely causes. This altered response to OF direction while walking may contribute to steering difficulties after stroke.
中风患者在行走时表现出转向困难，这可能是由于视觉运动感知改变所致。
研究中风患者在虚拟现实环境（VE）中行走时控制头部朝向的能力，该环境描述了从不同方向扩展的平移视流（OF）。
作者评估了 10 名中风患者和 11 名健康人，他们在头盔式显示器中可视化 VE 时在地面上行走。参与者被指示在 VE 中直走，并随机暴露于焦点扩展（FOE）位于 5 个可能位置（0 度、20 度和 40 度正负右或左）的 OF。使用 Vicon-512 系统记录身体质心（CoM）轨迹、头部方向和水平身体重新定向。
健康参与者在物理世界中向 FOE 位置的相反方向偏离，FOE 位置越偏，偏差越大。中风患者表现出改变的转向行为，其特征是 CoM 轨迹校正缺失、头部方向多次错误或系统偏向非偏瘫侧。两组都显示出相对较小的 CoM 轨迹校正，导致较大的虚拟头部误差。
中风影响了对不同 OF 方向的运动头部朝向的控制。头部朝向感知改变和/或感觉运动信息整合不良可能是原因。这种在行走时对 OF 方向的改变反应可能导致中风后转向困难。
