Department of Physical Therapy, Central Michigan University, Mount Pleasant, MI, USA.
J Neuroeng Rehabil. 2013 Jul 16;10:76. doi: 10.1186/1743-0003-10-76.
Although numerous virtual reality applications have been developed for sensorimotor retraining in neurologically impaired individuals, it is unclear whether the virtual environment (VE) changes motor performance, especially in patients with brain injuries. To address this question, the movement characteristics of forward arm reaches during standing were compared in physical and virtual environments, presented at different viewing angles.
Fifteen patients with traumatic brain injuries (TBI) and 15 sex- and age-matched healthy individuals performed virtual reaches in a computer-generated courtyard with a flower-topped hedge. The hedge was projected on a flat screen and viewed in 3D format in 1 of 3 angles: 10° above horizon (resembling a real-world viewing angle), 50° above horizon, or 90° above horizon (directly overhead). Participants were instructed to reach with their dominant hand avatar and to touch the farthest flower possible without losing their balance or stepping. Virtual reaches were compared with reaches-to-point to a target in an equivalent physical environment. A set of kinematic parameters was used.
Reaches by patients with TBI were characterized by shorter distances, lower peak velocities, and smaller postural displacements than reaches by control individuals. All participants reached ~9% farther in the VE presented at a 50° angle than they did in the physical environment. Arm displacement in the more natural 10° angle VE was reduced by the same 9-10% compared to physical reaches. Virtual reaches had smaller velocity peaks and took longer than physical reaches.
The results suggest that visual perception in the VE differs from real-world perception and the performance of functional tasks (e.g., reaching while standing) can be changed in TBI patients, depending on the viewing angle. Accordingly, the viewing angle is a critical parameter that should be adjusted carefully to achieve maximal therapeutic effect during practice in the VE.
尽管已经开发出许多虚拟现实应用程序来对神经功能障碍患者进行感觉运动再训练，但尚不清楚虚拟环境（VE）是否会改变运动表现，特别是在脑损伤患者中。为了回答这个问题，比较了在物理和虚拟环境中站立时向前手臂伸展的运动特征，这两种环境呈现不同的视角。
15 名创伤性脑损伤（TBI）患者和 15 名性别和年龄匹配的健康个体在具有带花顶树篱的计算机生成的庭院中进行了虚拟伸展。树篱投影在平坦的屏幕上，并以 3 种视角中的 1 种以 3D 格式查看：地平线上方 10°（类似于现实世界的视角），地平线上方 50°或上方 90°（直接在头顶上方）。要求参与者用其优势手替身伸展，并尽可能触摸最远的花朵，而不会失去平衡或踏足。将虚拟伸展与在等效物理环境中到达目标的伸展进行了比较。使用了一组运动学参数。
TBI 患者的伸展距离较短，峰值速度较低，姿势位移较小，与对照个体的伸展距离相比。所有参与者在 VE 中比在物理环境中伸展的距离长约 9％。与物理伸展相比，在更自然的 10°视角 VE 中，手臂位移减少了相同的 9-10％。虚拟伸展的速度峰值较小，用时较长。
结果表明，VE 中的视觉感知与现实世界的感知不同，并且功能任务（例如站立时伸展）的表现可以根据视角在 TBI 患者中发生变化。因此，视角是一个关键参数，在 VE 中进行练习时，应谨慎调整该参数以达到最大的治疗效果。
