Development of moving visual stimulation method for linear acceleration experiment using a virtual reality graphic display

内耳的耳石器官同时感知重力和线加速度，因此它对身体位置的变化很敏感。身体位置的信息也是根据视觉系统与前庭系统一起获得的。我们利用名古屋大学安装的直线加速装置(SLED)，利用虚拟现实计算机图形学(CG)绘制了一种视动刺激模式，旨在将视觉刺激和前庭刺激结合起来。(1)1995-1996年间，主要研究课题是实现与雪橇运动相配合的虚拟现实刺激模式。(2)在软件制作人准备CG的过程中，对另一对象进行测试，以考察线加速度对姿势再调节反应的影响。当雪橇以正弦运动向前和向后驱动到受试者身体时，SWAYD与驱动加速度成比例。(3)澄清了…在0.04g和0.06g之间可以区分出更多的两种姿势控制类型，在0.02g到0.04g之间，姿势调整由踝关节策略控制，而在0.06g到0.08g之间，姿势调整以髋关节策略为主。头部运动固定和稳定在0.06g以上的较高G。(4)颈部和四肢下肌的肌肉活动也证实了这一现象。作为一种可能的解释，讨论了前庭-结肠以及前庭-脊髓反射。(5)1996-1997年进行的下一项实验是研究CG产生的视动刺激对站立姿势的影响。视动刺激引起对被试的自我运动知觉(向量)，同时引起与视觉刺激相对应的身体摆动。(6)定义了身体运动首先产生头部运动，然后由头部运动触发身体摆动。(7)遗憾的是，在本项目期间，由于名古屋大学雪橇的使用受到严重限制，我们无法使用新开发的虚拟现实视动刺激实验进行雪橇实验。较少

The otolith organ in the inner ear perceives both the gravity and linear acceleration, so it is susceptible to the change of body position. Information of the body position gets also according to visual system together with the vestibular one. We developed an optokinetic stimulation pattern which was drawn up by a virtual reality computer graphics (CG), and intended to combine visual and vestibular stimulation using a linear acceleration equipment (sled) installed at Nagoya University. (1) From 1995 through 1996, main research subject was to accomplish the virtual reality stimulation patterns, which acted in cooperation with movement of the sled. (2) During preparing CG by a soft-ware maker, the other subject was proceeded, so that it was to examine an effect of linear acceleration on the postural readjustment response. When the sled was driven with a sinusoidal motion of fore and back to subject body swayd in proportion to a magnitude of driven acceleration. (3) It was clarified that … More two types of the postural control were distinguished between 0.04G and 0.06G.Namely, in 0.02G to 0.04G the postural readjustment was controlled by an ankle strategy, and in 0.06G to 0.08G a hip strategy was dominated. Head movement was fixed and stabilized at the higher G above 0.06G.(4) These phenomena were also proved by the muscle activities of the neck and under extremity muscles. As a possible explanation, the vestibulo-collic as well as the vestibulo-spinal reflexes were discussed. (5) The next experiment performed in 1996 to 1997 was to study effects of optokinetic stimulation produced by the CG on the standing posture. The optokinetic stimulation caused a self-motion perception (vection) to the subject, and simultaneously provoked a body sway corresponded with the visual stimulation. (6) It was defined that the vection produced firstly head movement and then the body sway which was triggered by the head movement. (7) Unfortunately, during the term of this project we could not conduct the sled experiment by using a newly developed virtual reality optokinetic stimulation experiment owing to severe restriction of utilization of the sled of Nagoya University. Less