Lee Beom-Chan, Martin Bernard J, Sienko Kathleen H
J Neuroeng Rehabil. 2013 Feb 13;10:21. doi: 10.1186/1743-0003-10-21.
Torso-based vibrotactile feedback may significantly reduce postural sway in balance-compromised adults during quiet standing or in response to perturbations. However, natural non-volitional postural responses to vibrotactile stimulation applied to the torso remain unknown.
The primary goal of this study was to determine, for two types of actuators (tactors) and in the absence of instruction, whether vibrotactile stimulation induces a directional postural shift as a function of stimulation location. Eleven healthy young adults (20-29 years old) were asked to maintain an upright erect posture with feet hip-width apart and eyes closed. Two types of tactors, Tactaid and C2, which differ in design and stimulation strength, were placed on the skin over the right and left external oblique, internal oblique, and erector spinae muscles in a horizontal plane corresponding approximately to the L4/L5 level. Each tactor of the same type was activated twice randomly for each individual location and twice simultaneously for all locations at a frequency of 250 Hz for a period of 5 s.
Vibration applied over the internal oblique and erector spinae muscle locations induced a postural shift in the direction of the stimulation regardless of the tactor type. For the aforementioned four locations, the root-mean-square (RMS) and power spectral density (PSD) of the body sway in both the A/P and M/L directions were also significantly greater during the vibration than before or after, and were greater for the C2 tactors than for the Tactaid tactors. However, simultaneous activation of all tactors or those over the external oblique muscle locations did not produce significant postural responses regardless of the tactor type.
The results suggest that the use of a torso-based vibrotactile sensory augmentation display should carefully consider the tactor type as well as the instruction of corrective movements. Attractive instructional cues ("move in the direction of the vibration") are compatible with the observed non-volitional response to stimulation and may facilitate postural adjustments during vibrotactile biofeedback balance applications.
基于躯干的振动触觉反馈可能会显著减少平衡能力受损的成年人在安静站立或对干扰做出反应时的姿势摆动。然而，施加于躯干的振动触觉刺激所引发的自然非自主姿势反应仍不为人知。
本研究的主要目的是，在没有指令的情况下，针对两种类型的致动器（触觉器），确定振动触觉刺激是否会根据刺激位置引起定向姿势偏移。11名健康的年轻成年人（20 - 29岁）被要求双脚与肩同宽、闭眼保持直立姿势。两种设计和刺激强度不同的触觉器，即Tactaid和C2，被放置在大约对应于L4/L5水平的横平面上右侧和左侧腹外斜肌、腹内斜肌以及竖脊肌上方的皮肤上。同一类型的每个触觉器在每个单独位置随机激活两次，在所有位置同时激活两次，频率为250Hz，持续5秒。
无论触觉器类型如何，施加于腹内斜肌和竖脊肌位置的振动都会引起向刺激方向的姿势偏移。对于上述四个位置，在振动期间身体在前后（A/P）和左右（M/L）方向上摆动的均方根（RMS）和功率谱密度（PSD）也显著大于振动前或振动后，并且C2触觉器比Tactaid触觉器的数值更大。然而，无论触觉器类型如何，同时激活所有触觉器或激活位于腹外斜肌位置的触觉器都不会产生显著姿势反应。
结果表明，使用基于躯干的振动触觉感觉增强显示器时应仔细考虑触觉器类型以及纠正运动的指令。有吸引力的指导性提示（“朝着振动方向移动”）与观察到的对刺激的非自主反应相匹配，并且可能有助于在振动触觉生物反馈平衡应用期间进行姿势调整。
