Postural readjustments induced by linear motion of visual scenes
Postural readjustments induced by linear motion of visual scenes
复制标题
视觉场景的线性运动引起的姿势调整
作者：
F. Lestienne;J. F. Soechting;A. Berthoz
摘要：通过在视场外围矢状面上投射一个在矢状面上线性运动的视觉场景，获得了健康受试者在力台上直立站立时的视觉诱导线性运动感觉（线性矢量）。这种线性的矢量引起姿势的调整，其特征是主体的倾斜，与视觉场景的运动方向相同，随后是后效应。体位变化的幅度与图像速度和图像模式的密度（或空间频率）成对数正比，在最高图像速度下，由于图像运动感知的限制，而不是生物力学的限制，体位效应达到饱和；B)明显依赖于移动场景的大小及其相对位置（在视野中）。体位调整的频率分析显示：a)体位摆动幅度增加，特别是在低频（0.02 ~ 0.2 Hz）；b)功率谱中位于0.15和0.5 Hz之间的尖峰。从运动视觉场景的速度与摇摆幅度之间的动态关系出发，得出姿态调整与速度对数的低通滤波成正比的结论。胫骨前肌和比目鱼肌的作用是用一种阻力对抗身体倾斜。这些结果就目前有关姿势机制中视觉、前庭和感知相互作用的理论进行了分析。
SummaryVisually induced linear motion sensation (linear vection) was obtained by projection of a visual scene moving linearly in a sagittal plane at the periphery of the visual field of healthy subjects standing erect on a force platform. This linear vection induces postural readjustments characterized by an inclination of the subject, in the same direction as the movement of the visual scene, followed by an after-effect. The amplitude of the postural changes was: a) logarithmically proportional to the image velocity and the density (or the spatial frequency) of the image pattern, at highest image velocities there was a saturation of the postural effect due to limits in image motion perception and not to biomechanical constraints; b) dependent appreciably on the size of the moving scene and its relative location (in the visual field).The frequency analysis of postural readjustments showed a) an increase of the amplitude of postural sway, especially at the low frequencies (from 0.02–0.2 Hz); b) sharp peaks in the power spectrum located between 0.15 and 0.5 Hz.From the dynamic relationships between the velocity of the moving visual scene and the amplitude of sway, it was concluded that the postural readjustment is proportional to a low pass filtering of the logarithm of the velocity. The contribution of Tibialis Anterior and Soleus was to oppose the body inclination with a resistive force.These results are analyzed in regard to the current theories concerning visual, vestibular and preceptive interaction in postural mechanisms.