Chen Li-Chiou, Jeka John, Clark Jane E
School and Graduate Institute of Physical Therapy, National Taiwan University, Taipei, Taiwan; Physical Therapy Center, National Taiwan University Hospital, Taipei, Taiwan.
Department of Kinesiology, University of Maryland, College Park, MD, USA; Graduate Program in Neuroscience and Cognitive Science, University of Maryland, College Park, MD, USA; Department of Kinesiology, Temple University, Philadelphia, PA, USA.
Gait Posture. 2016 Mar;45:157-63. doi: 10.1016/j.gaitpost.2016.01.020. Epub 2016 Jan 29.
A reliable and adaptive relationship between action and perception is necessary for postural control. Our understanding of how this adaptive sensorimotor control develops during infancy is very limited. This study examines the dynamic visual-postural relationship during early development. Twenty healthy infants were divided into 4 developmental groups (each n=5): sitting onset, standing alone, walking onset, and 1-year post-walking. During the experiment, the infant sat independently in a virtual moving-room in which anterior-posterior oscillations of visual motion were presented using a sum-of-sines technique with five input frequencies (from 0.12 to 1.24 Hz). Infants were tested in five conditions that varied in the amplitude of visual motion (from 0 to 8.64 cm). Gain and phase responses of infants' postural sway were analyzed. Our results showed that infants, from a few months post-sitting to 1 year post-walking, were able to control their sitting posture in response to various frequency and amplitude properties of the visual motion. Infants showed an adult-like inverted-U pattern for the frequency response to visual inputs with the highest gain at 0.52 and 0.76 Hz. As the visual motion amplitude increased, the gain response decreased. For the phase response, an adult-like frequency-dependent pattern was observed in all amplitude conditions for the experienced walkers. Newly sitting infants, however, showed variable postural behavior and did not systemically respond to the visual stimulus. Our results suggest that visual-postural entrainment and sensory re-weighting are fundamental processes that are present after a few months post sitting. Sensorimotor refinement during early postural development may result from the interactions of improved self-motion control and enhanced perceptual abilities.
姿势控制需要动作与感知之间建立可靠且适应性的关系。我们对于这种适应性感觉运动控制在婴儿期如何发展的理解非常有限。本研究考察早期发育过程中的动态视觉-姿势关系。20名健康婴儿被分为4个发育组（每组n = 5）：开始坐立、独自站立、开始行走以及行走后1年。在实验过程中，婴儿独立坐在一个虚拟移动房间里，使用正弦和技术以五种输入频率（从0.12至1.24赫兹）呈现视觉运动的前后振荡。婴儿在视觉运动幅度不同（从0至8.64厘米）的五种条件下接受测试。分析了婴儿姿势摇摆的增益和相位反应。我们的结果表明，婴儿从开始坐立几个月到行走后1年，能够根据视觉运动的各种频率和幅度特性来控制自己的坐姿。婴儿对视觉输入的频率反应呈现出类似成人的倒U形模式，在0.52和0.76赫兹时增益最高。随着视觉运动幅度增加，增益反应降低。对于相位反应，在所有幅度条件下，经验丰富的学步儿呈现出类似成人的频率依赖性模式。然而，刚开始坐立的婴儿表现出多变的姿势行为，并未对视觉刺激产生系统性反应。我们的结果表明，视觉-姿势同步和感觉重新加权是开始坐立几个月后就存在的基本过程。早期姿势发育过程中的感觉运动精细化可能源于自我运动控制改善与感知能力增强之间的相互作用。
