The temporal organization of posture changes during the first year of independent walking
The temporal organization of posture changes during the first year of independent walking
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DOI：
10.1007/s00221-004-2082-z
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发表时间：
2005-03-01
影响因子：
2
通讯作者：
Clark, JE
中科院分区：
文献类型：
--
作者：
Metcalfe, JS;Chen, LC;Clark, JE
虽然直立姿势的发展受到了相当大的关注，但婴儿在学习这一基本行为的最初几个月里的安静姿势还没有得到很好的研究。本研究的目的是表征这些婴儿不受干扰的直立姿势的时间进化特性或时间组织，并阐明躯体感觉信息如何影响该组织。对6名健康的足月婴儿进行了每月一次的测试，从开始步行到9个月的独立行走体验，无论是独立站立还是触摸静态表面。通过指数Ornstein-Uhlenbeck表征的稳定图扩散分析，对Sway的结构进行了评估。这项分析的结果揭示了对姿势发展的两个新见解。首先，安静姿势的发展变化涉及到摇摆衰减到最大方差的速度降低，而不是这种方差的大小衰减。具体地说，与独立站立状态相比，当触摸静态表面时，衡量摇摆方差的指标显著减少，但随着行走体验的增加，没有显示出任何变化。此外，平均衰减速率常数的减小表明长时间尺度的摇摆修正对整体摇摆轨迹的影响增加。其次，研究表明，在早期行走年龄，触摸的使用既减少了变异量，又使摇摆的速率常数向更长时间尺度的位移移动。在前人研究的背景下，这些结果支持了我们的结论，即早期姿势发展体现了校准感觉-运动关系以估计自我运动以及识别和调整控制系统特性的双重任务。
Although the development of upright posture has received considerable attention, the quiet stance of infants in their first months of learning this fundamental behavior has not been well studied. The purpose of the present study was to characterize the time evolutionary properties, or temporal organization, of these infants' unperturbed upright stance as well as to elucidate how somatosensory information influences that organization. Six healthy, full-term infants were tested monthly from walk onset until 9 months of independent walking experience while standing either independently or touching a static surface. The structure of sway was assessed through stabilogram-diffusion analysis using an exponential Ornstein-Uhlenbeck characterization. The results of this analysis revealed two new insights into postural development. First, the developmental changes in quiet stance involved a decreased rate at which sway decays to maximal variance, rather than an attenuation of the magnitude of that variance. Specifically, measures indexing amount of sway variance were significantly reduced when touching a static surface as compared with an independent stance condition, but revealed no change with increased walking experience. Further, a reduction in the average rate constant of decay indicated an increased influence of long time-scale sway corrections on the overall sway trajectory. Second, it was shown that, at early walk ages, the use of touch both reduced the amount of variance and shifted the rate constant of sway towards longer time-scale displacements. Taken in the context of previous research, these results support our conclusion that early postural development embodies the dual tasks of calibrating sensorimotor relations for estimation of self-motion as well as identification and tuning of control system properties.