Postural adaptations to repeated optic flow stimulation in older adults.
Postural adaptations to repeated optic flow stimulation in older adults.
复制标题
老年人对重复光流刺激的姿势适应。
DOI：
10.1016/j.gaitpost.2008.01.010
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发表时间：
2008
期刊：
影响因子：
2.4
通讯作者：
Sparto,PatrickJ
中科院分区：
文献类型：
--
作者：
O'Connor,KathrynW;Loughlin,PatrickJ;Redfern,MarkS;Sparto,PatrickJ
这项研究的目的是了解老年人和年轻人对视觉线索的适应(试验内姿势反应的变化)和习惯化(试验之间姿势反应的减少)的过程。特别令人感兴趣的是对光流量值突然增加的反应。测量了25名健康年轻人和24名健康老年人在观看前后0.4赫兹正弦波视频流45s时的姿势摆动。三种情况各进行三次试验：(1)恒定12 cm光流幅度(24 cm峰间)，(2)恒定4 cm波幅(8 cm p-t-p)，以及(3)波幅从4到12 cm的过渡。在试验期间，计算连续5s间隔的头部摇摆速度的平均功率(Pvel)，以检查试验内和试验之间的摇摆变化。使用混合因素重复测量方差分析来检验受试组、试验和间隔时间对Pvel的影响。在所有情况下，老年人的PVELL都更大(P<；0.001)。在12 cm恒幅试验中，所有受试者都发生了试验内适应，但试验间习服情况有所不同。在所有3个试验中，老年人的Pvelof显著降低，但只有在试验1和试验2之间，年轻人的Pvelof才下降。年轻人对4-12 cm视流转换的反应没有明显变化，而老年人在转换后的声速有所增加，从第一次的6.5db到第三次的3.4db。这些结果表明，老年人可以习惯于反复的视觉干扰暴露；然而，这种习惯需要比年轻人更多的暴露次数。这表明衰老影响了快速修改感觉反馈的相对权重以实现姿势稳定的能力。
The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior–posterior 0.4Hz sinusoidal optic flow for 45s. Three trials for each of three conditions were performed: (1) constant 12cm optic flow amplitude (24cm peak-to-peak), (2) constant 4cm amplitude (8cm p-t-p), and (3) a transition in amplitude from 4 to 12cm. The average power of head sway velocity (Pvel) was calculated for consecutive 5s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the Pvel. Pvelwas greater in older adults in all conditions (p<0.001). During the 12cm constant amplitude trials, within-trial adaptation occurred for all subjects, but there were differences in the between-trial habituation. Pvelof the older adults decreased significantly between all 3 trials, but decreased only between Trials 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12cm did not significantly change, older adults had an increase in Pvelfollowing the transition, ranging from 6.5dB for the first trial to 3.4dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization.