Neural basis of postural instability identified by VTC and EEG.
Neural basis of postural instability identified by VTC and EEG.
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DOI：
10.1007/s00221-009-1956-5
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发表时间：
2009-10
影响因子：
2
通讯作者：
Newell, Karl M.
中科院分区：
文献类型：
--
作者：
Slobounov, Semyon;Cao, Cheng;Jaiswal, Niharika;Newell, Karl M.
在这项研究中，我们研究了虚拟接触时间 (VTC) 的神经基础，以及 VTC 为未来姿势不稳定提供预测信息的假设。开发了一种新颖的方法，用于在受试者闭眼执行具有挑战性的单腿姿势时，在单个姿势试验中区分稳定的跌倒前阶段和过渡到不稳定阶段。具体来说，我们利用小波变换和阶段分割算法，使用 VTC 时间序列数据集作为输入。 VTC 时间序列与多通道 (n = 64) EEG 信号进行时间锁定，以检查其潜在的神经基质。为了识别VTC神经基质的焦点来源，设计了一种结合多通道脑电图的独立成分分析（ICA）和低分辨率断层扫描（LORETA）的两步法。主要发现有两个：（1）在向不稳定阶段过渡期间，观察到 VTC 最小值显着增加（以及 VTC 变异性增强），并逐渐发展为最终失去平衡和跌倒； (2) 这种 VTC 动态与主要在 θ、α 和 γ 频段内的 EEG 显着调制相关。这种脑电图调节的来源是在扣带皮层（ACC）、楔前叶和顶叶交界处以及枕叶皮层确定的。研究结果支持这样的假设：VTC 最小值的系统性增加伴随着额叶-中央和顶叶-枕叶区域脑电图信号的调制，共同预测未来姿势的不稳定。
In this study, we investigated the neural basis of virtual time to contact (VTC) and the hypothesis that VTC provides predictive information for future postural instability. A novel approach to differentiate stable pre-falling and transition-to-instability stages within a single postural trial while a subject was performing a challenging single leg stance with eyes closed was developed. Specifically, we utilized wavelet transform and stage segmentation algorithms using VTC time series data set as an input. The VTC time series was time-locked with multichannel (n = 64) EEG signals to examine its underlying neural substrates. To identify the focal sources of neural substrates of VTC, a two-step approach was designed combining the independent component analysis (ICA) and low-resolution tomography (LORETA) of multichannel EEG. There were two major findings: (1) a significant increase of VTC minimal values (along with enhanced variability of VTC) was observed during the transition-to-instability stage with progression to ultimate loss of balance and falling; and (2) this VTC dynamics was associated with pronounced modulation of EEG predominantly within theta, alpha and gamma frequency bands. The sources of this EEG modulation were identified at the cingulate cortex (ACC) and the junction of precuneus and parietal lobe, as well as at the occipital cortex. The findings support the hypothesis that the systematic increase of minimal values of VTC concomitant with modulation of EEG signals at the frontal-central and parietal–occipital areas serve collectively to predict the future instability in posture.
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