Modolo Julien, Thomas Alex W, Legros Alexandre
Human Threshold Research and Bioelectromagnetics Group, Imaging Program, Lawson Health Research Institute, London, Canada.
Department of Medical Biophysics, Western University, London, Canada.
Bioelectromagnetics. 2017 Sep;38(6):425-435. doi: 10.1002/bem.22064. Epub 2017 Jun 19.
We assessed the effects of power-line frequency (60 Hz in North America) magnetic fields (MF) in humans using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Twenty-five participants were enrolled in a pseudo-double-blind experiment involving "real" or "sham" exposure to sinusoidal 60 Hz MF exposures delivered using the gradient coil of an MRI scanner following two conditions: (i) 10 s exposures at 3 mT (10 repetitions); (ii) 2 s exposures at 7.6 mT (100 repetitions). Occipital EEG spectral power was computed in the alpha range (8-12 Hz, reportedly the most sensitive to MF exposure in the literature) with/without exposure. Brain functional activation was studied using fMRI blood oxygen level-dependent (BOLD, inversely correlated with EEG alpha power) maps. No significant effects were detected on occipital EEG alpha power during or post-exposure for any exposure condition. Consistent with EEG results, no effects were observed on fMRI BOLD maps in any brain region. Our results suggest that acute exposure (2-10 s) to 60 Hz MF from 3 to 7.6 mT (30,000 to 76,000 times higher than average public exposure levels for 60 Hz MF) does not induce detectable changes in EEG or BOLD signals. Combined with previous findings in which effects were observed on the BOLD signal after 1 h exposure to 3 mT, 60 Hz MF, this suggests that MF exposure in the low mT range (<10 mT) might require prolonged durations of exposure to induce detectable effects. Bioelectromagnetics. 38:425-435, 2017. © 2017 Wiley Periodicals, Inc.
我们通过同步脑电图（EEG）和功能磁共振成像（fMRI）评估了工频（北美为60Hz）磁场（MF）对人体的影响。25名参与者参加了一项伪双盲实验，该实验涉及在两种条件下使用MRI扫描仪的梯度线圈进行“真实”或“假”的正弦60Hz MF暴露：（i）在3mT下暴露10秒（重复10次）；（ii）在7.6mT下暴露2秒（重复100次）。在有/无暴露的情况下，计算枕叶脑电图在α波段（8 - 12Hz，据文献报道该波段对MF暴露最敏感）的频谱功率。使用fMRI血氧水平依赖（BOLD，与脑电图α功率呈负相关）图谱研究脑功能激活情况。在任何暴露条件下，暴露期间或暴露后均未检测到枕叶脑电图α功率有显著影响。与脑电图结果一致，在任何脑区的fMRI BOLD图谱上均未观察到影响。我们的结果表明，急性暴露（2 - 10秒）于3至7.6mT的60Hz MF（比60Hz MF的平均公众暴露水平高30,000至76,000倍）不会引起脑电图或BOLD信号的可检测变化。结合之前发现暴露于3mT、60Hz MF 1小时后BOLD信号有影响的研究结果，这表明在低mT范围（<10mT）的MF暴露可能需要较长的暴露时间才能引起可检测的影响。《生物电磁学》。38:425 - 435，2017年。©2017威利期刊公司。
