Near-infrared (NIR) light has been shown to produce a range of physiological effects in humans, however, there is still no agreement on whether and how a single parameter, like the flicker frequency of NIR light, affects the brain. An 810nm NIR LED was used as the stimulator. Fifty subjects participated in this experiment. Forty subjects were randomly divided into four groups. Each group underwent a 30-minute NIR LED radiation with four different frequencies (i.e., 0Hz, 5Hz, 10Hz and 20Hz, respectively) on the forehead. The remaining 10 subjects formed the control group, in which they underwent a 30-minute rest period without light radiation. EEG signals of all subjects during each test were recorded. Gravity frequency (GF), relative energy change, and sample entropy were analyzed. The experimental groups had larger GF values compared to the control group. Higher stimulation frequency would cause larger growth of GF (F=14.75, P<0.001). The amplitude of alpha waves relative energy increased, while theta waves decreased remarkably in the experimental groups (p<0.02), and the extent of increase/decrease was larger at higher stimulation frequency, compared to that of the control. Sample entropy of electrodes in the frontal areas were much larger than those in other brain areas in the experimental groups (p<0.001). Larger frequency of the NIR LED light would cause more distinct brain activities in the stimulated areas. It indicates that NIR LED light may have a positive effect on modulating brain activity. These results may help improve the design of photobiomodulation treatments in the future.

中文翻译：

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通过 EEG 测量量化 NIR LED 光照射对前额的刺激频率的影响

近红外 (NIR) 光已被证明会对人类产生一系列生理效应，但是，对于单个参数（如 NIR 光的闪烁频率）是否以及如何影响大脑仍然没有达成一致意见。810nm NIR LED 用作刺激器。五十名受试者参加了这个实验。四十名受试者被随机分为四组。每组接受 30 分钟的 NIR LED 辐射，具有四种不同的频率（即 0赫兹，5赫兹，10赫兹和 20Hz，分别）在额头上。其余 10 名受试者组成对照组，他们在没有光辐射的情况下进行了 30 分钟的休息时间。记录每次测试期间所有受试者的脑电信号。分析了重力频率 (GF)、相对能量变化和样品熵。与对照组相比，实验组的GF值更大。较高的刺激频率会导致较大的GF生长（F=14.75,磷<0.001）。实验组α波相对能量的幅度增加，而θ波的幅度显着降低（p<0.02), 与对照组相比, 在较高的刺激频率下, 增加/减少的程度更大。实验组额叶区域的电极样本熵远大于其他脑区（p<0.001）。NIR LED 光的更高频率会在受刺激区域引起更明显的大脑活动。这表明 NIR LED 灯可能对调节大脑活动有积极作用。这些结果可能有助于改进未来光生物调节治疗的设计。