この研究は、周波数0から500 Hzの範囲に大部分のパワーがあるパルス化超低周波磁界（ELF MF）へのばく露が、ヒトの脳電図（EEG）に影響するか否かを調べた。20人の被験者（男性10人、女性10人）に、磁界（MF）ばく露セッションと擬似ばく露セッション（どちらも15分間）の両方をカウンターバランスさせて受けさせた。分散分析（ANOVA）の結果、ばく露後のアルファ波活動は、後頭部電極（O1、Oz、O2）で有意に高く、頭頂部電極（P3、Pz、P4）でわずかに高かった；アルファ波活動の増強は一過性であり、ばく露から約7分後には、後頭部および頭頂部で擬似ばく露に比べわずかに低下した、と報告している。
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To study the effects of extremely low frequency magnetic fields with most power at frequencies between 0 and 500 Hz on the human EEG.
Modulation type: pulsed
ばく露時間: intermittent for 15 min, see Modulation
|Rise time||1 ms|
The (patented) pulsed MF design was made of individual pulses, each of which a doublet, combined in an 853 ms segment including 18 pulses. Each pulse had a maximum rise time of 1 ms resulting in a maximum time changing MF of 0.4 T/s. In between segments were varying refractory periods of 110, 220, 330 ms followed by a longer fourth refractory period of 1200 ms after which another pulse segment of 853 ms began. This pattern was repeated for 15 min.
|チャンバの詳細||The MF exposure system [Thomas et al., 2001] consisted of three orthogonal square Helmholtz-like coil pairs with 2, 1.75, and 1.5 m sides (10 turns of 8-gauge stranded conductor per coil with an incorporated high temperature, non-conductive cooling/heating tube wound on Lexan® frames). During exposure, only the vertical coil pair was driven by a constant current amplifier via a digital to analog converter; all other coils were unpowered. During sham exposure, the amplifiers were on but there was no signal.|
|ばく露装置の詳細||Subjects were fitted with the EEG recording apparatus (cap) and seated within the exposure system. They were instructed to relax, but to not fall asleep.|
|Sham exposure||A sham exposure was conducted.|
|Additional information||Twenty subjects received both an MF and a sham session approx. 1 week apart, in a random, counterbalanced, cross-over design. The experiment consisted of 5 min of pre-exposure baseline EEG followed by either 15 min of MF or sham exposure. Due to the interference of the pulsed MF with the recording, EEG was sampled approximately 7 s after the end of the MF or sham condition.|
Exposure to a specific pulsed extremely low frequency magnetic field was revealed to result in higher resting EEG alpha wave activity (8-13 Hz) compared to sham exposure.
The authors suggest that this result may be a nonspecific physiological response to the pulsed magnetic fields.