研究のタイプ: 医学/生物学の研究 (experimental study)

[7,14,21Hzで変調された450 MHzマイクロ波放射がヒトの脳波リズムに与える影響] med./bio.

Effect of 7, 14 and 21 Hz modulated 450 MHz microwave radiation on human electroencephalographic rhythms.

掲載誌: Int J Radiat Biol 2008; 84 (1): 69-79

【目的】様々な周波数で変調されたマイクロ波がヒトの脳波リズムに与える影響を評価すること。【方法】13人の健康なボランティアに、7、14、21Hzでパルス変調されたマイクロ波ばく露を行った。電力密度頭蓋で0.16mW/cm2であった。実験プロトコルは、ひとつの変調周波数について5回のばく露を繰り返し(オン1分、オフ1分)、それを2回行った。ばく露の有無におけるEEGパワーの相対的変化を定量的尺度とした。記録した脳波の周波数をシータ、アルファ、ベータ1、ベータ2波帯において解析した。【結果】変調マイクロ波は、平均EEGパワーをアルファ波帯(17%)とベータ波帯(7%)で増加させたが、シータ波のリズムには影響しなかった。アルファ波帯パワーとベータ波帯パワーの増加は、14および21Hzの変調周波数のばく露セッションの前半(30秒間)において統計学的に有意であった。ばく露に対する感受性の個人差も見られた。【結論】7,14,21Hzで変調された450MHzマイクロ波放射の影響は変調周波数によって異なることが示唆された。14,21Hzでの変調マイクロ波ばく露はアルファとベータ波帯のEEGパワーを増加させたが、7Hzではどのような増加も見られなかった。

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研究目的(著者による)

To study the effect of microwaves modulated at different frequencies (7, 14 and 21 Hz) on human electroencephalographic (EEG) rhythms.

詳細情報

13 subject participated.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 450 MHz
Modulation type: pulsed
ばく露時間: intermittent, 1 min off/1 min on, for 10 min per frequency

General information

Each subject went through two (or four?) EEG recording sessions on different days, double-blind and randomly assigned to real and sham exposure. Both exposure and sham protocols were applied twice to each subject. Microwave exposure was identical to previous studies [Lass et al., 2002 and Hinrikus et al., 2004], but three different modulation frequencies were applied.

ばく露1

主たる特性
周波数 450 MHz
タイプ
  • electromagnetic field
ばく露時間 intermittent, 1 min off/1 min on, for 10 min per frequency
Modulation
Modulation type pulsed
Duty cycle 50 %
Additional information

pulse rates of 7, 14, or 21 Hz

ばく露装置
ばく露の発生源/構造
  • quarter-wave antenna (13 cm)
Distance between exposed object and exposure source 10 cm
チャンバの詳細 During the EEG recording session, lasting 40 min, subjects were lying in a relaxed position, with eyes closed and ears blocked, in a dark room. The experimenter was also in the room.
ばく露装置の詳細 The antenna was located 10 cm from the skin on the left side of the head.
Sham exposure A sham exposure was conducted.
Additional information 10 minutes of reference recordings were followed by three times 10 min of exposure at a constant modulation frequency of 7, 14, or 21 Hz. The succession of the modulation frequencies was randomly assigned by a computer program.
パラメータ
測定量 種別 Method Mass 備考
電力密度 0.16 mW/cm² mean 推定値 - -
SAR 0.35 W/kg - 推定値 - [Hinrikus et al., 2004]

Reference articles

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
研究対象とした臓器系:
調査の時期:
  • ばく露前
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

The data support the authors' hypothesis that the effect of modulated microwaves on the EEG differs at different modulation frequencies. The microwave irradiation modulated at 14 and 21 Hz enhanced the EEG power in the alpha wave and beta wave frequencies whereas no enhancement of the EEG power was found during exposure at the modulation frequency of 7 Hz. Thus, it can be suggested that the effect of an external stimulus on brain oscillations is stronger if the frequency of the stimulus is higher or close to the physiological frequency of brain rhythms. The changes were more obvious at the beginning of the exposure segments. No changes in the EEG theta wave power were detected for any modulation frequencies.
Differences were also found in individual sensitivity to exposure.
The mechanisms of the observed effects of pulse modulated microwaves are unknown.

研究の種別:

研究助成

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