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

[ウサギの電気感知機能の局在化] med./bio.

Localization of electroreceptive function in rabbits.

掲載誌: Physiol Behav 2003; 79 (4-5): 803-810

この研究は、ウサギにおける電磁界EMF)の感覚的受容部位を調べるアプローチとして再帰定量化解析(RQA)を適用し、2.5 G、60 Hz磁界ばく露を受ける部位を変化させた場合のウサギ(n = 10)の脳電図(EEG)を解析した。この解析法は、定常性を考慮することなく、大きな信号中に埋もれた小さな決定論的な変化を検出するように設計された非線形解析の新しい方法である。その結果、全身ばく露の場合、RQAの2つの定量尺度の有意な増加が示されたことから、決定論性が増加した;動物の前半分のみをばく露した場合も同様の結果が得られた;後半分のみをばく露した場合、EEGへの影響は見られなかった;頭部への限局的ばく露の場合、EEGでの決定論性への影響が再び見られた;さらにばく露を眼に局所化した場合、影響は見られなかった;総括すると、電磁界の検出が、おそらく脳で起きるであろうことが示されたが、用いた方法では特定の脳構造を識別する解像度がなかった、と報告している。

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研究目的(著者による)

The anatomic location of magnetic field sensing in rabbits should be determined by partial body exposure to a 60 Hz magnetic field.

詳細情報

The EEG of 10 rabbits was recorded during several exposure trials. Each trial lastet 7 seconds, with exposure during the first 2 seconds (exposure condition) and no exposure during the other 5 seconds. The last 2 seconds (second 6 and 7) of each trial were definded as the control condition and seconds 4 and 5 were defined as the sham exposure condition (used to verify the control condition).
The area of exposure was scaled down decreasingly to identify the location of magnetic field sensing. First, a whole body exposure was conducted, then the front and back body half were exposed separately. Afterwards, exposure was focused on the head and finally on the eye of each animal. For each exposure condition, n=50 trials were recorded.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 60 Hz
ばく露時間: intermittent (2 s field on, 5 s field off) 50 times
whole body exposure
ばく露2: 60 Hz
ばく露時間: intermittent (2 s field on, 5 s field off) 50 times
body halfs exposure
ばく露3: 60 Hz
ばく露時間: intermittent (2 s field on, 5 s field off) 50 times
head exposure
ばく露4: 60 Hz
ばく露時間: intermittent (2 s field on, 5 s field off) 50 times
eye exposure
  • 磁束密度: 280 µT spatial average (± 50 µT; average over the retina)

General information

the average geomagnetic field was 30.5 µT, 22° below the horizontal; the geomagnetic component along the direction of 60 Hz was 23.9 µT

ばく露1

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 intermittent (2 s field on, 5 s field off) 50 times
Additional information whole body exposure
ばく露装置
ばく露の発生源/構造
チャンバの詳細 rabbits were restrained in an acrylic box, which was positioned in a light tight wooden box which was centered in the exposure unit such that its axis and the rabbit`s rostral-caudal axis were parallel
ばく露装置の詳細 multiple-turn coils of 12-gauge magnet wire; coaxial configuration of four square coils, each 66 cm on a side; field was 5% homogeneous in exposure area; the outer coils (85 turns each) were ± 33.4 cm from the unit's centerline; the inner coils (35 turns each) ± 8.5 cm
Sham exposure A sham exposure was conducted.
Additional information control coils produced the same heat but no magnetic field
パラメータ
測定量 種別 Method Mass 備考
磁束密度 250 µT spatial average 測定値 - -

ばく露2

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 intermittent (2 s field on, 5 s field off) 50 times
Additional information body halfs exposure
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
チャンバの詳細 see E1
ばく露装置の詳細 like E1 but the magnitudes and phases of the coil currents were chosen such that one half of the body was exposed stronger
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 250 µT peak 測定値 - in exposed body half
磁束密度 220 µT mean 測定値 - ± 60 µT; in exposed body half
磁束密度 50 µT mean 測定値 - ± 30 µT; in non-exposed body half

ばく露3

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 intermittent (2 s field on, 5 s field off) 50 times
Additional information head exposure
ばく露装置
ばく露の発生源/構造
Distance between exposed object and exposure source 4 cm
チャンバの詳細 see E1
ばく露装置の詳細 pair of 14-turn coils, each 5 cm in diameter and located 9 cm apart one on each side of the head with a distance of approx. 4 cm to the center of the brain
Sham exposure A sham exposure was conducted.
Additional information sham exposure served as temperature control
パラメータ
測定量 種別 Method Mass 備考
磁束密度 250 µT spatial average 測定値 - -

ばく露4

主たる特性
周波数 60 Hz
タイプ
  • magnetic field
ばく露時間 intermittent (2 s field on, 5 s field off) 50 times
Additional information eye exposure
ばく露装置
ばく露の発生源/構造
Distance between exposed object and exposure source 0.5 cm
チャンバの詳細 see E1
ばく露装置の詳細 24-turn coil, 2 cm in diameter, with a distance of approximately 0.5 cm to the cornea
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
磁束密度 280 µT spatial average 測定値 - ± 50 µT; average over the retina

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)

Whole body exposure led to significant changes in the EEG compared to the control condition. Exposure of the front half of the body led to a comparative result, whereas no changes could be observed when the back half was exposed. Further exposure of the head resulted in significant changes in the EEG in comparison the control condition, while an exposure of the eye did not show significant EEG changes.
There were no significant differences between control and sham exposure conditions.
The authors conclude that sensing of the 60 Hz magnetic field occurs in in the head of rabbits, probably in the brain.

研究の種別:

研究助成

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