Medical/biological study (experimental study)

Effect of low-frequency magnetic fields on brain electrical activity in human subjects med./bio.

By: Marino AA, Nilsen E, Chesson Jr AL, Frilot C

Published in: Clin Neurophysiol 2004; 115 (5): 1195-1201

Aim of study (acc. to author)

The effects of exposure of subjects to a 60 Hz magnetic field on the EEG should be investigated to prove the hypothesis that the human brain can detect extremely low frequency magnetic fields.

Background/further details

8 healthy subjects took part in the study, which consisted of an experimental and a positive control part. The experimental part was comprised of a minimum of 60 trials. Each trial consisted of a 2 seconds exposure period and a subsequent 5 seconds non-exposure period. The last 2 seconds (seconds 4 and 5) of these 5 seconds were defined and recorded as the control period and the 2 seconds before (seconds 2 and 3) as the sham exposure period.
A second set of identical trials was carried out as a positive control, where visible light was used as a stimulus during the 2 seconds exposure period.

Endpoint

effects on the neurological system: brain activity in the EEG

Exposure

- 60 Hz
- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: intermittent (2 s on/5 s off) for at least 60 times	magnetic flux density: 100 µT

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Waveform	unspecified
Exposure duration	intermittent (2 s on/5 s off) for at least 60 times

Exposure setup

Exposure source	Helmholtz coils
Setup	pair of coaxial coils, each 130 cm in diameter and consisting of 250 turns of copper wire; the coils were 65 cm apart (the Helmholtz condition) by means of a wooden frame; the subjects sat on a comfortable plastic chair in a dark room with their eyes closed; their sagittal plane was perpendicular to the MF produced by the coils; MF was uniform within 5% in the region of the head and upper chest and within 20% over the thorax and pelvis
Sham exposure	A sham exposure was conducted.
Additional info	the magnetic field was not accompanied by any visual or auditory cues to the subjects, and consequently the subjects were unaware of the precise times when it was applied

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	measured	-	-

Additional parameter details

average 60 Hz background magnetic field at the location of the subject was 10 nT, the average geomagnetic field at the location of the subject was 43.2 µT, the geomagnetic component along the direction of the 60 Hz field was 15.6 µT

Reference articles

Bell GB et al. (1989): Exposure System for Production of Uniform Magnetic Fields

Exposed system:

human
whole body

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: brain activity (linear and non-linear effects in a intra-subject analysis; recurrence plot and percentaged determinism, EEG)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

In all subjects, significant differences were detected in the EEG during the exposure periods compared to the control period. No significant differences were detected between sham exposure periods and control period.
The authors conclude that exposure of subjects to a 60 Hz magnetic field might cause changes in the EEG, and thus the human brain might detect extremely low frequency magnetic fields

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

not stated/no funding

Modolo J et al. (2017): Human exposure to power frequency magnetic fields up to 7.6 mT: An integrated EEG/fMRI study
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