Study type: Medical/biological study (experimental study)

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

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

Exposure

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

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
  • unspecified
Exposure duration intermittent (2 s on/5 s off) for at least 60 times
Exposure setup
Exposure source
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 - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
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:

Study funded by

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