Study type: Medical/biological study (experimental study)

Alterations of human electroencephalographic activity caused by multiple extremely low frequency magnetic field exposures. med./bio.

Published in: Med Biol Eng Comput 2009; 47 (10): 1063-1073

Aim of study (acc. to author)

To study whether extremely low frequency magnetic field exposures in series from 50 Hz, 16.66 Hz, 13 Hz, 10 Hz, 8.33 Hz to 4 Hz could alter relative power within the corresponding EEG frequency bands in 33 subjects.

Background/further details

The baseline EEG was recorded prior to any stimulation (exposure) for one minute. Each stimulation (50 Hz, 16.66 Hz, 13 Hz, 10 Hz, 8.33 Hz and 4 Hz) lasted for two minutes followed by one minute EEG recording. The same procedure was repeated for the sham exposure. The order of control and exposure sessions was determined randomly (there was a 30 minutes break between the two sessions and the order of control and exposure was considered as an important factor in the following EEG analysis).
The EEG frequency bands were custom defined (alpha wave 1 (7.5-9.5 Hz), alpha wave 2 (9-11 Hz), beta wave 1 (12-14 Hz), beta wave 2 (15.5-17.5 Hz)) and traditional EEG frequency band definitions were not considered.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 4–50 Hz
Exposure duration: 2 min for each frequency, followed by 1 min EEG recording

Exposure 1

Main characteristics
Frequency 4–50 Hz
Type
Waveform
Polarization
Exposure duration 2 min for each frequency, followed by 1 min EEG recording
Additional info the following frequencies were applied: 4 Hz, 8.33 Hz, 10 Hz, 13 Hz, 16.66 Hz, 50 Hz
Exposure setup
Exposure source
Setup pair of Helmholtz coils with a radius of 65 cm and 250 turns of 0.8 mm copper wire producing a highly homogeneous field; test person placed between the coils in supine position perpendicular to the coil's axis in a RF shielded room
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 20 µT effective value measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • after exposure

Main outcome of study (acc. to author)

Alpha wave 1 (7.5-9.5 Hz) and alpha wave 2 (9-11 Hz) frequency bands, associated with 8.33 Hz and 10 Hz magnetic field exposures, were significantly lower than control over the temporal and parietal regions within the 10-16 minutes of first magnetic field exposure session (i.e. exposure session first followed by control session). However, at the second session of magnetic field exposure (i.e. control session first, followed by exposure session), the relative power in alpha wave frequency bands was significantly higher than in the sham exposure session (i.e. 60-65 min from the start of testing).
Additionally, the beta wave 1 (12-14 Hz) frequency band exhibited a significant increase from before to after 13 Hz exposure during the first magnetic field exposure session at frontal region.
The data show that it is possible to alter the human EEG activity of alpha wave and beta wave frequency bands when exposed to magnetic fields at frequencies corresponding to those same frequency bands, depending on the order and period of magnetic field conditions. This type of EEG synchronisation of driving alpha wave and beta wave EEG by alpha wave and beta wave sinusoidal magnetic field stimulation, demonstrated in this study, could possibly be applied as therapeutic treatments of particular neurophysiological dysfunctionalities such as sleep and mental disorders.

Study character:

Study funded by

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