Medical/biological study (experimental study)

Effects of weak microwave fields amplitude modulated at ELF on EEG of symmetric brain areas in rats med./bio.

By: Vorobyov VV, Galchenko AA, Kukushkin NI, Akoev IG

Published in: Bioelectromagnetics 1997; 18 (4): 293-298

Aim of study (acc. to author)

To study dependence of the EEG frequency spectra of symmetrical areas of the rat brain on exposure duration of the weak microwave field amplitude modulated at extremely low frequency (ELF).

Endpoint

effects on the neurological system: EEG

Exposure

- low level microwaves

Exposure	Parameters
Exposure 1: 945 MHz Modulation type: AM Exposure duration: intermittent, 1 min on/1 min off for 10 min	power density: 0.2 mW/cm² maximum (to 0.1 mW/cm²)

Exposure 1

Main characteristics

Frequency	945 MHz
Type	electromagnetic field
Exposure duration	intermittent, 1 min on/1 min off for 10 min

Modulation

Modulation type	AM
Modulation frequency	4 Hz
Additional info	20 ms pulse width

Exposure setup

Exposure source	anechoic chamber circular antenna
Distance between exposed object and exposure source	30 cm
Setup	Animals kept in the plexiglas box ( 17 x 11 x 20 cm) which was kept in the anechoic chamber.
Additional info	Rats with chronically implanted carbon electrodes in the symmetrical areas of the brain somesthetic cortex, a reference carbon electrode placed in the nasal bone.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	0.2 mW/cm²	maximum	unspecified	-	to 0.1 mW/cm²

Exposed system:

animal
rat
whole body

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: EEG (power spectrum)

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

The hemispheric asymmetry in baseline EEG is identical in both the control and exposure experiments when the frequency spectra are averaged for 10-min period. The similarity between series is observed also in the successive 10-min periods. Thus, the irradiation does not cause any steady changes in the EEG asymmetry during the 10-min periods. A similar conclusion can be drawn from averaging the EEG frequency spectra for 1-min "field-on" and "field-off" periods. The influence of the microwave field on the EEG asymmetry was revealed when averaging of frequency spectra for 10-s periods was used. Compared to controls, the EEG hemispheric asymmetry in power of 10.5-14 Hz range increases significantly during the first 10-20 s after four from five onsets of the field. Under neither control nor pre- and postexposure conditions this effects was found. These data are discussed with respect to interaction of microwave fields with the EEG generators.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Xie T et al. (2011): EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves
Vorobyov V et al. (2010): Repeated exposure to low-level extremely low frequency-modulated microwaves affects cortex-hypothalamus interplay in freely moving rats: EEG study
Lipping T et al. (2009): Using the nonlinear control of anesthesia-induced hypersensitivity of EEG at burst suppression level to test the effects of radiofrequency radiation on brain function
Minasyan SM et al. (2007): Effects of the action of microwave-frequency electromagnetic radiation on the spike activity of neurons in the supraoptic nucleus of the hypothalamus in rats
Vorobyov V et al. (2004): Repeated exposure to low-level extremely low frequency-modulated microwaves affects baseline and scopolamine-modified electroencephalograms in freely moving rats