Simultaneous Response of Brain Electrical Activity (EEG) and Cerebral Circulation (REG) to Microwave Exposure in Rats

Abstract

The correlations between physiological modalities in microwave field-activated systemic or localized regulatory mechanisms with changes in the central nervous system (CNS) seem not to be identical. These problems are important because of the increased number of radiating appliances, e.g. portable radios and mobile telephones.In two series of experiments on anaesthetized rats (N=40) (i) before and after 10 min, whole body exposures to 2.45 GHz CW microwaves, and (ii) during 30 min exposures to 4 GHz amplitude modulated (AM, 16 Hz) microwaves, the effects on the CNS were observed simultaneously with those on the cardiovascular system by quantitative polygraphic measurement In acute experiments on rats, electroencephalograms (EEG), rheoencephalograms (REG) as an index of cerebral blood flow (CBF), brain tissue DC impedance and temperature and ECG were recorded simultaneously. The total power of EEG spectra increased after whole body 30 mW/cm 2 2.45 GHz CW exposure for 10 min. No changes occurred at 10 mW/cm 2 . The CBF increased after 10 mW/cm 2 exposure.The power of EEG delta (0.5-4 Hz) waves was increased by thermal level of brain localized 4 GHz CW exposure at 42 mW/g specific absorption rate (SAR) simultaneously with the REG amplitude as an index of cerebral blood flow. Amplitude modulation at 16 Hz and 8.4 mW/g SAR was associated with increased power of EEG beta (14.5-30 Hz) waves but changes in the CBF were not observed. CW radiation at 8.4 mW/g increased the cerebral blood flow, but did not change EEG spectra.

Biological effects of amplitude-modulated radiofrequency radiation

“…Whether the effects reported in these studies depend on the pres-' ence of the modulation is not known. Three studies (19,28,32) report effects with amplitude modulation but not with continuous radiation, and 4 studies report different effects with continuous and AM exposures (13,33,34,43).…”

“…No effects of continuous-wave microwaves at 10 pW/cm2 were found on the total power of the electroencephalographic (EEG) spectrum from rats (34). However, an increase in the delta band and a decrease of the alpha and beta bands were observed after a 5-minute exposure to 2.45-GHz pulsed microwaves at 3 pW/cm2 (217 Hz, 118 duty cycle) (35).…”

Microwave effects on the nervous system

“…In acute experiments on rats, changes were seen in EEG and cerebral blood flow (CBF) upon MWexposure [Thuroczy et al, 1994]. A whole body exposure of 30 mW/cm 2 , 2.45 GHz continuous wave (CW) for 10 min caused an increase in the total power of the EEG Klitzing et al [1995] (Continued) Human studies.…”

Effects of exposure to low level radiofrequency fields on acetylcholine release in hippocampus of freely moving rats

“…A microdialysis study of amino acid release in the brain has been performed on anaesthetised animals exposed to microwave thermal stress, but at SAR of 40 W/kg [Mason et al, 1997] it showed increases of aspartic acid, serine and glycine release. Some other works using lower power density indicated a slight disturbance of EEG [Thuroczy et al, 1994;Reiser et al, 1995;Vorobyov et al, 1997;Freude et al, 1998] and sleep pattern [Mann and Röschke, 1996;Wagner et al, 1998]. …”