Effect of modulated microwave radiation on electroencephalographic rhythms and cognitive processes

This paper is a review of the studies performed on microwave effects on resting electroencephalography (EEG) and visual memory and information processing during the last ten years. Some earlier results, obtained at the Biomedical Engineering Centre of the Tallinn University of Technology are reevaluated and generalized. Microwave radiation of 450 MHz, modulated at 7, 14, 21, 40, 70, 217 and 1000 Hz was applied. The calculated spatial peak SAR, averaged over 1 g, was 0.303 W/kg. The developed new methods of EEG analysis can detect small changes in the EEG signals caused by microwave exposure. Microwave exposure causes most remarkable increase in the EEG alpha power (reported also by other authors) and smaller increase in the beta power, detected by sensitive methods. The obtained results showed that the effect of microwave radiation depends on the modulation frequency and, consequently, has non-thermal origin. Sensitivity to microwave esposure is individual, the rate of the subjects significantly affected was 13–30% for different groups. The physiological adaptation of the brain compensates and even overcompensates the effect of the microwave exposure. The results confirm that the microwave effect is not linearly related to the intensity of the applied field. The changes in human performance of visual memory tasks and visual information processing are small, but statistically significant (p < 0.05).