The effect of magnetic fields on rabbit and human EEGs
There are many reports of effects of electromagnetic fields (EMFs) on living systems although little is known about how these effects occur; this study tested several theories on the interaction of fields with the body. The effect of magnetic fields, generated using Helmholtz coils, on the spectrum of the electroencephalogram (EEG) of animals and humans was investigated. The EEG was used as a measure of brain activity associated with the body's response. Fields were chosen based on the three major theories of EMF interaction considered: stressor theory (adaptive response), physiological resonance (field at predominant frequency in EEG), and the ion resonance theory (field at frequency and intensity defined by the ion charge-to-mass ratio). Each rabbit or human was its own control having exposure periods and nonexposure periods adjacent in time with a recovery period between repetition of trials.
Rabbits were exposed to light as a positive control, sham as a negative control, and fields. Six of nine rabbits showed an increase in power in the EEG of 1-3 Hz in response to light. There were changes in power in the EEG at the frequency of the field using the physiological resonance field but not with the other types of fields.
Light produced a change in 8-11 Hz power in ten of twenty-eight human subjects. There were effects on the human EEG using 0.25-0.5 Gauss, 35-40 Hz (stressor), 10 Hz, I Gauss (physiological resonance), and 0.784 Gauss, 60 Hz or DC (ion resonance) magnetic fields. Nine of twenty-eight subjects responded to the stressor field (decrease in power in EEG). Thirteen of nineteen subjects showed a change in power at the frequency of stimulation for the physiological resonance field. Seven, twelve, and eleven of twenty subjects responded to the DC, 60 Hz, both DC and 60 Hz fields, respectively. The DC field produced nondirectional change in the EEG, while using 60 Hz (with or without DC) produced increases in power in 1-3 Hz and 17-18.5 Hz of the EEG. Effects were seen with all three types of fields.