Resting EEG effects during exposure to a pulsed ELF magnetic field

Continuing evidence suggests that extremely low frequency magnetic fields (ELF MFs) can affect animal and human behavior. We have previously demonstrated that after a 15 min exposure to a pulsed ELF MF, with most power at frequencies between 0 and 500 Hz, human brain electrical activity is affected as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here, we report that a pulsed ELF MF affects the human EEG during the exposure period. Twenty subjects (10 males; 10 females) received both a magnetic field and a sham session of 15 min in a counterbalanced design. Analysis of variance (ANOVA) revealed that alyha activity was significantly lower over the occipital electrodes (O1, Oz, O2) [F-1.16 = 5.376, P < .01, eta(2) = 0.418] afterthe first 5 min of magnetic field exposure and was found to be related to the order of exposure (MF-sham vs. shamMF). This decrease in alpha activity was no longer significant in the 1 st min post-exposure, compared to sham (P > .05). This study is among the first to assess EEG frequency changes during a weak (+/- 200 mu T-pk), pulsed ELF MF exposure. (c) 2005 Wiley-Liss, Inc.