Geophysical variables and behavior: XCI. Ambulatory behavior in rats following prenatal exposures to complex magnetic fields designed to interact with genetic expression

A total of 45 litters were exposed during their entire prenatal development to one of two complex patterns of magnetic fields whose strengths varied w ithin one of four intensity ranges between 10 nT and 1000 nT or to sham-fie ld conditions. The litters exposed to the most complex pattern, composed of 50 200-msec. presentations of different pulses for 10 sec. every 50 sec.: displayed more ambulation in an open field at 21 days of age than the litte rs that had been exposed continuously to a repetitive frequency-modulated f ield or to sham-field conditions, This treatment explained 25% of the varia nce in the numbers of squares traversed. The results suggest that complexit y of the applied magnetic field during prenatal development may be more imp ortant than intensity for permanently affecting neuronal organization and b ehavior.