Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation.

There has been increasing interest on the possible harmful effects of prenatal exposure to magnetic fields. To investigate the effect of weak intensity magnetic fields on the prenatal brain, pregnant Wistar rats were continuously exposed to one of four intensities (reference: 5-20 nT; low 30-50 nT; medium 90-580 nT; high 590-1200 nT) of a complex magnetic field sequence designed to interfere with brain development. As adults, rats exposed to the low-intensity (30-50 nT) complex magnetic field displayed impairments in contextual fear learning and showed anomalies in the cytological and morphological development of the hippocampus.

Behavioral changes with brief exposures to weak magnetic fields patterned to stimulate long-term potentiation.

Brief whole body exposures of rats to weak (1 microT) complex magnetic fields whose patterns induce long term potential (LTP) when applied as electric current to hippocampal slices produced powerful behavioral changes. Rats exposed for 30 min before but not 30 min after hourly training sessions for spatial memory displayed impairments comparable to those elicited by complete electrode-induced saturation of hippocampal activity. Exposure to the same LTP-patterned magnetic fields after weaning during the induction of limbic seizures produced diminished learning of conditioned contextual fear during adulthood.