Pregnantrats were continuously exposed to one of four intensities during the pregnancy: 1.) 5-20 nT, 2.) 30-50 nT, 3.) 90-580 nT und 4.) 90-1200 nT (n=2 per group). After one year, the male offspring (n=6-7 per group) were used in the open field test and the contextual fear conditioning was examined. Additionally, the number and the structure of hippocampalneurons were analyzed (n=4 per group). Previous studies showed that there were no differences between ratsexposed to a weak magnetic field of 5-20 nT and a control group without any magnetic field. Therefore, in this study, the reference group (5-20 nT) was used as a control. The experiment was performed twice.
composite pattern: composed of 40 sequential 250 ms signatures of specific frequency-modulated patterns as well as of those derived from mathematical relationships; LTP-pattern: repeated sequences of a primer pulse followed 170 ms later by four working pulses; 50 Hz pattern: rise time and fall time of 1 ms and a plateau and trough of 20 ms; all patterns were presented in a repeating cycle for 10 s, followed by 40 s of no field for 24 h before the next pattern was initiated; each pattern repeated every fourth day throughout gestation
rats kept in one of four identical compartments of a 140 cm x 33 cm x 33 cm plastic cage; identical Herlmholtz coils positioned at each end of the cage; coils created by wrapping 38 cm x 33 cm x 27 cm cartons with 305 m of 30 AWG wire