Conspicuous Histomorphological Anomalies in the Hippocampal Formation of Rats Exposed Prenatally to a Complex Sequenced Magnetic Field within the Nanotesla Range

Abstract

The brains of adult rats, exposed prenatally to one of four intensities (between 10 nanoTesla and 1.2 microTesla) of either a frequency-modulated magnetic field or a complex sequenced field designed to affect brain development, were examined histologically. Although from each intensity some rats that had been exposed to the complex sequenced magnetic field showed minor anomalies, those exposed to intensities between 30 nT and 180 nT exhibited conspicuous anomalous organizations of cells within the hippocampal formation. In other studies, rats that had been exposed during their entire prenatal development to the complex sequenced field displayed significantly more activity in the open field and poorer spatial memory during maze learning. Photomicrographs are shown of one conspicuous morphological anomaly within the right hippocampus of an adult rat exposed prenatally to the complex sequenced magnetic field with intensities between .3 mG and .5 mG (30 nT to 50 nT). The results suggest that complex magnetic fields, whose temporal structures approach the time constants of normal biochemical processes, can permanently alter the development of the brain.

Developmental effects of perinatal exposure to extremely weak 7 Hz magnetic fields and nitric oxide modulation in the Wistar albino rat

“…While the 7 Hz waveform has been used in several experiments (Cook and Persinger, 2000; Persinger et al, 2000; Kinoshameg and Persinger, 2004), this is the first investigation into any developmental effects from exposure. Here, perinatal exposure to the field significantly impacted motor behaviour in a manner consistent with previous studies which used intensities many times greater (Persinger, 1969; St. Pierre and Persinger, 2003; McKay et al, 2003a,b). The effects seen here were pronounced at the higher intensities as the 50 and 500 nT‐exposed rats exhibited dramatic increases in movement and bodyweight.…”

Altered blood chemistry and hippocampal histomorphology in adult rats following prenatal exposure to physiologically-patterned, weak (50–500 nanoTesla range) magnetic fields

“…These anomalies occurred in the same region associated adult neuronal neurogenesis due to seizures in rats (Scharman et al 2000) and temporal lobe epileptic patients (Mathern et al 1995). In another experiment St-Pierre and Persinger (2003) found a massive collection of heterotypic cells, arranged as rosettes with normally shaped neurons, extending across the entire coronal area of the right hippocampus within the CA3-hilar region of one of the rats exposed to the low intensity complex sequence field.…”

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

“…The temporal structures of the complex magnetic fields used in this study (composite, LTP‐like, and non‐sinusoidal 50 Hz) have shown empirical effectiveness in influencing brain development and behavior when individually applied (Persinger and Koren, 2007; St‐Pierre et al, 2008; St‐Pierre and Persinger, 2003, 2008; Whissell et al, 2009). In summary, the composite pattern was composed of 40, 250 ms signatures that involved various frequency‐modulated patterns as well as those derived from mathematical relationships (Persinger, 2010; Persinger and Koren, 2007).…”