Experimental induction of intermale aggressive behavior in limbic epileptic rats by weak, complex magnetic fields: implications for geomagnetic activity and the modern habitat?

Weak, physiologically patterned magnetic fields do not affect maze performance in normal rats, but disrupt seized rats normalized with ketamine: possible support for a neuromatrix concept?

The concept of a neuromatrix as a determinant of behavior proposes that complex neuroelectromagnetic patterns supported by specific spatial configurations of neurons underlie the generation of behaviors. When the pattern of neuronal connectivity is changed, as occurs during limbic epilepsy, neuroelectromagnetic patterns change in parallel to sustain behavioral output. Thus, a testable prediction of the neuromatrix concept is that the "normal" behaviors of animals with markedly reorganized neuroelectromagnetic patterns are vulnerable to specific stimuli that are ineffective when applied to a normal population. Because rats treated with ketamine after being induced to seize with pilocarpine exhibit behaviors indistinguishable from those of control populations despite marked changes in brain structure, they represent an ideal population in which to examine this hypothesis. Ketamine-treated pilocarpine-seized rats and normal rats were exposed continuously either to a complex sequence magnetic field or to control conditions during the acquisition of a radial arm maze task for 8 consecutive days. After 14 days of subsequent exposure to a frequency-modulated field (7-500 nT), during which time there was no training, the rats that had been induced to seize and had been exposed continuously to this magnetic configuration exhibited conspicuously slower response durations per arm than rats that had been induced to seize and exposed to control conditions or normal rats that had been exposed to either magnetic fields or control conditions. Thus, the behaviors of rats who have sustained multiple, discrete injuries throughout the brain may be seriously disrupted by the appropriate pattern of exogenous weak magnetic fields. Our results represent the first empirical support for the concept of the neuromatrix.

Radial maze proficiency of adult Wistar rats given prenatal complex magnetic field treatments

Exposure to sinusoidal (power-frequency) magnetic fields during prenatal development is implicated in adulthood behavioral impairments. However, the effects of prenatal exposure to weak-intensity, nonsinusoidal complex magnetic fields (CMFs), an increasingly common feature of the modern environment, have not been rigorously examined. In the present study, male and female Wistar-strain rats were exposed continually during prenatal development to one of three extremely low-frequency CMFs or a sham condition. As adults, rats were trained in an acquisition/reversal radial maze task. All rats exposed to the prenatal CMFs increased their commission of reference memory errors, but differences in working memory and motivation to complete the maze task were specific to the type of prenatal CMF. These results provide the first evidence that prenatal exposures to specific shapes of CMFs impair complex learning behaviors into adulthood.

Effects of electromagnetic radiation of mobile phones on the central nervous system

With the increasing use of mobile communication, concerns have been expressed about the possible interactions of electromagnetic radiation with the human organism and, in particular, the brain. The effects on neuronal electrical activity, energy metabolism, genomic responses, neurotransmitter balance, blood-brain barrier permeability, cognitive function, sleep, and various brain diseases including brain tumors are reviewed. Most of the reported effects are small as long as the radiation intensity remains in the nonthermal range, and none of the research reviewed gives an indication of the mechanisms involved at this range. However, health risks may evolve from indirect consequences of mobile telephony, such as the sharply increased incidence rate of traffic accidents caused by telephony during driving, and possibly also by stress reactions which annoyed bystanders may experience when cellular phones are used in public places. These indirect health effects presumably outweigh the direct biological perturbations and should be investigated in more detail in the future.

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 within one of four intensity ranges between 10 nT and 1,000 nT or to sham-field 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 litters that had been exposed continuously to a repetitive frequency-modulated field or to sham-field conditions. This treatment explained 25% of the variance in the numbers of squares traversed. The results suggest that complexity of the applied magnetic field during prenatal development may be more important than intensity for permanently affecting neuronal organization and behavior.

Differential effects of low frequency, low intensity (<6 mG) nocturnal magnetic fields upon infiltration of mononuclear cells and numbers of mast cells in Lewis rat brains

Immediately after inoculation to induce experimental allergic encephalomyelitis, 64 female Lewis rats were exposed to either a reference condition (<10 nT) or to one of two frequencies (7 Hz, 40 Hz) of magnetic fields whose two intensities (either 50 nT or 500 nT) were amplitude-modulated for 6 min once per hour between midnight and 8 h for 15 nights. Rats that had been exposed to the 7 Hz, low intensity fields displayed fewer numbers of foci of infiltrations of mononuclear cells compared to all other groups that did not differ significantly from each other. Rats exposed to the 5 mG (500 nT), 40 Hz magnetic fields displayed more foci in the right thalamus while those exposed to the 5 mG, 7 Hz fields displayed more foci in the left thalamus. Numbers of mast cells within the thalamus were also affected by the treatments. These results suggest that weak magnetic fields can affect the infiltration of immunologically responsive cells and the presence of mast cells in brain parenchyma. Implications for the potential etiology of 'electromagnetic sensitivity' symptoms are discussed.

Wars and increased solar-geomagnetic activity: aggression or change in intraspecies dominance?

Human beings are extremely aggressive animals who are emersed within a steady-state geomagnetic field. A small component of this field displays periodic changes in amplitude. Symmetrical lag/lead analysis (-6 years to +6 years) in the present study, involving annual global geomagnetic activity, inferences of solar activity, and the release of the total, global seismic energy indicated that the numbers of armed conflicts (wars) for the first half of the twentieth century were moderately associated (rs approximately .50; 25% of the variance) only with the global geomagnetic activity of the same year. When the residuals between the predicted annual geomagnetic activity from the solar cycle and the observed geomagnetic activity were allowed to enter the equations, a comparable proportion of the variance in numbers of wars was accommodated. A factor associated with geomagnetic activity might, it is speculated, modulate changes within emergent processes that control the relative dominance of large aggregates of humans. Wars may have been the more obvious manifestations of these changes.