Long‐term behavioral effects observed in mice chronically exposed to static ultra‐high magnetic fields

Abstract

Purpose The primary goal of this study was to investigate whether chronic exposures to ultra‐high B0 fields can induce long‐term cognitive, behavioral, or biological changes in C57BL/6 mice. Methods C57BL/6 mice were chronically exposed to 10.5‐T or 16.4‐T magnetic fields (3‐h exposures, two exposure sessions per week, 4 or 8 weeks of exposure). In vivo single‐voxel 1H magnetic resonance spectroscopy was used to investigate possible neurochemical changes in the hippocampus. In addition, a battery of behavioral tests, including the Morris water‐maze, balance‐beam, rotarod, and fear‐conditioning tests, were used to examine long‐term changes induced by B0 exposures. Results Hippocampal neurochemical profile, cognitive, and basic motor functions were not impaired by chronic magnetic field exposures. However, the balance‐beam–walking test and the Morris water‐maze testing revealed B0‐induced changes in motor coordination and balance. The tight‐circling locomotor behavior during Morris water‐maze tests was found as the most sensitive factor indexing B0‐induced changes. Long‐term behavioral changes were observed days or even weeks subsequent to the last B0 exposure at 16.4 T but not at 10.5 T. Fast motion of mice in and out of the 16.4‐T magnet was not sufficient to induce such changes. Conclusion Observed results suggest that the chronic exposure to a magnetic field as high as 16.4 T may result in long‐term impairment of the vestibular system in mice. Although observation of mice may not directly translate to humans, nevertheless, they indicate that studies focused on human safety at very high magnetic fields are necessary.

The Effect of Long-Term Moderate Static Magnetic Field Exposure on Adult Female Mice

“…Consistent with previous research, our results also showed that 150 mT moderate intensity SMFs have a similar effect to ultra-high or high SMF [ 10 , 13 , 16 , 19 , 22 , 23 ]. For example, Lv et al found that time and distance in the center area, the number of entries to the center area and averaged velocity were reduced when compared immediately after 11.1–33.0 T 1 h exposure with sham in healthy male mice, whereas after a 2-week recovery, all these parameters changed from lower to higher [ 13 ].…”

“…For example, Kokoreva et al found that after the exposure (3 h/d) of 1.6 T SMF for 1 day, 5 days and 15 days, the swimming time of mice (unknown gender) was prolonged and exercise tolerance was enhanced [ 11 ]. Ivan Tkac et al found that 16.4 T SMF 4- or 8-week exposure (3 h/time, 2 times/week) did not affect cognition and motor function in female and male mice [ 19 ]. We found the SMF exposure time was short in the above research, and it is urgent to explore the biosafety and effect of long-term SMF exposure (continuous treat for several months) on females.…”

Behavioral and functional assessment of mice inner ear after chronic exposure to an ultrahigh B0 field of 11.7 T or 17.2 T

“…The differences in the experimental protocols may explain the different results obtained in the two studies. In Tkáč et al, 14 the mice were moving freely in the 7 × 14 cm 2 holders in which they were exposed by groups of N = 2 animals, whereas in the current study, the mice were static during the exposure, as during human scanning. In Tkáč et al, 14 the mice were awake, whereas in the current study they were anesthetized.…”

Consciousness and inward electromagnetic field interactions

“…Similarly, implanted deep brain stimulating electrodes appear to produce too localized a perturbation to alter the mind’s EMF, although effects on cognition do occur in some patients ( Agashe et al, 2022 ; Chang et al, 2022 ). It has long been known that high strength magnetic fields of MRI scanners effect both human and animal subjects, producing dizziness, altered behavioral responses and cognitive impairment ( Antunes et al, 2012 ; Tkáč et al, 2021 ). Weaker EMFs produced by cell phones, radios and headphones do not appreciably alter mental activity, although long-term exposure to these weak fields may disrupt some brain functions ( Bodewein et al, 2022 ; Schüz et al, 2022 ).…”