Human postural responses to high vestibular specific extremely low-frequency magnetic stimulations

Abstract

Background: International agencies recognize the lack of knowledge to further establish standards and guidelines to protect the workers and the public from extremely low-frequency magnetic fields (ELF-MF). In that regard, postural control has been proposed as a biomarker of potential adverse effects in humans. Considering its crucial role in postural control and its specific neurophysiological characteristics, the vestibular system emerges as an ELF-MF likely target. However, postural modulation to vestibular ELFMF exposure remains inconclusive. Previous studies led us to investigate stimulation orientation and point of application to clarify the ELF-MF impact on balance in humans. Objectives: This research aimed to investigate the acute postural impact of lateral vestibular-specific ELF-MF stimulations. Methods: Postural control of thirty eight healthy participants was analyzed with lateral vestibular-specific ELF-MF stimulations ranging from 20 Hz to 160 Hz, up to 142 T/s and vestibular electrical stimulations at the same frequencies. Both spatial orientation and quantity of movement variables were used to investigate postural modulations. Results: Despite a conclusive positive control effect, no significant effects of ELF-MF and alternating current stimulation exposures were found regardless of frequency conditions. Conclusions: Although important electric fields were generated, no postural modulationwas found. However, at these frequencies, the potential vestibular activation did not translate into functional postural sway but might be observed with refiexive vestibular outcomes.