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BMC Neuroscience

Open Access

Mechanism-based modeling of time-varying magnetic fields effects on cortical activity

BMC Neuroscience201415(Suppl 1):P116

https://doi.org/10.1186/1471-2202-15-S1-P116

Published: 21 July 2014

Background

Understanding how extremely low-frequency (ELF, < 300 Hz) magnetic fields (MF) interact with human brain activity is an important question, especially regarding potential effects of power-lines MF (60 Hz in North America). Such knowledge is critical to 1) contribute to guidelines protecting public and workers from exposure to ELF MFs [1, 2]; and 2) design novel non-invasive brain stimulation techniques using ELF MFs to interfere with pathological brain activity patterns.

Methods

We used an extensively validated neural mass model [3] describing the main neuronal populations forming a cortical column, which we extended by including 1) a time-dependent membrane potential perturbation caused by the induced electric field; 2) a model linking post-synaptic calcium concentration and synaptic plasticity processes [4]. We used increasing levels of MF flux density at 60 Hz to identify the threshold for significant effects on simulated EEG alpha (8-12 Hz) power. A 4x3x2 ANOVA for repeated measured measures was conducted on EEG alpha power before/during/after exposure, with/without 60 Hz MF exposure, with/without synaptic plasticity.

Results

Simulated EEG alpha power decreased with increased 60 Hz MF flux density (significant for 250<dV<500 μV when only pyramidal neurons were modulated), without significant effects from synaptic plasticity processes. If slow inhibitory interneurons [3] were also modulated, EEG alpha power decrease due to MF exposure was significantly diminished (see Figure).

Figure 1

Conclusions

The model will be used to 1) understand human data currently acquired in our group [5]; and 2) study in silico effects of transcranial alternating current stimulation and magnetic stimulation (tACS/TMS). Future work will include frequency-dependent effects from extracellular medium dielectric properties, and selective modulation of specific neuronal populations.

Declarations

Acknowledgements

Lawson Health Research Institute, Mitacs Elevate Program, Hydro-Québec/Electricité de France/Réseau de Transport d'Electricité, and Canadian Institutes of Health Research.

Authors’ Affiliations

(1)
Human Threshold Research Group, Lawson Health Research Institute
(2)
Department of Medical Biophysics, Western University
(3)
Department of Medical Imaging, Western University
(4)
School of Kinesiology, Western University

References

  1. ICNIRP: Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz). Health Phys. 2010, 99 (6): 818-836.Google Scholar
  2. IEEE: C95.6 – IEEE standard for safety levels with respect to human exposure to electromagnetic fields, 0-3 kHz. IEEE. 2002, New YorkGoogle Scholar
  3. Wendling F, Bartolomei F, Bellanger JJ, Chauvel P: Epileptic fast activity can be explained by a model of impaired GABAergic dendritic inhibition. Eur J Neurosci. 2005, 22: 343-356. 10.1111/j.1460-9568.2005.04213.x.View ArticleGoogle Scholar
  4. Shouval HZ, Castellani GC, Blais BS, Yeung LC, Cooper LN: Converging evidence for a simplified biophysical model of synaptic plasticity. Biol Cybern. 2002, 87: 383-391. 10.1007/s00422-002-0362-x.View ArticlePubMedGoogle Scholar
  5. Legros A, Modolo J, Goulet D, Plante M, Souques M, Deschamps F, Ostigui G, Mezei G, Lambrozo J, Thomas AW: Magnetophophene perception and associated neurophysiological responses of the human central nervous system exposed to 50 and 60 Hz magnetic fields of up to 50 mT. CIGRE EMF International colloquium. 2013Google Scholar

Copyright

© Modolo et al; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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