Mechanism-based modeling of time-varying magnetic fields effects on cortical activity
© Modolo et al; licensee BioMed Central Ltd. 2014
Published: 21 July 2014
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.
We used an extensively validated neural mass model  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 . 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.
The model will be used to 1) understand human data currently acquired in our group ; 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.
Lawson Health Research Institute, Mitacs Elevate Program, Hydro-Québec/Electricité de France/Réseau de Transport d'Electricité, and Canadian Institutes of Health Research.
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