In vitro Magnetic Stimulation: A Simple Stimulation Device to Deliver Defined Low Intensity Electromagnetic Fields.

Author: Grehl S1, Martina D2, Goyenvalle C3, Deng ZD4, Rodger J5, Sherrard RM3
Affiliation: <sup>1</sup>Sorbonne Universit├ęs, UPMC Univ Paris 06 &amp; CNRS, IBPS-B2A, UMR 8256 Biological Adaptation and AgeingParis, France; Experimental and Regenerative Neuroscience, School of Animal Biology, the University of Western Australia, PerthWA, Australia. <sup>2</sup>Institut Langevin, ESPCI ParisTech &amp; CNRS, UMR7587 INSERM ERL U979 Paris, France. <sup>3</sup>Sorbonne Universit├ęs, UPMC Univ Paris 06 &amp; CNRS, IBPS-B2A, UMR 8256 Biological Adaptation and Ageing Paris, France. <sup>4</sup>Non-invasive Neuromodulation Unit, Experimental Therapeutics and Pathophysiology Branch, Intramural Research Program, National Institute of Mental Health, National Institutes of Health, BethesdaMD, USA; Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, DurhamNC, USA. <sup>5</sup>Experimental and Regenerative Neuroscience, School of Animal Biology, the University of Western Australia, Perth WA, Australia.
Conference/Journal: Front Neural Circuits.
Date published: 2016 Nov 3
Other: Volume ID: 10 , Pages: 85 , Word Count: 347

Non-invasive brain stimulation (NIBS) by electromagnetic fields appears to benefit human neurological and psychiatric conditions, although the optimal stimulation parameters and underlying mechanisms remain unclear. Although, in vitro studies have begun to elucidate cellular mechanisms, stimulation is delivered by a range of coils (from commercially available human stimulation coils to laboratory-built circuits) so that the electromagnetic fields induced within the tissue to produce the reported effects are ill-defined. Here, we develop a simple in vitro stimulation device with plug-and-play features that allow delivery of a range of stimulation parameters. We chose to test low intensity repetitive magnetic stimulation (LI-rMS) delivered at three frequencies to hindbrain explant cultures containing the olivocerebellar pathway. We used computational modeling to define the parameters of a stimulation circuit and coil that deliver a unidirectional homogeneous magnetic field of known intensity and direction, and therefore a predictable electric field, to the target. We built the coil to be compatible with culture requirements: stimulation within an incubator; a flat surface allowing consistent position and magnetic field direction; location outside the culture plate to maintain sterility and no heating or vibration. Measurements at the explant confirmed the induced magnetic field was homogenous and matched the simulation results. To validate our system we investigated biological effects following LI-rMS at 1 Hz, 10 Hz and biomimetic high frequency, which we have previously shown induces neural circuit reorganization. We found that gene expression was modified by LI-rMS in a frequency-related manner. Four hours after a single 10-min stimulation session, the number of c-fos positive cells increased, indicating that our stimulation activated the tissue. Also, after 14 days of LI-rMS, the expression of genes normally present in the tissue was differentially modified according to the stimulation delivered. Thus we describe a simple magnetic stimulation device that delivers defined stimulation parameters to different neural systems in vitro. Such devices are essential to further understanding of the fundamental effects of magnetic stimulation on biological tissue and optimize therapeutic application of human NIBS.

KEYWORDS: LI-rMS; computational modeling; electric field; low intensity repetitive magnetic stimulation; magnetic coil design; magnetic field; magnetic stimulation; rTMS

PMID: 27857683 DOI: 10.3389/fncir.2016.00085