title: Construction and Evaluation of Rodent-Specific rTMS Coils.
abstract: Rodent models of transcranial magnetic stimulation (TMS) play a crucial role in aiding the understanding of the cellular and molecular mechanisms underlying TMS induced plasticity. Rodent-specific TMS have previously been used to deliver focal stimulation at the cost of stimulus intensity (12 mT). Here we describe two novel TMS coils designed to deliver repetitive TMS (rTMS) at greater stimulation intensities whilst maintaining spatial resolution. Two circular coils (8 mm outer diameter) were constructed with either an air or pure iron-core. Peak magnetic field strength for the air and iron-cores were 90 and 120 mT, respectively, with the iron-core coil exhibiting less focality. Coil temperature and magnetic field stability for the two coils undergoing rTMS, were similar at 1 Hz but varied at 10 Hz. Finite element modeling of 10 Hz rTMS with the iron-core in a simplified rat brain model suggests a peak electric field of 85 and 12.7 V/m, within the skull and the brain, respectively. Delivering 10 Hz rTMS to the motor cortex of anaesthetized rats with the iron-core coil significantly increased motor evoked potential amplitudes immediately after stimulation (n = 4). Our results suggest these novel coils generate modest magnetic and electric fields, capable of altering cortical excitability and provide an alternative method to investigate the mechanisms underlying rTMS-induced plasticity in an experimental setting.
authors.affiliation: Experimental and Regenerative Neurosciences, School of Animal Biology, University of Western Australia Perth, WA, Australia.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Tang
authors.affiliation: Departments of Communication Sciences & Disorders and Chemical & Biomedical Engineering, University of South FloridaTampa, FL, USA; Global Center for Hearing and Speech Research, University of South FloridaTampa, FL, USA.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Lowe
authors.affiliation: Experimental and Regenerative Neurosciences, School of Animal Biology, University of Western Australia Perth, WA, Australia.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Garrett
authors.affiliation: School of Physics, University of Western Australia Perth, WA, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Woodward
authors.affiliation: Wicking Dementia Research and Education Centre, University of Tasmania Hobart, TAS, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Bennett
authors.affiliation: Wicking Dementia Research and Education Centre, University of Tasmania Hobart, TAS, Australia.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Canty
authors.affiliation: Human Motor Control Lab, School of Medicine, University of Tasmania Hobart, TAS, Australia.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Garry
authors.affiliation: Human Motor Control Lab, School of Medicine, University of Tasmania Hobart, TAS, Australia.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Hinder
authors.affiliation: Human Motor Control Lab, School of Medicine, University of TasmaniaHobart, TAS, Australia.; Research Institute for Sport and Exercise SciencesLiverpool John Moores University, UK.
authors.forename: Jeffery J
authors.initials: JJ
authors.lastname: Summers
authors.affiliation: Department of Neurology, Boston Children's Hospital, Harvard Medical School Boston, MA, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Gersner
authors.affiliation: Department of Neurology, Boston Children's Hospital, Harvard Medical School Boston, MA, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Rotenberg
authors.affiliation: Burke-Cornell Medical Research Institute White Plains, NY, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Thickbroom
authors.affiliation: Departments of Communication Sciences & Disorders and Chemical & Biomedical Engineering, University of South FloridaTampa, FL, USA; Global Center for Hearing and Speech Research, University of South FloridaTampa, FL, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Walton
authors.affiliation: Experimental and Regenerative Neurosciences, School of Animal Biology, University of Western Australia Perth, WA, Australia.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Rodger
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004867:Equipment Design / Q000592:standards; D019054:Evoked Potentials, Motor / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation*
keywords: electric field; magnetic field; motor evoked potentials; rTMS; rodent models