Targeting of White Matter Tracts with Transcranial Magnetic Stimulation

Background: TMS activations of white matter depend not only on the distance from the coil, but also on the orientation of the axons relative to the TMS-induced electric field, and especially on axonal bends that create strong local field gradient maxima. Therefore, tractography contains potentially...

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Main Authors:	Aapo Nummenmaa, Jennifer A. McNab, Peter Savadjiev, Yoshio Okada, Matti S. Hämäläinen, Ruopeng Wang, Lawrence L. Wald, Alvaro Pascual-Leone, Van J. Wedeen, Tommi Raij
Format:	Article
Language:	English
Published:	Elsevier 2014-01-01
Series:	Brain Stimulation
Subjects:	Transcranial magnetic stimulation TMS Diffusion MRI tractography Electromagnetic modeling Navigation Coil orientation
Online Access:	http://www.sciencedirect.com/science/article/pii/S1935861X13002969

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spelling	doaj-ad25d93b91dc4f2ab2b719488f82dfb62021-03-18T04:37:03ZengElsevierBrain Stimulation1935-861X2014-01-01718084Targeting of White Matter Tracts with Transcranial Magnetic StimulationAapo Nummenmaa0Jennifer A. McNab1Peter Savadjiev2Yoshio Okada3Matti S. Hämäläinen4Ruopeng Wang5Lawrence L. Wald6Alvaro Pascual-Leone7Van J. Wedeen8Tommi Raij9MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USA; Department of Radiology, Stanford University, CA, USAHarvard Medical School, MA, USA; Brigham and Women's Hospital, MA, USAHarvard Medical School, MA, USA; Department of Neurology, Boston Children's Hospital, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USA; Harvard-MIT Division of Health Sciences and Technology, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USA; Harvard-MIT Division of Health Sciences and Technology, MA, USAHarvard Medical School, MA, USA; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USAMGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, MA, USA; Harvard Medical School, MA, USA; Corresponding author. MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, 149 Thirteenth Street, Suite 2301, Charlestown, Massachusetts 02129, USA. Tel.: +1 617 726 2000; fax: +1 617 726 7422.Background: TMS activations of white matter depend not only on the distance from the coil, but also on the orientation of the axons relative to the TMS-induced electric field, and especially on axonal bends that create strong local field gradient maxima. Therefore, tractography contains potentially useful information for TMS targeting. Objective/methods: Here, we utilized 1-mm resolution diffusion and structural T1-weighted MRI to construct large-scale tractography models, and localized TMS white matter activations in motor cortex using electromagnetic forward modeling in a boundary element model (BEM). Results: As expected, in sulcal walls, pyramidal cell axonal bends created preferred sites of activation that were not found in gyral crowns. The model agreed with the well-known coil orientation sensitivity of motor cortex, and also suggested unexpected activation distributions emerging from the E-field and tract configurations. We further propose a novel method for computing the optimal coil location and orientation to maximally stimulate a pre-determined axonal bundle. Conclusions: Diffusion MRI tractography with electromagnetic modeling may improve spatial specificity and efficacy of TMS.http://www.sciencedirect.com/science/article/pii/S1935861X13002969Transcranial magnetic stimulationTMSDiffusion MRI tractographyElectromagnetic modelingNavigationCoil orientation
collection	DOAJ
language	English
format	Article
sources	DOAJ
author	Aapo Nummenmaa Jennifer A. McNab Peter Savadjiev Yoshio Okada Matti S. Hämäläinen Ruopeng Wang Lawrence L. Wald Alvaro Pascual-Leone Van J. Wedeen Tommi Raij
spellingShingle	Aapo Nummenmaa Jennifer A. McNab Peter Savadjiev Yoshio Okada Matti S. Hämäläinen Ruopeng Wang Lawrence L. Wald Alvaro Pascual-Leone Van J. Wedeen Tommi Raij Targeting of White Matter Tracts with Transcranial Magnetic Stimulation Brain Stimulation Transcranial magnetic stimulation TMS Diffusion MRI tractography Electromagnetic modeling Navigation Coil orientation
author_facet	Aapo Nummenmaa Jennifer A. McNab Peter Savadjiev Yoshio Okada Matti S. Hämäläinen Ruopeng Wang Lawrence L. Wald Alvaro Pascual-Leone Van J. Wedeen Tommi Raij
author_sort	Aapo Nummenmaa
title	Targeting of White Matter Tracts with Transcranial Magnetic Stimulation
title_short	Targeting of White Matter Tracts with Transcranial Magnetic Stimulation
title_full	Targeting of White Matter Tracts with Transcranial Magnetic Stimulation
title_fullStr	Targeting of White Matter Tracts with Transcranial Magnetic Stimulation
title_full_unstemmed	Targeting of White Matter Tracts with Transcranial Magnetic Stimulation
title_sort	targeting of white matter tracts with transcranial magnetic stimulation
publisher	Elsevier
series	Brain Stimulation
issn	1935-861X
publishDate	2014-01-01
description	Background: TMS activations of white matter depend not only on the distance from the coil, but also on the orientation of the axons relative to the TMS-induced electric field, and especially on axonal bends that create strong local field gradient maxima. Therefore, tractography contains potentially useful information for TMS targeting. Objective/methods: Here, we utilized 1-mm resolution diffusion and structural T1-weighted MRI to construct large-scale tractography models, and localized TMS white matter activations in motor cortex using electromagnetic forward modeling in a boundary element model (BEM). Results: As expected, in sulcal walls, pyramidal cell axonal bends created preferred sites of activation that were not found in gyral crowns. The model agreed with the well-known coil orientation sensitivity of motor cortex, and also suggested unexpected activation distributions emerging from the E-field and tract configurations. We further propose a novel method for computing the optimal coil location and orientation to maximally stimulate a pre-determined axonal bundle. Conclusions: Diffusion MRI tractography with electromagnetic modeling may improve spatial specificity and efficacy of TMS.
topic	Transcranial magnetic stimulation TMS Diffusion MRI tractography Electromagnetic modeling Navigation Coil orientation
url	http://www.sciencedirect.com/science/article/pii/S1935861X13002969
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Targeting of White Matter Tracts with Transcranial Magnetic Stimulation

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