Transcranial magnetic stimulation: Improved coil design for deep brain investigation

Crowther, Lawrence J.; Marketos, P.; Williams, P. I.; Melikhov, Yevgen; Jiles, David; Starzewski, J. H.

doi:10.1063/1.3563076

Cited by 63 publications

(45 citation statements)

References 7 publications

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“…Therefore, new coil designs must be created for this purpose. Studies in human subjects 16 have found that increased localization of stimulation is usually possible at the expense of depth of penetration of the stimulating field. This is also expected to hold true for TMS coils designed for small animals.…”

Section: Resultsmentioning

confidence: 99%

Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models

Crowther

Hadimani

Kanthasamy

et al. 2014

Journal of Applied Physics

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Transcranial magnetic stimulation (TMS) offers the possibility of non-invasive treatment of braindisorders in humans. Studies on animals can allow rapid progress of the research including exploring a variety of different treatment conditions. Numerical calculations using animalmodels are needed to help design suitable TMS coils for use in animal experiments, in particular, to estimate the electric field induced in animal brains. In this paper, we have implemented a high-resolution anatomical MRI-derived mouse model consisting of 50 tissuetypes to accurately calculate induced electric field in the mouse brain. Magnetic field measurements have been performed on the surface of the coil and compared with the calculations in order to validate the calculated magnetic and induced electric fields in the brain.Results show how the induced electric field is distributed in a mouse brain and allow investigation of how this could be improved for TMS studies using mice. The findings have important implications in further preclinical development of TMS for treatment of human diseases. Transcranial magnetic stimulation (TMS) offers the possibility of non-invasive treatment of brain disorders in humans. Studies on animals can allow rapid progress of the research including exploring a variety of different treatment conditions. Numerical calculations using animal models are needed to help design suitable TMS coils for use in animal experiments, in particular, to estimate the electric field induced in animal brains. In this paper, we have implemented a high-resolution anatomical MRI-derived mouse model consisting of 50 tissue types to accurately calculate induced electric field in the mouse brain. Magnetic field measurements have been performed on the surface of the coil and compared with the calculations in order to validate the calculated magnetic and induced electric fields in the brain. Results show how the induced electric field is distributed in a mouse brain and allow investigation of how this could be improved for TMS studies using mice. The findings have important implications in further preclinical development of TMS for treatment of human diseases. V C 2014 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models

Crowther

Hadimani

Kanthasamy

et al. 2014

Journal of Applied Physics

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“…Although non-invasive, TMS procedures are often limited by non-focal stimulation of brain regions and low overall electric field strength. Recent advancements by Crowther et al [3,4] The present study investigates a methodical approach for designing a TMS coil for medical testing for mice on the basis of Halo coil designs. TMS coils that are currently used by other research groups for stimulation of animal brains are scaled down versions of standard TMS coils that are used for stimulation of the human brain [5].…”

Section: Introductionmentioning

confidence: 99%

Focused and deep brain magnetic stimulation using new coil design in mice

March

McAtee

Senter

et al. 2013

2013 6th International IEEE/EMBS Conference on Neural Engineering (NER)

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Deep brain transcranial magnetic stimulation (TMS) offers promising treatment for neurological disorders that originate from deeper regions of the brain, such as Parkinson's disease. Coils designed for the human head need significant redesigning to stimulate selective regions of the mouse brain for advanced TMS therapy analysis. We report a focused and deep brain TMS coil for mice that is based on a two coil configuration similar to the 'Halo coil'. A heterogeneous MRI derived head model of mouse was used to obtain an electric field of about 150 V/m in selective deeper regions of the brain. Focality of stimulation was quantified using the ratio of half value volume to half value of depth of electric field. A prototype of the final coil design was fabricated and characterized to compare simulated and physical magnetic field profiles.

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“…These shields can inhibit or divert the generated magnetic field, leading to more focused stimulation and improved field penetration. Complex coil designs (Zangen et al 2005, Crowther et al 2011, Deng et al 2013 have also been developed where the rate of decay from the surface is attenuated, such that the percentage of electric field intensity is increased in deeper brain regions, relative to the maximum field at the cortex. However, experiments reveal that standard TMS coils such as the figure-of-eight coil possess the ability to affect these deeper brain regions as well (Bestmann et al 2004, Hannula et al 2010, Ferreri et al 2011.…”

Section: Introductionmentioning

confidence: 99%

Modeling transcranial magnetic stimulation from the induced electric fields to the membrane potentials along tractography-based white matter fiber tracts

Geeter

Dupré²,

Crevecoeur³

2016

J. Neural Eng.

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Objective. Transcranial magnetic stimulation (TMS) is a promising non-invasive tool for modulating the brain activity. Despite the widespread therapeutic and diagnostic use of TMS in neurology and psychiatry, its observed response remains hard to predict, limiting its further development and applications. Although the stimulation intensity is always maximum at the cortical surface near the coil, experiments reveal that TMS can affect deeper brain regions as well. Approach. The explanation of this spread might be found in the white matter fiber tracts, connecting cortical and subcortical structures. When applying an electric field on neurons, their membrane potential is altered. If this change is significant, more likely near the TMS coil, action potentials might be initiated and propagated along the fiber tracts towards deeper regions. In order to understand and apply TMS more effectively, it is important to capture and account for this interaction as accurately as possible. Therefore, we compute, next to the induced electric fields in the brain, the spatial distribution of the membrane potentials along the fiber tracts and its temporal dynamics. Main results. This paper introduces a computational TMS model in which electromagnetism and neurophysiology are combined. Realistic geometry and tissue anisotropy are included using magnetic resonance imaging and targeted white matter fiber tracts are traced using tractography based on diffusion tensor imaging. The position and orientation of the coil can directly be retrieved from the neuronavigation system. Incorporating these features warrants both patient-and case-specific results. Significance. The presented model gives insight in the activity propagation through the brain and can therefore explain the observed clinical responses to TMS and their inter-and/or intra-subject variability. We aspire to advance towards an accurate, flexible and personalized TMS model that helps to understand stimulation in the connected brain and to target more focused and deeper brain regions.S Online supplementary data available from stacks.iop.org/jne/13/026028/mmedia

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Transcranial magnetic stimulation: Improved coil design for deep brain investigation

Cited by 63 publications

References 7 publications

Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models

Transcranial magnetic stimulation of mouse brain using high-resolution anatomical models

Focused and deep brain magnetic stimulation using new coil design in mice

Modeling transcranial magnetic stimulation from the induced electric fields to the membrane potentials along tractography-based white matter fiber tracts

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