Skip to main contentSkip to search and navigation

UEF eREPOSITORY

    • English
    • suomi
  • English 
    • English
    • suomi
  • Login
View Item 
  •   Home
  • Artikkelit
  • Luonnontieteiden ja metsätieteiden tiedekunta
  • View Item
  •   Home
  • Artikkelit
  • Luonnontieteiden ja metsätieteiden tiedekunta
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

The effect of coil placement and orientation on the assessment of focal excitability in motor mapping with navigated transcranial magnetic stimulation

Thumbnail
Files
Article (3.249Mb)
Self archived version
final draft
Date
2019
Author(s)
Reijonen, Jusa
Säisänen, Laura
Könönen, Mervi
Mohammadi, Ali
Julkunen, Petro
Unique identifier
10.1016/j.jneumeth.2019.108521
Metadata
Show full item record
More information
Research Database SoleCris

Self-archived article

Citation
Reijonen, Jusa. Säisänen, Laura. Könönen, Mervi. Mohammadi, Ali. Julkunen, Petro. (2019). The effect of coil placement and orientation on the assessment of focal excitability in motor mapping with navigated transcranial magnetic stimulation.  Journal of neuroscience methods, 331, 108521. 10.1016/j.jneumeth.2019.108521.
Rights
© Elsevier B.V.
Licensed under
CC BY-NC-ND https://creativecommons.org/licenses/by-nc-nd/4.0/
Abstract

Background
Navigated transcranial magnetic stimulation (nTMS) is used for mapping muscle representations in the primary motor cortex. We used sulcus-aligned mapping and electric field (E-field) modeling to investigate the excitability of the motor hand area for further understanding the methodological limitations of nTMS.

New method
We studied 10 healthy volunteers to locate the cortical target eliciting the largest responses (the hotspot) in the first dorsal interosseous (FDI) muscle. Six additional targets were placed along the central sulcus at 5-mm distances. Resting motor thresholds (rMTs) and optimal coil orientations were determined at all targets, and a conventional motor mapping was conducted. The cortical E-fields, induced by stimulating the targets with rMT intensities and optimal coil orientations, were modeled in a realistic head geometry to estimate the activated cortical sites.

Results
The rMTs increased with increasing distance from the hotspot (p < 0.001). The greatest motor-evoked potential (MEP) amplitudes occurred with the coil perpendicular to the sulcus and with the coil pointing towards the hotspot or the center of gravity of the motor map. The E-field strengths at the hotspot (99±26 V/m) remained above previously estimated thresholds for activation.

Comparison with existing methods
Depending on the target location, optimal coil orientations may deviate significantly from the conventional perpendicular-to-sulcus angle, which is often assumed optimal. These orientations seem to maintain the E-field stable in the hand knob, regardless of the sulcal shape near the stimulated target.

Conclusions
The coil orientation is crucial for the accuracy of motor mapping, and the apparent motor map may extend due to remote hotspot activation

Subjects
electric field   neuronavigation   neurophysiology   motor cortex   motor-evoked potential   transcranial magnetic stimulation   
URI
https://erepo.uef.fi/handle/123456789/7862
Link to the original item
http://dx.doi.org/10.1016/j.jneumeth.2019.108521
Publisher
Elsevier BV
Collections
  • Luonnontieteiden ja metsätieteiden tiedekunta [1109]
University of Eastern Finland
OpenAccess
eRepo
erepo@uef.fi
OpenUEF
Service provided by
the University of Eastern Finland Library
Library web pages
Twitter
Facebook
Youtube
Library blog
 sitemap
Search

Browse

All of the ArchiveResource types & CollectionsBy Issue DateAuthorsTitlesSubjectsFacultyDepartmentFull organizationSeriesMain subjectThis CollectionBy Issue DateAuthorsTitlesSubjectsFacultyDepartmentFull organizationSeriesMain subject

My Account

Login
University of Eastern Finland
OpenAccess
eRepo
erepo@uef.fi
OpenUEF
Service provided by
the University of Eastern Finland Library
Library web pages
Twitter
Facebook
Youtube
Library blog
 sitemap