Experimental Brain Research

, Volume 186, Issue 4, pp 539–550

Transcranial magnetic stimulation and brain atrophy: a computer-based human brain model study

  • Tim Wagner
  • Uri Eden
  • Felipe Fregni
  • Antoni Valero-Cabre
  • Ciro Ramos-Estebanez
  • Valerie Pronio-Stelluto
  • Alan Grodzinsky
  • Markus Zahn
  • Alvaro Pascual-Leone
Research Article

DOI: 10.1007/s00221-007-1258-8

Cite this article as:
Wagner, T., Eden, U., Fregni, F. et al. Exp Brain Res (2008) 186: 539. doi:10.1007/s00221-007-1258-8

Abstract

This paper is aimed at exploring the effect of cortical brain atrophy on the currents induced by transcranial magnetic stimulation (TMS). We compared the currents induced by various TMS conditions on several different MRI derived finite element head models of brain atrophy, incorporating both decreasing cortical volume and widened sulci. The current densities induced in the cortex were dependent upon the degree and type of cortical atrophy and were altered in magnitude, location, and orientation when compared to healthy head models. Predictive models of the degree of current density attenuation as a function of the scalp-to-cortex distance were analyzed, concluding that those which ignore the electromagnetic field–tissue interactions lead to inaccurate conclusions. Ultimately, the precise site and population of neural elements stimulated by TMS in an atrophic brain cannot be predicted based on healthy head models which ignore the effects of the altered cortex on the stimulating currents. Clinical applications of TMS should be carefully considered in light of these findings.

Keywords

Cortical atrophyFinite element modelTranscranial magnetic stimulationBrain stimulationNeuromodulationBrain plasticity

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Tim Wagner
    • 1
    • 2
    • 3
  • Uri Eden
    • 1
    • 4
  • Felipe Fregni
    • 2
  • Antoni Valero-Cabre
    • 2
    • 5
    • 6
  • Ciro Ramos-Estebanez
    • 2
  • Valerie Pronio-Stelluto
    • 1
  • Alan Grodzinsky
    • 3
    • 7
  • Markus Zahn
    • 3
  • Alvaro Pascual-Leone
    • 2
  1. 1.Division of Health Sciences and TechnologyHarvard Medical School/Massachusetts Institute of TechnologyBostonUSA
  2. 2.Harvard Center for Non-Invasive Brain Stimulation, Beth Israel Deaconess Medical CenterBostonUSA
  3. 3.Department of Electrical Engineering and Computer ScienceMassachusetts Institute of TechnologyCambridgeUSA
  4. 4.Department of Mathematics and StatisticsBoston UniversityBostonUSA
  5. 5.Boston University School of MedicineBostonUSA
  6. 6.CNRS UMR 5105, Grenoble, ERT TREAT Vision and Department of NeurologyFondation Ophtalmologique RothschildParisFrance
  7. 7.Center for Biomedical EngineeringMassachusetts Institute of TechnologyCambridgeUSA