Experimental Brain Research

, Volume 133, Issue 4, pp 425–430

Interindividual variability of the modulatory effects of repetitive transcranial magnetic stimulation on cortical excitability

  • Fumiko Maeda
  • Julian P. Keenan
  • Jose M. Tormos
  • Helge Topka
  • Alvaro Pascual-Leone
Research Article

DOI: 10.1007/s002210000432

Cite this article as:
Maeda, F., Keenan, J., Tormos, J. et al. Exp Brain Res (2000) 133: 425. doi:10.1007/s002210000432

Abstract.

Repetitive transcranial magnetic stimulation (rTMS) appears to have effects on cortical excitability that extend beyond the train of rTMS itself. These effects may be inhibitory or facilitatory and appear to depend on the frequency, intensity, duration and intertrain interval of the rTMS. Many studies assume facilitatory effects of high-frequency rTMS and inhibitory effects of low-frequency rTMS. Nevertheless, the interindividual variability of this modulation of cortical excitability by rTMS has not been systematically investigated. In this study, we applied 240 pulses of rTMS at 90% of the subjects' motor threshold to their motor cortex at different frequencies (1, 10, 15 and 20 Hz) and examined the effects on motor evoked potentials (frequency tuning curve). Although the averaged group data showed a frequency-dependent increase in cortical excitability, each subject had a different pattern of frequency tuning curve, i.e. a different modulatory effect on cortical excitability at different rTMS frequencies. The interindividual variability of these modulatory effects was still high, though less so, when the number of rTMS pulses was increased to 1600. These findings illustrate the degree of variability of the rTMS effects in the human brain.

Repetitive transcranial magnetic stimulation (rTMS) Train Frequency tuning curve Cortical excitability Neurophysiology 

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • Fumiko Maeda
    • 1
  • Julian P. Keenan
    • 1
  • Jose M. Tormos
    • 3
  • Helge Topka
    • 4
  • Alvaro Pascual-Leone
    • 1
  1. 1.Laboratory for Magnetic Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave. KS452, Boston, MA 02215, USA
  2. 2.Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
  3. 3.Institute for Bioengineering, Miguel Hernandez University, Alicante, Spain
  4. 4.Department of Neurology, University of Tübingen, Tübingen, Germany

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