Sham TMS: intracerebral measurement of the induced electrical field and the induction of motor-evoked potentials.

Journal Article

Testing the therapeutic potential of transcranial magnetic stimulation (TMS) in controlled trials requires a valid sham condition. Sham TMS is typically administered by tilting the coil 45--90 degrees off the scalp, with one or two wings of the coil touching the scalp. Lack of cortical effects has not been verified. We compared sham manipulations in their thresholds for eliciting motor-evoked potentials (MEPs) in human volunteers and in intracerebral measurements of voltage induced in the prefrontal cortex of a rhesus monkey. Three types of sham (one-wing 45 degrees and 90 degrees and two-wing 90 degrees tilt) induced much lower voltage in the brain than active TMS (67--73% reductions). However, the two-wing 45 degrees sham induced values just 24% below active TMS. This sham was about half as potent in inducing MEPs over the motor cortex as active TMS. Some sham TMS conditions produce substantial cortical stimulation, making it critical to carefully select the sham manipulation for clinical trials.

Full Text

Duke Authors

Cited Authors

  • Lisanby, SH; Gutman, D; Luber, B; Schroeder, C; Sackeim, HA

Published Date

  • March 1, 2001

Published In

Volume / Issue

  • 49 / 5

Start / End Page

  • 460 - 463

PubMed ID

  • 11274658

International Standard Serial Number (ISSN)

  • 0006-3223

Language

  • eng

Conference Location

  • United States