BRAIN STIMULATION: Basic, Translational, and Clinical Research in Neuromodulation
Volume 3, Issue 1 , Pages 2-14, January 2010

Brain responses evoked by high-frequency repetitive transcranial magnetic stimulation: An event-related potential study

  • Massihullah Hamidi

      Affiliations

    • Medical Scientist Training Program, University of Wisconsin-Madison, Madison, Wisconsin
    • Neuroscience Training Program, University of Wisconsin-Madison, Madison, Wisconsin
    • Corresponding Author InformationCorrespondence: Mr. Massihullah Hamidi, 1202 W Johnson St, Madison, WI 53706.
    • ,
  • Heleen A. Slagter

      Affiliations

    • Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, Wisconsin
    • ,
  • Giulio Tononi

      Affiliations

    • Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin
    • ,
  • Bradley R. Postle

      Affiliations

    • Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin
    • Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin

Received 23 December 2008; received in revised form 8 March 2009; accepted 13 April 2009. published online 08 May 2009.

Background

Many recent studies have used repetitive transcranial magnetic stimulation (rTMS) to study brain-behavior relationships. However, the pulse-to-pulse neural effects of rapid delivery of multiple TMS pulses are unknown largely because of TMS-evoked electrical artifacts limiting recording of brain activity.

Objective

In this study, TMS-related artifacts were removed with independent component analysis (ICA), which allowed for the investigation of the neurophysiologic effects of rTMS with simultaneous electroencephalographic (EEG) recordings.

Methods

Repetitive TMS trains of 10Hz, 3 seconds (110% of motor threshold) were delivered to the postcentral gyrus and superior parietal lobule in 16 young adults. Simultaneous EEG recordings were made with a TMS-compatible system. The stereotypical pattern of TMS-related electrical artifacts was identified by ICA.

Results

Removal of artifacts allowed for identification of a series of five evoked brain potentials occurring within 100 milliseconds of each TMS pulse. With the exception of the first potential, for both areas targeted, there was a quadratic relationship between potential peak amplitude and pulse number within the TMS train. This was characterized by a decrease, followed by a rise in amplitude.

Conclusions

ICA is an effective method for removal of TMS-evoked electrical artifacts in EEG data. With the use of this procedure we found that the physiologic responses to TMS pulses delivered in a high-frequency train of pulses are not independent. The sensitivity of the magnitude of these responses to recent stimulation history suggests a complex recruitment of multiple neuronal events with different temporal dynamics.

Keywords: transcranial magnetic stimulation, rTMS, electroencephalography, event-related potential, independent component analysis

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 This study was supported by National Institutes of Health (NIH) grants MH078705 (M.H.) and MH064498 (B.R.P.) and by a NARSAD grant (G.T.).

PII: S1935-861X(09)00050-3

doi:10.1016/j.brs.2009.04.001

BRAIN STIMULATION: Basic, Translational, and Clinical Research in Neuromodulation
Volume 3, Issue 1 , Pages 2-14, January 2010

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