BRAIN STIMULATION: Basic, Translational, and Clinical Research in Neuromodulation
Volume 4, Issue 1 , Pages 50-57, January 2011

Fast estimation of transcranial magnetic stimulation motor threshold

  • Feng Qi

      Affiliations

    • Neuroscience, University of Southern California, Los Angeles, California
    • ,
  • Allan D. Wu

      Affiliations

    • Department of Neurology, University of California at Los Angeles, Los Angeles, California
    • ,
  • Nicolas Schweighofer

      Affiliations

    • Neuroscience, University of Southern California, Los Angeles, California
    • Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California
    • Corresponding Author InformationCorrespondence: Nicolas Schweighofer, Neuroscience, University of Southern California, 1540 E. Alcazar, Los Angeles, CA 90089

Received 17 October 2009; received in revised form 7 June 2010; accepted 7 June 2010. published online 05 July 2010.

Background

In Transcranial Magnetic Stimulation (TMS), the Motor Threshold (MT) is the minimum intensity required to evoke a liminal response in the target muscle. Because the MT reflects cortical excitability, the TMS intensity needs to be adjusted according to the subject's MT at the beginning of every TMS session.

Objective

Shorten the MT estimation process compared to existing methods without compromising accuracy.

Methods

We propose a Bayesian adaptive method for MT determination that incorporates prior MT knowledge and uses a stopping criterion based on estimation of MT precision. We compared the number of TMS pulses required with this new method with existing MT determination methods.

Results

The proposed method achieved the accuracy of existing methods with as few as seven TMS pulses on average when using a common prior and three TMS pulses on average when using subject-specific priors.

Conclusions

Our adaptive Bayesian method is effective in reducing the number of pulses to estimate the MT.

Keywords: TMS, motor threshold, Bayesian method

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 This work was in part supported by National Science Foundation grant IIS 0535282 to NS.

PII: S1935-861X(10)00060-4

doi:10.1016/j.brs.2010.06.002

BRAIN STIMULATION: Basic, Translational, and Clinical Research in Neuromodulation
Volume 4, Issue 1 , Pages 50-57, January 2011

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