title: Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.
abstract: OBJECTIVE
  The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies.
  
  
  METHODS
  Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to create recruitment curves. The Boltzmann sigmoidal function was fit to the data, and parameters relating to maximal motor-evoked potential size, curve slope, and stimulus intensity leading to half-maximal motor-evoked potential size were computed from the curve fit.
  
  
  RESULTS
  Good to excellent test-retest reliability was found for all corticospinal parameters at rest and during activation with 40 transcranial magnetic stimulation pulses.
  
  
  CONCLUSIONS
  Through the use of curve fitting, important features of the corticospinal system can be determined with fewer stimuli than typically used for the same information. Determining the recruitment curve provides a basis to understand the state of the corticospinal system and select subject-specific parameters for transcranial magnetic stimulation testing quickly and without unnecessary exposure to magnetic stimulation. This method can be useful in individuals who have difficulty in maintaining stillness, including children and patients with motor disorders.
authors.affiliation: *Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, U.S.A.; †Functional and Applied Biomechanics Lab, Rehabilitation Medicine Department, NIH Clinical Center, National Institutes of Health, Bethesda, Maryland, U.S.A.; ‡Department of Neurology, National Taiwan University Hospital, Taipei City, Taiwan.
authors.forename: Sahana N
authors.initials: SN
authors.lastname: Kukke
authors.forename: Rainer W
authors.initials: RW
authors.lastname: Paine
authors.forename: Chi-Chao
authors.initials: CC
authors.lastname: Chao
authors.forename: Ana C
authors.initials: AC
authors.lastname: de Campos
authors.forename: Mark
authors.initials: M
authors.lastname: Hallett
mesh_terms: D000328:Adult; D004576:Electromyography / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D015203:Reproducibility of Results; D050781:Transcranial Magnetic Stimulation / Q000379:methods* / Q000592:standards; D055815:Young Adult