title: Probing changes in corticospinal excitability following theta burst stimulation of the human primary motor cortex.
abstract: OBJECTIVE
  To determine whether the intensity of transcranial magnetic stimulation (TMS) used to probe changes in corticospinal excitability influences the measured plasticity response to theta burst stimulation (TBS) of the human primary motor cortex.
  
  
  METHODS
  Motor evoked potential (MEP) input/output (I/O) curves were recorded before and following continuous TBS (cTBS) (Experiment 1; n=18) and intermittent TBS (iTBS) (Experiment 2; n=18).
  
  
  RESULTS
  The magnitude and consistency of MEP depression induced by cTBS was greatest when probed using stimulus intensities at or above 150% of resting motor threshold (RMT). In contrast, facilitation of MEPs following iTBS was strongest and most consistent at 110% of RMT.
  
  
  CONCLUSIONS
  The plasticity response to both cTBS and iTBS is influenced by the stimulus intensity used to probe the induced changes in corticospinal excitability.
  
  
  CONCLUSIONS
  The results highlight the importance of the test stimulus intensity used to assess TBS-induced changes in corticospinal excitability when interpreting neuroplasticity data, and suggest that a number of test intensities may be required to reliably probe the plasticity response.
authors.affiliation: The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia. Electronic address: mitchell.goldsworthy@adelaide.edu.au.
authors.forename: Mitchell R
authors.initials: MR
authors.lastname: Goldsworthy
authors.affiliation: The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia; School of Psychology and Exercise Science, Murdoch University, WA, Australia.
authors.forename: Ann-Maree
authors.initials: AM
authors.lastname: Vallence
authors.affiliation: The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Nicolette A
authors.initials: NA
authors.lastname: Hodyl
authors.affiliation: Discipline of Physiology, School of Medical Sciences, University of Adelaide, Adelaide, SA, Australia.
authors.forename: John G
authors.initials: JG
authors.lastname: Semmler
authors.affiliation: The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Julia B
authors.initials: JB
authors.lastname: Pitcher
authors.affiliation: The Robinson Research Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Ridding
mesh_terms: D000293:Adolescent; D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D017774:Long-Term Potentiation / Q000502:physiology; D036881:Long-Term Synaptic Depression / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Input/output curve; Motor evoked potential; Plasticity; Transcranial magnetic stimulation; cTBS; iTBS