title: Inter- and Intra-individual variability following intermittent theta burst stimulation: implications for rehabilitation and recovery.
abstract: BACKGROUND
  The continued refinement of non-invasive brain stimulation (NBS) techniques is indicative of promising clinical and rehabilitative interventions that are able to modulate cortical excitability. Intermittent theta burst stimulation (iTBS) is one such technique that can increase cortical excitability, purportedly via LTP-like mechanisms. While iTBS may have the capacity to promote recovery after neurological injury, and to combat cognitive and motor decline, recent reports observed highly variable effects across individuals, questioning the efficacy of iTBS as a clinical tool.
  
  
  OBJECTIVE
  The aim of this study was to examine intra-individual reliability and inter-individual variability in responses to iTBS.
  
  
  METHODS
  Thirty healthy participants completed two experimental sessions of the iTBS protocol 1-3 weeks apart. Motor evoked potentials in response to single pulse TMS were used to assess corticospinal excitability prior to, and up to 36 min following, iTBS.
  
  
  RESULTS
  At the group level, iTBS evoked statistically significant increases in motor cortical excitability across both sessions (P < 0.001), with 22 out of 30 participants exhibiting increases in excitability in both sessions. A strong intraclass correlation demonstrated that both the direction, and magnitude of the plastic changes were reliable at the individual level.
  
  
  CONCLUSIONS
  Overall, our results suggest that iTBS is capable of inducing relatively robust and consistent effects within and between young individuals. As such, the capacity for iTBS to be exploited in clinical and rehabilitative interventions should continue to be explored.
authors: Human Motor Control Laboratory, School of Medicine, University of Tasmania, Private Bag 30, Hobart, Tasmania 7001, Australia. Electronic address: Mark.Hinder@utas.edu.au.
authors: Mark R
authors: MR
authors: Hinder
authors: Human Motor Control Laboratory, School of Medicine, University of Tasmania, Private Bag 30, Hobart, Tasmania 7001, Australia.
authors: Emily L
authors: EL
authors: Goss
authors: Human Motor Control Laboratory, School of Medicine, University of Tasmania, Private Bag 30, Hobart, Tasmania 7001, Australia; Movement Control and Neuroplasticity Research Group, Department of Kinesiology, KU Leuven, Belgium.
authors: Hakuei
authors: H
authors: Fujiyama
authors: School of Medicine, University of Tasmania, Australia.
authors: Alison J
authors: AJ
authors: Canty
authors: Human Motor Control Laboratory, School of Medicine, University of Tasmania, Private Bag 30, Hobart, Tasmania 7001, Australia.
authors: Michael I
authors: MI
authors: Garry
authors: Experimental and Regenerative Neuroscience, School of Animal Biology, University of Western Australia, Australia.
authors: Jennifer
authors: J
authors: Rodger
authors: Human Motor Control Laboratory, School of Medicine, University of Tasmania, Private Bag 30, Hobart, Tasmania 7001, Australia; Research Institute for Exercise and Sport Sciences, Liverpool John Moores University, UK.
authors: Jeffery J
authors: JJ
authors: Summers
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000473:pathology / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D012044:Regression Analysis; D012046:Rehabilitation; D015203:Reproducibility of Results; D013826:Theta Rhythm / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Cortical plasticity; Inter- and intra-individual variability; TMS; Theta burst stimulation