title: Efficacy and Time Course of Theta Burst Stimulation in Healthy Humans.
abstract: BACKGROUND
  In the past decade research has shown that continuous (cTBS) and intermittent theta burst stimulation (iTBS) alter neuronal excitability levels in the primary motor cortex.
  
  
  OBJECTIVE
  Quantitatively review the magnitude and time course on cortical excitability of cTBS and iTBS.
  
  
  METHODS
  Sixty-four TBS studies published between January 2005 and October 2014 were retrieved from the scientific search engine PubMED and included for analyses. The main inclusion criteria involved stimulation of the primary motor cortex in healthy volunteers with no motor practice prior to intervention and motor evoked potentials as primary outcome measure.
  
  
  RESULTS
  ITBS applied for 190 s significantly increases cortical excitability up to 60 min with a mean maximum potentiation of 35.54 ± 3.32%. CTBS applied for 40 s decreases cortical excitability up to 50 min with a mean maximum depression of -22.81 ± 2.86%, while cTBS applied for 20 s decreases cortical excitability (mean maximum -27.84 ± 4.15%) for 20 min.
  
  
  CONCLUSIONS
  The present findings offer normative insights into the magnitude and time course of TBS-induced changes in cortical excitability levels.
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, the Netherlands. Electronic address: m.wischnewski@donders.ru.nl.
authors.forename: Miles
authors.initials: M
authors.lastname: Wischnewski
authors.affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, the Netherlands.
authors.forename: Dennis J L G
authors.initials: DJ
authors.lastname: Schutter
mesh_terms: D019054:Evoked Potentials, Motor / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D017774:Long-Term Potentiation; D036881:Long-Term Synaptic Depression; D009044:Motor Cortex / Q000502:physiology*; D013826:Theta Rhythm; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
keywords: Cortical excitability; Cortical plasticity; Long-term depression; Long-term potentiation; Primary motor cortex; Theta burst stimulation