title: Intermittent θ burst stimulation over primary motor cortex enhances movement-related β synchronisation.
abstract: OBJECTIVE
  The objective of this study is to investigate how transcranial magnetic intermittent theta burst stimulation (iTBS) with a prolonged protocol affects human cortical excitability and movement-related oscillations.
  
  
  METHODS
  Using motor-evoked potentials (MEPs) and movement-related magnetoencephalography (MEG), we assessed the changes of corticospinal excitability and cortical oscillations after iTBS with double the conventional stimulation time (1200 pulses, iTBS1200) over the primary motor cortex (M1) in 10 healthy subjects. Continuous TBS (cTBS1200) and sham stimulation served as controls.
  
  
  RESULTS
  iTBS1200 facilitated MEPs evoked from the conditioned M1, while inhibiting MEPs from the contralateral M1 for 30 min. By contrast, cTBS1200 inhibited MEPs from the conditioned M1. Importantly, empirical mode decomposition-based MEG analysis showed that the amplitude of post-movement beta synchronisation (16-26 Hz) was significantly increased by iTBS1200 at the conditioned M1, but was suppressed at the nonconditioned M1. Alpha (8-13 Hz) and low gamma-ranged (35-45 Hz) rhythms were not notably affected. Movement kinetics remained consistent throughout.
  
  
  CONCLUSIONS
  TBS1200 modulated corticospinal excitability in parallel with the direction of conventional paradigms with modestly prolonged efficacy. Moreover, iTBS1200 increased post-movement beta synchronisation of the stimulated M1, and decreased that of the contralateral M1, probably through interhemispheric interaction.
  
  
  CONCLUSIONS
  Our results provide insight into the underlying mechanism of TBS and reinforce the connection between movement-related beta synchronisation and corticospinal output.
authors.affiliation: Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ya-Fang
authors.initials: YF
authors.lastname: Hsu
authors.forename: Kwong-Kum
authors.initials: KK
authors.lastname: Liao
authors.forename: Po-Lei
authors.initials: PL
authors.lastname: Lee
authors.forename: Yun-An
authors.initials: YA
authors.lastname: Tsai
authors.forename: Chia-Lung
authors.initials: CL
authors.lastname: Yeh
authors.forename: Kuan-Lin
authors.initials: KL
authors.lastname: Lai
authors.forename: Ying-Zu
authors.initials: YZ
authors.lastname: Huang
authors.forename: Yung-Yang
authors.initials: YY
authors.lastname: Lin
authors.forename: I-Hui
authors.initials: IH
authors.lastname: Lee
mesh_terms: D000328:Adult; D001611:Beta Rhythm / Q000502:physiology* / Q000528:radiation effects; D003344:Cortical Synchronization / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009044:Motor Cortex / Q000502:physiology* / Q000528:radiation effects; D009068:Movement / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology / Q000528:radiation effects; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult