title: Theta-burst Transcranial Magnetic Stimulation Alters the Functional Topography of the Cortical Motor Network.
abstract: BACKGROUND
  Transcranial magnetic stimulation (TMS) is a non-invasive tool that is able to modulate the electrical activity of the brain depending upon its protocol of stimulation. Theta burst stimulation (TBS) is a high-frequency TMS protocol that is able to induce prolonged plasticity changes in the brain. The induction of plasticity-like effects by TBS is useful in both experimental and therapeutic settings; however, the underlying neural mechanisms of this modulation remain unclear. The aim of this study was to investigate the effects of continuous TBS (cTBS) on the intrahemispheric and interhemispheric functional connectivity of the resting and active brain.
  
  
  METHODS
  A total of 26 healthy humans were randomly divided into two groups that received either real cTBS or sham (control) over the left primary motor cortex. Surface electroencephalogram (EEG) was used to quantify the changes of neural oscillations after cTBS at rest and after a choice reaction time test. The cTBS-induced EEG oscillations were computed using spectral analysis of event-related coherence (ERCoh) of theta (4-7.5 Hz), low alpha (8-9.5 Hz), high alpha (10-12.5 Hz), low beta (13-19.5 Hz), and high beta (20-30 Hz) brain rhythms.
  
  
  RESULTS
  We observed a global decrease in functional connectivity of the brain in the cTBS group when compared to sham in the low beta brain rhythm at rest and high beta brain rhythm during the active state. In particular, EEG spectral analysis revealed that high-frequency beta, a cortically generated brain rhythm, was the most sensitive band that was modulated by cTBS.
  
  
  CONCLUSIONS
  Overall, our findings suggest that cTBS, a TMS protocol that mimics the mechanism of long-term depression of synaptic plasticity, modulates motor network oscillations primarily at the cortical level and might interfere with cortical information coding.
authors.affiliation: Department of Medical Science, Faculty of Medicine and Health Sciences, Universiti Sains Islam Malaysia, Pandan Indah, 55100, Kuala Lumpur, Malaysia.
authors.forename: Nor Azila
authors.initials: NA
authors.lastname: Noh
authors.affiliation: College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, United Kingdom.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Fuggetta
authors.affiliation: Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Clinical Neurology, G.B. Rossi Hospital, University of Verona, Verona, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Manganotti
keywords: electroencephalogram; long-term depression; motor cortex; neuromodulation; neuroplasticity