title: Relation of brain stimulation induced changes in MEP amplitude and BOLD signal.
abstract: BACKGROUND
  Non-invasive human brain stimulation can induce long-term plasticity reflected by changes in putative markers of synaptic activation, such as the motor evoked potential (MEP) amplitude elicited by transcranial magnetic stimulation or the task-dependent blood oxygenation level-dependent (BOLD) signal measured by functional magnetic resonance imaging.
  
  
  OBJECTIVE
  To study the relationship between brain stimulation induced changes in MEP amplitude and BOLD signal.
  
  
  METHODS
  Paired associative stimulation of the hand area of the left primary somatosensory cortex (S1-PAS) was applied in 15 healthy subjects to induce excitability change in the adjacent primary motor cortex (M1) [Kriváneková et al. 2011, Eur J Neurosci 34:1292-1300]. Before and after S1-PAS, MEP amplitude in a right hand muscle, and the BOLD signal during a right hand motor or somatosensory activation task were measured.
  
  
  RESULTS
  S1-PAS resulted in substantial individual MEP and BOLD signal changes, but these changes did not correlate in M1 or S1.
  
  
  CONCLUSIONS
  Findings indicate that MEP amplitude and BOLD signal within the tested M1 reflect physiologically distinct aspects of synaptic excitability change. Therefore, it is suggested that MEP amplitude and BOLD signal are complementary rather than interchangeable markers of synaptic excitability.
authors: Department of Neurology, Goethe University of Frankfurt, Schleusenweg 2-16, D-60528 Frankfurt am Main, Germany.
authors: Lucia
authors: L
authors: Kriváneková
authors: Simon
authors: S
authors: Baudrexel
authors: Barbara
authors: B
authors: Bliem
authors: Ulf
authors: U
authors: Ziemann
mesh_terms: D000704:Analysis of Variance; D018592:Cross-Over Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000098:blood supply* / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation; D009434:Neural Pathways / Q000098:blood supply / Q000502:physiology; D010100:Oxygen / Q000097:blood; D013003:Somatosensory Cortex / Q000098:blood supply* / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation
chemical_list: D010100:Oxygen