title: Paired-Pulse TMS and Fine-Wire Recordings Reveal Short-Interval Intracortical Inhibition and Facilitation of Deep Multifidus Muscle Fascicles.
abstract: OBJECTIVE
  Paired-pulse transcranial magnetic stimulation (ppTMS) is used to probe inhibitory and excitatory networks within the primary motor cortex (M1). These mechanisms are identified for limb muscles but it is unclear whether they share properties with trunk muscles. The aim was to determine whether it was possible to test the intracortical inhibition and facilitation of the deep multifidus muscle fascicles (DM) and at which inter-stimulus intervals (ISI).
  
  
  METHODS
  In ten pain-free individuals, TMS was applied over M1 and motor evoked potentials (MEP) were recorded using fine-wire electrodes in DM. MEPs were conditioned with subthreshold stimuli at ISIs of 1 to 12 ms to test short-interval intracortical inhibition (SICI) and at 15 ms for long-interval intracortical facilitation. Short-interval facilitation (SICF) was tested using 1-ms ISI.
  
  
  RESULTS
  SICI of DM was consistently obtained with ISI of 1-, 3-, 4- and 12-ms. Facilitation of DM MEP was only identified using SICF paradigm.
  
  
  CONCLUSIONS
  A similar pattern of MEP modulation with ISI changes for deep trunk and limb muscles implies that M1 networks share some functional properties.
  
  
  CONCLUSIONS
  The ppTMS paradigm presents a potential to determine how M1 inhibitory and excitatory mechanisms participate in brain re-organization in back pain that affects control of trunk muscles.
authors: Laboratory of Clinical Neuroscience and neuroStimulation, Université Laval (Dept of Rehabilitation), CHU de Québec Research Center, Neuroscience Unit (CHUL), Quebec City, QC, Canada.
authors: Hugo
authors: H
authors: Massé-Alarie
authors: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury & Health, School of Health & Rehabilitation Sciences, Brisbane, Qld Australia.
authors: Edith
authors: E
authors: Elgueta Cancino
authors: Laboratory of Clinical Neuroscience and neuroStimulation, Université Laval (Dept of Rehabilitation), CHU de Québec Research Center, Neuroscience Unit (CHUL), Quebec City, QC, Canada.
authors: Cyril
authors: C
authors: Schneider
authors: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury & Health, School of Health & Rehabilitation Sciences, Brisbane, Qld Australia.
authors: Paul
authors: P
authors: Hodges
mesh_terms: D000328:Adult; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D006801:Humans; D009119:Muscle Contraction; D064170:Paraspinal Muscles / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult