title: Spinal Direct Current Stimulation Modulates Short Intracortical Inhibition.
abstract: OBJECTIVE
  Transcutaneous spinal direct current stimulation (tsDCS) is a new and safe technique for modulating spinal cord excitability. We assessed changes in intracortical excitability following tsDCS by evaluating changes in cortical silent period (cSP), paired-pulse short intracortical inhibition (SICI), and intracortical facilitation (ICF).
  
  
  METHODS
  Healthy subjects were studied before (T0) and at different intervals (T1 and T2) after anodal, cathodal, and sham tsDCS (20', 2.0 mA) applied over the thoracic spinal cord (T10-T12). We assessed changes in cSP, SICI (interstimulus interval, ISI = 3 ms) and ICF (ISI = 10 ms). Motor-evoked potentials (MEPs) were recorded from first digital interosseus (FDI) and tibialis anterior (TA) muscles.
  
  
  RESULTS
  Cathodal tsDCS increased MEP amplitudes at interstimulus interval of 3 ms, while anodal one elicited opposite effects (FDI: p = 0.0023; TA: p = 0.0004); conversely, tsDCS left MEP amplitudes unchanged at ISI of 10 ms (FDI: p = 0.39; TA: p = 0.45). No significant change in cSP duration was found from upper limb (p = 0.81) and lower limb (p = 0.33).
  
  
  CONCLUSIONS
  tsDCS modulates inhibitory GABA(A)ergic drive, as assessed by SICI, without interfering with cSP and ICF. The possibility to interfere with cortical processing makes tsDCS a useful approach to modulate spinal drive through nonspinal mechanisms. tsDCS could also represent an early rehabilitation strategy in patients with acute brain lesions, when other noninvasive brain stimulation (NIBS) tools are not indicated due to safety concerns, as well as in the treatment of spinal diseases or pain syndromes.
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University Medical School, Pisa, Italy.|Department of Neurological and Neurosensorial Sciences, Neurology and Clinical Neurophysiology Section, Brain Investigation and Neuromodulation Lab., Azienda Ospedaliera Universitaria Senese, Siena, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Bocci
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University Medical School, Pisa, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Barloscio
authors.affiliation: Department of Neurological Sciences, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Vergari
authors.affiliation: Department of Clinical and Experimental Medicine, Cisanello Neurology Unit, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Di Rollo
authors.affiliation: Department of Neurological and Neurosensorial Sciences, Neurology and Clinical Neurophysiology Section, Brain Investigation and Neuromodulation Lab., Azienda Ospedaliera Universitaria Senese, Siena, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Rossi
authors.affiliation: Department of Neurological Sciences, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Priori
authors.affiliation: Department of Clinical and Experimental Medicine, Unit of Neurology, Pisa University Medical School, Pisa, Italy.|Department of Clinical and Experimental Medicine, Cisanello Neurology Unit, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy.|CNR Neuroscience Institute, Pisa, Italy.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Sartucci
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Cortical silent period; motor system; short intracortical facilitation; short intracortical inhibition; transcutaneous spinal direct current stimulation; tsDCS