title: Cortical inhibition and excitation by bilateral transcranial alternating current stimulation.
abstract: OBJECTIVE
  Transcranial electric stimulations (tES) with amplitude-modulated currents are promising tools to enhance neuromodulation effects. It is essential to select the correct cortical targets and inhibitory/excitatory protocols to reverse changes in specific networks. We aimed at assessing the dependence of cortical excitability changes on the current amplitude of 20 Hz transcranial alternating current stimulation (tACS) over the bilateral primary motor cortex.
  
  
  METHODS
  We chose two amplitude ranges of the stimulations, around 25 μA/cm2 and 63 μA/cm2 from peak to peak, with three values (at steps of about 2.5%) around each, to generate, respectively, inhibitory and excitatory effects of the primary motor cortex. We checked such changes online through transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs).
  
  
  RESULTS
  Cortical excitability changes depended upon current density (p = 0.001). Low current densities decreased MEP amplitudes (inhibition) while high current densities increased them (excitation).
  
  
  CONCLUSIONS
  tACS targeting bilateral homologous cortical areas can induce online inhibition or excitation as a function of the current density.
authors.affiliation: Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, at Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy Institute of Neurology, Department of Geriatrics, Neurosciences & Orthopaedics, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cancelli
authors.affiliation: Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, at Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy Department of Neuroscience and Imaging, G. d'Annunzio University of Chieti - Pescara, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Cottone
authors.affiliation: Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, at Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy Department of Clinical Neuroscience, Fatebenefratelli Hospital, Rome, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Zito
authors.affiliation: Department of Clinical Neuroscience, Fatebenefratelli Hospital, Rome, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Di Giorgio
authors.affiliation: Medical Statistics and Information Technology, Fatebenefratelli Foundation for Health Research and Education, AFaR Division, Rome, Italy Unit of Neuroimaging, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Patrizio
authors.initials: P
authors.lastname: Pasqualetti
authors.affiliation: Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, at Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy Unit of Neuroimaging, IRCCS San Raffaele Pisana, Rome, Italy.
authors.forename: Franca
authors.initials: F
authors.lastname: Tecchio
mesh_terms: D000328:Adult; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D050781:Transcranial Magnetic Stimulation
keywords: Neuromodulation; motor cortex (M1); neuronavigation; personalized electrode; superficial current density; transcranial alternating current stimulation (tACS)