title: Reduced Current Spread by Concentric Electrodes in Transcranial Electrical Stimulation (tES).
abstract: We propose the use of a new montage for transcranial direct current stimulation (tDCS), called concentric electrodes tDCS (CE-tDCS), involving two concentric round electrodes that may improve stimulation focality.
  
  
  
  To test efficacy and focality of CE-tDCS, we modelled the current distribution and tested physiological effects on cortical excitability. Motor evoked potentials (MEPs) from first dorsal interosseous (FDI) and abductor digiti minimi (ADM) were recorded before and after the delivery of anodal, cathodal and sham stimulation on the FDI hotspot for 10 minutes.
  
  
  
  MEP amplitude of FDI increased after anodal-tDCS and decreased after cathodal-tDCS, supporting the efficacy of CE-tDCS in modulating cortical excitability. Moreover, modelled current distribution and no significant effects of stimulation on MEP amplitude of ADM suggest high focality of CE-tDCS.
  
  
  
  CE-tDCS may allow a better control of current distribution and may represent a novel tool for applying tDCS and other transcranial current stimulation approaches.
authors.affiliation: Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenfratelli, Brescia, Italy. Electronic address: marta.bortoletto@cognitiveneuroscience.it.
authors.forename: M
authors.initials: M
authors.lastname: Bortoletto
authors.affiliation: Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenfratelli, Brescia, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Rodella
authors.affiliation: Institute of Biophysics and Biomedical Engineering (IBEB), Faculdade de Ciências, Universidade de Lisboa, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Salvador
authors.affiliation: Institute of Biophysics and Biomedical Engineering (IBEB), Faculdade de Ciências, Universidade de Lisboa, Portugal.
authors.forename: P C
authors.initials: PC
authors.lastname: Miranda
authors.affiliation: Cognitive Neuroscience Section, IRCCS Centro San Giovanni di Dio Fatebenfratelli, Brescia, Italy; Neuroscience section, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Miniussi
mesh_terms: D000328:Adult; D004566:Electrodes; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Electric field; Electrode shape; Focality; Modelling; Motor cortex; Motor evoked potentials; Transcranial direct current stimulation; tDCS; tES montage