title: Transcranial direct current stimulation: a computer-based human model study.
abstract: OBJECTIVE
  Interest in transcranial direct current stimulation (tDCS) in clinical practice has been growing, however, the knowledge about its efficacy and mechanisms of action remains limited. This paper presents a realistic magnetic resonance imaging (MRI)-derived finite element model of currents applied to the human brain during tDCS.
  
  
  METHODS
  Current density distributions were analyzed in a healthy human head model with varied electrode montages. For each configuration, we calculated the cortical current density distributions. Analogous studies were completed for three pathological models of cortical infarcts.
  
  
  RESULTS
  The current density magnitude maxima injected in the cortex by 1 mA tDCS ranged from 0.77 to 2.00 mA/cm(2). The pathological models revealed that cortical strokes, relative to the non-pathological solutions, can elevate current density maxima and alter their location.
  
  
  CONCLUSIONS
  These results may guide optimized tDCS for application in normal subjects and patients with focal brain lesions.
authors.affiliation: Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA. twagner@mit.edu <twagner@mit.edu>
authors.forename: Tim
authors.initials: T
authors.lastname: Wagner
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.forename: Shirley
authors.initials: S
authors.lastname: Fecteau
authors.forename: Alan
authors.initials: A
authors.lastname: Grodzinsky
authors.forename: Markus
authors.initials: M
authors.lastname: Zahn
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
mesh_terms: D001921:Brain / Q000502:physiology*; D003198:Computer Simulation; D004574:Electromagnetic Fields; D020342:Finite Element Analysis; D006257:Head / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation; D050781:Transcranial Magnetic Stimulation / Q000379:methods*