title: Inter-Individual Variation during Transcranial Direct Current Stimulation and Normalization of Dose Using MRI-Derived Computational Models.
abstract: BACKGROUND
  Transcranial Direct Current Stimulation (tDCS) is a non-invasive, versatile, and safe neuromodulation technology under investigation for the treatment of neuropsychiatric disorders, adjunct to rehabilitation, and cognitive enhancement in healthy adults. Despite promising results, there is variability in responsiveness. One potential source of variability is the intensity of current delivered to the brain which is a function of both the operator controlled tDCS dose (electrode montage and total applied current) and subject specific anatomy. We are interested in both the scale of this variability across anatomical typical adults and methods to normalize inter-individual variation by customizing tDCS dose. Computational FEM simulations are a standard technique to predict brain current flow during tDCS and can be based on subject specific anatomical MRI.
  
  
  OBJECTIVE
  To investigate this variability, we modeled multiple tDCS montages across three adults (ages 34-41, one female).
  
  
  RESULTS
  Conventional pad stimulation led to diffuse modulation with maximum current flow between the pads across all subjects. There was high current flow directly under the pad for one subject while the location of peak induced cortical current flow was variable. The High-Definition tDCS montage led to current flow restricted to within the ring perimeter across all subjects. The current flow profile across all subjects and montages was influenced by details in cortical gyri/sulci.
  
  
  CONCLUSIONS
  This data suggests that subject specific modeling can facilitate consistent and more efficacious tDCS.
authors.affiliation: Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of City University of New York New York, NY, USA ; Soterix Medical New York, NY, USA.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Datta
authors.forename: Dennis
authors.initials: D
authors.lastname: Truong
authors.forename: Preet
authors.initials: P
authors.lastname: Minhas
authors.forename: Lucas C
authors.initials: LC
authors.lastname: Parra
authors.forename: Marom
authors.initials: M
authors.lastname: Bikson
keywords: HD-tDCS; TMS; head model; tACS; tDCS; transcranial electrical stimulation