Validation of finite element model of transcranial electrical stimulation using scalp potentials: implications for clinical dose

OBJECTIVE During transcranial electrical stimulation, current passage across the scalp generates voltage across the scalp surface. The goal was to characterize these scalp voltages for the purpose of validating subject-specific finite element method (FEM) models of current flow. APPROACH Using a recording electrode array, we mapped skin voltages resulting from low-intensity transcranial electrical stimulation. These voltage recordings were used to compare the predictions obtained from the high-resolution model based on the subject undergoing transcranial stimulation. MAIN RESULTS Each of the four stimulation electrode configurations tested resulted in a distinct distribution of scalp voltages; these spatial maps were linear with applied current amplitude (0.1 to 1 mA) over low frequencies (1 to 10 Hz). The FEM model accurately predicted the distinct voltage distributions and correlated the induced scalp voltages with current flow through cortex. SIGNIFICANCE Our results provide the first direct model validation for these subject-specific modeling approaches. In addition, the monitoring of scalp voltages may be used to verify electrode placement to increase transcranial electrical stimulation safety and reproducibility.

[1]  M. Hallett,et al.  A theoretical comparison of electric and magnetic stimulation of the brain , 2006, Annals of Biomedical Engineering.

[2]  Lior Horesh,et al.  Design of electrodes and current limits for low frequency electrical impedance tomography of the brain , 2007, Medical & Biological Engineering & Computing.

[3]  Won Hee Lee,et al.  Reduced spatial focality of electrical field in tDCS with ring electrodes due to tissue anisotropy , 2010, 2010 Annual International Conference of the IEEE Engineering in Medicine and Biology.

[4]  R. Salvador,et al.  Modeling the electric field induced in a high resolution realistic head model during transcranial current stimulation , 2010, 2010 Annual International Conference of the IEEE Engineering in Medicine and Biology.

[5]  Julie M. Baker,et al.  Individualized model predicts brain current flow during transcranial direct-current stimulation treatment in responsive stroke patient , 2011, Brain Stimulation.

[6]  A. Tarakanova,et al.  Molecular modeling of protein materials: case study of elastin , 2013 .

[7]  David Atkinson,et al.  Use of anisotropic modelling in electrical impedance tomography; Description of method and preliminary assessment of utility in imaging brain function in the adult human head , 2008, NeuroImage.

[8]  M Crawford,et al.  Transcranial electrical stimulation of the motor cortex in man: further evidence for the site of activation. , 1994, The Journal of physiology.

[9]  Abhishek Datta,et al.  Transcranial DC stimulation in fibromyalgia: optimized cortical target supported by high-resolution computational models. , 2011, The journal of pain : official journal of the American Pain Society.

[10]  M. Hallett,et al.  A finite element analysis of the effect of electrode area and inter-electrode distance on the spatial distribution of the current density in tDCS , 2011, Journal of neural engineering.

[11]  R. E. Barr,et al.  Quantitative analysis of the electroencephalogram during cranial electrotherapy stimulation , 2001, Clinical Neurophysiology.

[12]  L. Parra,et al.  Optimized multi-electrode stimulation increases focality and intensity at target , 2011, Journal of neural engineering.

[13]  A Tizzard,et al.  Solving the forward problem in electrical impedance tomography for the human head using IDEAS (integrated design engineering analysis software), a finite element modelling tool , 2001, Physiological measurement.

[14]  W. Paulus,et al.  Transcranial direct current stimulation (tDCS). , 2003, Supplements to Clinical neurophysiology.

[15]  D S Holder,et al.  A modelling study to inform specification and optimal electrode placement for imaging of neuronal depolarization during visual evoked responses by electrical and magnetic detection impedance tomography , 2009, Physiological measurement.

[16]  Abhishek Datta,et al.  High‐Resolution Modeling Assisted Design of Customized and Individualized Transcranial Direct Current Stimulation Protocols , 2012, Neuromodulation : journal of the International Neuromodulation Society.

[17]  M. Hallett,et al.  Modeling the current distribution during transcranial direct current stimulation , 2006, Clinical Neurophysiology.

[18]  Rosalind J. Sadleir,et al.  Transcranial direct current stimulation (tDCS) in a realistic head model , 2010, NeuroImage.

[19]  C. Im,et al.  Evaluation of local electric fields generated by transcranial direct current stimulation with an extracephalic reference electrode based on realistic 3D body modeling , 2012, Physics in Medicine and Biology.

[20]  Markus Zahn,et al.  Transcranial direct current stimulation: A computer-based human model study , 2007, NeuroImage.

[21]  Warren M Grill,et al.  Analysis of the quasi-static approximation for calculating potentials generated by neural stimulation , 2008, Journal of neural engineering.

[22]  J. Yager Electroconvulsive Therapy for Unipolar and Bipolar Depressions , 2010 .

[23]  Arnaud Delorme,et al.  EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis , 2004, Journal of Neuroscience Methods.

[24]  Stephen M. Smith,et al.  Segmentation of brain MR images through a hidden Markov random field model and the expectation-maximization algorithm , 2001, IEEE Transactions on Medical Imaging.

[25]  F. X. Bostick,et al.  Potential and current density distributions of cranial electrotherapy stimulation (CES) in a four-concentric-spheres model , 1996, IEEE Transactions on Biomedical Engineering.

[26]  Alexander Opitz,et al.  Electric field calculations in brain stimulation based on finite elements: An optimized processing pipeline for the generation and usage of accurate individual head models , 2013, Human brain mapping.

[27]  Abhishek Datta,et al.  tDCS‐Induced Analgesia and Electrical Fields in Pain‐Related Neural Networks in Chronic Migraine , 2012, Headache.

[28]  Stephen M Smith,et al.  Fast robust automated brain extraction , 2002, Human brain mapping.

[29]  D. A. Driscoll,et al.  Current Distribution in the Brain From Surface Electrodes , 1968, Anesthesia and analgesia.

[30]  Abhishek Datta,et al.  Cranial electrotherapy stimulation and transcranial pulsed current stimulation: A computer based high-resolution modeling study , 2013, NeuroImage.

[31]  S. Reeves,et al.  A pilot study of the tolerability and effects of high-definition transcranial direct current stimulation (HD-tDCS) on pain perception. , 2011, The journal of pain : official journal of the American Pain Society.

[32]  Abhishek Datta,et al.  Imaging artifacts induced by electrical stimulation during conventional fMRI of the brain , 2014, NeuroImage.

[33]  W Harris,et al.  "Threshold-level" multipulse transcranial electrical stimulation of motor cortex for intraoperative monitoring of spinal motor tracts: description of method and comparison to somatosensory evoked potential monitoring. , 1998, Journal of neurosurgery.

[34]  Mark M. Stecker,et al.  Transcranial electric stimulation of motor pathways: a theoretical analysis , 2005, Comput. Biol. Medicine.

[35]  M. Bikson,et al.  Transcranial current stimulation focality using disc and ring electrode configurations: FEM analysis , 2008, Journal of neural engineering.

[36]  Alessia Paglialonga,et al.  Transcranial Direct Current Stimulation: Estimation of the Electric Field and of the Current Density in an Anatomical Human Head Model , 2011, IEEE Transactions on Biomedical Engineering.

[37]  L. Parra,et al.  Inter-Individual Variation during Transcranial Direct Current Stimulation and Normalization of Dose Using MRI-Derived Computational Models , 2012, Front. Psychiatry.

[38]  M. Bikson,et al.  Electrodes for high-definition transcutaneous DC stimulation for applications in drug delivery and electrotherapy, including tDCS , 2010, Journal of Neuroscience Methods.

[39]  Vincent Walsh,et al.  Frequency-Dependent Electrical Stimulation of the Visual Cortex , 2008, Current Biology.

[40]  Richard H. Bayford,et al.  Three-Dimensional Electrical Impedance Tomography of Human Brain Activity , 2001, NeuroImage.

[41]  Serafetinides Ea,et al.  Intracerebral current levels in man during electrosleep therapy. , 1975 .

[42]  M. Bikson,et al.  Electrode montages for tDCS and weak transcranial electrical stimulation: Role of “return” electrode’s position and size , 2010, Clinical Neurophysiology.

[43]  J. Born,et al.  Boosting slow oscillations during sleep potentiates memory , 2006, Nature.

[44]  Martin Schuettler,et al.  A novel method for recording neuronal depolarization with recording at 125–825 Hz: implications for imaging fast neural activity in the brain with electrical impedance tomography , 2011, Medical & Biological Engineering & Computing.

[45]  D. Reato,et al.  Gyri-precise head model of transcranial direct current stimulation: Improved spatial focality using a ring electrode versus conventional rectangular pad , 2009, Brain Stimulation.

[46]  Sergio P. Rigonatti,et al.  Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory , 2005, Experimental Brain Research.

[47]  M. Nitsche,et al.  Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation , 2000, The Journal of physiology.

[48]  Abhishek Datta,et al.  Neuroplastic changes following rehabilitative training correlate with regional electrical field induced with tDCS , 2011, NeuroImage.

[49]  Abhishek Datta,et al.  Guidelines for precise and accurate computational models of tDCS , 2012, Brain Stimulation.

[50]  David S. Holder,et al.  Impedance changes recorded with scalp electrodes during visual evoked responses: Implications for Electrical Impedance Tomography of fast neural activity , 2009, NeuroImage.

[51]  A. Antal,et al.  Comparatively weak after-effects of transcranial alternating current stimulation (tACS) on cortical excitability in humans , 2008, Brain Stimulation.

[52]  Marc Modat,et al.  A method for rapid production of subject specific finite element meshes for electrical impedance tomography of the human head , 2012, Physiological measurement.

[53]  Sarah H Lisanby,et al.  Electroconvulsive therapy for depression. , 2007, The New England journal of medicine.