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Marom Bikson on EEG guided tES / TDCS

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Marom Bikson speaks at the BrainSTIM2015 - Targeting transcranial Electrical Stimulation (tES) using EEG. Includes how to use EEG to inform transcranial Direct Current Stimulation (tDCS) montages. And critical pitfalls in concurrent recording. Stay tuned for our upcoming paper on reciprocity.

The complete video can be found here: https://www.youtube.com/watch?v=yYmDQB7qSCE

The first publication on the topic can be found here http://neuralengr.com/wp-content/uploads/2016/05/2016-Cancelli-A-simple-method.pdf

Related technology can be found here http://soterixmedical.com/research/monitoring/eeg

Published in: Health & Medicine
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Marom Bikson on EEG guided tES / TDCS

  1. 1. July 11, 2015, BrainSTIM 2015 Conference Targeting transcranial Electrical Stimulation using EEG: The scalp space approach Modeling: Lucas Parra, Asif Rahman, Dennis Truong, Jacek Dmochowski, Abhi Datta, Mahtab Alam, Alexander David, Asif Rahman, Maged Elwassif, Salman Shahid, Mohammed Aboseria, Ole Seibt, Andoni Mourdoukoutas Marom Bikson, The City College of New York Electrode Design: Preet Minhas, Johnson Ho, Abhi Datta, Chris Thomas, Varun Bansal, Jinal Patel, Justin Rice, Niranjan Khadka, Vaishali Patel Scalp-Space EEG inversion: Franca Tecchio, Andrea Cancelli, Carlo Cottone “The problem with EEG + TES”: Emily Kappenman, Vladimir Miskovic, Karl Kuntzelman
  2. 2. Disclosure: Soterix Medical Inc. produces tDCS and High-Definition tDCS. Marom Bikson is founder and has shares in Soterix Medical. Some of the clinical data presented may be supported by Soterix Medical Marom Bikson serves on the scientific advisory board of Boston Scientific Inc. Support: NIH (NINDS, NCI, NIBIB), NSF, Epilepsy Foundation, Wallace Coulter Foundation, DoD (USAF, AFOSR)
  3. 3. Transcranial Direct Current Stimulation (tDCS) • Non-invasive, portable, well-tolerated neuromodulation. • Low-intensity (mA) current passed between scalp electrodes. • Tested for cognitive neuroscience and neuropsychiatric treatment. tDCS Publications +-
  4. 4. Transcranial Direct Current Stimulation (tDCS) • Non-invasive, portable, well-tolerated neuromodulation. • Low-intensity (mA) current passed between scalp electrodes. • Tested for cognitive neuroscience and neuropsychiatric treatment. tDCS Publications +- Depression, Pain, Migraine, Epilepsy, PTSD, Schizophrenia, Tinnitus, Neglect, Rehabilitation (motor, aphasia), TBI, OCD, Attention / Vigilance, Accelerated learning (reading, motor skills, math, threat detection), Memory, Creativity, Sleep (SW, Lucid dreaming, Threat detection, Impulsivity, Compassion, Jelousy, Reality Filtering, IQ, Prejudice…
  5. 5. Transcranial Direct Current Stimulation (tDCS) • Non-invasive, portable, well-tolerated neuromodulation. • Low-intensity (mA) current passed between scalp electrodes. • Tested for cognitive neuroscience and neuropsychiatric treatment. tDCS Publications +- Depression, Pain, Migraine, Epilepsy, PTSD, Schizophrenia, Tinnitus, Neglect, Rehabilitation (motor, aphasia), TBI, OCD, Attention / Vigilance, Accelerated learning (reading, motor skills, math, threat detection), Memory, Creativity, Sleep (SW, Lucid dreaming, Threat detection, Impulsivity, Compassion, Jelousy, Reality Filtering, IQ, Prejudice… How do we optimize tDCS for a specific indication and individual
  6. 6. tDCS electrode position on the head determines which regions are stimulated  Current flows from one electrode to the other Truong et al. Clinician accessible tools for GUI computational models. “BONSAI” and “SPHERES”. Brain Stimulation 2014 Zero Max
  7. 7. Extra-cephalic electrode won’t solve the issue of diffuse bi-directional flow  tDCS is deep Datta et al. Electrode montage for tDCS: Role of return electrode. Clinical Neurophysiology 2010
  8. 8. Datta et al. Electrode montage for tDCS: Role of return electrode. Clinical Neurophysiology 2010 Extra-cephalic electrode won’t solve the issue of diffuse bi-directional flow  tDCS is deep
  9. 9. “4x1” montage of High-Definition tDCS Zero Max  Allows targeting of selected cortical regions Datta et al. Gyri-precise model of tDCS: Improved spatial focality using a ring versus conventional pad. Brain Stimulation 2009
  10. 10. Center electrode: CATHODE Center electrode: ANODE Outward current (inhibitory) Inward current (excitatory)  Total of 5 small “HD” electrodes (4+1)  Center electrode over target determines polarity 4 return electrodes - Ring radius determines modulation area “4x1” montage of High-Definition tDCS
  11. 11. “4x1” montage of High-Definition tDCS  2006-2008 Gyri-precise brain models  2008 3rd International Brain Stimulation Conference  2008-09 Publications on Theory  2008-10 Safety (Wassermann et al.)  2012: Experimental Pain (George et al.)  2012 Fibromyalgia (Fregni et al.)  2013 Neuro-plasticity (Nitsche et al.)  2013 Focality Physiology (Edwards et al.)  2015 Cognitive Performance (Loo et al.) Datta et al. Gyri-precise model of tDCS: Improved spatial focality using a ring versus conventional pad. Brain Stimulation 2009
  12. 12. It won’t work because:  The skull is resistive  Current is diffused in the skin and CSF, not skull, and can be controlled inside ring  Prior efforts limited by use of large pads, not by physics Minhas et al. Electrodes for High-Definition transcutaneous DC. J Neuroscience Methods 2010
  13. 13. It won’t work because:  The skull is resistive  Current is diffused in the skin and CSF, not skull, and can be controlled inside ring  Prior efforts limited by use of large pads, not by physics  DC can’t be applied through little electrodes  2008-10 design of High-Definition Electrodes  3cm2 electrode-electrolyte contact area, Ag/AgCl electrodes, high-capacity gel (e.g. Signa), rated 2 mA + 22 minutes Minhas et al. Electrodes for High-Definition transcutaneous DC. J Neuroscience Methods 2010
  14. 14. High-Definition tDCS uses arrays of electrodes to focus current to targets  Without need for “search” there is a single solution given a target (2009-11) Dmochowksi et al. Optimized multi-electrodes stimulation increases focality and intensity at target. J Neural Engr 2011
  15. 15. What target?
  16. 16. Use EEG to guide HD-tDCS targeting (~1978)  Easy – HD easily integrated with any EEG  Individualized – Sure  Automatic – But how? Still Easy?  Real time – Beware
  17. 17. Model driven EEG to HD-tDCS. Easy? 1) Get and process high resolution MRI 2) Conduct high-density EEG 3) Localize sources (assumptions) 4) Run full HD-tDCS optimization using all electrodes
  18. 18. Model driven EEG to HD-tDCS. Easy? 1) Get and process high resolution MRI 2) Conduct high-density EEG 3) Localize sources (assumptions) 4) Run full HD-tDCS optimization using all electrodes Scalp Space EEG to HD-tDCS. Easy. 1) Conduct EEG 2) Scalp Space Inversion with no scans, no source assumptions, easy math 3) HD-tDCS with minimal electrodes
  19. 19. Single dipole – Basic scalp-space inversion Scalp Potential(v) BrainElectric Field(v/m) Local dipole Source
  20. 20. Single dipole – Basic scalp-space inversion Scalp Potential(v) BrainElectric Field(v/m) Local dipole Source Voltage inversion Voltage to current
  21. 21. Single dipole – Laplacian inversionVoltage tocurrentLaplacian Current source density at each electrode, apply that current (exclude borders) 256 128 64 32 16 8 Number electrodes
  22. 22. Single dipole – Two HD electrodes Scalp Potential(v) BrainElectric Field(v/m) Local dipole Source Ad hoc position
  23. 23. Single dipole – Two HD electrodes Scalp Potential(v) BrainElectric Field(v/m) Local dipole Source Ad hoc position At laplacian peaks
  24. 24. 2 Electrode: Ad-Hoc / Model-Based Placement Close Electrodes Distant Electrodes Off-angle Electrodes Targeted (focused current flow) but low intensity in brain Diffuse across brain but high intensity Current flow orientation along target key Dmochowksi et al. Optimized multi-electrodes stimulation increases focality and intensity at target. J Neural Engr 2011
  25. 25. Scalp-Space EEG to HD-tDCS Method 1) Collect EEG 2) Laplacian at all channels 3) 2 HD electrodes at MAX and MIN Outcome 1) Direction of current flow at source matched 2) Balance between targeting and intensity 3) Simple
  26. 26. Scalp-Space EEG to HD-tDCS Method 1) Collect EEG 2) Laplacian at all channels 3a) If bipolar: 2 HD electrodes at MAX and MIN 3b) If unipolar: 4x1 HD-tDCS over MAX/MIN Outcome 1) Direction of current flow at source matched 2) Balance between targeting and intensity 3) Simple
  27. 27. The problem with concurrent tDCS and EEG • No stimulation source is perfect. Noise limits signal change size detectable. Must be reported. • Stimulation alters tissue conductivity, most evident in scalp erythema. Will alter detection of EEG in a montage + time specific fashion. • Stimulation effects amplifiers. Volts can drive non-linear performance (e.g. filtering) in a montage + time specific fashion. Active head-stages, DRL… • Physiologic artifacts. Eye-blink artifact, retinal sensitivity, EKG… • Electrode distortion. Electrochemical change in impedance. When same one used. Kappenman et al. The problem with concurrent tES and EEG.
  28. 28. The problem with concurrent tDCS and EEG Kappenman et al. The problem with concurrent tES and EEG. • No stimulation source is perfect. Noise limits signal change size detectable. Must be reported. • Stimulation alters tissue conductivity, most evident in scalp erythema. Will alter detection of EEG in a montage + time specific fashion. • Stimulation effects amplifiers. Volts can drive non-linear performance (e.g. filtering) in a montage + time specific fashion. Active head-stages, DRL… • Physiologic artifacts. Eye-blink artifact, retinal sensitivity, EKG… • Electrode distortion. Electrochemical change in impedance. When same one used. Not systematically addressing all these issues, in a trial specific fashion, leads to meaningless data
  29. 29. Take home messages 1) tDCS can be focal at cortex using 4x1 (2008). 2) HD electrodes needed for tolerability (2008). 3) Given MRI + target: optimization “solved” (2011). 4) Simple inversion of EEG to HD-tDCS fails. 5) Scalp Space-Inversion provides simple targeting without need for MRI. 6) Limited EEG and only few HD electrodes needed: Bipolar or 4x1 montage. 7) Concurrent EEG + tDCS problematic.
  30. 30. “Functional Sets” of HD electrodes  Set of HD electrodes that share a total current  Bain current flow does not depend on the relative current split of between electrode within function set  Skin current density is reduced
  31. 31. July 11, 2015, BrainSTIM 2015 Conference Targeting transcranial Electrical Stimulation using EEG: The scalp space approach Modeling: Lucas Parra, Asif Rahman, Dennis Truong, Jacek Dmochowski, Abhi Datta, Mahtab Alam, Alexander David, Asif Rahman, Maged Elwassif, Salman Shahid, Mohammed Aboseria, Ole Seibt, Andoni Mourdoukoutas Marom Bikson, The City College of New York Electrode Design: Preet Minhas, Johnson Ho, Abhi Datta, Chris Thomas, Varun Bansal, Jinal Patel, Justin Rice, Niranjan Khadka, Vaishali Patel Scalp-Space EEG inversion: Franca Tecchio, Andrea Cancelli, Carlo Cottone “The problem with EEG + TES”: Emily Kappenman, Vladimir Miskovic, Karl Kuntzelman

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