Marom Bikson on EEG guided tES / TDCS

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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

Transcript of Marom Bikson on EEG guided tES / TDCS

Page 1: Marom Bikson on EEG guided tES / TDCS

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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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)

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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

+-

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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…

Page 5: Marom Bikson on EEG guided tES / TDCS

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

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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

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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

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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

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“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

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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

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“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

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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

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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

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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

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What target?

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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

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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

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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

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Single dipole – Basic scalp-space inversion S

calp

P

ote

nti

al

(v)

Bra

in E

lectr

ic

Fie

ld

(v/m

)

Local dipole

Source

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Single dipole – Basic scalp-space inversion S

calp

P

ote

nti

al

(v)

Bra

in E

lectr

ic

Fie

ld

(v/m

)

Local dipole

Source Voltage inversion

Voltage to current

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Single dipole – Laplacian inversion V

oltage

to c

urr

ent

Lapla

cia

nCurrent source density at each electrode, apply that current (exclude borders)

256 128 64 32 16 8Number electrodes

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Single dipole – Two HD electrodesS

calp

P

ote

nti

al

(v)

Bra

in E

lectr

ic

Fie

ld

(v/m

)

Local dipole

Source Ad hoc position

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Single dipole – Two HD electrodesS

calp

P

ote

nti

al

(v)

Bra

in E

lectr

ic

Fie

ld

(v/m

)

Local dipole

Source Ad hoc position

At laplacian peaks

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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

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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

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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

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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.

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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

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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.

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“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

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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