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Y P O C Behavioral Intervention Research T using tDCS O N - PowerPoint PPT Presentation

Dec 20, 2023 •436 likes •1.38k views

Y P O C Behavioral Intervention Research T using tDCS O N What to think about? O What guesses do we make? D What do we know and what dont we? Disclosure Y P Scientific Advisory Board Member for O Neuronix, Nexstim, Neosync,

  1. Y P O C Behavioral Intervention Research T using tDCS O N What to think about? O What guesses do we make? D What do we know and what don’t we?

  2. Disclosure Y P • Scientific Advisory Board Member for O Neuronix, Nexstim, Neosync, Starlab, C Neuroelectrics, Neurostim, Magstim, Axilium T • Serve on Device Expert Panel at FDA O • Funding from National Institutes of Health, N National Science Foundation, Michael J Fox O Foundation, Sidney-Baer Foundation, various D other private Foundations • I will talk about off-label applications of tCS

  3. Dylan Edwards Y P O C T O N O D

  4. Dylan Edwards Y P O C T O N O D

  5. Dylan Edwards Y P O C T O N O D

  6. tCS in Behavioral Research Y P • Why do tCS? O • When do tCS? C • For how long to do tCS? T • How to do tCS? O – How much? N – With what electrode arrangements? O – What electrode size? D

  7. Anodal or Cathodal tCS ? Y P Extra- Cephalic O Cephalic Reference C Reference + + T O N - O - D

  8. Anodal or Cathodal tCS ? Y P O Multiple C “Exit” Electrodes T O N O D Nearly Monopolar Stimulation

  9. Anodal or Cathodal tCS ? Y P O C T O We have a nomenclature problem !! N Do not be fooled by it !! O D

  10. What is tES dose? Y Transcranial Electrical Stimulaiton (tES ) dose is defined by all Y P parameters of the stimulation device that affect the current flow generated in the brain : O X C 1. Electrode Montage : number, shape, size, position. 2. Waveform : Current waveform parameters: pulse width, T amplitude, polarity, repetition frequency; and interval between O stimulation sessions and total number of sessions. N tDCS: Direct Current O Nomenclature defined : Guleyupoglu, Bikson et al. Classification of D Y methods in transcranial electrical stimulation (tES). J Neurosci Methods 2013; 219(2) 287-311 Dose defined : Peterchev, Bikson et al. Fundamentals of transcranial X electric and magnetic stimulation dose: Definition, selection, and reporting practices. Brain Stimulation 2012; (5) 435-53

  11. tDCS dose: Waveform Intensity (mA), Duration (minutes) Ramp (e.g. LTE), repetition… Y P O 2 mA Current intensity Anode (1 mA, 20 min) 30 min) C Cathode (-1 mA, 20 min) 30 min) T -2 mA O N Time Outcome (behavior) + O Linear dose-reponse D - + Intensity -

  12. tDCS dose: Waveform Intensity (mA), Duration (minutes) Ramp (e.g. LTE), repetition… Y P O 2 mA Current intensity Anode (1 mA, 20 min) 30 min) C Cathode (-1 mA, 20 min) 30 min) T -2 mA O N Time Outcome (behavior) + O Non-linear dose-reponse D (none-monotonic) - + Intensity -

  13. tDCS dose: Electrode montage Materials, High-Definition… Number, position, and shape. Y P O C T O N Extra-cephalic 5x5 cm, M1 (anode), “Lateralized” Montage Montage O SO (cathode) D ….

  14. tDCS dose: Electrode montage Materials, High-Definition… Number, position, and shape. Y P (!) Electrode design and preperation is the most important factor for consistent set-up, tolerability, and safety O C • Pad fluid leak (e.g. pressure, view T obstructed) O • Dry out (e.g. pad material, view N obstructed) O • Pad re-use (contamination) D • Critical with High-Definition electrodes (but cannot be ignored with pads)

  15. tDCS dose Y ? P O - C + + + - T O N Simple Goal: To increase excitability in cortex under the anode and decrease excitability under the cathode O (ignore rest of brain) D (!) There is a biophysical basis for polarity specific exctiability changes. But, this simple dose approach is NOT supported by engineering design (or much clinical testing)

  16. Getting from tDCS dose to brain current flow Y P Computational models predict the current Pharmacologic activity Clinical dose is set by O (efficacy and safety) is systemic application flow generated in the brain for a specific C determined by drug (tablets…) stimulation configuration/settings concentration at tissue T O N Electrical activity (efficacy tDCS dose is set by surface and safety) is determined by application (stimulators and O current flow at tissue pads/coils) D

  17. Computational models predict brain current flow Y • Two pad electrodes placed on head and connected to DC P current stimulator. O • Current passed between ANODE(+) and CATHODE(-) • DC CURRENT FLOW across cortex. C • Current is INWARD under ANODE and OUTWARD under CATHODE T Brain current Brain current O intensity direction N O D MRI derived computational model

  18. Individual variability of tDCS: anatomy Truong et. al. Neuroimage Clinical 2013 D Y P O C T O N • Evaluated range of conventional and HD tDCS montages O • Male/female, super-obese/low-BMI… D • Considered magnitude of peak current in brain • Location of peak current inside brain • Maximum stimulator voltage (safety) • Current density at scalp (sensation)

  19. tDCS in children Kessler Dosage considerations for transcranial direct current stimulation in E Y children: a computational modeling study. PLoS One 2013 P O C T O N O D

  20. Y P O C T O N O D

  21. What do we know? Y P • Does not lead to neuronal firing O – Purely modulatory C – Combination with other interventions • Does change firing rate likelihood of neuronal ensembles T – Polarity dependent O – Neuronal network impact N – Shifts oscillatory brain activity O • Bipolar D – Both anode and cathode have an effect – Entry and exit electrodes – Can be ‘almost monopolar’

  22. Neurons? Which ones? Y P O C T O N O D • Pyramidal Neurons? • Glia? • Axon hillocks? • Dendritic branches?

  23. Neurons? Which ones? Y + P O C T O N O D

  24. Theory of neuron polarization by tDCS Y P O C T Current flow outward inward O N O D

  25. Theory of neuron polarization by tDCS Y P O Head Surface C T Current flow outward inward O Cortical Neuron N O D

  26. Theory of neuron polarization by tDCS Y P O Head Surface C T Current flow Current Hyperpolarized cell Flow outward inward O compartments N O Depolarized cell D compartments ? Increased Excitability / Plasticity

  27. Theory of neuron polarization by tDCS Y P O Head Surface C T Current flow Current Depolarized cell Flow outward inward O compartments N O Hyper-polarized cell D compartments Decreased Excitability / Plasticity

  28. Modulation of “excitability” under DCS Y Depolarized soma P Increased O Excitability / C Plasticity T Current flow outward inward O Hyperpolarized soma N Decreased O Excitability / Plasticity D

  29. Y P O C T O N O D

  30. tDCS modifies MEP’s Y P O C T O N O D

  31. Can tDCS modify other ‘behaviors’ ? Y P O C Did it T feel the O same? N O D What brain region helps respond to that question? Beware of circular ‘experimental designs’

  32. Brain Behavior Relations Y Genetic Defect Environmental Factors Acquired Insult P O C Pathology T Brain Adaptation/ Compensation Change in Cognitive Strategy O N O Pattern of Brain Activity D Behavior Symptoms of Disease

  33. Neurons or Networks ? Y P O 10 12 Neurons C 10 4 Connections T per neuron O 10 18 Synapses N O D

  34. Modulating Brain’s Intrinsic Activity with tDCS Y P O C T O N O D

  35. Modulating Brain’s Intrinsic Activity with tDCS Y P O C T O N O D

  36. Modulating Brain’s Intrinsic Activity with tDCS Y P O C T O N O D

  37. Y P O C T O N O D

  38. Y P O C T O N O D

  39. Targeting brain patterns (& Y oscillations) with tDCS / tACS P O C T O N O D Rs-fcMRI with Subgenual Simulated E field Collaboration with Giulio Ruffini and StarStim

  40. What do we know? Y P • Safe if done correctly O • Easy to apply DEPENDS ON DOSE !! C • Double blinding possible Davis et al Eur J Neurosci. 2013 T – Subject cannot tell whether anodal or cathodal O – Subject cannot tell whether sustained or transient stim N O Real D Sham

  41. Why do tDCS ? Y P • Modify brain activity during stimulation O and beyond C • Affect behavior T O • Causal relations between brain activity and N behavior • Prime brain activity to ‘enhance’ impact of O behavioral intervention, task performance D

  42. When do tDCS ? Y P • Before – During – After Task O C Task T O Before N Offline O During - Online D After - Offline

  43. For how long to do tDCS ? Y P O C Task T How long does the effect last? O N O D • Membrane effect • Network impact with induction of plastic changes • ? LTP- or LTD-like effects

  44. For how long to do tDCS ? Y P Task Related Changes O in Brain Activity Anticipatory Reflective Brain C Task Preparatory Activity Brain Activity - Consolidation T O N O • Interaction between tDCS and ongoing brain activity in the brain D • Nature of the task may affect the nature of the effects of tDCS • Different tasks may modify tDCS effects differently • More/longer tDCS may not necessarily mean more of the same effect • Physiologic measures in addition to behavioral measures desirable

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