tCS and EEG Faranak Farzan, PhD Assistant Professor, Simon Fraser - PowerPoint PPT Presentation

tCS and EEG Faranak Farzan, PhD Assistant Professor, Simon Fraser University Chair in Technology Innovations for Youth Addiction Recovery and Mental Health Email: ffarzan@sfu.ca 1

y p o C Why & How t o N o D

Where Did It All Begin? Torpedo Fish y 46 AD p o C t o N o D http://www.painbytes.com/images/History/Electroanalgesia/EAFig.png 8 to 220 volts Guess Game: Maximum Voltage a Torpedo Fish Can Generate? 3

Galvanism y 46 AD Late 1700s p Galvani Le Roy o C t o N o D Luigi Galvani Late 18 th century founder of Charles Le Roy bioelectromagnetics Treating blind with famous for his animal electricity experiments 4 1755

Galvanism 46 AD Late 1700s y Galvani p Giovanni Aldini Le Roy o 1804: First report of electricity for treating psychosis and melancholia C t o N o D Aldini’s Showmanship 5 DC current stimulation mostly ignored in scientific community

Today… y p o 1982 46 AD 1900s Late 1700s 1800s Anthony Barker Thompson Galvani Faraday C Reza Jalinous Kolin D’Arsonval Le Roy Ian Freeston t o N tDCS ECT MST tACs TMS TES o 2000 2008 2000 1934 1980 1985 D Antal Nitsche Paulus 6

tCS Application y • Basic & Cognitive Neuroscience p o C • Intervene with a function to examine causality t o N • Clinical Application • Depression o D • Pain • Addiction • ADHD

y p o C Mechanism of Action? t o N o D

tCS Outcome? Nitsche & Paulus, 2000 : Changes in cortical excitability in humans y demonstrated using TMS Motor-Evoked Potentials (MEP)s as a metric p o C t o N o D Peak-to-Peak Motor Evoked Amplitude 1 mV Potentials Latency 20 ms

tCS Outcome? Nitsche et al, 2003: After 5 or 7 minutes of stimulation MEP amplitudes y return to baseline within a few minutes. After 9 minutes, effects last for at least p 60 minutes. o C t o N o D Peak-to-Peak Motor Evoked Amplitude 1 mV Potentials Latency 20 ms

tCS Outcome? Kuo et al, 2012: 4x1 ring tDCS stimulates a y smaller area, but the p resulting change in cortical o excitability is dramatically C different t o N o D Peak-to-Peak Motor Evoked Amplitude 1 mV Potentials Latency 20 ms

tCS Outcome Depends on Many Factors y p o C • Stimulation Parameters • Duration of stimulation t o • Number of electrodes N • Electrode size and shape o • Electrode positions D • Current intensity • Brain State

Where, When and How Matters … y p o C t o N o D Bergmann et al., 2016

tCS-Induced Outcomes? We know relatively little about the neurophysiological y mechanisms in humans; little we know about local effect, and p much less about the network effect; Difficulty tailoring its o parameters for desired impact. C t o N Brain Recording to Rescue? o D Peak-to-Peak Amplitude Motor Evoked 1 mV Potentials Latency 20 ms

Brain Recording? EEG, fMR, PET, DTI, … y p o C t o N http://www.nature.com/scitable/content/ion-channels-14615258 o A change in membrane EPSP + IPSP generated by D potential, release of synchronous activity of neurotransmitters, change in neurons. Interplay between concentration of ions channels excitatory pyramidal neurons may change the state of and inhibitory interneurons. membrane channels and give rise to an oscillatory activity.

Added Value of tCS+EEG EEG may tell us about: Excitability of cortical tissue; y excitation/inhibition balance; brain state; the integrity of local p and distributed networks. o 1- Detailed understanding of the tCS-induced effect on neural activity C o To not fall for the “circular experimental results/conclusions” o Examine both local and network effects in humans, non-invasively t o 2- Monitor brain state N o Brain state influences the tCS effect o Improve tCS protocols considering brain state dynamics o o By monitoring dynamical state , design closed-loop systems D 3- Guide the tCS input parameters o An infinite number of stimulation parameters to choose from o Guide the Location, Stimulation Parameters, Time of Delivery More efficacious treatments Better understanding of brain-behavior relationship

y p o C t o N o Retrieved from: http://3.bp.blogspot.com/_- sFohRgxOBI/RiH4NDo37zI/AAAAAAAAAG8/ZwS5CBfB3qI/ D s320/Married+couple+fighting.jpg TCS + EEG

System Diagram for Designing tCS+EEG Studies y p o C t o N o D

tCS+EEG Approaches y p • Offline Stop tCS Record EEG Stop EEG o Record EEG (Rest/+Event) Apply tCS (Rest/+Event) C t o Record EEG Stop tCS • Online Record EEG N & Record EEG (Rest/+Event) Apply tCS (Rest/+Event) o D • EEG-Guided (Online or Offline) Apply tCS Stop tCS Record EEG guided by Record EEG (Rest/+Event) EEG (Rest/+Event)

y p o C EEG Signal Processing t o N o D

EEG: History Berger’s Waves y p o C t o N o D EEG in humans introduced by Hans Berger in 1920s

EEG: Language y p o Delta (1-3Hz) C t o Theta (4-7Hz) N Alpha (8-12Hz) o D Beta (12-28Hz) Gamma (30Hz+) F

EEG language y p o Amplitude (or Power) Strength C (µ V or µ V 2 ) t o N 10Hz Frequency # of Cycles/Second o (Hz) 20Hz D 0 Phase π (Radians) F

Time vs. Frequency Domain y p o C t o N Frequency Domain X i ( f ) o imag D Phase real F

When/How to Record EEG? y Continuous Recording (No Event) p Event/Stimulus • Anesthesia, o • Sleep C • Resting (eyes open/closed) Trial 1 t o Trial 2 Relative to An Event/Stimulation N • Sensory, motor, cognitive processing o • Electrical stimulation D Trial 100 Time: Event Related Potential or Evoked potentials Frequency: Event Related Spectral Perturbation Phase F

EEG Features 2 1 3 y p (3) Global Dynamic (1) Local o Response C t o (2) Connectivity N o Adapted from Khanna A, Pascual- D Leone A, Farzan F, 2014 Θ Adapted from Shafi et al., 2012 1 2 3 26

System Diagram for Designing tCS+EEG Studies y p o C t o N o D

tCS Outcomes: Local Effects y p Continuous EEG Recording (No Event) o C Change in Power      t o N Power o 10 20 30 50 40 Frequency (Hz) D Jacobson et al., 2012 Montage : Anodal rIFG, cathodal lOFC tDCs Resting EEG : Selective decrease of theta band Zaehle., 2012 (EEG-guided) Montage : Posterior tACs at individual alpha oscillations Resting EEG : Increase in alpha in parieto-central electrodes

tCS Outcomes: Local Effects EEG + Event y p o Change in ERSP or ERD/ERS C Change in ERP t o 20 µV N 50 ms o Keeser et al., 2011 Matsumoto et al., 2010 D • Montage: Anodal tDCS on LDLPFC, cathode • Montage: Anodal/cathodal tDCS on MC • EEG+ Motor Imagery: Mu rhythms ERD on contralateral supraorbital region • EEG Rest: Reduced left frontal delta, source increased after anodal tDCS analysis localized this to ACC and orbitofrontal Zaehle., 2011 regions • Montage: anodal or cathodal left DLPFC tDCS • EEG+ Working Memory : Increased P2 and P3 • EEG+ Working Memory: Enhanced ERP amplitudes • Performance: Reduced error rates in working performance and amplified oscillatory power in the theta and alpha bands after anodal tDCS memory

tCS Outcomes: Network Effects y p o Real (before vs after) C t o N o Sham vs active Sham (before vs after) D Gamma during voluntary hand movement Polania et al, Human Brain Mapping 2011 • M1 anodal + contralateral frontopolar cathodal stimulation • shifted brain network connectivity at rest and especially during task performance

tCS Outcomes: Network Effects Beta y p o Pre C t o N Post o D Polania et al, Human Brain Mapping 2011 • M1 anodal + contralateral frontopolar cathodal stimulation shifted brain network connectivity at rest and especially during task performance

TMS Pulse TMS-EEG Magnetic Field Cortical P30 Evoked y Potentials p o 20 µV C 50 ms N100 t I 1 Descending I 4 o Volleys D N 20 µV o 5 ms D Motor Evoked Peak-to-Peak Amplitude Potentials Latency mV 1 20 ms 32

Inhibition, Connectivity, Plasticity, … Neural inhibition Markers Inhibition mediated modulation y M1 DLPFC LICI MC of oscillations p Markers LICI DLPFC LICI MC δ ,LICI DLPFC δ Motor DLPF o LICI MC Θ ,LICI DLPFC Θ C C LICI MC α ,LICI DLPFC α LICI MC β ,LICI DLPFC β t LICI MC  ,LICI DLPFC  o Farzan et al., 2009, Neuropsychopharmacology N Daskalakis, Farzan et al., 2008, Neuropsychopharmacology Neural inhibition Markers o TEP Amp Interhemispheric connectivity D Markers TEP Dur ISP MC TEP Peaks ISP DLPFC TEP Power GMFA AMP GMFA Dur GMFA Peaks Voineskos*, Farzan *et al., 2010. Biological Psychiatry GMFA Power Farzan et al., 2013, NeuroImage 33

TMS-EEG in extracting Markers of Health y p o C t o N o D 34 Farzan F et al., Frontiers in Neural Circuits , 2016

tCS Outcomes: TMS-EEG Magnetic Field P30 Cortical y Evoked p Potentials o 20 µV C 50 ms N100 t o N o D Bai, 2017 Differential changes in tDCS-induced cortical excitability in MCS and VS.

tCS Outcomes: TMS-EEG Magnetic Field P60 P30 Cortical y Evoked p Potentials o 20 µV C 50 ms N100 t o N o D Hill, 2017 HD tDCS induced changes in P60.