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Disclosure: no potential conflicts of interest. Funding EU, SNF, DFG, University grants.

OHBM 2017 EEG and MEG Connectivity Course

Connectivity in ERP analyses

Daniel Brandeis

1) Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/

Heidelberg University, Mannheim, Germany2) Department of Child and Adolescent Psychiatry and Psychotherapy,

Pychiatric Hospital, University of Zurich, 3) Center for Integrative Human Physiology, 4)Neuroscience Center Zurich, University of Zurich and ETH

Zurich, Switzerland

23th Human Brain Mapping Meeting, June 2017, Vancouver, Canada

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Connectivity

•Stability - dynamics

– ERPs: dynamic, event-related, baseline connectivity

– Structural and methods constraints

•Synchronization - lagged correlation

– Complementary aspects of connectivity

•Applications

– Zero lag connectivity relevant for BCI

•Neurophysiology

– Mechanism, lag and acceleration

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[Hbdeoxy

] [Hboxy]

O2

fMRI Activation …

Hemodynamics, O2

EEG - fMRI (t)

0 5 10 15 20s

0 .5 1.0 1.5 2.0s

EEG/MEG Activation

Synchronization

Fields- BOLD

Synchronization- Hemodynamics

Mass Polarization - … (DTI)

Estimate - Localise

Direct - Indirect

Fast and Slow - Slow

Connectivity no lag in fMRI

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EEG connectivity - correlation ?

Two or more dipoles –no lag AND lagged correlation

+50 µV

-50 µV

+50 µV

-50 µV

Haufe NIMG 2008

Single dipole or synchronized dipoles – no lag (0, 180deg) correlation

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EEG connectivity – methods

Synchronization, common input, zero lag correlation just “problem” ?

Bastos & Schoffelen 2016

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EEG Connectivity

Roelfsema Science 1997

Genuine instant (zero lag) as well as lagged connectivity

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EEG and MEG Connectivity

Winter 2007, Michels et al 2013

EEGVolume conduction

MEGField spread

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Time domain

ERPs etc

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ms (Milliseconds)

+50 µV

-50 µV

5001000

Event-related potentials (ERP) –phase locked averaging of EEG

(Microvolt,

1/1’000’000

Volt)

1. Event

2. Event

... Event

30. Event

Average

---- ERP: time course of information processing

ERP - prestimulus mean, variability, connectivity

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ERP Microstates stable, peaking or oscillating topographies

Averaged ERP microstates - synchronizationKoenig & Gianotti, in Michel 2011, Maurer et al JCN 2011

StrengthGlobal Field Power

Distribution

TopographyCentroids, Sources

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ERP Microstates –Clustering and Crossvalidation

Pascual-Marqui, R. D., Michel, C. M., & Lehmann, D. (1995). Segmentation of brain electrical activity into microstates:

model estimation and validation. IEEE Transactions on Biomedical Engineering, 42(7), 658-665.

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ERP Microstates stable, peaking or oscillating topographies

Averaged ERP microstates –network synchronization, maturation, propagation

Maurer et al et al JCN 2005

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ERP Microstates stable, peaking or oscillating topographies

Averaged ERP microstates –network synchronizationation, maturation, propagation

Brem et al NIMG 2006

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ERP – lag interaction

Steger et al Psychophysiology 2001

Experimental approaches disentangle synchronization and interaction

Bilateral P1 preceeds sum – physiological interaction, not volume conduction

Left

Right

Bilateral

…Sum

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Frequency domain

ERD/ERS, DICS, PLI…

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Connectivity – Synchronization

Wackerman & Allefeld 2009. Michel et al 2009

Development – synchronization and strength decrease

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Zero-phase coupling matters - BCI

Zero phase coupling predictive – eliminated by spatial filter (CSD)

Jian et al 2017

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EEG

Hipp et al Neuron 2011

ERS – beta synchronization with perception

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Global field synchronization (GFS)

Global Field Synchronization - reference free)

Michels et al 2012

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Global connectivity (GFS)

Global Field synchronization -complements global field strength

Michels et al 2012

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Global connectivity (GFS – EEG-fMRI)

Global Field synchronization – EEG-fMRI

Michels et al 2012

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Lagged source connectivity

Lagged source coherence increases during development

Yvert et al J. Neurosci 2012

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Directed ERP Connectivity

Single trial directed ERP connectivity - early recurrence

Plomp et al SciRep 2015

N=16, for beta peaking at C1 (spectrally weighted Partial Directed Coherence)

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Conclusion

•(ERP) Connectivity includes synchronizationconsider zero lag correlation and microstates

•Connectivity – experimental cluessynchronization beyond field spread - can speed processingexperimental approaches

•Baseline connectivity – considerconsider baseline connectivity, active state subtraction, interpretation of change

•Use proper methods including experimentsbased on design, hypotheses, inspection

Probe connectivity– synchronization and lag

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Thank you !

daniel.brandeis@zi-mannheim.de

brandeis@kjpd.uzh.ch

Maurer, U., Brem, S., Bucher, K., & Brandeis, D. (2005). Emerging neurophysiological specialization for letter strings. Journal of Cognitive Neuroscience,

17(10), 1532-1552.

Jian, W., Chen, M., & McFarland, D. J. (2017). Use of phase-locking value in sensorimotor rhythm-based brain–computer interface: zero-phase coupling

and effects of spatial filters. Medical & Biological Engineering & Computing, in press, 1-12.

Wackermann, J., & Allefeld, C. (2009). State space representation and global descriptors of brain electrical activity. In C. M. Michel, T. Koenig, D. Brandeis,

L. R. R. Gianotti & J. Wackermann (Eds.), Electrical Neuroimaging (pp. 191-214). Cambridge: Cambridge University Press.

Koenig, T., & Gianotti, L. R. R. (2009). Scalp field maps and their characterization. In C. M. Michel, T. Koenig, D. Brandeis, L. R. R. Gianotti & J.

Wackermann (Eds.), Electrical Neuroimaging (pp. 25-47). Cambridge: Cambridge University Press.

Steger, J., Imhof, K., Denoth, J., Pascual-Marqui, R. D., Steinhausen, H.-C., & Brandeis, D. (2001). Brain mapping of bilateral visual interactions in children.

Psychophysiology, 38, 243-253.

Brem, S., Bucher, K., Halder, P., Summers, P., Dietrich, T., Martin, E., & Brandeis, D. (2006). Evidence for developmental changes in the visual word

processing network beyond adolescence. Neuroimage, 29(3), 822-837.

Pascual-Marqui, R. D., Michel, C. M., & Lehmann, D. (1995). Segmentation of brain electrical activity into microstates: model estimation and validation.

IEEE Transactions on Biomedical Engineering, 42(7), 658-665.

Winter, W. R., Nunez, P. L., Ding, J., & Srinivasan, R. (2007). Comparison of the effect of volume conduction on EEG coherence with the effect of field

spread on MEG coherence. Statistics in Medicine, 26(21), 3946-3957.

Michels, L., Lüchinger, R., Koenig, T., Martin, E., & Brandeis, D. (2012). Developmental changes of BOLD signal correlations with global human EEG power

and synchronization during working memory. PLoS ONE, 7(7), e39447.

Plomp, G., Hervais-Adelman, A., Astolfi, L., & Michel, C. M. (2015). Early recurrence and ongoing parietal driving during elementary visual processing.

Scientific Reports, 5, 18733. Roelfsema, P. R., Engel, A. K., Konig, P., & Singer, W. (1997). Visuomotor integration is associated with zero time-lag

synchronization among cortical areas. Nature, 385(6612), 157-161.

Haufe, S., Nikulin, V. V., Ziehe, A., Müller, K.-R., & Nolte, G. (2008). Combining sparsity and rotational invariance in EEG/MEG source reconstruction.

NeuroImage, 42(2), 726-738.

Bastos, A. M., & Schoffelen, J. M. (2015). A Tutorial Review of Functional Connectivity Analysis Methods and Their Interpretational Pitfalls. Frontiers in

System Neuroscience, 9, 175.

Hipp, J. F., Engel, A. K., & Siegel, M. (2011). Oscillatory Synchronization in Large-Scale Cortical Networks Predicts Perception. Neuron, 69(2), 387-396.

Yvert, G., Perrone-Bertolotti, M., Baciu, M., & David, O. (2012). Dynamic causal modeling of spatiotemporal integration of phonological and semantic

processes: an electroencephalographic study. J Neurosci, 32(12), 4297-4306.