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Brain Coordination Dynamics

H uman B rain and B ehavior L aboratory. Brain Coordination Dynamics & Integrative Functions of Human Mind/Behavior E. Tognoli, January 20 th , 2009, Neuroscience Seminar. Goals present an interdisciplinary framework for Neuroscience~Complexity Science

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Brain Coordination Dynamics

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  1. Human Brain and Behavior Laboratory Brain Coordination Dynamics & Integrative Functions of Human Mind/BehaviorE. Tognoli, January 20th, 2009, Neuroscience Seminar

  2. Goals present an interdisciplinary framework for Neuroscience~Complexity Science 2. introduce basics of brainwaves and EEG signal 3. discuss theories of integrative brain functions

  3. Zeller, hypothetical model of the evolution and structure of science

  4. Philosophy Psychology Engineering Biomedical science Mathematics Neurosciences Biology Complexity Chemistry Physics Interdisciplinarity

  5. Our model of neuroscience~complexity: Team work / common framework Time-dependent description of the components time Time-dependent description of their coordination time What is Brain Coordination Dynamics?

  6. Function: emergent property at the macroscopic level (e.g. perceive, think, act, remember, attend, decide…) Function emerges from the interaction of the components at a lower level of description ->coordination This interaction is not immediate and immutable: most interactions are patterned in time -> dynamics One key aspect of BCD is to choose the level of description Is BCD a meaningful approach? Goal: understand brain function time

  7. The story of Neural Cell Assemblies

  8. Understanding integrative brain functions: binding problem (Von DerMalsburg, 1981)

  9. Binding by synchronization Adapted from Gray, König, Engel & Singer, 1989

  10. EEG rhythms “synchronized” – rhythm is regular – amplitude is large – observed during idling “desynchronized” – rhythm is irregular – small amplitude – observed during engaged cognitive states

  11. Alert Desynchronized Idling Synchronized Desynchronized No integrative percept Synchronized Integrative percept

  12. Where do EEG signals come from?

  13. Spatial scales: • local synchrony: increased power • large scale synchrony: increased coherence

  14. Synchronization from anesthetic? Binding by synchronization in awake animals (Gray & Viana Di Prisco, 1997)

  15. Active/passive rhythms, fMRI Galuske et al

  16. Integrative brain function explained: Brain areas working together will (linearly) synchronize their oscillations. High frequencies (g) are especially meaningful Interim summary

  17. A first hint at nonlinearity

  18. Non-linearity, criticality, pathologies information segregation integration Too little coordination (schizophrenia, autism etc…) Too much coordination (epilepsy) Cognition

  19. Now, the nonlinear brain: models of integration~segregation f = dw - a sinf - 2b sin (2f) + Qxt Kelso et al., 1990 Bressler and Kelso, 2001 Kelso &Tognoli, 2007 Tognoli & Kelso, 2009

  20. Coordination variable : Relative Phase (phase of one oscillator) time time

  21. Coordination variable : Relative Phase (phase of two oscillators) For two oscillations, xt and yt rpt=f(xt)-f(yt) If rpt=rpt+1=rpt+2… Oscillations are phase-locked time

  22. Now, the nonlinear brain: models of integration~segregation f = dw - a sinf - 2b sin (2f) + Qxt If rpt=rpt+1=rpt+2… Oscillations are phase-locked Kelso et al., 1990 Bressler and Kelso, 2001 Kelso &Tognoli, 2007 Tognoli & Kelso, 2009

  23. Advantages? • Coordination extended to a larger range of components • Speed: no need for a disengagement mechanism (phase scattering) • Flexibility: a series of attracting tendencies can be visited dynamically over the time course of the Coordination Variable • Balance integration~segregation: situates the system in the range of maximal information • Why? • Brain is a complexnonlinear system • Key features: • patterned connectivity (locally dense, remotely sparse and selective) • Symmetry breaking: • -Heterogeneity of the coordinating elements: different intrinsic frequencies • -Heterogeneity of their coupling Metastability: why and what for?

  24. Theory~experiment

  25. With Bernier, Muriaset al. imitation behavior in autistic adults Tognoli & Kelso, in prep

  26. Difficulties in interpreting synchrony Predicting true and false synchrony Coordinated inphase Coordinated antiphase 2 or more sources Coordinated out of phase Metastable Uncoordinated Sulcal 1 cortical source Gyral

  27. Brain dynamics: a 4D problem

  28. 4d dynamical analysis of continuous EEG is key to recognize real synchrony Benites et al., in prep In most cases, not a lot of synchrony

  29. Theories of information in complex, self organized brain Information transfer (Shannonian theory) Linearly coupled oscillations (Hebbian assemblies theory) ~ Metastability (Kelso)

  30. Human Brain and Behavior Laboratory paradigms of information processing coordination dynamics non-linear brain models brainwaves function emergence coordination linear synchronization interdisciplinary neuroscience A journey in nonlinear brain dynamics neuroscience~complexity

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