Human Brain and Behavior Laboratory Brain Coordination Dynamics

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

Goals 1. present an interdisciplinary framework for Neuroscience~Complexity Science 2. introduce basics of brainwaves and EEG signal 3. discuss theories of integrative brain functions

Zeller, hypothetical model of the evolution and structure of science

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

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

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

The story of Neural Cell Assemblies

Understanding integrative brain functions: binding problem (Von Der Malsburg, 1981)

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

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

Alert Desynchronized No integrative percept Idling Synchronized Integrative percept

Where do EEG signals come from?

Spatial scales: -local synchrony: increased power -large scale synchrony: increased coherence

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

Active/passive rhythms, f. MRI Galuske et al

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

A first hint at nonlinearity

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

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

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

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

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

Why? Brain is a complex nonlinear system Advantages? Key features: patterned connectivity (locally dense, remotely sparse and selective) 2. Speed: no need for a disengagement mechanism (phase scattering) Symmetry breaking: -Heterogeneity of the coordinating elements: different intrinsic frequencies -Heterogeneity of their coupling 1. Coordination extended to a larger range of components 3. Flexibility: a series of attracting tendencies can be visited dynamically over the time course of the Coordination Variable 4. Balance integration~segregation: situates the system in the range of maximal information Metastability: why and what for?

Theory~experiment

With Bernier, Murias et al. imitation behavior in autistic adults Tognoli & Kelso, in prep

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

Brain dynamics: a 4 D problem

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

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

Human Brain and Behavior Laboratory brainwaves interdiscipli nary neuroscienc e function emergence coordination non-linear brain models coordination dynamics paradigms of information processing linear synchroniza tion A journey in nonlinear brain dynamics neuroscience~complexity