Brain Coordination Dynamics & Integrative Functions of Human

Mind/BehaviorE. Tognoli, January 20th, 2009, Neuroscience

Seminar

Human Brain and Behavior Laboratory

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

Neurosciences Mathematics

Chemistry

Biomedical science

Psychology

Physics

Biology

Engineering

Philosophy

Complexity

Interdisciplinarity

What is Brain Coordination Dynamics?

Time-dependent description of their coordination

time

time

Time-dependent description of the components

Our model of neuroscience~complexity:Team work / common framework

This interaction is not immediate and immutable: most interactions are patterned in

time -> dynamics

Goal: understand brain function timeIs BCD a meaningful approach?

Function emerges from the interaction of the components at a lower level of description ->

coordination

Function: emergent property at the macroscopic level (e.g. perceive, think, act, remember,

attend, decide…)

One key aspect of BCD is to choose the level of description

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

DesynchronizedNo integrative

percept

SynchronizedIntegrative percept

IdlingSynchronized

AlertDesynchronize

d

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, fMRI

Galuske et al

Interim summary

Brain areas working together will (linearly) synchronize their

oscillations.High frequencies (g) are especially

meaningful

Integrative brain function explained:

A first hint at nonlinearity

Non-linearity, criticality, pathologies

Too much coordination

(epilepsy)Cognition

Too little coordination

(schizophrenia, autism etc…)

segregation integration

info

rmat

ion

Now, the nonlinear brain: models of integration~segregation

Kelso et al., 1990Bressler and Kelso, 2001Kelso &Tognoli, 2007Tognoli & Kelso, 2009 f = dw - a sinf - 2b sin (2f) +

Qxt

Coordination variable : Relative Phase

time

time

(phase of one oscillator)

For two oscillations, xt

and yt

rpt=f(xt)-f(yt)

If rpt=rpt+1=rpt+2…Oscillations are phase-locked

Coordination variable : Relative Phase(phase of two oscillators)

time

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., 1990Bressler and Kelso, 2001Kelso &Tognoli, 2007Tognoli & Kelso, 2009

Metastability: why and what for?

Advantages?1. Coordination extended to

a larger range of components

2. Speed: no need for a disengagement mechanism (phase scattering)

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

Why?Brain is a complex nonlinear 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

Theory~experiment

With Bernier, Murias et al. imitation behavior in

autistic adults

Tognoli & Kelso, in prep

Difficulties in interpreting synchronyPredicting true and false

synchrony

2 or more sources

Coordinated inphase

Coordinated antiphase

Coordinated out of phase

Metastable

Uncoordinated

1 cortical sourceSulcal

Gyral

Brain dynamics: a 4D problem

In most cases, not a lot of synchrony

Benites et al., in prep

4d dynamical analysis of continuous EEG is key to recognize real synchrony

Theories of information in complex, self organized brain

Information transfer(Shannonian theory)

Linearly coupled oscillations

(Hebbian assemblies theory)

~Metastability

(Kelso)

A journey in nonlinear brain dynamics

interdisciplinary

neuroscience

function emergenc

e coordinati

on

linear synchroniz

ation

non-linear brain

models

coordination

dynamics

paradigms of

information

processingbrainwaves

Human Brain and Behavior Laboratory

neuroscience~complexity