Download - Brain Coordination Dynamics
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