The Metastable Brain: Coordination Dynamics of Binding~Breakdown

A considerable amount of evidence and theory suggests that transient, short-lived phase-coupled oscillations within and between specialized areas of the brain provide a mechanism for neural integration. The idea is that these oscillations are coupled or “bound” together into a coherent network when people attend to a stimulus, perceive, remember, think and act. However, information processing in the brain requires a mechanism not only for the rapid formation of cell assemblies, but also their dissolution (“breakdown”).

I show that the key to understanding both binding and its breakdown lies in the brain’s metastable coordination dynamics (Kelso, 1992; 1995; Bressler & Kelso, 2001). Metastability is characterized by partially coordinated tendencies (not states) in which individual neural regions are neither completely independent of each other (“segregated”) nor fully linked in a fixed mutual relationship (“integrated”).

In experimental brain recordings, metastability is revealed by brief epochs of phase-locking synchrony interspersed in time with phase wandering. Theoretical modeling demonstrates that metastability arises as a result of changes in the dynamic balance between the coupling among neural ensembles (mediated, typically by reciprocal pathways in the brain) and the expression of each individual neural ensemble’s intrinsic properties (typically heterogeneous in nature).

At a more microscopic level, this metastable mechanism for binding and its breakdown is realized biophysically by coupling neural populations, themselves composed of groups of Hodgkin-Huxley, conductance-based neurons. More generally, coexisting tendencies for functional integration and segregation on all levels attest to the brain’s inherently complementary nature (Kelso & Engstrøm,  MIT Press 2006).

New Vistas for the Plasticity of the Brain – Taipei, Taiwan, Feb. 2004.

References

Bressler, S.L. and Kelso, J.A.S. (2001). Cortical coordination dynamics and cognition. Trends in Cognitive Sciences, 5, 26-36.

Kelso, J.A.S. (1992). Coordination dynamics of human brain and behavior. Springer Proc. in Physics, 69, 223 234.

Kelso, J.A.S. (1995). Dynamic Patterns: The Self Organization of Brain and Behavior. Cambridge: MIT Press. [Paperback edition, 1997].

Kelso, J. A. S. and Engstrøm, D. A. (2006) The Complementary Nature. Cambridge: MIT Press