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Macroscopic Organization of Brain Activity in the EEG and MEG: Theory and Concepts


Speaker: Prof. Viktor Jirsa, Center for Complex Systems and Brain Sciences, Florida Atlantic University
Location: 693 Kerr
Start time: Mon, Jun 12 2000, 4:10PM

Our goal is the development of a biologically motivated description of spatiotemporal pattern formation and computation in the human brain activity measured by the electroencephalogram (EEG) and the magnetoencephalogram (MEG). Our approach resembles a situation found in ^Mthe 1960s in the physics of the laser and superconductivity: the dynamics of the system's microscopic building blocks is known and a coherent macroscopic spatiotemporal dynamics is observed, but we lack a theory which explains the traverse of scales of organization reaching beyond a simple Ginzburg-Landau theory of pattern formation. We would like to address this issue by introducing physiological and biological meaning to pattern formation theories. Our underlying hypothesis is that the large-scale dynamics of EEG/MEG is determined by the ^Mlong-range fiber system of the neocortex. Its local dynamics emerges coherently in space and time and individual areas may be represented by spatial modes which generally will be attributed a functional significance. These functional units are embedded into a spatially continuous sheet of neural ensembles and additionally interconnected by a heterogeneous fiber system contributing to a hierarchy in the information processing stream. We operationalize this concept by focusing on brain-behavior experiments under a coordination paradigm. This ^Mdynamics affords an interpretation of functional activity of EEG/MEG, the interaction of ^Mdifferent modalities (motor, sensorimotor, auditory) and thus its neurocomputational processes. The simultaneous behavioral dynamics provides an entry point to the connection between brain and behavior.