EEG Microstates and Modes of Conscious Experience
Translational Research Center, University Hospital of Psychiatry, Bern, Switzerland
Abstract: The phenomenology of the spatial dynamics of resting state EEG can be described surprisingly well in terms of microstates; i.e. as a non-random and non-overlapping sequence of a few and transiently stable prototypical scalp field configurations, constituting a microstate. From a physical point of view, this observation can only be reasonably explained by the assumption that within a single microstate, the predominant part of the EEG sources oscillates either in phase or in antiphase to the other sources. According to Fries (2005) model of communication through coherence, such relatively slow in- and antiphase oscillations temporally align or misalign neuronal excitability and can therefore drastically alter the flow of information among brain regions. Thus, from a mechanistic point of view, the switching between microstates may represent a global, flexible and adaptive gating of communication between large-scale networks. Finally, Tonoi’s information integration theory of consciousness (2004) states that “the quantity of consciousness corresponds to the capacity of a system to integrate information” and that “the quality of consciousness is determined by the informational relationships among the elements of a complex”. As microstates may dynamically switch these relationships through the gating of information flow, microstates may dynamically modify the quantity and quality of conscious experience. In my contribution, I will carefully review the methodology, the empirical findings and the theoretical background behind the microstate model, critically evaluate the claims that have been made based on it, and outline its possible extensions into the time-frequency domain.
About the Speaker: Thomas König is a professor of psychiatric neurophysiology and head of the EEG research laboratories of the University Hospital of Psychiatry of the University of Bern. His research has been focused on linking mental processes and experiences to EEG data, which includes both the development of theoretical models and the corresponding analysis tools, as well as empirical studies in healthy and mentally ill subjects. Methods and theory wise, he has been one of the key promotors of the EEG microstate methodology that is receiving increasing attention in the EEG community, and where he has contributed a series of software tools to conduct such analyses. He also developed novel statistical procedures for the analysis of ERPs, and make a continuously evolving open-source toolbox implementing those tools openly available. Apart from this professional commitment, he is an eager student of philosophy and currently finishing a master thesis in the domain of philosophy of mind.
Head CIBM EEG HUG-UNIGE Clinical and Translational Neuroimaging Section
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