Topographies of the electrical potential measured by electroencephalography (EEG) carry key information about the global brain state. We have shown that EEG microstate sequences during spontaneous activity exhibit scale-free dynamics, that is, their temporal succession is characterized by mono-fractal behavior for timescales spanning two orders of magnitude. The video on the right illustrates a random-walk embedding of the microstate sequence as derived from the EEG data. Visual observation reveal similar 'roughness' of the curve at different timescales (zooms), thus confirming our quantitative evaluation. Such organization might play a key role for supporting complex brain processes:
“To generate information, a system must be capable of behaving in an unpredictable fashion” (Goldberger et al., 2002)
D. Van De Ville, J. Britz, C. M. Michel, "EEG Microstate Sequences in Healthy Humans at Rest Reveal Scale-Free Dynamics", Proceedings of the National Academy of Sciences of the USA, vol. 107, pp. 18179-18184, 2010.