Application of a neural complexity measure to multichannel EEG

We apply a recently suggested measure for neural complexity (G. Tononi, O. Sporns, G.M. Edelman, Proc. Natl. Acad. Sci. 91 (1994) 5033), that is hypot hesised to capture the interplay between two fundamental aspects of brain o rganisation, functional segregation and integration, to human EEG recording s. This measure is based on a weighted sum of entropy differences evaluated at different length scales of the system. A strong prediction is that this measure correlates with the conscious state of the subject, having lower v alues if consciousness is reduced (G. Tononi, G.M. Edelman, Science 282 (19 98) 1846). It is found, however, that this neural complexity measure increa ses in neurological disorders where consciousness is severely reduced or ab sent. We discuss several possible explanations for this observation and sug gest directions for future work. (C) 2001 Elsevier Science B.V. All rights reserved.