AUTHOR=Nolte Guido , Mueller Klaus R. TITLE=Localizing and Estimating Causal Relations of Interacting Brain Rhythms JOURNAL=Frontiers in Human Neuroscience VOLUME=4 YEAR=2010 URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2010.00209 DOI=10.3389/fnhum.2010.00209 ISSN=1662-5161 ABSTRACT=

Estimating brain connectivity and especially causality between different brain regions from EEG or MEG is limited by the fact that the data are a largely unknown superposition of the actual brain activities. Any method, which is not robust to mixing artifacts, is prone to yield false positive results. We here review a number of methods that allow for addressing this problem. They are all based on the insight that the imaginary part of the cross-spectra cannot be explained as a mixing artifact. First, a joined decomposition of these imaginary parts into pairwise activities separates subsystems containing different rhythmic activities. Second, assuming that the respective source estimates are least overlapping, yields a separation of the rhythmic interacting subsystem into the source topographies themselves. Finally, a causal relation between these sources can be estimated using the newly proposed measure Phase Slope Index (PSI). This work, for the first time, presents the above methods in combination; all illustrated using a single, simulated data set.