Toward a comprehensive understanding of EEG and its analyses

Summary Background EEG is the oldest tool for studying human cognitive function, but it is blamed to be useless because its poor spatial resolution despite it excellent temporal discrimination. Such comments arise from a reductionist point of view about the cerebral function. However, if the brain is assumed to be a distributed processing system recruiting different types of cells widely distribute over the cortex, then EEG temporal resolution and the many different tools available for its analysis, turn it the tool of choice to investigate human cognition. Proposal To better understand the different types of information encoded in the recorded cortical electrical activity, a clear model of the cortical structure and function of the different cortical column layers is presented and discussed. Taking this model into consideration, different available techniques for EEG analysis are discussed, under the assumption that tool combination is a necessity to provide a full comprehension of dynamics of the cortical activity supporting human cognition. Methodology The present approach combines many of the existing methods of analysis to extract better and richer information from the EEG, and proposes additional analysis to better characterize many of the EEG components identified by these different methods. Analysis Data on language understanding published elsewhere are used to illustrate how to use this combined and complex EEG analysis to disclose important details of cognitive cerebral dynamics, which reveal that cognitive neural circuits are scale free networks supporting entrainment of a large number of cortical column assemblies distributed all over the cortex. Conclusions Reasoning is then assumed to result from a well orchestrated large scale entrainment