EEG informational code dependence on the functional state: General trends and characteristic period

Abstract

EEG signal is an important source to study the brain signalization in all its variety. The consideration of this signal as an informational process leads to the exploration of the properties of these processes, which are described in the terms of the information theory. Particularly, we can study the specifics of the information coding in EEG, such as: ‘vocabulary’ diversity (the information code), its evolution and characteristic time-scales of the latter. In order to study characteristics mentioned above, the Lempel–Ziv complexity (LZC) values were applied in our research. The EEGs we used were recorded for two states (relaxed arousal with open and closed eyes). The international electrode position system 10-20 was used. We used EEGs recorded in band range from 0.16 to 50 Hz and 50 Hz notch filter as well. For the processing, we selected artefacts-free EEG fragments.