Zastosowanie zagadnienia odwrotnego EEG do oceny aktywności elektrycznej kory mózgowej na użytek interfejsu BCI

Treścią artykułu jest ocena aktywności elektrycznej kory mózgowej w badaniach wykonywanych na potrzeby interfejsu mózg-komputer (BCI). Analiza ta może być przydatna do optymalizacji liczby i rozmieszczenia elektrod oraz wyboru cech najlepiej separujących określone klasy zadań myślowych. Wyniki rozwiązania zagadnienia odwrotnego EEG pokazują, że w tej mierze najbardziej predysponowane są centralne obszary kory (pod elektrodami: C3, C4 i Cz), w paśmie alfa (8-12 Hz).

The subject of the paper is evaluation of the brain electrical activity associated with imagining some specific motor actions assigned to the specific classes in an asynchronous brain-computer interface (BCI) (Section 1, [1, 2, 3, 4]). These analyzes, called as inverse problems of EEG, can be useful to optimize the number and placement of electrodes and also to select the features which best separate the considered classes. Dedicated calculations were carried out using the algorithm sLORETA (Section 3, [7, 8, 9, 10]). Evaluation of brain activity in the time domain indicates the regular activation of the: frontal, temporal, occipital, and the central part of the cerebral cortex (Section 5, Fig. 5). However, the evaluation of activity in the frequency domain provides reliable information about the differences between the selected classes. The obtained results lead to the conclusion that in this matter the most important differences are observed in the central parts of the cortex, over which the electrodes: C3, C4 and Cz are located; in the alpha band, i.e. 8-12 Hz (Section 6, Fig. 6-8). Limitation of the analysis to 8 EEG time series confirms the correctness of the electrodes selection applied in the dedicated system g.tec, used in the Department of Information and Measuring Systems of the Warsaw University of Technology (Section 7, Fig. 9, [1, 2]). All the onclusions from performed calculations are consistent with the general neurobiological knowledge [5, 6].