Summary
Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Biosignal Interpretation: Advanced Methods for Neural Signals and Images”.
Objectives: The main objectives of the paper regard the analysis of amplitude spatial distribution
of the P300 evoked potential over a scalp of a particular subject and finding an averaged
spatial distribution template for that subject. This template, which may differ for
two different subjects, can help in getting a more accurate P300 detection for all
BCIs that inherently use spatial filtering to detect P300 signal. Finally, the proposed
averaging technique for a particular subject obtains an averaged spatial distribution
template through only several epochs, which makes the proposed averaging technique
fast and possible to use without applying any prior training data as in case of data
enhancement technique.
Methods: The method used in the proposed framework for the averaging of spatial distribution
of P300 evoked potentials is based on the statistical properties of independent components
(ICs). These components are obtained by using independent component analysis (ICA)
from different target epochs.
Results: This paper gives a novel averaging technique for the spatial distribution of P300
evoked potentials, which is based on the P300 signals obtained from different target
epochs using the ICA algorithm. Such a technique provides a more reliable P300 spatial
distribution for a subject of interest, which can be used either for an improved spatial
selection of ICs, or more accurate P300 detection and extraction. In addition, the
experiments demonstrate that the values of spatial intensity computed by the proposed
technique for P300 signal converge after only several target epochs for each electrode
allocation. Such a speed of convergence allows the proposed algorithm to easily adapt
to a subject of interest without any additional artificial data preparation prior
the algorithm execution such in case of data enhancement technique.
Conclusion: The proposed technique averages the P300 spatial distribution for a particular subject
over all electrode allocations. First, the technique combines P300-like components
obtained by the ICA run within a target epoch in order to obtainan averaged P300 spatial
distribution. Second, the technique averages spatial distributions of P300 signals
obtained from different target epochs in order to get the final averaged template.
Such an template can be useful for any BCI technique where spatial selection is used
to detect evoked potentials.
Keywords
ICA - BCI Competition Dataset - P300 - P300 spatial distribution