Channel selection methods for the P300 Speller

•Active electrode (“channel”) selection leads to higher average P300 Speller classification performance compared to a standard channel set of similar size.•Jumpwise regression is capable of selecting an effective electrode subset at runtime.•Some experimental subjects see large gains in accuracy wit...

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Bibliographic Details
Published in:	Journal of neuroscience methods 2014-07, Vol.232, p.6-15
Main Authors:	Colwell, K.A., Ryan, D.B., Throckmorton, C.S., Sellers, E.W., Collins, L.M.
Format:	Article
Language:	eng
Subjects:	Brain Mapping Brain-Computer Interfaces Brain–computer interface Channel selection Discriminant Analysis Electroencephalography Event-Related Potentials, P300 - physiology Female Humans Male P300 Speller Photic Stimulation ROC Curve Students Universities
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Summary:	•Active electrode (“channel”) selection leads to higher average P300 Speller classification performance compared to a standard channel set of similar size.•Jumpwise regression is capable of selecting an effective electrode subset at runtime.•Some experimental subjects see large gains in accuracy with channel selection. The P300 Speller brain–computer interface (BCI) allows a user to communicate without muscle activity by reading electrical signals on the scalp via electroencephalogram. Modern BCI systems use multiple electrodes (“channels”) to collect data, which has been shown to improve speller accuracy; however, system cost and setup time can increase substantially with the number of channels in use, so it is in the user's interest to use a channel set of modest size. This constraint increases the importance of using an effective channel set, but current systems typically utilize the same channel montage for each user. We examine the effect of active channel selection for individuals on speller performance, using generalized standard feature-selection methods, and present a new channel selection method, termed jumpwise regression, that extends the Stepwise Linear Discriminant Analysis classifier. Simulating the selections of each method on real P300 Speller data, we obtain results demonstrating that active channel selection can improve speller accuracy for most users relative to a standard channel set, with particular benefit for users who experience low performance using the standard set. Of the methods tested, jumpwise regression offers accuracy gains similar to the best-performing feature-selection methods, and is robust enough for online use.
ISSN:	0165-0270 1872-678X