Could the beta rebound in the EEG be suitable to realize a "brain switch"?
OBJECTIVE
Performing foot motor imagery is accompanied by a peri-imagery ERD and a post-imagery beta ERS (beta rebound). Our aim was to study whether the post-imagery beta rebound is a suitable feature for a simple "brain switch". Such a brain switch is a specifically designed brain-computer interface (BCI) with the aim to detect only one predefined brain state (e.g. EEG pattern) in ongoing brain activity.


METHODS
One EEG (Laplacian) recorded at the vertex during cue-based brisk foot motor imagery was analysed in 5 healthy subjects. The peri-imagery ERD and the post-imagery beta rebound (ERS) were analysed in detail between 6 and 40Hz and classified with two support vector machines.


RESULTS
The ERD was detected in ongoing EEG (simulation of asynchronous BCI) with a true positive rate (TPR) of 28.4%+/-13.5 and the beta rebound with a TPR of 59.2%+/-20.3. In single runs with 30 cues each, the TPR for beta rebound detection was 78.6%+/-12.8. The false positive rate was always kept below 10%.


CONCLUSIONS
The findings suggest that the beta rebound at Cz during foot motor imagery is a relatively stable and reproducible phenomenon detectable in single EEG trials.


CONCLUSIONS
Our results indicate that the beta rebound is a suitable feature to realize a "brain switch" with one single EEG (Laplacian) channel only.
Pfurtscheller
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Laboratory of Brain-Computer Interfaces, Institute for Knowledge Discovery, Graz University of Technology, Krenngasse 37, 8010 Graz, Styria, Austria. Pfurtscheller@tugraz.at
Solis-Escalante
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D000328:Adult; D001611:Beta Rhythm; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods*; D005246:Feedback / Q000502:physiology*; D007839:Functional Laterality; D006801:Humans; D007092:Imagination; D008297:Male; D009068:Movement; D013997:Time Factors; D014584:User-Computer Interface; D055815:Young Adult