No surprise--sequence event-related potentials for brain-computer interfaces.
BACKGROUND
In the field of Brain-Computer Interfaces (BCI), the original two-class oddball paradigm has been extended to multiple stimuli with balanced probabilities and random presentation sequences. Exploiting the differences between standard and deviant ERP responses, these multi-class paradigms are suitable for communication and control.


METHODS
The present study investigates the effect of giving up the randomness of stimulation sequences in favor of a repeated, predictable pattern. Data of healthy subjects (n=10) who performed a single session with a 6-class spatial auditory ERP paradigm were analyzed offline. Their auditory evoked potentials (AEP) resulting from the potentially simpler task (using fixed sequences) are compared with the AEP evoked by pseudo-randomized stimulation sequences.


RESULTS
Class-discriminative EEG responses between target and non-target stimuli were observed for both conditions. The binary classification error estimated for standard epochs of was comparable for both conditions (random: 24%, fixed: 25%). Expanding the standard epochs to include pre-stimulus intervals, we found that the regular structure of the fixed sequence can be exploited. Compared to the standard epoch, the MSE improves by 7%, while in the random condition an improvement could not be observed.
Dept. Machine Learning, Berlin Institute of Technology (TU Berlin), Berlin, Germany. michael.tangermann at tu-berlin.de
Michael
M
Tangermann
Johannes
J
Hohne
Heiko
H
Stecher
Martijn
M
Schreuder
D062207:Brain-Computer Interfaces; D005071:Evoked Potentials / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans