title: N1 wave in the P300 BCI is not sensitive to the physical characteristics of stimuli.
abstract: One of the widely used paradigms for the brain-computer interface (BCI), the P300 BCI, was proposed by Farwell and Donchin as a variation of the classical visual oddball paradigm, known to elicit the P300 component of the brain event-related potentials (ERP). We show that this paradigm, unlike the standard oddball paradigm, elicit not only the P300 wave but also a strong posterior N1 wave. Moreover, we present evidence that the sensitivity of this ERP component to targets cannot be explained by the variations of the perceived stimuli energy. This evidence is based on comparing the ERP obtained for usual P300 BCI stimuli and for the "inverted" stimulation scheme with low stimulus related variations of light energy (gray letters on the light gray background, "highlighted" by very light darkening). Despite the dramatic difference between the stimuli in the standard and "inverted" schemes, no difference between N1 amplitudes were found, supporting the view that this component's sensitivity to targets cannot be based simply on "foveating" the target, but may be related to spatial attention mechanisms, which involvement is natural for the P300 BCI. Efforts to optimize the P300 BCI should address better use of both P300 and N1 waves.
authors.affiliation: Faculty of Biology, M. V. Lomonosov Moscow State University, 1/12, Leninskie Gory, Moscow, 119991, Russia. sergshishkin@mail.ru
authors.forename: Sergey L
authors.initials: SL
authors.lastname: Shishkin
authors.forename: Ilya P
authors.initials: IP
authors.lastname: Ganin
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Basyul
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Zhigalov
authors.forename: Alexander Ya
authors.initials: AY
authors.lastname: Kaplan
mesh_terms: D000465:Algorithms; D001288:Attention / Q000502:physiology; D001676:Biofeedback, Psychology / Q000502:physiology; D001931:Brain Mapping / Q000379:methods; D003071:Cognition / Q000502:physiology; D003143:Communication Devices for People with Disabilities; D003213:Conditioning, Psychological / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods*; D011597:Psychomotor Performance / Q000502:physiology; D011603:Psychophysiology / Q000295:instrumentation / Q000379:methods*; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013647:Task Performance and Analysis; D013663:Teaching / Q000379:methods; D013813:Therapy, Computer-Assisted; D014584:User-Computer Interface; D055815:Young Adult