title: Coherent Activity in Bilateral Parieto-Occipital Cortices during P300-BCI Operation.
abstract: The visual P300 brain-computer interface (BCI), a popular system for electroencephalography (EEG)-based BCI, uses the P300 event-related potential to select an icon arranged in a flicker matrix. In earlier studies, we used green/blue (GB) luminance and chromatic changes in the P300-BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray (WG) luminance flicker matrix. To highlight areas involved in improved P300-BCI performance, we used simultaneous EEG-fMRI recordings and showed enhanced activities in bilateral and right lateralized parieto-occipital areas. Here, to capture coherent activities of the areas during P300-BCI, we collected whole-head 306-channel magnetoencephalography data. When comparing functional connectivity between the right and left parieto-occipital channels, significantly greater functional connectivity in the alpha band was observed under the GB flicker matrix condition than under the WG flicker matrix condition. Current sources were estimated with a narrow-band adaptive spatial filter, and mean imaginary coherence was computed in the alpha band. Significantly greater coherence was observed in the right posterior parietal cortex under the GB than under the WG condition. Re-analysis of previous EEG-based P300-BCI data showed significant correlations between the power of the coherence of the bilateral parieto-occipital cortices and their performance accuracy. These results suggest that coherent activity in the bilateral parieto-occipital cortices plays a significant role in effectively driving the P300-BCI.
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities , Tokorozawa , Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Takano
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities , Tokorozawa , Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ora
authors.affiliation: Department of Systems Design and Engineering, Tokyo Metropolitan University , Tokyo , Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sekihara
authors.affiliation: Cognition and Action Research Group, Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba , Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Iwaki
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities , Tokorozawa , Japan ; Brain Science Inspired Life Support Research Center, The University of Electro-Communications , Tokyo , Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kansaku
keywords: BMI; P300 speller; chromatic stimuli; imaginary coherence; magnetoencephalography