title: Direction and viewing area-sensitive influence of EOG artifacts revealed in the EEG topographic pattern analysis.
abstract: The influence of eye movement-related artifacts on electroencephalography (EEG) signals of human subjects, who were requested to perform a direction or viewing area dependent saccade task, was investigated by using a simultaneous recording with ocular potentials as electro-oculography (EOG). In the past, EOG artifact removals have been studied in tasks with a single fixation point in the screen center, with less attention to the sensitivity of cornea-retinal dipole orientations to the EEG head map. In the present study, we hypothesized the existence of a systematic EOG influence that differs according to coupling conditions of eye-movement directions with viewing areas including different fixation points. The effect was validated in the linear regression analysis by using 12 task conditions combining horizontal/vertical eye-movement direction and three segregated zones of gaze in the screen. In the first place, event-related potential topographic patterns were analyzed to compare the 12 conditions and propagation coefficients of the linear regression analysis were successively calculated in each condition. As a result, the EOG influences were significantly different in a large number of EEG channels, especially in the case of horizontal eye-movements. In the cross validation, the linear regression analysis using the appropriate dataset of the target direction/viewing area combination demonstrated an improved performance compared with the traditional methods using a single fixation at the center. This result may open a potential way to improve artifact correction methods by considering the systematic EOG influence that can be predicted according to the view angle such as using eye-tracker systems.
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196 Japan.
authors.forename: Guangyi
authors.initials: G
authors.lastname: Ai
authors.affiliation: School of Systems Information Science, Future University Hakodate, 116-2 Kamedanakano-cho, Hakodate, Hokkaido 041-8655 Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Sato
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196 Japan.
authors.forename: Balbir
authors.initials: B
authors.lastname: Singh
authors.affiliation: Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196 Japan ; RIKEN BSI, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Wagatsuma
keywords: Artifact correction; Electro-oculogram (EOG); Electroencephalogram (EEG); Event-related potential (ERP); Linear regression analysis