title: A noninvasive brain computer interface using visually-induced near-infrared spectroscopy responses.
abstract: Visually-induced near-infrared spectroscopy (NIRS) response was utilized to design a brain computer interface (BCI) system. Four circular checkerboards driven by distinct flickering sequences were displayed on a LCD screen as visual stimuli to induce subjects' NIRS responses. Each flickering sequence was a concatenated sequence of alternative flickering segments and resting segments. The flickering segment was designed with fixed duration of 3s whereas the resting segment was chosen randomly within 15-20s to create the mutual independencies among different flickering sequences. Six subjects were recruited in this study and subjects were requested to gaze at the four visual stimuli one-after-one in a random order. Since visual responses in human brain are time-locked to the onsets of visual stimuli and the flicker sequences of distinct visual stimuli were designed mutually independent, the NIRS responses induced by user's gazed targets can be discerned from non-gazed targets by applying a simple averaging process. The accuracies for the six subjects were higher than 90% after 10 or more epochs being averaged.
authors.affiliation: Department of Electrical Engineering, National Central University, Taoyuan 32001, Taiwan; Department of Electrical Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan.
authors.forename: Cheng-Hsuan
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Electrical Engineering, National Central University, Taoyuan 32001, Taiwan.
authors.forename: Ming-Shan
authors.initials: MS
authors.lastname: Ho
authors.affiliation: Department of Electrical Engineering, National Central University, Taoyuan 32001, Taiwan.
authors.forename: Kuo-Kai
authors.initials: KK
authors.lastname: Shyu
authors.affiliation: Department of Electrical Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan.
authors.forename: Kou-Cheng
authors.initials: KC
authors.lastname: Hsu
authors.affiliation: Department of Electrical Engineering, National Central University, Taoyuan 32001, Taiwan; Department of Medical Imaging, Taiwan Landseed Hospital, Taoyuan 32402, Taiwan.
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Wang
authors.affiliation: Department of Electrical Engineering, National Central University, Taoyuan 32001, Taiwan; Center for Dynamical Markers and Translational Medicine, National Central University, Taoyuan 32001, Taiwan. Electronic address: pllee@ee.ncu.edu.tw.
authors.forename: Po-Lei
authors.initials: PL
authors.lastname: Lee
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D062207:Brain-Computer Interfaces; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D019265:Spectroscopy, Near-Infrared; D014796:Visual Perception; D055815:Young Adult
keywords: Brain computer interface; Flickering sequence; Hemodynamic response; Near infrared spectroscopy; Visual response