title: Toward more intuitive brain-computer interfacing: classification of binary covert intentions using functional near-infrared spectroscopy.
abstract: In traditional brain-computer interface (BCI) studies, binary communication systems have generally been implemented using two mental tasks arbitrarily assigned to “yes” or “no” intentions (e.g., mental arithmetic calculation for “yes”). A recent pilot study performed with one paralyzed patient showed the possibility of a more intuitive paradigm for binary BCI communications, in which the patient’s internal yes/no intentions were directly decoded from functional near-infrared spectroscopy (fNIRS). We investigated whether such an “fNIRS-based direct intention decoding” paradigm can be reliably used for practical BCI communications. Eight healthy subjects participated in this study, and each participant was administered 70 disjunctive questions. Brain hemodynamic responses were recorded using a multichannel fNIRS device, while the participants were internally expressing “yes” or “no” intentions to each question. Different feature types, feature numbers, and time window sizes were tested to investigate optimal conditions for classifying the internal binary intentions. About 75% of the answers were correctly classified when the individual best feature set was employed (75.89% ± 1.39 and 74.08% ± 2.87 for oxygenated and deoxygenated hemoglobin responses, respectively), which was significantly higher than a random chance level (68.57% for p < 0.001). The kurtosis feature showed the highest mean classification accuracy among all feature types. The grand-averaged hemodynamic responses showed that wide brain regions are associated with the processing of binary implicit intentions. Our experimental results demonstrated that direct decoding of internal binary intention has the potential to be used for implementing more intuitive and user-friendly communication systems for patients with motor disabilities.
authors.affiliation: Kumoh National Institute of Technology, Department of Medical IT Convergence Engineering, 61 Daehak-ro, Gumi, Gyeongbuk 730-701, Republic of Korea.
authors.forename: Han-Jeong
authors.initials: HJ
authors.lastname: Hwang
authors.affiliation: Hanyang University, Department of Biomedical Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
authors.forename: Han
authors.initials: H
authors.lastname: Choi
authors.affiliation: Hanyang University, Department of Biomedical Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
authors.forename: Jeong-Youn
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Hanyang University, Department of Biomedical Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
authors.forename: Won-Du
authors.initials: WD
authors.lastname: Chang
authors.affiliation: Hanyang University, Department of Biomedical Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of KoreacBerlin Institute of Technology, Machine Learning Group, Marchstraße 23, 10587 Berlin, Germany.
authors.forename: Do-Won
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Korea Research Institute of Standard and Science, 267 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Kiwoong
authors.initials: K
authors.lastname: Kim
authors.affiliation: Korea Advanced Institute of Science and Technology, Department of Computer Science, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Sungho
authors.initials: S
authors.lastname: Jo
authors.affiliation: Hanyang University, Department of Biomedical Engineering, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Im
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000502:physiology; D062207:Brain-Computer Interfaces; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010108:Oxyhemoglobins / Q000032:analysis; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin