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Journal of Biomedical Optics • Open Access

Toward more intuitive brain–computer interfacing: classification of binary covert intentions using functional near-infrared spectroscopy
Author(s): Han-Jeong Hwang; Han Choi; Jeong-Youn Kim; Won-Du Chang; Do-Won Kim; Kiwoong Kim; Sungho Jo; Chang-Hwan Im

Paper 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.

Paper Details

Date Published: 5 April 2016
PDF: 11 pages
J. Biomed. Opt. 21(9) 091303 doi: 10.1117/1.JBO.21.9.091303
Published in: Journal of Biomedical Optics Volume 21, Issue 9
Show Author Affiliations
Han-Jeong Hwang, Hanyang Univ. (Korea, Republic of)
Kumoh National Institute of Technology (Korea, Republic of)
Han Choi, Hanyang Univ. (Republic of Korea)
Jeong-Youn Kim, Hanyang Univ. (Republic of Korea)
Won-Du Chang, Hanyang Univ. (Republic of Korea)
Do-Won Kim, Hanyang Univ. (Republic of Korea)
Berlin Institute of Technology (Germany)
Kiwoong Kim, Korea Research Institute of Standards and Science (Republic of Korea)
Sungho Jo, KAIST (Republic of Korea)
Chang-Hwan Im, Hanyang Univ. (Republic of Korea)

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