High-speed spelling with a noninvasive brain-computer interface.
The past 20 years have witnessed unprecedented progress in brain-computer interfaces (BCIs). However, low communication rates remain key obstacles to BCI-based communication in humans. This study presents an electroencephalogram-based BCI speller that can achieve information transfer rates (ITRs) up to 5.32 bits per second, the highest ITRs reported in BCI spellers using either noninvasive or invasive methods. Based on extremely high consistency of frequency and phase observed between visual flickering signals and the elicited single-trial steady-state visual evoked potentials, this study developed a synchronous modulation and demodulation paradigm to implement the speller. Specifically, this study proposed a new joint frequency-phase modulation method to tag 40 characters with 0.5-s-long flickering signals and developed a user-specific target identification algorithm using individual calibration data. The speller achieved high ITRs in online spelling tasks. This study demonstrates that BCIs can provide a truly naturalistic high-speed communication channel using noninvasively recorded brain activities.
Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China;
Xiaogang
X
Chen
Swartz Center for Computational Neuroscience, University of California, San Diego, CA 92093; State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China wangyj@semi.ac.cn gxr-dea@tsinghua.edu.cn.
Yijun
Y
Wang
Swartz Center for Computational Neuroscience, University of California, San Diego, CA 92093;
Masaki
M
Nakanishi
Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China; wangyj@semi.ac.cn gxr-dea@tsinghua.edu.cn.
Xiaorong
X
Gao
Swartz Center for Computational Neuroscience, University of California, San Diego, CA 92093;
Tzyy-Ping
TP
Jung
Department of Biomedical Engineering, Tsinghua University, Beijing 100084, China;
Shangkai
S
Gao
D062207:Brain-Computer Interfaces; D005074:Evoked Potentials, Visual; D006801:Humans; D007802:Language
brain–computer interface; electroencephalogram; joint frequency-phase modulation; steady-state visual evoked potentials