title: A high-speed brain speller using steady-state visual evoked potentials.
abstract: Implementing a complex spelling program using a steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) remains a challenge due to difficulties in stimulus presentation and target identification. This study aims to explore the feasibility of mixed frequency and phase coding in building a high-speed SSVEP speller with a computer monitor. A frequency and phase approximation approach was developed to eliminate the limitation of the number of targets caused by the monitor refresh rate, resulting in a speller comprising 32 flickers specified by eight frequencies (8-15 Hz with a 1 Hz interval) and four phases (0°, 90°, 180°, and 270°). A multi-channel approach incorporating Canonical Correlation Analysis (CCA) and SSVEP training data was proposed for target identification. In a simulated online experiment, at a spelling rate of 40 characters per minute, the system obtained an averaged information transfer rate (ITR) of 166.91 bits/min across 13 subjects with a maximum individual ITR of 192.26 bits/min, the highest ITR ever reported in electroencephalogram (EEG)-based BCIs. The results of this study demonstrate great potential of a high-speed SSVEP-based BCI in real-life applications.
authors: Graduate School of Science and Technology, Keio University, Yokohama, Kanagawa, 223-8522, Japan.
authors: Masaki
authors: M
authors: Nakanishi
authors: Yijun
authors: Y
authors: Wang
authors: Yu-Te
authors: YT
authors: Wang
authors: Yasue
authors: Y
authors: Mitsukura
authors: Tzyy-Ping
authors: TP
authors: Jung
mesh_terms: D000465:Algorithms; D000818:Animals; D001703:Biophysics; D001921:Brain / Q000502:physiology*; D062207:Brain-Computer Interfaces; D003142:Communication; D003198:Computer Simulation; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors
keywords: Steady-state visual evoked potential; brain-computer interface; mixed frequency and phase coding; speller