Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, People's Republic of China.
Department of Biomedical Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China.
J Neural Eng. 2021 Dec 28;18(6). doi: 10.1088/1741-2552/ac40a1.
Steady-state visual evoked potential (SSVEP) based brain-computer interface (BCI) has the characteristics of fast communication speed, high stability, and wide applicability, thus it has been widely studied. With the rapid development in paradigm, algorithm, and system design, SSVEP-BCI is gradually applied in clinical and real-life scenarios. In order to improve the ease of use of the SSVEP-BCI system, many studies have been focusing on developing it on the hairless area, but due to the lack of redesigning the stimulation paradigm to better adapt to the new area, the electroencephalography response in the hairless area is worse than occipital region.. This study first proposed a phase difference estimation method based on stimulating the left and right visual field separately, then developed and optimized a left and right visual field biphasic stimulation paradigm for SSVEP-based BCIs with hairless region behind the ear.In the 12-target online experiment, after a short model estimation training, all 16 subjects used their best stimulus condition. The paradigm designed in this study can increase the proportion of applicable subjects for the behind-ear SSVEP-BCI system from 58.3% to 75% and increase the accuracy from 74.6 ± 20.0% (the existing best SSVEP stimulus with hairless region behind the ear) to 84.2±14.7%, and the information transfer rate from 14.2±6.4 bits minto 17.8±5.7 bits min.These results demonstrated that the proposed paradigm can effectively improve the BCI performance using the signal from the hairless region behind the ear, compared with the standard SSVEP stimulation paradigm.
稳态视觉诱发电位（SSVEP）脑-机接口（BCI）具有通信速度快、稳定性高、适用性广的特点，因此得到了广泛的研究。随着范式、算法和系统设计的快速发展，SSVEP-BCI 逐渐应用于临床和实际场景。为了提高 SSVEP-BCI 系统的易用性，许多研究都集中在开发无毛区的系统上，但由于缺乏重新设计刺激范式以更好地适应新区域，无毛区的脑电图反应不如枕区好。本研究首先提出了一种基于左右视野分别刺激的相位差估计方法，然后开发并优化了一种用于基于 SSVEP 的 BCI 的左右视野双相刺激范式，该范式用于耳后无毛区。在 12 目标在线实验中，在进行了短暂的模型估计训练后，所有 16 名受试者都使用了他们的最佳刺激条件。本研究设计的范式可以将耳后 SSVEP-BCI 系统的适用受试者比例从 58.3%提高到 75%，将准确率从 74.6±20.0%（现有的最佳耳后无毛区 SSVEP 刺激）提高到 84.2±14.7%，信息传输率从 14.2±6.4 bit min 提高到 17.8±5.7 bit min。这些结果表明，与标准 SSVEP 刺激范式相比，所提出的范式可以有效地利用耳后无毛区的信号提高 BCI 性能。
