Yu Tianyou, Xiao Jun, Wang Fangyi, Zhang Rui, Gu Zhenghui, Cichocki Andrzej, Li Yuanqing
IEEE Trans Biomed Eng. 2015 Jul;62(7):1706-17. doi: 10.1109/TBME.2015.2402283. Epub 2015 Feb 10.
Motor imagery-related mu/beta rhythms, which can be voluntarily modulated by subjects, have been widely used in EEG-based brain computer interfaces (BCIs). Moreover, it has been suggested that motor imagery-specific EEG differences can be enhanced by feedback training. However, the differences observed in the EEGs of naive subjects are typically not sufficient to provide reliable EEG control and thus result in unintended feedback. Such feedback can frustrate subjects and impede training. In this study, a hybrid BCI paradigm combining motor imagery and steady-state visually evoked potentials (SSVEPs) has been proposed to provide effective continuous feedback for motor imagery training.
During the initial training sessions, subjects must focus on flickering buttons to evoke SSVEPs as they perform motor imagery tasks. The output/feedback of the hybrid BCI is based on hybrid features consisting of motor imagery- and SSVEP-related brain signals. In this context, the SSVEP plays a more important role than motor imagery in generating feedback. As the training progresses, the subjects can gradually decrease their visual attention to the flickering buttons, provided that the feedback is still effective. In this case, the feedback is mainly based on motor imagery.
Our experimental results demonstrate that subjects generate distinguishable brain patterns of hand motor imagery after only five training sessions lasting approximately 1.5 h each.
The proposed hybrid feedback paradigm can be used to enhance motor imagery training.
This hybrid BCI system with feedback can effectively identify the intentions of the subjects.
与运动想象相关的μ/β节律可由受试者自主调节，已在基于脑电图的脑机接口（BCI）中广泛应用。此外，有人提出通过反馈训练可以增强特定于运动想象的脑电图差异。然而，在未经训练的受试者脑电图中观察到的差异通常不足以提供可靠的脑电图控制，从而导致意外反馈。这种反馈会使受试者感到沮丧并阻碍训练。在本研究中，提出了一种结合运动想象和稳态视觉诱发电位（SSVEP）的混合BCI范式，为运动想象训练提供有效的连续反馈。
在初始训练阶段，受试者在执行运动想象任务时必须专注于闪烁的按钮以诱发SSVEP。混合BCI的输出/反馈基于由与运动想象和SSVEP相关的脑信号组成的混合特征。在这种情况下，SSVEP在生成反馈中比运动想象发挥更重要的作用。随着训练的进行，只要反馈仍然有效，受试者可以逐渐减少对闪烁按钮的视觉关注。在这种情况下，反馈主要基于运动想象。
我们的实验结果表明，受试者在仅进行了五次每次持续约1.5小时的训练后，就产生了可区分的手部运动想象脑模式。
所提出的混合反馈范式可用于增强运动想象训练。
这种具有反馈的混合BCI系统可以有效地识别受试者的意图。
