Eidel M, Pfeiffer M, Ziebell P, Kübler A
Institute of Psychology, University of Würzburg, Würzburg, Germany.
Front Hum Neurosci. 2024 Jun 12;18:1371631. doi: 10.3389/fnhum.2024.1371631. eCollection 2024.
Brain-computer interfaces (BCIs) are scientifically well established, but they rarely arrive in the daily lives of potential end-users. This could be in part because electroencephalography (EEG), a prevalent method to acquire brain activity for BCI operation, is considered too impractical to be applied in daily life of end-users with physical impairment as an assistive device. Hence, miniaturized EEG systems such as the cEEGrid have been developed. While they promise to be a step toward bridging the gap between BCI development, lab demonstrations, and home use, they still require further validation. Encouragingly, the cEEGrid has already demonstrated its ability to record visually and auditorily evoked event-related potentials (ERP), which are important as input signal for many BCIs. With this study, we aimed at evaluating the cEEGrid in the context of a BCI based on tactually evoked ERPs. To compare the cEEGrid with a conventional scalp EEG, we recorded brain activity with both systems simultaneously. Forty healthy participants were recruited to perform a P300 oddball task based on vibrotactile stimulation at four different positions. This tactile paradigm has been shown to be feasible for BCI repeatedly but has never been tested with the cEEGrid. We found distinct P300 deflections in the cEEGrid data, particularly at vertical bipolar channels. With an average of 63%, the cEEGrid classification accuracy was significantly above the chance level (25%) but significantly lower than the 81% reached with the EEG cap. Likewise, the P300 amplitude was significantly lower (cEEGrid R2-R7: 1.87 μV, Cap Cz: 3.53 μV). These results indicate that a tactile BCI using the cEEGrid could potentially be operated, albeit with lower efficiency. Additionally, participants' somatosensory sensitivity was assessed, but no correlation to the accuracy of either EEG system was shown. Our research contributes to the growing amount of literature comparing the cEEGrid to conventional EEG systems and provides first evidence that the tactile P300 can be recorded behind the ear. A BCI based on a thus simplified EEG system might be more readily accepted by potential end-users, provided the accuracy can be substantially increased, e.g., by training and improved classification.
脑机接口（BCIs）在科学上已得到充分确立，但它们很少进入潜在终端用户的日常生活。部分原因可能是，脑电图（EEG）作为一种获取脑活动以用于BCI操作的常用方法，被认为过于不切实际，无法作为辅助设备应用于有身体障碍的终端用户的日常生活中。因此，已经开发出了诸如cEEGrid这样的小型化EEG系统。虽然它们有望朝着弥合BCI开发、实验室演示和家庭使用之间的差距迈出一步，但仍需要进一步验证。令人鼓舞的是，cEEGrid已经展示了其记录视觉和听觉诱发的事件相关电位（ERP）的能力，这些电位作为许多BCI的输入信号很重要。在这项研究中，我们旨在基于触觉诱发的ERP对cEEGrid在BCI背景下进行评估。为了将cEEGrid与传统头皮EEG进行比较，我们同时用这两种系统记录脑活动。招募了40名健康参与者，让他们在四个不同位置基于振动触觉刺激执行P300奇偶数任务。这种触觉范式已被反复证明对BCI是可行的，但从未用cEEGrid进行过测试。我们在cEEGrid数据中发现了明显的P300偏转，特别是在垂直双极通道处。cEEGrid的分类准确率平均为63%，显著高于机遇水平（25%），但显著低于EEG帽达到的81%。同样，P300波幅也显著更低（cEEGrid的R2 - R7：1.87 μV，帽状电极的Cz：3.53 μV）。这些结果表明，使用cEEGrid的触觉BCI可能具有潜在的可操作性，尽管效率较低。此外，对参与者的体感敏感性进行了评估，但未显示出与任何一种EEG系统的准确率有相关性。我们的研究为将cEEGrid与传统EEG系统进行比较的文献数量不断增加做出了贡献，并提供了首个证据，证明可以在耳后记录触觉P300。基于如此简化的EEG系统的BCI，如果准确率能够大幅提高，例如通过训练和改进分类，可能更容易被潜在终端用户接受。
