Sasatake Yuta, Matsushita Kojiro
Intelligent Production Technology Research & Development Center for Aerospace, Institute for Advanced Study, Gifu University, Gifu 501-1193, Japan.
Department of Mechanical Engineering, Gifu University, Gifu 501-1193, Japan.
Sensors (Basel). 2025 Jun 7;25(12):3592. doi: 10.3390/s25123592.
The P300 event-related potential, evoked by attending to specific sensory stimuli, is utilized in non-invasive brain-computer interface (BCI) systems and is considered the only interface through which individuals with complete paralysis can operate devices based on their intention. Conventionally, visual stimuli used to elicit P300 have been presented using displays; however, placing a display directly in front of the user obstructs the field of view and prevents the user from perceiving their surrounding environment. Moreover, every time the user changes posture, the display must be repositioned accordingly, increasing the burden on caregivers. To address these issues, we propose a novel system that employs wirelessly controllable LED visual stimulus presentation devices distributed throughout the surrounding environment, rather than relying on traditional displays. The primary challenge in the proposed system is the communication delay associated with wireless control, which introduces errors in the timing of stimulus presentation-an essential factor for accurate P300 analysis. Therefore, it is necessary to evaluate how such delays affect P300 detection accuracy. The second challenge lies in the variability of visual stimulus strength due to differences in viewing distance caused by the spatial distribution of stimulus devices. This also requires the validation of its impact on P300 detection. In Experiment 1, we evaluated system performance in terms of wireless communication delay and confirmed an average delay of 352.1 ± 30.9 ms. In Experiment 2, we conducted P300 elicitation experiments using the wireless visual stimulus presentation device under conditions that allowed the precise measurement of stimulus presentation timing. We compared P300 waveforms across three conditions: (1) using the exact measured stimulus timing, (2) using the stimulus timing with a fixed compensation of 350 ms for the wireless delay, and (3) using the stimulus timing with both the 350 ms fixed delay compensation and an additional pseudo-random error value generated based on a normal distribution. The results demonstrated the effectiveness of the proposed delay compensation method in preserving P300 waveform integrity. In Experiment 3, a system performance verification test was conducted on 21 participants using a wireless visual presentation device. As a result, statistically significant differences ( < 0.01) in amplitude between target and non-target stimuli, along with medium or greater effect sizes (Cohen's d: 0.49-0.61), were observed under all conditions with an averaging count of 10 or more. Notably, the P300 detection accuracy reached 85% with 40 averaging trials and 100% with 100 trials. These findings demonstrate that the system can function as a P300 speller and be utilized as an interface equivalent to conventional display-based methods.
通过关注特定的感觉刺激诱发的P300事件相关电位，被应用于非侵入性脑机接口（BCI）系统，并且被认为是完全瘫痪的个体能够基于其意图操作设备的唯一接口。传统上，用于诱发P300的视觉刺激是通过显示器呈现的；然而，将显示器直接放置在用户面前会遮挡视野，阻止用户感知周围环境。此外，每次用户改变姿势时，显示器都必须相应地重新定位，增加了护理人员的负担。为了解决这些问题，我们提出了一种新颖的系统，该系统采用分布在周围环境中的无线可控LED视觉刺激呈现设备，而不是依赖传统显示器。所提出系统的主要挑战是与无线控制相关的通信延迟，这会在刺激呈现的时间上引入误差——这是准确P300分析的一个关键因素。因此，有必要评估这种延迟如何影响P300检测精度。第二个挑战在于由于刺激设备的空间分布导致的观看距离差异引起的视觉刺激强度的变化。这也需要验证其对P300检测的影响。在实验1中，我们从无线通信延迟方面评估了系统性能，并确认平均延迟为352.1±30.9毫秒。在实验2中，我们在允许精确测量刺激呈现时间的条件下，使用无线视觉刺激呈现设备进行了P300诱发实验。我们比较了三种条件下的P300波形：（1）使用精确测量的刺激时间，（2）使用对无线延迟固定补偿350毫秒的刺激时间，以及（3）使用具有350毫秒固定延迟补偿和基于正态分布生成的额外伪随机误差值的刺激时间。结果证明了所提出的延迟补偿方法在保持P300波形完整性方面的有效性。在实验3中，使用无线视觉呈现设备对21名参与者进行了系统性能验证测试。结果，在平均计数为10次或更多的所有条件下，观察到目标刺激和非目标刺激之间在幅度上有统计学显著差异（<0.01），以及中等或更大的效应大小（科恩d值：0.49 - 0.61）。值得注意的是，在40次平均试验时P300检测准确率达到85%，在100次试验时达到100%。这些发现表明该系统可以作为P300拼写器发挥作用，并可被用作等同于传统基于显示器方法的接口。
