A Comparison of Two Spelling Brain-Computer Interfaces Based on Visual P3 and SSVEP in Locked-In Syndrome

ObjectivesWe study the applicability of a visual P3-based and a Steady State Visually Evoked Potentials (SSVEP)-based Brain-Computer Interfaces (BCIs) for mental text spelling on a cohort of patients with incomplete Locked-In Syndrome (LIS).MethodsSeven patients performed repeated sessions with each BCI. We assessed BCI performance, mental workload and overall satisfaction for both systems. We also investigated the effect of the quality of life and level of motor impairment on the performance.ResultsAll seven patients were able to achieve an accuracy of 70% or more with the SSVEP-based BCI, compared to 3 patients with the P3-based BCI, showing a better performance with the SSVEP BCI than with the P3 BCI in the studied cohort. Moreover, the better performance of the SSVEP-based BCI was accompanied by a lower mental workload and a higher overall satisfaction. No relationship was found between BCI performance and level of motor impairment or quality of life.ConclusionOur results show a better usability of the SSVEP-based BCI than the P3-based one for the sessions performed by the tested population of locked-in patients with respect to all the criteria considered. The study shows the advantage of developing alternative BCIs with respect to the traditional matrix-based P3 speller using different designs and signal modalities such as SSVEPs to build a faster, more accurate, less mentally demanding and more satisfying BCI by testing both types of BCIs on a convenience sample of LIS patients.

研究目标：本研究旨在探讨基于视觉P3（visual P3-based）与基于稳态视觉诱发电位（Steady State Visually Evoked Potentials, SSVEP）的脑机接口（Brain-Computer Interfaces, BCIs）在不完全闭锁综合征（Locked-In Syndrome, LIS）患者队列中实现心理文本拼写的适用性。方法：7名患者分别完成每种BCI的重复测试会话。我们评估了两种系统的BCI性能、心理负荷及整体满意度，并探究了生活质量与运动损伤程度对BCI性能的影响。结果：所有7名患者使用基于SSVEP的BCI时，准确率均可达到70%及以上；而基于P3的BCI仅3名患者达标，表明本研究队列中SSVEP-BCI的性能优于P3-BCI。此外，SSVEP基BCI的更佳性能伴随更低的心理负荷与更高的整体满意度。未发现BCI性能与运动损伤程度或生活质量存在关联。结论：本研究结果显示，针对受试的闭锁综合征患者群体，在所有考量指标下，基于SSVEP的BCI易用性优于基于P3的BCI。本研究通过在便利抽样的LIS患者样本中测试两种BCI，证实了相较于传统基于矩阵的P3拼写器，开发采用不同设计与信号模态（如SSVEP）的替代BCI具有显著优势，可构建更快、更准确、心理负荷更低且用户满意度更高的脑机接口系统。