National Electronics and Computer Technology Center, 112 Thailand Science Park (Head Office) Phahonyothin Road, Klong Neung, Klong Luang District, Pathumthani 12120, Thailand.
J Neural Eng. 2013 Jun;10(3):036012. doi: 10.1088/1741-2560/10/3/036012. Epub 2013 Apr 23.
We propose a new stimulation pattern design for the P300-based matrix speller aimed at increasing the minimum target-to-target interval (TTI).
Inspired by the simplicity and strong performance of the conventional row-column (RC) stimulation, the proposed stimulation is obtained by modifying the RC stimulation through alternating row and column flashes which are selected based on the proposed design rules. The second flash of the double-flash components is then delayed for a number of flashing instants to increase the minimum TTI. The trade-off inherited in this approach is the reduced randomness within the stimulation pattern.
We test the proposed stimulation pattern and compare its performance in terms of selection accuracy, raw and practical bit rates with the conventional RC flashing paradigm over several flash rates. By increasing the minimum TTI within the stimulation sequence, the proposed stimulation has more event-related potentials that can be identified compared to that of the conventional RC stimulations, as the flash rate increases. This leads to significant performance improvement in terms of the letter selection accuracy, the raw and practical bit rates over the conventional RC stimulation.
These studies demonstrate that significant performance improvement over the RC stimulation is obtained without additional testing or training samples to compensate for low P300 amplitude at high flash rate. We show that our proposed stimulation is more robust to reduced signal strength due to the increased flash rate than the RC stimulation.
我们提出了一种新的基于 P300 的矩阵拼写器刺激模式设计，旨在增加最小目标-目标间隔（TTI）。
受传统行-列（RC）刺激的简单性和强大性能的启发，所提出的刺激是通过交替行和列闪烁来修改 RC 刺激而获得的，这些闪烁是基于所提出的设计规则选择的。双闪烁组件的第二个闪烁然后延迟几个闪烁瞬间，以增加最小 TTI。这种方法所继承的权衡是刺激模式中随机性的降低。
我们测试了所提出的刺激模式，并在不同闪烁频率下，根据选择准确率、原始比特率和实际比特率，将其性能与传统 RC 闪烁范式进行了比较。通过增加刺激序列中的最小 TTI，与传统 RC 刺激相比，所提出的刺激在闪烁频率增加时可以识别出更多的与事件相关的潜在信息，从而在字母选择准确率、原始比特率和实际比特率方面获得显著的性能提升。
这些研究表明，在不增加测试或训练样本的情况下，可以获得比 RC 刺激更好的性能，从而补偿高闪烁频率下 P300 幅度较低的问题。我们表明，与 RC 刺激相比，我们提出的刺激对由于闪烁频率增加而导致的信号强度降低更具鲁棒性。
