Institute for Knowledge Discovery, Graz University of Technology, Inffeldgasse 13, 8010 Graz, Austria.
Artif Intell Med. 2013 Oct;59(2):81-90. doi: 10.1016/j.artmed.2013.07.003. Epub 2013 Sep 13.
Within this work an auditory P300 brain-computer interface based on tone stream segregation, which allows for binary decisions, was developed and evaluated.
Two tone streams consisting of short beep tones with infrequently appearing deviant tones at random positions were used as stimuli. This paradigm was evaluated in 10 healthy subjects and applied to 12 patients in a minimally conscious state (MCS) at clinics in Graz, Würzburg, Rome, and Liège. A stepwise linear discriminant analysis classifier with 10×10 cross-validation was used to detect the presence of any P300 and to investigate attentional modulation of the P300 amplitude.
The results for healthy subjects were promising and most classification results were better than random. In 8 of the 10 subjects, focused attention on at least one of the tone streams could be detected on a single-trial basis. By averaging 10 data segments, classification accuracies up to 90.6% could be reached. However, for MCS patients only a small number of classification results were above chance level and none of the results were sufficient for communication purposes. Nevertheless, signs of consciousness were detected in 9 of the 12 patients, not on a single-trial basis, but after averaging of all corresponding data segments and computing significant differences. These significant results, however, strongly varied across sessions and conditions.
This work shows the transition of a paradigm from healthy subjects to MCS patients. Promising results with healthy subjects are, however, no guarantee of good results with patients. Therefore, more investigations are required before any definite conclusions about the usability of this paradigm for MCS patients can be drawn. Nevertheless, this paradigm might offer an opportunity to support bedside clinical assessment of MCS patients and eventually, to provide them with a means of communication.
本研究开发并评估了一种基于音调流分离的、可进行二进制决策的听觉 P300 脑-机接口。
使用两个短蜂鸣声音调流作为刺激，其中随机位置偶尔会出现偏差音调。该范式在 10 名健康受试者中进行了评估，并应用于格拉茨、维尔茨堡、罗马和列日诊所的 12 名最小意识状态（MCS）患者。使用具有 10×10 交叉验证的逐步线性判别分析分类器来检测 P300 的存在，并研究 P300 幅度的注意力调制。
健康受试者的结果很有希望，大多数分类结果都优于随机结果。在 10 名受试者中的 8 名中，可以在单次试验的基础上检测到至少一个音调流的集中注意力。通过平均 10 个数据段，可以达到高达 90.6%的分类准确率。然而，对于 MCS 患者，只有少数分类结果高于机会水平，没有任何结果足以用于通信目的。然而，在 12 名患者中的 9 名中检测到了意识迹象，不是在单次试验的基础上，而是在平均所有对应数据段并计算显著差异后。然而，这些显著的结果在各个会话和条件之间变化很大。
这项工作展示了从健康受试者到 MCS 患者的范式转变。然而，健康受试者的有希望结果并不能保证患者的结果良好。因此，在得出关于该范式对 MCS 患者可用性的任何明确结论之前，还需要进行更多的研究。然而，该范式可能为床边临床评估 MCS 患者提供机会，并最终为他们提供一种交流手段。
