Hwang Han-Jeong, Ferreria Valeria Y, Ulrich Daniel, Kilic Tayfun, Chatziliadis Xenofon, Blankertz Benjamin, Treder Matthias
Machine Learning Group, Berlin Institute of Technology (TU Berlin), Marchstrasse 23, 10587 Berlin, Germany.
Neurotechnology Group, Berlin Institute of Technology (TU Berlin), Marchstrasse 23, 10587 Berlin, Germany.
Sci Rep. 2015 Oct 29;5:15890. doi: 10.1038/srep15890.
A classical brain-computer interface (BCI) based on visual event-related potentials (ERPs) is of limited application value for paralyzed patients with severe oculomotor impairments. In this study, we introduce a novel gaze independent BCI paradigm that can be potentially used for such end-users because visual stimuli are administered on closed eyelids. The paradigm involved verbally presented questions with 3 possible answers. Online BCI experiments were conducted with twelve healthy subjects, where they selected one option by attending to one of three different visual stimuli. It was confirmed that typical cognitive ERPs can be evidently modulated by the attention of a target stimulus in eyes-closed and gaze independent condition, and further classified with high accuracy during online operation (74.58% ± 17.85 s.d.; chance level 33.33%), demonstrating the effectiveness of the proposed novel visual ERP paradigm. Also, stimulus-specific eye movements observed during stimulation were verified as reflex responses to light stimuli, and they did not contribute to classification. To the best of our knowledge, this study is the first to show the possibility of using a gaze independent visual ERP paradigm in an eyes-closed condition, thereby providing another communication option for severely locked-in patients suffering from complex ocular dysfunctions.
基于视觉事件相关电位（ERP）的传统脑机接口（BCI）对于患有严重眼球运动障碍的瘫痪患者应用价值有限。在本研究中，我们引入了一种新型的不依赖注视的BCI范式，该范式可能适用于此类终端用户，因为视觉刺激是施加在闭合的眼睑上。该范式涉及口头提出问题并给出3个可能答案。我们对12名健康受试者进行了在线BCI实验，他们通过关注三种不同视觉刺激之一来选择一个选项。结果证实，在闭眼且不依赖注视的条件下，典型的认知ERP能够明显受到目标刺激注意力的调制，并且在在线操作过程中能够以较高准确率进行分类（74.58%±17.85标准差；机遇水平为33.33%），证明了所提出的新型视觉ERP范式的有效性。此外，刺激期间观察到的特定刺激眼动被证实是对光刺激的反射反应，它们对分类没有贡献。据我们所知，本研究首次展示了在闭眼条件下使用不依赖注视的视觉ERP范式的可能性，从而为患有复杂眼功能障碍的严重闭锁综合征患者提供了另一种交流选择。
