语义匹配性及刺激间隔对视听双模态脑控字符输入系统的影响
Effects of Semantic Congruency and Stimulus-Onset Asynchrony on Audiovisual Bimodal Stimuli Based BCI Speller

近年来, 基于事件相关电位(ERP)的脑控字符输入系统的研究越来越多, 视觉与听觉的多模态刺激范式作为一种新型的复合刺激越来越受到关注．然而, 研究视听双模态刺激的脑控字符输入系统性能因素的文章却很少报道．本研究旨在初步探究视听觉刺激的语义匹配性以及刺激间隔(SOA)对视听双模态脑控字符输入系统的影响．为此, 本研究设计了语义匹配、语义失配两种刺激范式, 每种范式又设置两种不同的刺激间隔(200 ms或400 ms)．10名健康被试参与了本实验, 通过对比事件相关电位特征、可分性及分类正确率发现视听觉匹配性、刺激间隔以及两者交互作用对非目标刺激大脑反应、目标刺激大脑反应及其可分性都有显著性影响, 且视听觉的匹配性对视听联合脑控字符输入系统分类正确率影响显著, 但是不同刺激间隔脑机接口分类正确率之间并无显著性差异．本研究的结果能够为基于双模态刺激脑控字符输入系统的范式选择和优化提供一定的指导意见．
In recent years，researches on event-related potential(ERP)-based brain computer interface(BCI)speller have become increasingly popular. Visual and auditory based multimodal stimuli paradigms as new paradigms have attracted more and more attention. Studies on the effect of experimental parameters on system performance of visual-auditory stimuli based BCI speller have rarely been reported. This study aims at investigating the effects of audiovisual semantic congruency and stimulus-onset asynchrony(SOA)on audiovisual bimodal stimuli based BCI speller. Therefore，two audiovisual paradigms(semantic congruent and semantic incongruent)with two different SOAs(200 ms and 400 ms)were adopted，and 10 healthy subjects participated in the experiment. ERP，discrimination of targets and non-targets，and classification accuracy were analyzed. Results indicated that semantic congruency，SOA and the interaction factors have significant effect on the brain response and discrimination of target and non-target stimuli. Semantic congruency also has significant effect on system classification accuracy，whereas no significant difference was found on factor SOA. This study could provide a theoretical guidance for the design of new paradigms on visual and auditory based bimodal BCI speller