注意对稳态视觉诱发电位的调节及脑机接口应用

The steady-state visual evoked potentials (SSVEP) are electrophysiological signals elicited in visual cortical areas by a repetitive flicker, and have the same fundamental frequencies as the driving stimuli. Space-based attention and feature-based attention were both found to affect the amplitude of SSVEPs. Some recent studies demonstrated that object-based attention modulated SSVEPs too. The brain-computer interface (BCI) is a kind of man-machine communication interfaces that do not depend on the brain's normal output pathways of the peripheral nerves and muscles. By now, major input sources of BCIs are electrophysiological signals originated from cerebral cortex, mainly slow cortical potential, u/β rhythm and P300. Nowadays, BCIs based on them have some obviously limitations in accuracy and efficiency of information transmission and usability. On the one hand, SSVEP-based BCIs could make up these deficiencies in a way. On the other hand, the progresses in exploration of relevance of SSVEPs to attention have provided some solid theoretical foundations for the development of SSVEP-based BCIs. Therefore, the present study will examine the effects of attention on SSVEPs in depth, and then preliminarily construct SSVEP-based chord and Chinese character stroke speller systems. The study not only contributes to reveal the characteristics and neuromechanism of attention, but also brings up an idea and methods for the development of new BCIs.

稳态视觉诱发电位（SSVEP）是由以固定频率闪烁的视觉刺激所产生的诱发电位。已有证据证明，基于空间的注意和基于特征的注意对SSVEP均具有调节作用。近来的研究也显示，基于客体的注意对SSVEP也存在影响。脑机接口是一种不依赖于外周神经和肌肉等常规输出的信息交流界面。目前，脑机接口的输入主要源自大脑活动的电信号，以皮层慢电位、u/β节律和P300为主。基于这些技术的脑机接口在信息准确率、传递效率和可用性等方面均有待提高。我们发现，一方面，基于SSVEP的脑机接口在一定程度上能克服这些局限，而另一方面近年来注意与SSVEP相关性研究丰富了建立基于SSVEP脑机接口的理论基础。鉴于此，本项目致力于考察注意对SSVEP的影响效应，并希望在此基础上初步建立基于SSVEP的和弦拼写系统和汉字笔画拼写系统。本研究不仅有利于进一步揭示注意的特性及其脑机制，而且可为发展这种脑机交互技术提供方法和理论依据。

已有证据证明，基于空间的注意和基于特征的注意对SSVEP均具有调节作用。近来的研究也显示，基于客体的注意对SSVEP也存在影响。脑机接口是一种不依赖于外周神经和肌肉等常规输出的信息交流界面。目前，脑机接口的输入主要源自大脑活动的电信号，以皮层慢电位、u/β节律和P300为主。基于这些技术的脑机接口在信息准确率、传递效率和可用性方面均有待提高。我们认为，一方面，基于SSVEP的脑机接口在一定程度上能克服这些局限，而另一方面，近年来注意与SSVEP相关性研究丰富了建立基于SSVEP脑机接口的理论基础。鉴于此，本项目致力于考察注意对SSVEP的影响效应，希望为后续研究中建立基于SSVEP的和弦拼写系统和汉字笔画拼写系统提供依据。本研究发现：稳态视觉诱发电位依赖于注意的调节而独立于注视点的变化；基于客体的注意对稳态视觉诱发电位具有调节作用，其振幅与注意资源的分配存在对应关系。本研究的结果不仅有利于进一步揭示注意的特性及其脑机制，而且可为发展这种脑机交互技术提供方法和理论依据。