不同占空比光刺激对稳态视觉诱发电位的影响研究

Influence on the SSVEP evoked by visual flicker with different duty-cycle

目前稳态视觉诱发电位(Steady-State Visual Evoked Potentials,SSVEP)被广泛应用于脑机接口技术和医学临床检测和治疗.了解影响SSVEP参数及其规律非常必要.针对目前不同学者在不同实验条件下测试闪烁光脉冲占空比对SSVEP影响的结果差异较大而难以归纳其共性规律问题,将光脉冲刺激下产生神经冲动的视觉皮层细胞沿内外膜流动的电流等效为一磁偶极子,在此基础上建立了人头部空间电场及SSVEP计算模型.采用该模型对光脉冲占空比影响SSVEP的规律进行了分析,并开展了相关实验.研究结果表明:在闪烁光频率和强度相同条件下,光脉冲占空比对SSVEP各次谐波振幅及其平均功率的影响呈现多"窗口"效应.实验数据与理论研究结果一致.

At present time, steady-state visual evoked potentials （SSVEP） are highly applied in brain- computer interface and clinical diagnosis and therap. It is equally important to understand the influencial actors and the laws on the SSVEP. There are many differences between the SSVEP evoked by visual flick- er with different duty-cycle in different experiments, so it is hard to summarize the common rules of the SSVEP changing with the change of the duty-cycle of the visual flicker. The membrane current of the visu- al neurons inducing action potential is taken as a magnetic dipoles to build the computational models for the electric fields in the head and the SSVEP on the scale of the human in this paper. Then the basic rules of the duty-cycle of the visual flicker influencing on the SSVEP were researched according to the computation- al model and the experiments were completed accordingly. The results show that under the conditions of the same frequency and intensity of the visual flicker, the variation curves of the harmonic amplitude and the average power of the SSVEP change along with the change of different duty-cycle of the visual flicker show several ＂window＂ patterns. The results of the experiments agree with that of the theoretical studies.