视觉感知空间分布对SSVEP调制成分的影响

Effect of spatial distribution of visual perception on intermodulation SSVEP

目的研究视觉感知空间分布对稳态视觉诱发电位(steady state visual evoked potential,SSVEP)调制成分的影响,为后续研究SSVEP调制成分与认知的关系奠定基础。方法使用两种闪烁频率分别标记两个刺激图像,设计并实现了"完全重合"、"左右半分"和"对角四分"三种不同空间分布的脑电实验。共9名被试参与此次研究。本文计算并比较了3种实验条件下SSVEP基本成分与调制成分的信噪比空间分布,并做配对t检验。结果调制成分的信噪比在"完全重合"时远大于"左右半分"和"对角四分",且在大部分电极处都具有显著性差异。后两种分布下调制成分非常微弱,并且"对角四分"略高于"左右半分"。结论当不同频率的刺激图像的视觉感知空间交叠时,SSVEP调制成分强,反之,则弱,且可能与交界区域有关。因此在有关SSVEP调制成分的研究中。

Objective To study the relationship between intermodulation components of steady state visual evoked potential （SSVEP） and spatial distribution of visual perception, laying a foundation for follow-up research of cognition related to intermodulation components. Methods This article adopted two flashing frequencies to tag two stimuli respectively, designed and implemented three experiments with different patterns of spatial distributions, which were named Overlap, Halves and Diagonals. Nine ~＇~ubjects voluntarily took part in those experiments. The signal-to-noise ratio （SNR）＇ s spatial distributions of basic components and intermodulation components were compared under these three experimental conditions with paired t test. Results The intermodulation components＇ SNR in Overlap was much larger than the ones in Halves and Diagonals, with significant differences in most of the electrodes. The latter two were both extremely weak, and the Halves＇ was slightly higher than the Diagonals ＇ . Conclusions When the stimuli ＇ s spatial distribution is overlap, the intermodulation components of SSVEP are larger, otherwise they are weaker and may be related to the border of the stimuli. Therefore, researches related to intermodulation components of SSVEP need to take the spatial distribution of stimuli labeled with different flashing frequencies into account.