Comparison of Visual Cortex Functional Connectivity Patterns Based on Steady-state Monochromatic Flicker and Oscillating Checkerboard Visual Stimulus

Steady-state visual evoked potential (SSVEP) and steady-state motion visual evoked potential (SSMVEP) are commonly implemented in brain computer interfaces (BCIs). The primary visual system is believed to consist of two pathways: a ventral pathway involved with conscious perception and a dorsal pathway for moving visual information processing. In this paper, as monochromatic flicker and oscillating checkerboard served as distinct stimuli for the elicit of SSVEP and SSMVEP respectively, we investigated functional connectivity patterns of SSVEP and SSMVEP by applying directed transfer function (DTF) to electroencephalography (EEG) signals. The value of flow gain, which is defined as the ratio of outflow to inflow of information flows in one channel, was used to measure the activating level of specific brain region in the information transmission process. We found that the occipital region was strongly activated by flicker stimulation whereas the strongest response of oscillating checkerboard was in the middle temporal visual region. Owing to the difference of activating area, fourteen-channel canonical correlation analysis (CCA) was also applied to compare the recognition accuracy. Results indicated that, due to the wider area activated by oscillating checkerboard, it achieved a higher recognition performance with short response time when compared to monochromatic flicker.