Study on Induced Factors and Power Variations of the Steady-State Visual Evoked Potential Subharmonics

Harmonic and subharmonic components are contained in the spectrum of the steady-state visual evoked potential (SSVEP). These components are widely used in the brain-computer interface (BCI) technology and neuroscience research. Subharmonics cannot be easily induced, and the mechanism of the power variation of these components are ambiguous. In this paper, the induced factors and power variation of the SSVEP subharmonics are studied by a visual cortex network model simulation. The SSVEP subharmonics with orders higher than 1/2 are easily suppressed by noise. Therefore, the power variation of the SSVEP subharmonics with 1/2 order, and their induction factors are further analyzed. Simulation results show that the stimulus frequency, stimulus intensity, and noise intensity are three important parameters affecting the generation and power variations of the SSVEP subharmonics. If the stimulus intensity is weak, the 1/2 subharmonics cannot be induced. When the stimulus intensity increases to a certain value, 1/2 subharmonics appear in the SSVEP, and their power increases sharply with the increasing stimulus intensity. However, when the stimulus intensity exceeds a certain threshold, the 1/2 subharmonics remain constant. The bandwidth of the stimulus frequency, which can induce 1/2 subharmonics increases with increasing stimulus intensity under the same noise condition. Generation of 1/2 subharmonics and its power are suppressed by noise.