Duty-cycle beyond three stimulation frequencies effect based on evoked signal of SSVEP paradigms

摘要

Steady-state visual evoked potentials (SSVEPs) recently progressively used within brain-computer interface (BCI) techniques. Typically, the SSVEP response is evoked signals were leveraged by flickering under certain frequency that consequence directly on amplitude signal; selecting stimuli frequencies lower than 20Hz to achieve a high SNR. Therefore, the critical frequency based stimuli flickers are often make subjects feel inconvenience and fatigue through evoking signal. Achieve three intensities of evoking flickers type by propose design that utilized a single LED/flicker. Base three frequencies at 5Hz, 12Hz and 24Hz, which are driven by consisting of regular sequences with repetitive stimulus cycles and fixed duration based on three different duty-cycle 25%, 50% and 75% respectively. Evoked signal of SSVEPs were recorded using three-EEG/channels and frequency-time besides statistical topography analyzed that applied to achieve a final comparison between different paradigms. The extracted result provides a relationship between amplitude and duty-cycle of each stimulus; lead to different influences in brain activities based SSVEP referred to diverse paradigms.