Stimulation frequency extraction in SSVEP-based brain-computer interface

A periodogram-based method is used to extract the stimulation frequency in a brain-computer interface (BCI) based on steady-state visual evoked potential (SSVEP). In the system, tens of buttons illuminated at different frequencies are used to generate deterministic sinusoidal responses or SSVEP at the visual cortex, which are derived from the electroencephalogram (EEG) by a suitable electrode array. Based on the periodogram of a time-series, we test the EEG data for the presence of hidden periodic components, which correspond to SSVEP, and extract the stimulation frequencies. The method performs well in simulation, and is applied successfully to real data.