Asynchronous BCI control using high-frequency SSVEP

Background: steady-state visual evoked potential (ssvep) is a visual cortical response evoked by repetitive stimuli with a light source flickering at frequencies above 4 hz and could be classified into three ranges: low (up to 12 hz),medium (12-30) and high frequency (> 30 hz). ssvep-based brain-computer interfaces (bci) are principally focused on the low and medium range of frequencies whereas there are only a few projects in the high-frequency range. however,they only evaluate the performance of different methods to extract ssvep. methods. this research proposed a high-frequency ssvep-based asynchronous bci in order to control the navigation of a mobile object on the screen through a scenario and to reach its final destination. this could help impaired people to navigate a robotic wheelchair. there were three different scenarios with different difficulty levels (easy,medium and difficult). the signal processing method is based on fourier transform and three eeg measurement channels. results: the research obtained accuracies ranging in classification from 65% to 100% with information transfer rate varying from 9.4 to 45 bits/min. conclusions: our proposed method allows all subjects participating in the study to control the mobile object and to reach a final target without prior training. © 2011 diez et al; licensee biomed central ltd.