Toward binary brain computer interface using steady-state visually evoked potential under eyes closed condition

It is highly difficult for severely amyotrophic lateral sclerosis and heavily spinal cord injury patients to use the brain computer interfaces (BCIs) based on the steady-state visual evoked potential (SSVEP) which need to control the direction of their eye gaze. We investigated amplitude change of the SSVEP associated with mental concentration on flicker to develop the SSVEP-based BCI usable under eyes-closed condition. Under the stimulus conditions of the flickering frequency of 10 Hz and the stimulus intensity of 5 lx, significant difference between the SSVEP amplitude in relaxed state and that in concentrated state was observed in the wide region of the scalp except the left frontal region, while such significance was also seen in the bilateral occipital lobes and left parietal region under the conditions of 14 Hz and 5 lx. Such an impact of mental concentration on the SSVEP amplitude was reproducible.