The highly accurate BCI using alpha waves was developed for controlling the robot arm, and real-time operation was succeeded by using noninvasive electrodes. The significant components of the alpha wave were identified by spectral analysis and confirmation of the amplitude of the alpha wave. When the alpha wave was observed in the subject, the subjects were instructed to select the multiple decision branches, concerning 7 motions (including "STOP") of a robot arm. As a result, high accuracy (70-95%) was obtained, and the subject succeeded in transferring a small box by controlling the robot arm. Since high accuracy was obtained by use of this method, it can be applied to control equipments such as a robot arm. Since the alpha wave can be easily generated, the BCI using alpha waves does not need more training than that using other signals. Moreover, we tried to reduce the false positive errors by effectively detecting artifacts using spectral analysis and detecting signals of 50 µV or more. As a result, the false positive errors could be reduced from 25% to 0%. Therefore, this technique shows great promise in the area of communication and the control of other external equipments, and will make great contribution in the improvement of Quality of Life (QOL) of mobility disabled.

The objective of this paper is to study the relationship between a visual stimulus and the amplitude and phase of the alpha wave as a first step to investigating a change in the background wave after a sensory stimulus and an evoked potential. We examined the effect of a single visual stimulus on the amplitude and phase of alpha waves using the complex demodulation method. The visual stimuli were generated by an LED mounted in goggles with the eyes-closed condition. The amplitude of the alpha wave decreased gradually after the stimulus, until it reached a minimum at around 300 ms after the stimulus. The alpha wave continued to increase, showing some rebound, and returning again to the pre-stimulus level. The phase variation after the stimulus tends to be considerably larger than that before the stimulus. Moreover, the average phase returned to the same slope as the pre-stimulus by 2550 ms after the stimulus. The visual stimulus has an effect on the alpha wave until about 2500 ms after the stimulus. The phase variation difference before and after stimulus is significant from 112 ms to 678 ms after the stimulus. This finding suggests there is a partially pararell time course between the change in VEPs plus ERP complex and the alpha wave.