Simultaneous identification of eye fixation related potentials and reaction related potentials from single-trial signals.

To obtain the effective components from event related potentials (ERPs), it has been necessary to average the waveforms of several trials. ERP data reflect the psychophysiological state of a subject. Time variation is an important feature in ERP analysis, and so the single-trial method is required. A method is proposed to identify simultaneously both eye fixation related potentials (EFRPs) and reaction related potentials (RRPs) using wavelength transforms. The EFRP is an ERP associated with saccadic eye movement. The RRP is defined as a component similar to P300 gained from the reaction signal. Six subjects participate in the oddball task. The task takes 30 min for each subject. Electroencephalograms (EEGs), electro-oculograms (EOGs) and electromyograms (EMGs) are simultaneously recorded. The EFRP is extracted for the offset of saccade from EOG, and the RRP is extracted for the onset of reaction from EMG. The results show that the estimated waveforms described well each of the components in the EFRP and RRP. Moreover, the simulation results show that the amplitudes of the lambda wave are estimated to within an error of 4%, and those of the latencies are within 0.4%, with an SNR of 4.5dB. Those of P300 were 11 and 4%, respectively. The reliability of the method is proved to be sufficient for estimating ERPs.