Analysis of P300 evoked by multisensory stimulus consisting of visual and auditory stimuli

In this study, we investigated P300 amplitude and latency when multisensory stimuli are presented, and compared the results with those in a single sensory stimulus. Here, visual and auditory stimulus were used as sensory stimulus, and these stimuli were presented to the subject simultaneously in the case of multisensory stimuli. In the experiment, three kinds of stimuli, visual, auditory, and multisensory stimuli were prepared, and either one of visual and auditory stimulus or both were set as target stimulus. The subject was instructed to push a button when target stimulus occurred. As a results, P300 amplitude of grand averaged waveform in visual evoked potential (VEP) changed a lot depending on the kind of target stimulus. The other hand, P300 amplitudes in auditory evoked potential (AEP) were almost same regardless of the kind. Furthermore, the amplitude in VEP and AEP was decreasing in the following order: target stimulus is consistent with the corresponding sensory stimulus; both visual and auditory stimuli are the target; the target is inconsistent with a sensory stimulus; and no target is set. The amplitude in multisensory evoked potential (MEP) was decreasing in the following order: both visual and auditory stimuli are the target; the target is auditory stimulus; the target is visual stimulus; no target is set. A significant difference was recognized in P300 amplitudes between visual target and no target. Regarding P300 latency of grand averaged waveform in VEP and AEP, the latencies with target stimulus were longer than that without target. However, in the case of MEP, there was rare difference in the existence of target stimulus. As for response time until button pushing, in MEP, the time when target is both of visual and auditory stimuli tended to be shorter than that when target is single sensory stimulus though significant difference could not be recognized.