The interaction of somatosensory and auditory stimuli on event-related potentials

The effects of dual somatosensory and/or auditory stimuli on event-related potentials (ERPs) were studied. In experiment 1, ERPs were recorded following four stimulus conditions which were randomly presented: electrical stimuli to the right median nerve (Con 1), auditory stimuli (Con 2), Con 1+Con 2 (Con 3) and electrical stimuli to the bilateral median nerves (Con 4). In experiment 2, Con 2 was changed to electrical stimulation of the left median nerve. In experiment 1, a positive peak with a latency of about 180 ms (P180) and a negative peak with a latency of about 380 ms appeared after subtracting waveforms under Con 1 and 2 from those under Con 3. In experiment 2, the similar subtraction (C4-C1-C2) showed small P180 and increased P300. The present results suggest interactions of central processing of both auditory and somatosensory stimuli on ERPs. We speculate that there are specific components of ERPs reacting with bimodal sensory inputs.