The interaction between sornatosensory and auditory cognitive processing assessed with event-related Potentials

Event-related potentials induced by somatosensory and after auditory stimulation or bilateral somatosensory stimulation in young adults were studied, aiming to evaluate interactions of cognitive processing of somatosensory and auditory information. In experiment 1, event-related potentials were elicited by four stimulus conditions which were randomly presented with an interstimulus interval of 20 +/- 3 milliseconds: electric stimuli delivered to the right median nerve (Con 1), auditory stimuli delivered to both ears (Con 2), electric and subsequent auditory stimuli (Con 3), and electric stimuli delivered to the bilateral median nerve (Con 4). In experiment 2, Con 2 was changed to electric stimulation of the left median nerve. The subtraction of grand averaged event-related potentials of Con I and Con 2 from those of Con 3 demonstrated a positivenegative peak complex with a positive peak at approximately 165 to 170 milliseconds after stimuli and a negative peak with a mean latency of 372 milliseconds in experiment 1. In experiment 2, the subtraction of event-related potentials in Con I and 2 from those in Con 4 revealed positive and negative peaks resembling those in experiment 1, but the distribution or latencies of the peaks differed from those in experiment 1. We speculate that the subtracted positive and negative peaks reflect different cognitive processing of bimodal and bifocal sensory information.