Abstract
The aim of the present study was to examine the evoked potentials which related to discrimination of tactile stimuli with pressure. As a natural tactile stimulus, rotations of brushes were presented to the tip of the right index finger. The rotations were controlled by a stepping motor. Evoked potentials were recorded in two conditions : the non discrimination condition in which subjects were instructed to ignore brush stimuli; and the discrimination condition in which subjects were required to discriminate two directions of stimulus rotations and to count the number of the right rotation. In the discrimination condition, the two direction-stimuli (right : 20%, left : 80%) were presented in random order. N60 appeared dominantly at the regions of C3 and C3'. The amplitudes of N60 for the discrimination condition were larger than those for the non discrimination condition. P300 waves appeared dominantly at parietal region to the right rotating rare stimuli for the discrimination condition. This amplitude-distribution of P300 wave was similar to those of P300 waves to auditory and visual stimuli. This result indicates that P300 waves might reflect the common processing system of multimodal information.
