[The normal response process of the dynamic topography of pattern visual evoked potentials].

The dynamic topography of pattern visual evoked potentials (PVEPs) were studied in 20 normal subjects. PVEPs, recorded from 16 electrodes referenced to balanced non-cephalic electrode (BNE), were elicited by a binocular checkerboard pattern (15 min) that alternated at 1 Hz rate on a 14 x 8.5 degree TV monitor 1m distant from the eyes. N70, P100, N100, N150 and P200 components were recorded each time. In 65% of subjects the P100 components appeared in the lateral region in 120-150 msec. In flash VEP, the P100 component did not appear in the lateral region. Recorded on lateral electrodes, N100 components first appeared in the deep frontal region and gradually distributed throughout the frontal region while the P100 component was localized at the occipital pole. In the focused state, the peak latency of the N100 component was the same as that of the P100 component, but in the moderately defocused state, the peak latency of the N100 component was delayed compared with that of the P100 component. This study suggested that the appearance of the P100 component in the lateral region is related to form recognition, and that the N100 component is not the inverse dipole of the P100 component.