Visual evoked potential and visual information processing

The following three topics on 'VEP and visual information processing' were reviewed: 1) Recent knowledge in visual information processing; 2) Neural generators of ERGs and VEPs; and 3) Algorithm for electrodiagnosis of visual pathways. Visual information is processed via multiple, parallel channels: parvocellular (P) and magnocellular (M) pathways. The P system plays an important role in color and object vision and the M system in motion and stereopsis. These pathways can be selectively stimulated by using isoluminant red-green sinusoidal gratings at 2 c/deg and apparent motion display. Flash ERGs are useful for evaluating preganglionic activity, while pattern ERGs reflect retinal ganglion cell activity. The generator source of the P100 of pattern VEPs was estimated around the calcarine fissure using magnetoencephalography. Combined use of ERGs and VEPs with appropriate stimuli can therefore evaluate the functions of the visual pathways.