BINOCULAR FACILITATION OF VEPs BY REAL STEREO-TARGET
The VEPs was detected with the binocular liquid crystal shutter and with the wooden block stereoptic target set up around the Vieth-Muller circle. The surface of the whole target was arranged in a checkerboard pattern with an uneven surface to produce binocular disparity. Visual stimulation was given by the binocular liquid crystal shutter which triggered an average computer to induce a steady state VEPs. The binocular excitatory effect was smallest when the distance to the target measured as long as 150 cm, while it was largest when the distance was shortened to some 45 cm. The amplitudes of the binocular VEPs grew by more than √4 times. The stimulating area also showed a relationship to the binocular effect and it seemed to be necessary to stimulate more than 10°of uneven surface. The maximum binocular effect was also obtained when the uneven surface of the blocks had an average 4 cm depth. In patients with binocularity disturbance, the binocular excitation was limited to less than √2 times. Therefore, the VEPs excitation by real stereo viewing indicates a binocular activity of disparity sensitive neurons in the visual cortex.