[Fourier analysis of binocular VEP with stimulation of fusional areas]

Dioptic stimulation, by which each eye was stimulated by the same checkerboard pattern but at different pattern reversal rates, was performed and the visually evoked potentials (VEP) were analyzed with a Fourier processor. When both images from each eye were superimposed using fusional targets and prisms, the intermediate frequency component (IFC) was recognized besides two components corresponding to each stimulating frequency reversal rate. The relationship between IFC and the superimposed area (SA) was studied. IFC appeared clearly when the visual angle of SA was above 60 min. (18% of SA). The amplitude of IFC was saturated at a visual angle of 140 min. (53% of SA). Furthermore, when the SA was 200 min. of the visual angle (100% of SA), the IFC showed 0.6 times the activity of the monocular component. When dioptic stimulation was used, only one component corresponding to the stimulating pattern rates was observed and the amplitude became higher with increase of SA. The amplitude of the SA (areas of each eye were fully superimposed) was 1.4 times greater than that of 0% SA.