[Linearity and nonlinearity of pattern ERG and pattern VECP].

To investigate the linearity and nonlinearity of both pattern electroretinogram (P-ERG) and pattern visually evoked cortical potential (P-VECP), a checkerboard pattern was presented to normal subjects with the reversal rate of transient and steady-state condition. Using a personal computer (BASIC) system, we made simulated waves (linear model) at 3 to 15 rev/s stimuli summated from an original wave evoked at 1 rev/s stimulation. Both simulated P-ERGs and P-VECPs were found to be different from the original ones, and the nonlinear component, which was interpreted as the difference between the original and simulated waves, was thought to increase with the increment of pattern reversal rate. However the 2 nd harmonic component of the original wave drastically decreased at above 7.5 rev/s stimulation. Thus, it is concluded that the nonlinearity of both P-ERG and P-VECP does not correlate with those 2 nd harmonic components.