[Contingent negative variation (CNV) as presaccadic potential]

By recording contingent negative variation (CNV) with saccade as the response, EEGs were recorded before, during and after saccade. Light-emitting diodes (LEDs) were used as the warning stimulus (S1) and the imperative stimulus (S2), and a different electrode was placed on Cz according to the international 10-20 system. Evoked potentials were amplified by a D.C. amplifier and 16 responses were averaged. EOGs were recorded simultaneously. There were no remarkable changes in CNV according to the S1-S2 interval or angle of saccade. A positive wave of approximately 10 microV was observed prior to saccade, and was not believed to be the influence of either EOG or blinking. This positive wave may be similar to the spike potential in presaccadic potentials or may be a component of postimperative negative variation (PINV).