[Cerebral refractory period of visual evoked potentials following total field and foveal stimulation]

Ten normal subjects of the age of 21 to 57 years were examined with single stimulus- and double stimulus-VEP following checkerboard whole field stimulation, foveal stimulation with a small checkerboard and flash. The latencies of the VEP following foveal stimulation are longer than those following whole field stimulation. There could not be determined a relative refractory period following checkerboard whole field stimulation at double stimulation. There is a relative refractory period following foveal stimulation between 80 and 100 ms. With retrobulbar neuritis at a late stage the relative refractory period is prolonged and it appears at about 150 ms.