Early wavelets in the VECP.

With the use of a Maxwellian view optical system to present light flashes to the right eye, electroretinograms (ERGs) and visual evoked cortical potentials (VECPs) were recorded from normal subjects. The first 120 msec postflash onset was examined. A series of five VECP wavelets was recorded with implicit times of 50, 72, 82, 90, and 101 msec, at the highest radiance used. Recordings of ERGs in the same experimental session revealed a series of three wavelets with implicit times of 23, 30, and 38 msec. It is concluded that the VECP wavelets are not volume-conducted from the retina and probably represent initial arrival of visual information at the cortex, or subcortical activity.