Four publications and six previous SfN Posters have presented and developed the finding that stimulus onset always evokes a ganglion cell volley lasting about 300 ms from both the rat and human retina. We show here that these 300 ms volleys are divided into two parts, early and late. The retinal marker for the early part is the series of electrophysiological deflections called Oscillating Potentials (OPs) that appear on the rising limb of the retinal b–wave. Rat and human OPs have the form of a cluster of four or five wavelets lasting about 25 ms. The rat cluster leaves the retina and is recorded at the optic chiasm level about four ms later, and at the visual cortex about six ms after that. At the cortical level the rat cluster generates the first negative wave of the visual evoked potential; a corresponding early negative wave with a similar latency is recorded from the human scalp. Although OPs are widely considered to be “oscillations” due to retinal amacrine cell activity, our evidence indicates that ...