Spatial characteristics of the oscillatory potentials of the electroretinogram.

The spatial properties of the trans- and intra-retinal oscillatory potentials (OPs), a- and b-waves of the mudpuppy electroretinogram (ERG) were analyzed. A comparison of the intra-retinal potentials was made with the proximal negative response (PNR), an extracellular response, predominantly from amacrine cells. The spatial characteristics of the OPs differed from the a- and b-waves and the PNR. The OPs integrated spatially up to full field illumination. They seem to represent summated neuronal activity over broader areas than that of the PNR and the a- and b-waves. The results indicate that the OPs reflect activity of second order neurons to which visual information converge from the whole retina. These neurons may be the bipolar cells. No evidence that the OPs orginate in the laterally extending amacrines was obtained. The b-wave data further suggested a centre-surround organization for the neurons indirectly involved in the b-wave generation.