The pigeon pattern electroretinogram is not affected by massive loss of cell bodies in the ganglion layer induced by chronic section of the optic nerve.

In pigeons, electroretinographic responses to contrast reversal of sinusoidal gratings (pattern ERGs) were recorded before and after section of the left optic nerve. Ninety and 270 days following optic nerve section the ganglion cell layer of the side that underwent the surgical procedure showed an 80% reduction in the number of cell bodies as compared with the intact side. At these times the pattern ERGs showed comparable amplitudes in both eyes. There is a possibility that the inner nuclear layer of the pigeon retina plays a major role in the generation of the pattern ERG.