Previous studies of the varibility of firing of retinal ganglion cells have led to apparently contradictory conclusions. To a first approximation, the variance of rate of maintained discharges of ganglion cells in cat is independent of the mean firing rate. On the other hand, the variability of responses to abrupt changes in lighting of ganglion cells in goldfish increascs with increasing firing rate. To examine whether the difference is due to differences between species, we examined the variablility of responses of cat ganglion cells, and find it similar to that of goldfish ganglion cells. The variance of rate of ganglion cells is neither independent of mean rate, as might be expected from maintained dischargs, nor directly proportional to the mean rate, as it is for cat cortical cells. Rather, there is a monlinear relationship between varience of rate and mean rate.
