Spatial summation properties of goldfish ganglion cells.

At threshold the eye is known to sum quanta as though the total catch were important and not the distribution on the retina. In humans, spatial summation is larger under dark adapted conditions. The extent of this spatial summation is studied in goldfish retinal ganglion cells which are known to receive both rod and cone inputs. The area of summation in single ganglion cells is found to be much larger for rod input compared to cone input. It seems that in single ganglion cells, the spatial summating properties increase markedly in the dark due largely to the neural organization of rod and cone input.