Ganglion cells

These are nerve cells that are responsible for processing and transmitting nerve impulses from receptor cells. With regard to the biological effect of light the retinal ganglion cells are of particular importance. For a long time it was assumed that these ganglion cells were responsible only for processing information from the visual receptors – the cones and the rods. Ganglion cells for example take the mix of signals from red and green-sensitive cones and produce a signal for yellow that is transmitted to the brain. It is this ability to mix signals that enables us to perceive all the different colors. Around 2 to 3% of these ganglion cells are themselves sensitive to blue light. They act as “third photoreceptors”.