Third photoreceptor

These are sensory cells in the human eye that transmit information about the brightness of the surroundings via the SCN (suprachiasmatic nucleus) to the pineal gland and thereby influence the production and secretion of the hormone melatonin. Studies by Brainard have shown that these cells are sensitive to light at the blue end of the spectrum (Brainard 2001). In 2002 Berson identified the ganglion cells containing melanopsin in the retina as the cells responsible (Berson 2002). In addition to their function in processing stimuli for visual signals they have their own (intrinsic) sensitivity to light. The light sensitivity of the retinal ganglion cells is approximately factor 100 less than that of the cones responsible for color vision.