On the other hand, we have three different types of cones, and each one of these different types of cones contains its own unique pigment that can basically absorb its own unique frequency of light, its own unique wavelength of light. And so that means it's the cones and not the rods that are capable of distinguishing and producing the different colors that we actually see. Now, what exactly happens when the photons of light hit our rods and cones? Well, when the photons of light actually hits these photochemicals known as our pigments, what basically happens is we have a conformational change taking place on the proteins inside the membrane of our cells. And that basically increases or decreases the permeability of ions such as sodium ions. So that can either depolarize or hyperpolarize our cell membrane and that can ultimately create our electrical signal, which will basically pass up to our brain through a nerve known as our optic nerve.