Mechanics of Sight

To understand the process of visualization, it is important to first consider its mechanics. This may all sound a bit arcane but I can't help resisting the science nerd part of me. Knowing how the brain processes visual information can afford the artist insight into how to craft their creation. As will be shown later, the artist can intentionally orchestrate a trajectory or visual pathway for the viewer to follow by knowing what visual clues have the most impact. Understanding the cognitive process of how the brain visualizes geometry can also be instructive in imparting a sense of volume in one's work. 

How it works:
 When we open our eyes, the available light that is illuminating our world and reflecting off of objects, is instantaneously transduced by the retina through neural ganglion to the thalamus and then to the occipital cortex of the brain. There it is coded and processed into a mental image of that world around us. Although grossly oversimplified, this is basically a description of the mechanics of sight. Incredibly, the coding and processing of sight all occur almost instantaneously, as the brain updates, cross-references, evaluates, remembers, and learns: all within the blink of an eye.
 As our eyes gaze at the world around us, the electromagnetic energy of light permeates back into the inner lining of our eyeballs which is called the retina (1). The retina is lined with specialized cells, which are stratified into layers. The layers toward the back of the retina are arranged radially into a honeycomb – like configuration. and are the photoreceptor cells- the rods and cones. Photoreceptors ate a specialized type of neuron found in the retina that is capable of photo transduction.The great biological importance of photoreceptors is that they convert light(electromagnetic radiation) into signals that can stimulate the biological processes. More specifically, photoreceptor proteins- Rhodopsin and Opsin absorb photons triggering a change in that cells membrane potential.(2) Stacked by the thousands inside these cylindrical like rods and cones, are membrane cells containing the photoreceptor protein Rhodopsin. Rhodopsin reacts with light and undergoes a chemical reaction which is the first in an entire chain of catalyzed reactions.The mechanism that seems to drive all this is the electrical flux of membrane potential- newly created binding sites generated by changes in the Rhodopsin provoke Sodium ions to enter the cell through a gateway in the cell membrane.When too many Sodium ions saturate the cell it results in a resulting in a flood of Glutamate which neutralizes the excessive accumulation of ions.This process results in membrane potentials hyperpolarizing and depolarizing up along the retinal structure from the rods and cones to the bipolar cells which are stimulated to produce a burst of electrical impulses.(3) It is the bipolar cell that can fire an electrical signal to the ganglia neuron which creates an action potential.This now is the encoded signal which can be transmitted from the ganglion,(4) and then routed to the brain through the thalamus.(5)
This is very simply the process of phototransduction.

Light and Neuronal Activity

How rods and Cones respond to light