The Accident That Led to Machines That Can See
For something so effortless and automatic, vision is a tough job for the brain. It’s remarkable that we can transform electromagnetic radiation—light—into a meaningful world of objects and scenes. After all, light focused into an eye is merely a stream of photons with different wave properties, projecting continuously on our retinas, a layer of cells on the backside of our eyes. Before it’s transduced by our eyes, light has no brightness or color, which are properties of animal perception. It’s basically a mess of energy. Our retinas transform this energy into electrical impulses that propagate within our nervous system. Somehow this comes out as a world: skies, children, art, auroras, and occasionally ghosts and UFOs.
It’s even more amazing when you take a closer look. The image projected in each eye is upside down, having a slightly different perspective than the image in the other eye. Our nervous system reorients them, matches each point in the projection, and uses the difference in geometry between the images to create the appearance of depth—stereopsis—in a unified scene. It processes basic features like shape and motion. It separates the objects from each other and the background, and distinguishes visual motion caused by our own movement or the movement of objects. Estimates of the percentage of the human brain devoted to seeing range from 30 percent to over 50 percent.
Each new cell-type seemed like finding a new piece of a jigsaw puzzle.
Today, mapping the human brain is one of the great projects in science. Scientists have before they understand the brain’s architecture and interaction of billions of neurons behind our every action
