The brain employs a complex assembly line to construct the world around us. The primary visual cortex, or V1, connects to a maze of other regions known as V2, V3, and so on. ("Nobody knows exactly how many areas there are up there," Gallant says, a finger to his head.) Each region performs specific vision-related functions, like distinguishing colors, discerning shapes, gauging depth, or sensing motion. When I look at a dog, for instance, I don't just see the shape of a four-legged animal; I recognize that it's the brown-and-white dog I owned as a child, romping in a familiar way in the backyard I grew up in. It might even trigger a memory of playing with him. Each of these aspects of "seeing" would be represented by different patterns in the visual cortex.