In humans, the process of learning is driven by different groups of cells in the brain firing together. For instance, when the neurons associated with the process of recognizing a dog begin to fire in a coordinated manner in response to the cells that encode the features of a dog -- four legs, fur, a tail, etc. -- a young child will eventually be able to identify dogs going forward. But brain wiring begins before humans are born, before they have experiences or senses like sight to guide this cellular circuitry. How does that happen?