My friend Thomas is an artist but whenever we look at the same things he illuminates an important problem in neuroscience. He sees things differently from me. In bland walls he sees the plaster’s structure nicely contrasting the weathered chromium green of a nearby car. Thus, his pictures of boring environments make great paintings. Thomas’ exceptional visual abilities have been honed by years of training and practice as an artist. But those abilities must be supported by real differences in his brain. Where do these differences reside? How do they come about? And what are they? To become better at ‘seeing things’ and at discrimination tasks is referred to as perceptual learning. The mechanisms that mediate perceptual learning and the locations in the brain are still poorly understood. We will investigate (1) where in the brain perceptual learning occurs, and whether there a hierarchy of perceptual learning? (2) How does attention influence perceptual learning? (3) Which brain chemicals mediate perceptual learning? Answers to these questions will improve our understanding of learning in general and may pave the way to better regeneration of brain function following brain injury and better therapy for learning disorders.