A Harvard Medical School (HMS) research team used a new technique to obtain the first close-up look at the neural circuits that produce vision in cats and rats. “Put simply, this technique allows us to see the brain seeing,” said R. Clay Reid, HMS professor of neurobiology, a member of the HMS Systems Neuroscience initiative, and principal investigator on the project. “It’s an entirely new way of looking at brain function.” The method, the first to track the responses of all the neurons in a visual circuit simultaneously, promises to rapidly advance our understanding of how the brain is wired for complex image processing. Lessons learned by studying the visual system may eventually apply to other brain functions like movement, thinking, and learning, as well as neurodegenerative diseases. The results were reported in the Jan. 19, 2005 issue of the journal Nature.