Nicolelis says unpublished data from a follow-up experiment shows that rats learn even faster when the sensors feed directly into their visual cortex, taking just 6 or 7 hours. Nicolelis thinks the speed-up comes from using a part of the brain that already interprets light. He is planning a subsequent experiment in which the rats can only get a reward if they “see” both parts of the spectrum at once, visual and infrared.