The team at Duke University fitted the rats with an infrared detector wired up to microscopic electrodes that were implanted in the part of their brains that processes tactile information.
The researchers said that, in theory at least, a human with a damaged visual cortex might be able to regain sight through a device implanted in another part of the brain.
Lead author Miguel Nicolelis, from the Duke University Medical Center in Durham, North Carolina, said this was the first time a brain-machine interface has augmented a sense in adult animals.
The experiment also showed that a new sensory input could be interpreted by a region of the brain that normally does something else (without having to "hijack" the function of that brain region).
The results of the study were published in Nature Communications journal.