Courtesy Ben M.:

Here is a really cool article on an experiment done recently on some
lab rats at Duke University. They found they were able to literally
give these rats a sixth sense, the ability to sense infrared light
which is normally not visible. By implanting microelectrodes in their
brains, scientists were able to force a reaction to infrared light,
which after a time the rat began to understand. The significance of
this is that now in theory a human with a damaged visual cortex would
be able to regain sight through a device implanted in another part of
the brain.