Scientists at the Duke Center for Neuroengineering have successfully given lab rats a sixth sense: the ability to detect infrared light, a part of the electromagnetic spectrum that is normally invisible to them. The rats were wired with a brain-machine interface that included an infrared detector — but the scientists implanted it in the part of the brain that typically processes the sense of touch. Initial training of the rats involved rewarding them with water when they successfully poked their nose into a port attached to a visible LED light. Then, over the course of a month, the researchers gradually replaced the LED lights with infrared lighting; those lights were picked up by sensors attached to the rats' foreheads that connect to the implant in the rat's brain.

Initially, the rats' behavior indicated they were interpreting the signals as touch — but by the end of the month, the rats were successfully searching out and honing in on the infrared source by sweeping their heads left and right. Perhaps the biggest finding was that the rats' sense of touch was unaffected by the additional stimulus. "When we recorded signals from the touch cortex of these animals, we found that although the cells had begun responding to infrared light, they continued to respond to whisker touch," said lead researcher Miguel Nicolelis. "It was almost like the cortex was dividing itself evenly so that the neurons could process both types of information."

The fact that the rats' sense of touch was unaffected is probably the most exciting finding for the researchers, who envision a future where doctors could "hijack" one of a person's working senses to help aid one that is no longer functioning properly. The researchers gave the example of someone with a damaged visual cortex regaining sight thanks to a neuroprosthesis implanted in another part of the brain. While that would be a highly useful medical advance, it wouldn't surprise us if the biohackers out there were more interested in how this might eventually offer humans a way to have a sixth sense, just like the lab rats in this experiment.