Researchers have gone beyond what mammals can usually see, and given rats the ability to "see" infrared light.
The research paper (.pdf, uncorrected proof available) documents the experiments of scientists at Duke University, Durham NC, USA. A neuroprosthesis -- which is often used as a way to restore nerve function when a subject has experience damage -- was developed by the team which allowed rats to see part of the electromagnetic spectrum usually outside of mammalian detection.
Neuroprosthesis development has previously been used to restore hand movement in paralyzed monkeys, as well as other numerous studies to help scientists better understand brain and nerve function. The rats used in this latest experiment were fitted with infrared detectors surgically connected to electrodes implanted within their brains, in a particular section that detects tactile data.
The scientists then created a test chamber equipped with three different light sources that could be switched randomly. The rats were first trained to go towards the "active," brightest light source through the use of LED lighting, and then once the infrared detecting neuroprosthesis was attached, it was programmed to send electrical signals to a rat's brain when the animal moved closer to an infrared light -- increasing in frequency and intensity as the rat closed in.
After roughly a month of trials, the rats began to respond to infrared sources in the same way as active, LED lights.
According to Duke University neurobiologist Miguel Nicolelis, the study shows it may be possible to restore elements of sight lost in a human's visual cortex -- perhaps through implanting such a neuroprosthesis in a part of the brain which has not been damaged. The rats in the study may have only been given infrared vision, but there is no reason why this detective capability couldn't be expanded to other parts of the electromagnetic spectrum.
"We could create devices sensitive to any physical energy," he said. "It could be magnetic fields, radio waves, or ultrasound. We chose infrared initially because it didn't interfere with our electrophysiological recordings."