By Nick Collins
2:58PM GMT 17 Feb 2013
Although the light could not be seen lab rats were able to detect it via electrodes in the part of the brain responsible for their sense of touch.
Similar devices have previously been used to make up for lost capabilities, for example giving paralysed patients the ability to move a cursor around the screen with their thoughts.
But the new study, by researchers from Duke University in North Carolina, is the first case in which such devices have been used to give an animal a completely new sense.
Dr Miguel Nicolelis said the advance, reported in the Nature Communications journal this week, was just a prelude to a major breakthrough on a “brain-to-brain interface” which will be announced in another paper next month.
Speaking at the annual meeting of the American Academy for the Advancement of Science in Boston on Sunday, he described the mystery work as something “no one has dreamed could be done”.
The second paper is being kept secret until it is published but Dr Nicolelis’s comments raise the prospect of an implant which could allow one animal’s brain to interact directly with another.
In the first study, rats wore an infrared detector on their head which was connected to electrodes in the part of their brain which governs touch.
When one of three ultraviolet light sources in their cage was switched on, the rats initially began rubbing their whiskers, indicating that they felt as if they were touching the invisible light.
After a month of training, they learned to link the new sensation with the light sources and were able to find which one was switched on with 100 per cent accuracy. A monkey has since been taught to perform the same task.
The study demonstrates that a part of the brain which is designed to process one sense can interpret other types of sensory information, researchers said.
It means that in theory, someone who is blind because of damage to their visual cortex could regain their sight using an implant in another part of the brain.
Dr Nicolelis said: “What we did here was to demonstrate that we could create a new sense in rats by allowing them to “touch” infrared light that mammals cannot detect.
“The nerves were responding to both touch and infrared light at the same time. This shows that the adult brain can acquire new capabilities that have never been experienced by the animal before.
“This suggests that, in the future, you could use prosthetic devices to restore sensory modalities that have been lost, such as vision, using a different part of the brain.”
The study is part of an international effort to build a whole-body suit which allows paralysed people to walk again using their brain to control the device’s movement.
Infrared sensing could be built into the suit to inform the person inside about where their limbs are and to help them “feel” objects.
Dr Nicolelis and his collaborators on the project hope to unveil the “exoskeleton” at the opening ceremony of the football World Cup in Brazil in 2014.