The researchers say 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 said this was the first time a brain-machine interface has augmented a sense in adult animals.
Within the space of a few weeks the rats learnt through training to distinguish this extra, artificial sense from real stimulation of their whiskers and use it to find water in a completely dark chamber, Professor Nicolelis said.
“It’s like driving a car or riding a bike. My suspicion is that these animals are feeling touch, its different from regular touch in that they are projecting the feeling of touch, not from their body, but to the external world,” he said.
“We have a monkey now that learned the same task and I was surprised at how quick he was. Now we are equipping our rats with a 360-degree view of the environment so that they can see infrared anywhere, up and down,” he added.
Sensory neuroprostheses show great potential for alleviating major sensory deficits. It is not known, however, whether such devices can augment the subject’s normal perceptual range. Here we show that adult rats can learn to perceive otherwise invisible infrared light through a neuroprosthesis that couples the output of a head-mounted infrared sensor to their somatosensory cortex (S1) via intracortical microstimulation. Rats readily learn to use this new information source, and generate active exploratory strategies to discriminate among infrared signals in their environment. S1 neurons in these infrared-perceiving rats respond to both whisker deflection and intracortical microstimulation, suggesting that the infrared representation does not displace the original tactile representation. Hence, sensory cortical prostheses, in addition to restoring normal neurological functions, may serve to expand natural perceptual capabilities in mammals.
The research into the “man-machine interface” could one day allow people to communicate directly with electronic devices by thought alone. It could allow paralysed people to control artificial limbs or give blind or deaf people the possibility of seeing or hearing with the help of brain implants.
Professor Nicolelis said that he has now taken the research into a different realm by creating what he has called the “brain-to-brain inferface”. He said he could not provide further details because the work is due to be published later this month in a peer-reviewed journal under a strict confidentiality agreement.
The rats were able to sense infra-red light effectively through the region of the brain connected to their whiskers. They used the light to locate water in a totally dark chamber.
It was the first time that animals have been given a “sixth sense” using electronic devices connected directly to their brain, he said.
“Our rats learn to touch invisible light. They are not seeing infrared light, but they are learning a concept that is similar to synesthesia [when one sense is detected by a different kind of sensory organ],” Professor Nicolelis said.
“They learned to touch invisible light that is delivered by stimulating the touch cortex [of the brain]. In 30 days these animals acquired this pseudo-touch and we learned that they could use this to control other devices,” he told the American Association for the Advancement of Science in Boston.
“It was a big surprise because we bypassed the skin, we didn’t use the skin to deliver this signal…the animal is feeling light, not seeing light. It’s very interesting,” he said.
SOURCES – BBC News, Independent, Nature Communication