Implant Gives Rats Super Senses

A rat with a brain implant that allows it to sense infrared (IR) light using its whiskers. Infrared light is normally invisible to rats. CREDIT: Nature Communications View full size image

Call them Superrats. Just like Superman has X-ray vision, these lab rats can sense something normal rats can't. Researchers have created a surgical implant that allows rats to sense infrared light through their whiskers. The animals normally can't see this kind of light.

This is the first time a mammal has been given the ability to sense something beyond what its species normally can, said Miguel Nicolelis, a Duke University neuroengineer who led the rat experiment. "The meaning is that the brain is not limited by the transducers that exist in our body," he told TechNewsDaily. "We can actually allow the brain to incorporate new information from the external world."

Nicolelis is best known for his work in making mind-controlled prosthetics, such as his plan to develop devices that would allow a quadriplegic child to walk onto a soccer field and make the first kick of the 2014 FIFA World Cup. He says that the ability of an adult, mammalian brain to interpret infrared light means future replacement arms and legs could communicate with the brain using infrared light, which can send messages faster than nerves do.

"Augmenting human function," as Nicolelis calls it, brings to mind things like Raytheon's exoskeletons for augmenting soldiers' strength. However, Nicolelis says his interest is in health, not military applications. Still, he said, prosthetics often do need super-human speeds, because the devices replace nerves that have been badly damaged and don't work at natural speeds. "If you're building an artificial body, you need to take any advantage you can get," Nicolelis said.

The infrared-sensing rat

For the rat system, Nicolelis and his colleagues implanted a small infrared sensor a few millimeters deep into the brains of six rats. The sensor "sees" infrared light, then turns the light into electrical pulses that correspond to how intense the light is and where it's located. The sensor's electrical signals go into the part of the rats' brains normally used to sense touch in the whiskers.

At first, the rats didn't know what to make of the new sensation. Researchers placed them in a box with three doors. One door hid a bit of water, and researchers marked it an infrared light. The rats would poke their noses into the doors randomly, sometimes scratching their faces when the infrared light stimulated their whiskers. After about four weeks, however, the rats learned to swing their heads to seek the infrared light and zero in on the door they wanted.

The infrared sensing worked on top of the tactile sensations that whiskers normally communicate, and did not reduce those natural sensory abilities, the researchers found. When Nicolelis and his colleagues bent the rats' whiskers while watching the animals' brain activity, the rats' brains still reacted to the touch.

From rats to humans

Experiments in rats and other lab animals often take years to decades to make it to human testing phases. Nicolelis said he couldn't guess how long this experiment would take to translate into a human prosthesis, but pointed out that he had conducted research previously that took only three years to move from rat to human testing. "It can be quick," he said.

Nicolelis and his colleagues published their work today (Feb. 12) in the journal Nature Communications.

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