Perhaps unsurprisingly, we can see wavelengths of light that fall within a range we call the visible spectrum, and while our eyesight is pretty good, vision most certainly doesn’t end there for animals. Many species, ranging from insects to fish and mammals, can see ultraviolet (UV) light, and a select few can even pick up infrared (IR). But remarkably, with a bit of engineering, scientists can now bestow the ability to sense the latter in animals that normally can’t, and there are plans to progress this work into humans.
Perhaps to your disappointment, though, the goal is not to create superhumans with extraordinary vision. The main motivation was to investigate how flexible, or plastic, the adult brain is.
“We know that before certain critical periods of development, the brain is very plastic and can quickly adapt to new information, like acquiring a new language,” researcher Eric Thomson from Duke University told IFLScience. “The received wisdom is that adult brains are less flexible to new types of inputs. So we wanted to see if the brains of adult rats are smart enough to absorb and use this completely new type of information to behave adaptively in the environment.”
But this project is also about more than just furthering our understanding of the brain: Thomson says they hope to use this information to help the development of prosthetic arms. If you were to pick up a delicate object versus something more robust, you would exert a different amount of pressure on the object, but that’s something prosthetic hands struggle with. “If we can incorporate tactile [touch] feedback using sensors in the hand that transmit information to the brain, the person should be able to exhibit finer motor control,” explains Thomson.
Before we get ahead of ourselves, back to the research in question. Presented at the annual meeting of the Society for Neuroscience, the study began back in 2013 when Thomson and project leader Miguel Nicolelis inserted a single IR detector into an area of a rat’s brain. The implanted microelectrode projected IR information from the environment to the somatosensory cortex – the region that processes incoming data from the whiskers.
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The scientists then placed sources of IR light in the environment and when the animal approached or oriented itself toward them, their somatosensory cortex would receive increased stimulation. At first, this was evidently a little strange for the confused rat that couldn’t work out what was seemingly manhandling its whiskers. But after some time spent running round in circles, fidgeting and screwing up their faces, the rats “became infrared scavengers, using this sensor and sweeping it round like it’s an additional eye to forage and navigate,” said Thomson.
But the researchers weren’t satisfied with this: They wanted to see if they could make things more interesting by ramping up the flow of information. To do this, they inserted four IR sensors into the brain, evenly distributed, so that the animal could have a 360 degree panoramic view of its infrared environment.
They then tested out their abilities on a simple reward task whereby four plastic blocks were attached with both IR lights and water spigots. Only one was switched on at a time, and if they poked the right block they would get a water reward. Within just four days they got it right 85 percent of the time, and within a week this went up to between 90-100 percent; considerably better than the rats with only one implant, which took 30-40 days to learn the task.
“The brain is kind of an information sponge,” said Thomson. “It really absorbed the information quickly and they actually thrived on it.”