Out of all the electromagnetic waves, most animal creatures can only sense the visible light. Pythons and vampire bats are just two of the few species who can naturally perceive infrared through their eyes. However, a new scientific breakthrough has made it possible for rats, for the first time, to see infrared light through brain-implanted sensors.
Researchers from Duke University were able to augment the vision of rats by inserting infared-detecting electrodes into their visual cortex - a brain region responsible for vision. One end of the electrodes were placed outside the rat's head which served as the sensor of infrared light that delivers signals toward the visual cortex.
In the experiment led by neuroscientist Miguel Nicolelis and postdoc Eric Thomson, rats were implanted a total of four electrodes - positioned 90 degrees apart - to make them capable of sensing infrared light anywhere. The rats were trained to perform water-reward task which they completely learned in just 4 days.
Their previous study in 2013 had provided them the initial scheme of their novel engineering. In this first trial, they inserted one electrode directly to the somatosensory cortex - region that processes touch. In response to detecting infrared waves, the rats were found rubbing their whiskers, suggesting that they developed a physical sensation when infrared was detected. However, they learned the water-reward task after about 40 days - quite longer due to the fact that they only have one electrode implant.
"Frankly, this was a surprise," says Thomson in a statement. "I thought it would be really confusing for [the rats] to have so much stimulation all over their brain, rather than [at] one location."
This time, the researchers redirected the same infrared traffic to the rat's visual cortex. The rats were able to learn the same water-reward task in just one day. Thomson speculate that the animal's visual cortex adaptation may be due to infrared having relatively the same wavelength as that of the visible light, making it easy for the brain to process the visual information.
With this novel research, it may be possible to develop treatments soon for patients who want to restore their lost senses, or if possible, augment human senses through developing sensory prosthetic devices.
"I'm still pretty amazed," Thomson says. "Yes, the brain is always hungry for new sources of information, but the fact that it actually absorbed this new, completely foreign type so quickly is auspicious for the field of neuroprosthetics. And that's why I'm excited."
The research was presented at Neuroscience 2015.
