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Researchers use brain-machine interface to create a sixth sense in rats

a rat up close and personal
Jean-Jacques Boujot/Flickr

In the medical field, most brain-machine interface research focuses on trying to replace lost sensory information, such as restoring a sense of touch to people with spinal cord injuries. However, a recent study has taken a different approach by using a brain-machine interface to augment existing sensory systems and create a “sixth sense” in rats.

“This constitutes an important step in the direction of ‘Cyber-Physical’ systems, which meld computers with the living brain,” senior author Dr. Tim Lucas, Assistant Professor of Neurosurgery at the University of Pennsylvania, told Digital Trends. He said the technology could be developed in the future to restore sensory experiences to people suffering from paralysis.

Brain-computer interfaces can be used to control everything from drones to bionic arms, and they’ve become a hot topic in emerging technology. Elon Musk is working on the Neuralink project to use cybernetic implants to allow people to interface with gadgets or software, and Facebook is working on its own brain-reading computer system. These projects are a long way from creating usable prototypes, however. Before humans can interface neurally with computers, researchers need to find a way to integrate incoming information from a computer into the brain.

The new study from Penn Medicine does just that, by implanting tiny electrodes into the brains of rats and feeding them information in the form of sensory feedback. The researchers began by surgically implanting the electrodes into the rats’ brains. Then they put the animals in a water maze which was painted black inside, with a platform hidden beneath the water that they needed to reach in order to escape.

The rats couldn’t see the platform, so they received no visual information about how to navigate the maze. But they did have information from the interface. The electrodes stimulated their brains to inform the rats where the platform was located relative to their current position, and the rats were able to use this information to reach the platform even in the darkness.

The researchers used a technique called intracortical microstimulation, which is much more precise than other kinds of brain stimulation (such as transcutaneous direct current stimulation). These other methods activate thousands or millions of neurons and other neural elements, while intracortical microstimulation only activates around ten elements. This means that the stimulation applied to the brain can be precisely targeted, giving researchers the ability to create a single, discrete perception instead of activating a whole brain area.

With this more precise stimulation, the researchers could target very specific brain areas to convey information. However, there’s a challenge. It’s not enough to simply stimulate a brain area and assume that the animal will be able to understand that information. One of the breakthroughs the team made was to show that the “Rat-Robot” could assimilate the information, processing the externally produced signals just as successfully as if it was using its natural-born senses.

There have been previous attempts to create a “sixth sense” for directions using external tools like a vibrating belt which can help visually impaired people navigate around their environment. However, there are limitations on who can use these external tools — they can’t be used by people with paralysis, for example, who cannot experience sensory feedback.

“One eventual application of this brain-computer device is to restore sensation to individuals who have suffered from spinal cord injury,” Lucas said. “A patient like Christopher Reeve can neither lift his finger, nor feel a needle jabbed into his finger. Christopher Reeve would have little use for a vibrating belt.”

Before the researchers could consider implanting a brain stimulation device into a human, they would need to conduct many more trials in animals to ensure the technology is safe. Eventually, though, they believe they can use a brain-computer devices to integrate computers into human brains.

That opens the door for applications which connect devices in the brains to devices elsewhere in the body. “Our long term vision is to link this system with implantable sensors in paralyzed limbs to provide a complete sensory experience for paralyzed patients,” Lucas said.

And this research isn’t only of interest in terms of helping people with disabilities. It could potentially open up a whole new field of brain-computer devices, such as biorobots which can perform search and rescue operations.

The findings are published in the journal PNAS.

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