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Scientists build an implant that restores sight
Bionic vision for the blind one step further
The graph shows how scientists are developing techniques that they hope will one day help restore sight to people with damaged eyes by sending electronic signals directly to the brain.
WASHINGTON: Scientists are one step closer to restoring vision for the blind, having built an implant that bypasses the eyes and allows monkeys to perceive artificially induced patterns in their brains.
The technology, developed by a team from the Dutch Institute of Neuroscience (NIN), was featured in the journal Science on Thursday.
It is based on an idea first conceived decades ago: to electrically stimulate the brain so that it “sees” illuminated dots known as phosphenes, similar to pixels on a computer screen.
But the concept had never realized its full potential due to technical limitations.
A team led by NIN director Pieter Roelfsema developed implants consisting of 1,024 electrodes connected to the visual cortex of two sighted monkeys, achieving much higher resolution than previously achieved.
The visual cortex is located in the back of the brain and many of its features are common to humans and other primates.
“The number of electrodes we have implanted in the visual cortex, and the number of artificial pixels we can generate to produce high-resolution artificial images, is unprecedented,” Roelfsema said.
This allowed the pair of monkeys to distinguish shapes such as letters of the alphabet, moving lines and dots, which they had previously been trained to respond to by moving their eyes in a particular direction to win a reward.
Monochromatic models are still crude compared to real vision, but represent a big step up from previous implants, which allowed human users to determine only vague areas of light and dark.
Roelfsema compared it to a highway matrix and said his team now had a “proof of principle” that laid the foundation for a neuro-prosthetic device for the world’s 40 million blind people.
It could consist of a camera that the user wears or a pair of glasses, which uses artificial intelligence to convert what it sees into a model that it can send to the user’s brain.
Similar technology has appeared in science fiction works, such as the headset worn by Geordi La Forge in “Star Trek: The Next Generation”.
In a written comment, Michael Beauchamp and Daniel Yoshor of the University of Pennsylvania hailed the breakthrough as a “technical tour de force”.
The NIN team benefited from advances in miniaturization and also devised a system to make sure their input currents were large enough to create noticeable dots, but not so large that the pixels grow too large.
They achieved this by placing some electrodes in a more advanced stage of the visual cortex, to monitor the amount of signal that passed and then adjust the input.
– Wireless future –
Roelfsema said his team hopes to make similar devices for humans in about three years.
But the electrodes used by the team require silicon needles that work for about a year before the tissue builds up around the needles and no longer works.
“So we want to create new types of electrodes that are better accepted by the body,” he said.
Ultimately, a wireless solution would be best, as it would mean the user would not need to wear an implant on the back of the skull, which requires scientists to operate and puts the user at risk for infection.
Fortunately, wireless devices that interface with the brain are advancing rapidly.
Dentures would only be suitable for people who once had vision and then lost it due to illness or injury.
The brain of people born blind dedicates the visual cortex to other functions. But in people whose eyes stop working, the brain region remains inactive, waiting for input that never comes.
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