Scientists are a step closer to restoring the sight of blind people using brain implants, researchers from the Netherlands Institute for Neuroscience said, after a series of successful experiments on monkeys.
Researchers developed implants containing 1,024 electrodes -- conductors that carry electrical currents into and out of the brain -- and implanted them in the visual cortex, the part of the brain that processes visual information, in two macaque monkeys.
By sending electrical signals to the monkeys' brains, researchers created "phosphenes" -- dots of light that could be "seen" or perceived by the brain, and can be used to create the illusion of shapes and objects.
Lead researcher Pieter Roelfsema told CNN that the team wanted to show that it was possible to induce "vision of objects" through direct electrical stimulation of the brain, explaining that the visual cortex has "a sort of visual map of space."
"You can work with it like a matrix board along the highway. If you stimulate or light up multiple boards, you can see patterns," he told CNN.
The monkeys performed a series of tasks, and, using their artificial vision, they were able to recognize shapes and "percepts" including lines, moving dots and letters, researchers reported Friday in findings published in the journal Science.
Wider implications for restoring sight
The team believes that such technology could one day be used to simulate sight in blind people who have been able to see at some point in their lives.
Roelfsema told CNN that when people's eyes stop functioning and they lose their sight, their cortex is deprived of input.
"What you then do is then bypass the malfunctioning eyes, and directly plug the images that you normally see into the visual cortex," he said.
"If you stimulate with one electrode, you get one dot of light. If you stimulate with a pattern of electrodes, you can create a pattern of these dots, and from these patterns, of dots you can reproduce meaningful images," he said, explaining that dots could be used to create letters of the alphabet.
In the future, Roelfsema said, a person could carry a camera on their glasses which could translate the images into electrical stimulation patterns for the brain, and send them to the electrodes.
"The electrodes would then activate the appropriate cells, and the person would be able to see maybe a car that's coming by, or a person who is walking into the road. It will give rise to a form of vision," he said, adding that he hopes the technology will be ready to trial in humans by 2023.
'Holy grail' of research
Researchers from around the world are looking at the cortex as a way of restoring vision. This year, a team from Spain's Miguel Hernández University revealed they were able to use brain implants to temporarily restore rudimentary vision in blind patients.
"The ability to artificially impose patterns of neural activity that resemble those in the brain is a holy grail of neuroprosthetic research," Tom Mrsic-Flogel, director of the Sainsbury Wellcome Centre for Neural Circuits and Behaviour at University College London, told CNN via email.
Mrsic-Flogel, who was not involved with the research, told CNN that the team from Amsterdam "demonstrate that non-human primates can react to complex patterns of stimulation in the visual cortex in a way that is similar when viewing normal shapes.
"Although we will never know what another animal perceives, it is tempting to speculate that electrical stimulation resulted in visual perception," he said.
"This transformative study adds to the growing body of evidence that links neural activity and sensation.
"Studies like these will pave the way for brain implants that augment the function of the brain when it becomes compromised, for example when we lose peripheral vision or hearing," he added.