Two monkeys manage to "see" without using their eyes thanks to a brain stimulation device


by Esteban Tejedor

Posted on December 21, 2020

Two monkeys manage to

There are currently 40 million blind people in the world, according to the World Health Organisation.

The Vision and Cognition group of the Dutch Institute of Neuroscience and the Neuroprosthesis and Visual Rehabilitation Unit of the Bioengineering Institute of the Miguel Hernández University in Spain have created high-resolution implants that made possible to create interpretable images for animals through electrical stimuli. They were able to see moving lines, letters, shapes and dots without using their eyes thanks to this new brain stimulation device.

The scientists used 1.5-millimeter-long needle-shaped silicon electrode arrays. The team implanted 16 arrays, each with 64 electrodes, through the visual cortex of two macaques, for a total of 1,024 electrodes in each macaque.

The results of the research, published in the latest issue of the journal Science, reinforce the hypothesis that a neuroprosthesis implanted in the visual cortex, the part of the brain responsible for processing information that comes from the retina, could one day restore the functional vision in people who have been blind.

The researchers are cautious in stating that there are still many problems to be solved in order to implant a prosthesis with similar characteristics in the brain of human beings. "The implants that we are using in monkeys are not wireless and they stop working after a year. That is why we are developing a version that does not need cables and (hopefully) it can last many more years, at least 10", acknowledges Roelfsema. He adds: "We hope to be able to test it in humans in 2023. But it is not yet guaranteed to work. We are doing everything possible to make this happen".

These prostheses that were implanted in monkeys differ from other experiments. "Currently there are groups working on implants in the retina, others on prostheses for the optic nerve cable. We go directly to the part of the brain that processes the information", says Eduardo Fernández, director of the Neuroprosthesis and Visual Rehabilitation Unit of the Miguel Hernández University. "Humans do not see with the eyes, we really see with the brain". According to the researcher, in the future, this technology could be used to restore low vision in blind people who have suffered injuries or degeneration of the retina, the eye or the optic nerve, but whose visual cortex remains intact.

In the opinion of this Spanish doctor, who has been working on the development of a method to recover the vision of the blind for more than 30 years, the new device is an important step because it confirms that with a high number of electrodes in prostheses it is "relatively simple to induce simple perceptions such as letters, shapes or movements in the brain of humans". Fernández insists that the experiment shows that the monkeys were unable to distinguish whether what was presented to them was an electrical stimulation or if they saw a real image on the computer screen. "It was as if they were really seeing it," celebrates Fernández.

However, the two researchers insist on not creating false expectations: "This is an ongoing investigation and not a clinical treatment", says Roelfsema. Fernández adds that prostheses do not allow the recognition of colours or depth. "For now we are thinking of a system that can help blind people in simple tasks such as orientation, mobility or reading large characters".


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