Scientists were able to make two blind people able to visualize and identify the design of letters and other geometric shapes from electrical stimuli in the brain.
The feat was published on Thursday (14) in an article in the scientific journal Cell, one of the most rigorous in the field of biology. The work was carried out by researchers at the Baylor Medical University and the University of California at Los Angeles, in the United States.
To produce the effect, the researchers implanted a grid of ordered electrodes in the brain of the study participants. The devices were positioned superficially in the visual cortex, part of the brain responsible for processing images.
"People who have acquired blindness typically have damage to their eyes or optic nerves, but not to the visual cortex, the region of the brain that contains maps of the visual world," Daniel Yoshor, head of the Department of Neurosurgery at Baylor University and one of the authors of the article.
According to Yoshor, it was already known that even in blind people the electrical stimulation of the region can make people perceive points of light, which offers the possibility of creating a device capable of providing visual information directly to the brain and, thus, restoring a type of vision useful.
Previous studies had managed to make the points of light visible to blind people. The challenge transposed by Yoshor and his team was to organize these points in identifiable geometric shapes and letters. The scientists did this by using electricity to draw on the electrode plate.
The electricity passed through the electrodes, one after the other, until a trace was established on the surface of the participant's brain. Yoshor describes the technique as drawing on someone's palm with their fingers.
"Instead of stimulating the shape of a letter at once, we traced a precise pattern of the shape we wanted with the electric current over the visual cortex", explains the doctor.
The experiment was carried out with four people with vision who have electrodes installed to monitor epilepsy episodes and two blind people who also already had the device in the brain as part of another study on the visual cortex.
While receiving the stimulus, participants reproduced the drawings with their fingers on a touchscreen (see the video). One of the blind participants had a hit rate greater than 90%.
One of the possibilities for the future is to connect a microcamera to the electrodes, allowing the images to be translated into electrical stimuli.
“To achieve this, we need improvements in hardware and software. We hope to be able to produce a grid with up to thousands of electrodes. But knowing that we are able to make these people understand letters with the stimulus in the brain is already very encouraging, ”says Yosher.
For Mário Motta, professor of ophthalmology at Unirio (Federal University of the State of Rio de Janeiro) and former president of the Brazilian Society of Ophthalmology (SBO), the study brings the perspective that in up to ten years the technique can be applied in a major scale.
“For those who are in the dark, without seeing anything, it is an immense benefit. This will allow to know a world that was not known, to gain a new life ”, says the doctor.
According to Motta, most blind people have a functional visual cortex, which means that a considerable number of people can benefit from the technique, including those born without vision.
“To understand this, just remember that when we are sleeping and dreaming, we can still see images, even with our eyes closed. The brain produces these images, based on our memories ”, explains Motta.
According to Eduardo Büchele Rodrigues, professor of ophthalmology at Saint Louis University, in the United States, the article represents an advance in attempts to use this technique in blind people.
"But understanding how to communicate electrical energy to the human body and develop a way to do this stimulation for several years in a safe way are the big challenges," he says.
In the American experiment, a low-intensity electrical current was used. The effects that this stimulus can cause when applied for a longer period is not yet known. In the article, researchers consider using other ways to stimulate the brain in the future, such as ultrasound, which could also be less harmful and more accurate.
Motta and Rodrigues add that the study needs to go through other phases and the experiment must be carried out with a larger number of people so that the effectiveness and safety of the method is proven.