The scientists stimulated the brain using electrodes implanted on its surface. Blind and sighted participants could "see" letters traced on their brains.
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00:00By sending electrical currents over the surface of people's brains, scientists were able to get them to see things that weren't actually there.
00:12These scientists are working to develop what are known as visual prosthetics, which in the future could be devices
00:19implanted in the brain
00:20that help to restore people's vision after they've lost their sight. In this particular study,
00:27they implanted an array of electrodes, which transfer electrical currents into tissues,
00:33onto the surface of the visual cortex,
00:36which is located at the very back of the brain. And that is a region of the brain where visual information gathered from your eyes
00:43typically gets funneled for early processing.
00:46Scientists have known that by stimulating specific points of the visual cortex,
00:51you can generate what are known as phosphenes,
00:54which are these little pinpricks of light that you can see even if no light is actually entering your eyes.
01:01Another way you can generate phosphenes is by rubbing your eyes really hard in a dark room.
01:06Little pinpricks of light appear. That can also happen when you stimulate the brain itself.
01:11So even though scientists knew how to generate individual phosphenes, they'd had trouble in the past
01:18connecting the dots into one coherent picture, which would make this technology much more useful. In this experiment,
01:25they managed to connect the dots in this way and get the participants to see different letters.
01:30So here in this video, we can see one of the participants in the study.
01:34He has had electrodes implanted on the surface of his brain under the skull,
01:39but it's being stimulated by that device you see on top of his baseball cap.
01:43When the device is stimulated, the idea is that this electrical current is being sent through a flurry of electrodes in the shape of
01:51a letter that the participant will then draw on the touch screen in front of them.
01:57Now, the letter has to be slightly manipulated when it's traced onto the brain because the visual
02:03information that enters our eyes is
02:05reflected and flipped upside down and then our brain makes sense of it later.
02:09So that's how these letters are drawn on the brain, and the participant, as you can see, is drawing them the correct way around.
02:16This study included both sighted individuals and blind individuals,
02:20and it is important to note that the blind individuals had lost their sight in adulthood. For now, these visual prosthetics
02:28are mostly aimed at helping to restore vision in people who have lost it at some point in their life,
02:33rather than to grant vision to people who have never been able to see.
02:37Perhaps that could be a goal of the far distant future,
02:39but for now, this is where the technology is, and it's still in its very early days.
02:45But as the author said,
02:47once this reached some sort of usable form, even having the ability to detect the form of a family member or to allow for more
02:56independent navigation would be a wonderful advance for many blind patients.