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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00:00 By sending electrical currents over the surface of people's brains,
00:03 scientists were able to get them to see things that weren't actually there.
00:07 These scientists are working to develop what are known as visual prosthetics,
00:16 which in the future could be devices implanted in the brain that help to restore people's vision
00:23 after they've lost their sight. In this particular study, they implanted an array of electrodes,
00:30 which transfer electrical currents into tissues, onto the surface of the visual cortex, which is
00:36 located at the very back of the brain. And that is a region of the brain where visual information
00:41 gathered from your eyes typically gets funneled for early processing. Scientists have known that
00:47 by stimulating specific points of the visual cortex, you can generate what are known as phosphenes,
00:54 which are these little pinpricks of light that you can see even if no light is actually entering
01:00 your eyes. Another way you can generate phosphenes is by rubbing your eyes really hard in a dark room.
01:05 Little pinpricks of light appear. That can also happen when you stimulate the brain itself.
01:11 So even though scientists knew how to generate individual phosphenes, they'd had trouble in
01:17 the past connecting the dots into one coherent picture, which would make this technology much
01:22 more useful. In this experiment, they managed to connect the dots in this way and get the
01:28 participants to see different letters. So here in this video, we can see one of the participants in
01:33 the study. He has had electrodes implanted on the surface of his brain under the skull,
01:39 but it's being stimulated by that device you see on top of his baseball cap. When the device is
01:45 stimulated, the idea is that this electrical current is being sent through a flurry of
01:49 electrodes in the shape of a letter that the participant will then draw on the touch screen
01:56 in front of them. Now, the letter has to be slightly manipulated when it's traced onto the
02:01 brain because the visual information that enters our eyes is reflected and flipped upside down,
02:07 and then our brain makes sense of it later. So that's how these letters are drawn on the brain,
02:12 and the participant, as you can see, is drawing them the correct way around. This study included
02:17 both sighted individuals and blind individuals, and it is important to note that the blind
02:22 individuals had lost their sight in adulthood. For now, these visual prosthetics are mostly aimed at
02:29 helping to restore vision in people who have lost it at some point in their life, rather than to
02:33 grant vision to people who have never been able to see. Perhaps that could be a goal of the far
02:38 distant future, but for now, this is where the technology is, and it's still in its very early
02:44 days. But as the author said, once this reached some sort of usable form, even having the ability
02:51 to detect the form of a family member or to allow for more independent navigation would be a
02:57 wonderful advance for many blind patients.
03:00 [Music]