Writing On the Brain with Electricity

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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

00:05get them to see things that weren't actually there.

00:12These scientists are working to develop what are known as visual prosthetics, which in

00:17the future could be devices implanted in the brain that help to restore people's vision

00:23after they've lost their sight.

00:25In this particular study, they implanted an array of electrodes, which transfer electrical

00:31currents into tissues, onto the surface of the visual cortex, which is located at the

00:37very back of the brain.

00:39And that is a region of the brain where visual information gathered from your eyes typically

00:43gets funneled for early processing.

00:47Scientists have known that by stimulating specific points of the visual cortex, you can generate

00:53what are known as phosphenes, which are these little pinpricks of light that you can see

00:58even 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.

01:08That can also happen when you stimulate the brain itself.

01:12So even though scientists knew how to generate individual phosphenes, they'd had trouble in

01:17the past connecting the dots into one coherent picture, which would make this technology much

01:22more useful.

01:24In this experiment, they managed to connect the dots in this way and get the participants

01:29to see different letters.

01:31So 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, but it's being

01:40stimulated by that device you see on top of his baseball cap.

01:44When the device is stimulated, the idea is that this electrical current is being sent through

01:49a flurry of electrodes in the shape of a letter that the participant will then draw on the text

01:56screen in front of them.

01:57Now the letter has to be slightly manipulated when it's traced onto the brain because the

02:02visual information that enters our eyes is reflected and flipped upside down, and then

02:08our brain makes sense of it later.

02:09So that's how these letters are drawn on the brain.

02:12And the participant, as you can see, is drawing the correct way around.

02:17This study included both sighted individuals and blind individuals, and it is important

02:21to note that the blind individuals had lost their sight in adulthood.

02:25For now, these visual prosthetics are mostly aimed at helping to restore vision in people

02:31who have lost it at some point in their life, rather than to grant vision to people who have

02:35never been able to see.

02:37Perhaps that could be a goal of the far distant future, but for now, this is where the technology

02:42is, and it's still in its very early days.

02:46But as the author said, once this reached some sort of usable form, even having the ability

02:52to detect the form of a family member or to allow for more independent navigation would

02:57be a wonderful advance for many blind patients.

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