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Scientists have developed a new way to activate neurons in the brain, which brings us one step closer to being able to program those big, meaty computers on top of our necks.

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[INTRO ♪].

You hear people make comparisons all the time about how your brain is like one big, ultra-sophisticated computer. And that's fine, but the idea really only goes so far.

Because, like, you can't really program your brain like you can your desktop. Which is kind of a bummer—I want to know kung fu! And if we could just get in there and start manipulating neurons, we could solve a lot of the struggles our brains and bodies cause.

But what if we could do that? Recently, scientists working with mice have been able to send new signals into their brains— ones that seemed so natural, the mice may have no idea they weren't their own. It seems a little sci-fi, but it's real research.

And someday, it could lead to some pretty amazing new treatments. These studies center around a branch of neuroscientific research called optogenetics, which makes use of light-sensitive proteins inserted into neurons through genetic manipulation. Once the proteins are there, researchers can control the firing of those neurons using just a flash of light.

We actually did a whole episode on the mechanics and history of optogenetics that we'll link to after this. But the general idea is that this method alters what certain receptors on cells respond to. Instead of waiting for a chemical neurotransmitter to tell them to do their job, an altered receptor will take the command from a flash of light transmitted through a wire.

When optogenetics first entered the scientific literature in 2005, the initial technique involved flooding a relatively large area of the brain with light to activate it. This is still generally the way it's done for now, and it does work. With it, we've been able to get groups of neurons to fire, and even induce behavioral changes in rodents.

Like, one experiment used optogenetics to get rats to walk in circles, which is pretty amazing. Also a little upsetting. “Why is—I have to do this now. This is my life.

I'm a rat!” But one of the downsides of this method is that lighting up a whole area can be imprecise. Trying to tease apart what's happening with the specific neurons you want to study, versus what's coming from ones lit up in the crossfire, can be pretty darn tricky. However: the times, they are a-changin'.

Thanks to advances in tech and biology, a group of scientists recently figured out a way to target specific, individual neurons, rather than a relatively large patch of tissue. They published their results in April 2018 in the journal Nature. And, brace yourself for some sci-fi….

Because they're doing it using holograms. Visual holograms—the kind you see in Star Trek or Star Wars—use multiple beams of light to project an image. But holography in general is really just about light interference, and that's what this technique relies on.

The team called their method 3D-SHOT, which stands for three-dimensional scanless holographic optogenetics with temporal focusing. Which—I'm glad they have such a good acronym for that! Unlike the original optogenetics technique, 3D-SHOT focuses light from several sources on individual target neurons.

Only the specific neurons in the tiny area all the light crosses receive enough light to activate. That can eliminate a lot of unintended firing, so these results are much less muddy. And it seems effective.

Scientists using this method have already observed mice brains firing at a natural timing and frequency when stimulated. They can tell based on the amount of calcium the cells are using, which is a good estimate for the rate of neural firing. And because that firing appears to really closely mimic the way their brains would naturally detect and process stimuli, it's likely that to those mice, any experiences induced using 3D-SHOT would be pretty realistic.

I mean, unfortunately we cannot ask the mice about this, but if we can stimulate their brains into firing in the same patterns as it would when say, seeing, feeling, or smelling something real, that seems reasonable. One way we can test this hypothesis is by observing actual behavioral changes—like a flick of a switch causing a mouse to stop in its tracks—which we haven't done yet. But the good news is, those experiments are currently underway, so we'll keep you updated.

If scientists are able to make neurons fire realistically, though, and if those experiences feel real, even though they're not…. Well, in theory, this technology could eventually be used to alter, like, memories by editing the way neurons associated with those events fire. We could make mice perceive things that aren't really there, all with the flash of a few lights.

We could download kung-fu into their brain like in The Matrix! Finally, rats doing kung fu! That might be getting a little ahead of ourselves, but honestly, maybe not far as you'd think.

The research team responsible for 3D-SHOT already have a few ideas about how they're going to sort of "copy and paste" brain activity to achieve something like this. If they can measure the sequences of activations and specific neurons involved in the behavior they want to program, 3D-SHOT could feasibly send that pattern into a different brain. Basically… programming it.

Brain programming. Now, even if we're making great progress with mice, applications in humans are likely a very long way off. Optogenetic methods require specific, light-sensitive proteins to be placed into the genome, which could get risky.

But if we could do it safely, that would be… like, hugely useful, not only for research—it would be, for research—but also for future treatment options. Think about it: if we could design a prosthetic eye that picked up visuals from the world and transformed them into the right patterns of neural firing, you might be able to restore someone's vision. That's just one out of thousands of examples, but we have a lot of work to do before we can get there.

So, I'm sorry if you wanted to download, like, very good dancing skills. I also want that to happen to me, but it's going to be a while. Until then, maybe we should take some classes until the research is a little further along.

Thank you for watching this episode of SciShow Psych! If you'd like to learn more about how optogenetics works and how we figured it all out, you can watch our episode all about it over at And as always, don't forget to go to and subscribe. [OUTRO ♪].