Virtual Reality for flies and fish!

24 August 2017

Interview with

Andrew Straw, Frieburg University

freemovr_fly.jpg

The 'Flycave', a 1-m high, 1-m diameter cylindrical flight arena. Images are displayed on the walls of the cylinder using three projectors.

Do you remember the Holodeck that appeared in some episodes of Star Trek - the virtual reality room which could turn into anything you could think of? Well this week, scientists have made one - but before you get too excited to try it- it’s not for humans - but for animals! This new virtual reality room can help scientists run experiments they couldn’t before, testing how animals understand their environments - something that’s been tricky for free moving animals before, because you can’t exactly get a fly to wear a VR headset. Georgia Mills caught up with Andrew Straw, professor of biology at Frieburg University, to find out how they did it…

Andrew - I’ve always been inspired by the holodeck of Star Trek. Basically what we did is we made an arena where animals can go in and we track them as they move around in 3D, and we track them almost instantaneously. Then based on the position of where it’s eye is, then we draw with computer projectors on the walls of the arena everything we need to draw, so that from the position of that animal it sees whatever kind of virtual world that we want because, basically, the animal’s in a computer game.

Then the real trick is, not that we just do that once but we then update the position of the animal and we update the world, so it’s a completely dynamic process. When the animal moves around what it sees is completely consistent with it being really inside this computer game. So, to the animal, it’s immersed in this 3D world that it can see.

Georgia - I see. So it’s a holodeck for animals. So the animals in this environment, can you make it as if there are obstacles in the way, it’s not just running around in a space looking at the walls, it does look as if to it there’s stuff in the middle?

Andrew - Yeah, exactly. Some of the first experiments that we did were kind of validation experiments where we could test how an animal would behave and we did this with flies and fish. We put in just a simple vertical post, a cylinder, in the middle of the arena - a real one - and we quantified animal behaviour with the same tracking system. We measured how they swam or flew around this post and then we could do that same thing, not with a real post, but with a virtual post, and then we could calculate the same statistics again. We could see that the animals behave indistinguishably to the virtual post as they do to real world post and so I think it’s fair to call this a virtual reality for the animals.

Georgia - What animals are can go in it because animals have very, very different visual systems from each other, so does it work on all of them?

Andrew - You’re completely right that animals have very different visual systems. For example, our displays are tuned for humans so in terms of the spectrum, the colours, we use the RGB for humans and that works pretty well for the kind of experiments that we’ve been doing and that we’re interested in. But a lot of animals are sensitive to ultraviolet for example and we’d have to think about some kind of modifications or different display technology if we wanted to really give a good virtual reality in the ultraviolet spectrum.

But in terms of what kind of animals? We’re really interested in model species that are used commonly in neuroscience. Those are rodents, fish like zebrafish, and drosophila (fruit flies). Those are the ones that we spend the most effort testing.

Georgia - What kind of research do you foresee people doing with this?

Andrew - This technique really allows people who are interested in studying interactions between an animal and its environment, or an animal and other animals to do the kind of experiments that they weren’t able to do before. There’s the area where I come from which is the interaction of visual processing with higher level processing like spatial cognition. So, how does an animal know where it is and what it’s seeing. You can imagine that by being able to play games with an animal, like have it teleport from A to B, we can ask, for example, is it building a map of it’s environment or not? People have historically been doing experiments on freely moving animals and there, of course, it’s very difficult to control the visual world. Or they’ve been doing these restrained animal virtual realities and there the feedback that the animal gets is not natural. And so, the innovation here is doing free moving virtual reality.

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