How you can make a fruit fly eat veggies DIY Neuroscience a TED series

Translator: Joseph Geni
Reviewer: Krystian Aparta

Greg Gage: It’s an age-old
pursuit of all parents,

getting their kids
to eat their vegetables.

But getting them to eat
cookies or ice cream

is relatively easy,

and that’s because our brains
prefer sweetness.

Now, there’s a new technology
called optogenetics

which may be able to trick our taste buds,

for instance preferring
vegetables over sweets.

We’re going to try this today
using fruit flies.

[DIY Neuroscience]

The reason why we experiment
with fruit flies

is they have a small enough nervous system

that gives us a fighting chance
to really understand what’s going on.

And believe it or not, their taste buds
are very similar to ours.

But before we try to manipulate
their taste preferences,

we need to establish:
What is the baseline of the fruit fly?

What does it prefer?

We call this a control experiment.

Spencer’s been hard at work doing this.

OK, Spencer, let’s do
our first experiment.

We want to test to see if fruit flies
prefer bananas or broccoli.

So what do we need?

Spencer Brown: So we need the fly pad,
which is basically an iPad for flies.

It measures the touch.

GG: You put a fly in each chamber?

SB: Yeah. Inside, we’ll offer them
banana and broccoli

to see which one they prefer.

GG: In order to count how many times

the fruit fly eats a banana
versus the broccoli,

these chambers have been outfitted
with a small electrode

that sends data to a computer.

And so what were your findings
on banana versus broccoli?

SB: I found that the flies
visited banana the most.

GG: Both were there, but like most kids,

they choose not to eat the broccoli,
and they go switch to something sweeter.

GG: Now a quick background
on how taste works.

Taste buds are made up
of specialized neurons

called taste receptors.

When we eat something
that triggers a particular taste,

those taste neurons will fire
a signal to the brain.

This allows our brain to know
what’s sweet and what’s bitter.

So when a fruit fly eats a banana,
its sweet taste neurons will fire.

But when it eats broccoli,
those same neurons stay pretty quiet.

But what if we could force
those sweet-tasting neurons to fire

every time the fruit fly eats broccoli?

We may be able to get the fruit fly

to like broccoli as much as banana.

Enter optogenetics.

This is the revolutionary new tool
that’s taking neuroscience by storm,

and in this case, “opto” means light

and “genetic” refers to the fact
that these fruit flies have been modified

to contain a special gene that makes
only certain neurons respond to light.

In our case, we’ve added the special gene
to the sweet taste receptors.

Now here’s the fun part.

Optogenetics means that we
can control these special neurons

whenever they’re exposed
to a bright-colored light,

causing them to send
messages to the brain.

In this experiment, we’re going to have
these modified fruit flies

choose between banana and broccoli again,

only this time, every time
the fruit fly eats the broccoli,

we’re going to trigger
a big bright red light.

And when the channels see that red light,
they’re going to open up,

and they’re going to cause
that neuron to fire,

and the sweet taste message
will be sent to the brain.

How do you get them out?

SB: So we’re going to be using
a mouth aspirator,

so it’s just two straws put together.

GG: So it’s a fancy name for a straw.

SB: Basically.

GG: So you’re going to suck those out.

Have you ever sucked up a fly before?

SB: Once or twice.

GG: There we go. You got all four.

OK, perfect.

So you’re going to turn on
your OptoStimmers here.

You’re going to park the light
right on top of the chambers.

So now we sit here and we wait
for them to eat broccoli,

and then when the light fires,

they’re going to think
it’s tasting something sweet.

Come on. Oh, he’s getting closer.

Come on. It tastes good now.

SB: It’s about to.

GG: Oh, he’s back. All right!

All right, so now we see
that some of these flies

are switching over from
the banana to the broccoli.

SB: Exactly, yeah.

GG: Every time this light goes off,

that means that they think
they’re tasting something sweet.

SB: Yeah. So this guy’s
really going after it.

GG: So we saw that we were able
to rescue broccoli

and make it just as appealing
as banana to our fruit flies.

And we’re able to replicate
these same results

in all of our experiments.

So the question is: Can we
do the same thing in humans?

Well, that depends on a number of items.

First, do optogenetic tools
even work in humans?

And that looks like the answer is yes,

and in fact, clinical trials
are already being planned

that will treat chronic pain
and blindness using optogenetics.

And the next question is,
can we easily trigger a light source

so that every time we eat
vegetables, it will go off?

For that, I’m afraid at least
at this time, the answer is still no.

But today, we got to witness
just a taste of optogenetics

and its amazing potential.

(Music)