How to control someone else's arm with your brain

Greg Gage is on a mission to make brain science accessible to all. In this fun, kind of creepy demo, the neuroscientist and TED Senior Fellow uses a simple, inexpensive DIY kit to take away the free will of an audience member. It’s not a parlor trick; it actually works. You have to see it to believe it.

The brain is an amazing and complex organ.

And while many people
are fascinated by the brain,

they can't really tell you that much

about the properties
about how the brain works

because we don't teach
neuroscience in schools.

And one of the reasons
why is that the equipment

is so complex and so expensive

that it's really only done at major
universities and large institutions.

And so in order to be able
to access the brain,

you really need to dedicate your life

and spend six and a half years
as a graduate student

just to become a neuroscientist
to get access to these tools.

And that's a shame
because one out of five of us,

that's 20 percent of the entire world,
will have a neurological disorder.

And there are zero cures
for these diseases.

And so it seems that
what we should be doing

is reaching back earlier
in the eduction process

and teaching students about neuroscience
so that in the future,

they may be thinking about possibly
becoming a brain scientist.

When I was a graduate student,
my lab mate Tim Marzullo and myself,

decided that what if we took
this complex equipment that we have

for studying the brain and made it simple
enough and affordable enough

that anyone that you know, an amateur
or a high school student,

could learn and actually participate
in the discovery of neuroscience.

And so we did just that.

A few years ago, we started
a company called Backyard Brains

and we make DIY neuroscience equipment
and I brought some here tonight,

and I want to do some demonstrations.

You guys want to see some?

So I need a volunteer.

So right before -- what is your name?
(Applause)

Sam Kelly: Sam.

Greg Gage: All right, Sam, I'm going
to record from your brain.

Have you had this before?

SK: No.

GG: I need you to stick out
your arm for science,

roll up your sleeve a bit,

So what I'm going to do,
I'm putting electrodes on your arm,

and you're probably wondering,

I just said I'm going to record from your
brain, what am I doing with your arm?

Well, you have about 80 billion neurons
inside your brain right now.

They're sending electrical messages
back and forth, and chemical messages.

But some of your neurons
right here in your motor cortex

are going to send messages down
when you move your arm like this.

They're going to go down
across your corpus callosum,

down onto your spinal cord
to your lower motor neuron

out to your muscles here,

and that electrical discharge
is going to be picked up

by these electrodes right here

and we're going to be able to listen

to exactly what your brain
is going to be doing.

So I'm going to turn this on for a second.

Have you ever heard
what your brain sounds like?

SK: No.

GG: Let's try it out.
So go ahead and squeeze your hand.

(Rumbling)

So what you're listening to,

so this is your motor units
happening right here.

Let's take a look at it as well.

So I'm going to stand over here,

and I'm going to open up our app here.

So now I want you to squeeze.

(Rumbling)

So right here, these are the motor units
that are happening

from her spinal cord
out to her muscle right here,

and as she's doing it,

you're seeing the electrical activity
that's happening here.

You can even click here
and try to see one of them.

So keep doing it really hard.

So now we've paused

on one motor action potential that's
happening right now inside of your brain.

Do you guys want to see some more?

(Applause)

That's interesting,
but let's get it better.

I need one more volunteer.

What is your name, sir?

Miguel Goncalves: Miguel.

GG: Miguel, all right.

You're going to stand right here.

So when you're moving your arm like this,

your brain is sending a signal
down to your muscles right here.

I want you to move your arm as well.

So your brain is going to send
a signal down to your muscles.

And so it turns out that there is
a nerve that's right here

that runs up here that innervates
these three fingers,

and it's close enough to the skin
that we might be able

to stimulate that so that what we can do

is copy your brain signals
going out to your hand

and inject it into your hand,

so that your hand will move
when your brain tells your hand to move.

So in a sense, she will take away
your free will

and you will no longer have
any control over this hand.

You with me?

So I just need to hook you up.

(Laughter)

So I'm going to find your ulnar nerve,

which is probably right around here.

You don't know what you're signing up for

when you come up.

So now I'm going to move away
and we're going to plug it in

to our human-to-human interface over here.

Okay, so Sam, I want you
to squeeze your hand again.

Do it again. Perfect.

So now I'm going to hook you up
over here so that you get the --

It's going to feel
a little bit weird at first,

this is going to feel like a --
(Laughter)

You know, when you lose your free will,
and someone else becomes your agent,

it does feel a bit strange.

Now I want you to relax your hand.

Sam, you're with me?

So you're going to squeeze.

I'm not going to turn it on yet,
so go ahead and give it a squeeze.

So now, are you ready, Miguel?

MG: Ready as I'll ever be.

GG: I've turned it on, so go ahead
and turn your hand.

Do you feel that a little bit?
MG: Nope.

GG: Okay, do it again?
MG: A little bit.

GG: A little bit? (Laughter)

So relax.

So hit it again.

(Laughter)

Oh, perfect, perfect.

So relax, do it again.

All right, so right now,

your brain is controlling your arm
and it's also controlling his arm,

so go ahead and just do it one more time.

All right, so it's perfect. (Laughter)

So now, what would happen
if I took over my control of your hand?

And so, just relax your hand.

What happens?

Ah, nothing.

Why not?

Because the brain has to do it.

So you do it again.

All right, that's perfect.

Thank you guys for being
such a good sport.

This is what's happening
all across the world --

electrophysiology!

We're going to bring on
the neuro-revolution.

Thank you.

(Applause)