0:00:12.987,0:00:15.237
... just as everyone goes,[br]'Great, quick nap.'

0:00:15.881,0:00:17.131
Don't have a nap!

0:00:17.726,0:00:20.926
Raise your hand - just squeeze[br]your left ear as hard as you can.

0:00:21.427,0:00:23.007
Raise your hand if it hurt.

0:00:23.245,0:00:25.035
Fantastic. Thanks for having me.

0:00:25.035,0:00:26.035
(Laughter)

0:00:26.035,0:00:27.481
No, no - it's not true.

0:00:27.481,0:00:28.771
Let me tell you a story.

0:00:28.771,0:00:31.351
I just want to take that[br]off the screen for the moment.

0:00:31.351,0:00:33.744
I want to tell you a story[br]that will explain to you

0:00:33.744,0:00:36.034
the first three years[br]of the Neurobiology of Pain

0:00:36.034,0:00:38.242
that you would study[br]at university.

0:00:38.491,0:00:40.741
Eight years ago, [br]I was walking in the bush.

0:00:41.138,0:00:42.621
I had a sarong on.

0:00:43.046,0:00:44.116
(Laughter)

0:00:45.519,0:00:47.639
Very cool. This is what happened.

0:00:50.653,0:00:52.033
Did you see that?

0:00:52.384,0:00:54.414
Hang on, this is what happened.

0:00:57.131,0:01:00.141
Biologically, I'm going to tell you [br]what happened just then.

0:01:00.141,0:01:03.012
Something touched the outside [br]of my left leg in the skin.

0:01:03.649,0:01:05.046
That activates receptors

0:01:05.046,0:01:08.236
on the end of big fat, myelinated,[br]fast-conducting nerve fibres,

0:01:08.572,0:01:10.626
and they stream[br]straight up my leg - whizz -

0:01:10.626,0:01:13.871
straight into my spinal cord - [br]whizz - up to this part of my brain,

0:01:13.871,0:01:14.881
and they say,

0:01:14.881,0:01:18.301
'You've just been touched on the outside[br]of your left leg in the skin.'

0:01:18.301,0:01:20.291
(Panting) (Laughter)

0:01:20.291,0:01:22.478
Meanwhile, whatever it was

0:01:22.933,0:01:26.143
is sufficiently intense[br]to activate free nerve endings;

0:01:26.143,0:01:28.067
we call them 'nociceptors'.

0:01:28.067,0:01:32.357
They're thin, unmyelinated, [br]slow-conducting Lada Niva -

0:01:33.965,0:01:35.663
someone knows[br]what a Lada Niva is -

0:01:35.663,0:01:36.653
(Laughter)

0:01:36.653,0:01:37.663
nerve fibres.

0:01:37.663,0:01:40.515
And that message travels[br]up to my spinal cord,

0:01:40.515,0:01:42.439
and that's as far as it goes.

0:01:42.439,0:01:46.251
And it says to a fresh neuron[br]in my spinal cord,

0:01:46.810,0:01:51.883
'Something dangerous has happened on[br]the outside of your left leg in the skin,

0:01:53.403,0:01:54.471
mate.'

0:01:54.481,0:01:55.660
(Laughter)

0:01:55.660,0:01:58.960
And the spinal nociceptor[br]takes that message up to the thalamus,

0:01:58.960,0:02:00.402
which sits in there somewhere,

0:02:00.402,0:02:05.412
and says, 'There's danger on the outside[br]of your left leg in the skin, mate.'

0:02:06.434,0:02:09.506
Now the brain has to evaluate [br]how dangerous this really is.

0:02:09.821,0:02:11.368
So it looks at everything.

0:02:11.663,0:02:14.731
And the way that I make sense of this,[br]of what happened to me,

0:02:14.731,0:02:18.739
is the brain thought, 'Frontal lobe,[br]have we been anywhere like this before?'

0:02:18.739,0:02:21.795
Hang on, I'll just ask [br]the posterior parietal cortex.

0:02:22.490,0:02:24.502
Have we been in this environment before?

0:02:24.502,0:02:25.552
Yes, we have.

0:02:26.068,0:02:28.498
Has it happened at this stage[br]of the gait cycle?

0:02:28.498,0:02:29.697
Yes it has.

0:02:29.929,0:02:31.650
Is it coming from the same location?

0:02:31.650,0:02:33.090
Yes it is.[br]What is it?

0:02:33.304,0:02:37.222
Well your whole life growing up, [br]you used to scratch your legs on twigs.

0:02:37.862,0:02:39.508
This is not dangerous.

0:02:40.234,0:02:42.714
I'm going to give you,[br]the organism, something

0:02:42.714,0:02:45.899
so you can kick off the twig[br]and continue on your merry way.

0:02:46.246,0:02:48.023
And that's what happened for me.

0:02:48.396,0:02:50.752
I can't show you now, [br]but I took off my sarong,

0:02:51.135,0:02:53.346
got in the river, got out of the river,

0:02:53.354,0:02:55.472
and that's the last thing I remember,

0:02:55.817,0:02:58.107
having been bitten[br]by an eastern brown snake.

0:02:58.107,0:02:59.397
(Mumbling)

0:02:59.515,0:03:00.625
Survivor.

0:03:00.625,0:03:01.859
(Laughter)

0:03:02.223,0:03:03.873
Thank you very much.

0:03:03.873,0:03:05.163
(Applause)

0:03:05.359,0:03:06.404
Now, for some reason,

0:03:06.404,0:03:10.008
the eastern brown snake[br]works by poisoning you - clearly -

0:03:10.391,0:03:12.964
and one of the things it does is[br]activate nerve fibres.

0:03:12.964,0:03:15.299
So actually my brain[br]would have got these messages

0:03:15.302,0:03:17.635
saying, Danger! Danger! Danger! Danger!

0:03:17.644,0:03:20.837
and, in its wisdom, it said, No. No. No.

0:03:21.927,0:03:26.827
Six months later, I'm walking[br]in the bush with a boring talker.

0:03:27.430,0:03:29.013
You know what a boring talker is?

0:03:29.013,0:03:31.770
Those people, it doesn't matter[br]what they say, it's boring.

0:03:31.770,0:03:32.770
(Laughter)

0:03:32.770,0:03:36.743
It's irrelevant, but we'll call her Naomi

0:03:38.270,0:03:40.072
because that is her name.

0:03:40.072,0:03:41.340
(Laughter)

0:03:41.696,0:03:43.666
Anyway, this is what happened, right?

0:03:45.400,0:03:46.560
Ow! Wah!

0:03:46.730,0:03:47.949
And I'm in agony.

0:03:47.949,0:03:51.469
I have got a white-hot poke of pain[br]screaming up my leg.

0:03:52.392,0:03:54.768
I'll tell you, biologically,[br]what's happened.

0:03:54.772,0:03:57.493
Something touched the outside [br]of my left leg in the skin.[br]

0:03:57.493,0:04:00.016
That activates big, fat, [br]myelinated nerve fibres

0:04:00.016,0:04:02.416
which send a message -[br]whizz - whizz - up to here.

0:04:02.416,0:04:05.415
Just been touched on the outside [br]of your left leg in the skin.

0:04:05.755,0:04:08.753
It's sufficiently intense to activate[br]these free nerve endings.

0:04:08.753,0:04:11.915
Danger receptors take[br]the message to my spinal cord:

0:04:11.919,0:04:15.871
something dangerous has happened on[br]the outside of your left leg in the skin.

0:04:15.871,0:04:16.871
(Audience) Mate.

0:04:16.871,0:04:18.083
Yes!

0:04:18.083,0:04:19.456
(Laughter)

0:04:19.835,0:04:21.555
Well done, you weren't planted.

0:04:22.178,0:04:24.582
That goes to the thalamus[br]and says the same thing:

0:04:24.588,0:04:26.371
something dangerous has just happened

0:04:26.371,0:04:28.441
on the outside[br]of your left leg in the skin.

0:04:28.441,0:04:29.538
(Audience) Mate!

0:04:29.538,0:04:33.286
So the brain says, thanks very much, [br]Thalamus, kids alright? Good, anyway ...

0:04:33.286,0:04:34.335
(Laughter)

0:04:34.335,0:04:36.537
Frontal cortex,[br]anything to tell me about this?

0:04:36.537,0:04:39.745
Hang on, I'll ask the posterior [br]parietal cortex: where are we?

0:04:39.748,0:04:41.326
We're walking in the bush.

0:04:44.934,0:04:46.975
You're a bit 'mate' happy.

0:04:48.095,0:04:49.645
At this stage of the gait cycle?

0:04:49.645,0:04:51.947
Where's it coming from?[br]Have we been here before?

0:04:51.947,0:04:53.408
Oh yes, we have.

0:04:53.807,0:04:55.927
Last time we were here, you almost died.

0:04:56.679,0:04:59.857
I'm going to make this hurt so much [br]that you can do nothing else.

0:04:59.857,0:05:03.360
And I was in absolute agony [br]for what seemed like minutes.

0:05:03.700,0:05:05.184
Screaming pain -

0:05:06.185,0:05:10.162
until one of my mates looked at my leg,[br]and there's a little scratch from a twig.

0:05:10.162,0:05:11.648
(Laughter)

0:05:12.284,0:05:14.781
The pain in those situations [br]was totally different

0:05:15.462,0:05:16.796
because of meaning.

0:05:17.466,0:05:20.526
I want to convince you that pain[br]is an illusion 100% of the time.

0:05:20.526,0:05:22.178
Here's a visual illusion ...

0:05:22.363,0:05:23.871
So have a look at this picture,

0:05:23.871,0:05:26.961
you've got a square that's got A in it[br]and one that's got B in it.

0:05:27.437,0:05:30.389
Raise your hand if you think [br]that the square with A in it

0:05:30.393,0:05:33.247
looks darker than the square with B in it.

0:05:34.346,0:05:35.737
Thank goodness for that.

0:05:35.737,0:05:40.178
None of you have a really socially[br]embarrassing neurological disorder.

0:05:40.498,0:05:41.691
Except you.

0:05:41.691,0:05:42.756
(Laughter)

0:05:42.756,0:05:43.965
That's not true.

0:05:44.762,0:05:47.186
Watch what happens [br]if we have another look at this.

0:05:47.186,0:05:50.226
These are those two squares[br]taken out of that picture.

0:05:50.831,0:05:54.619
Hopefully you can see they're identical,[br]and some of you may not believe me.

0:05:54.624,0:05:58.019
I'll just put A on top of that, [br]and I'll put B on top of that.

0:05:59.221,0:06:01.211
Some of you may still not believe me,

0:06:01.211,0:06:04.331
so why don't we [br]just move A over on top of B,

0:06:05.671,0:06:07.751
or B over on top of A.

0:06:08.781,0:06:12.011
No matter how long you look at this, [br]A will look darker than B

0:06:12.011,0:06:15.215
because your brain's doing [br]some really groovy stuff,

0:06:15.760,0:06:18.056
really quickly, outside of your awareness.

0:06:18.056,0:06:19.159
Have a look at this.

0:06:19.159,0:06:22.368
Turn your head on the side[br]and have a look at the same picture.

0:06:23.140,0:06:24.627
Nothing changes.

0:06:24.634,0:06:26.360
(Laughter)

0:06:27.133,0:06:29.427
Fantastic. 100% take!

0:06:32.107,0:06:33.926
So what really happens here,

0:06:34.739,0:06:37.395
exactly the same frequency [br]is hitting your retina,

0:06:38.013,0:06:40.438
and that sends a message [br]to the back of the brain,

0:06:40.707,0:06:43.549
and then all of this groovy stuff[br]happens very quickly

0:06:43.549,0:06:46.113
to ask the question,[br]What does this really mean?

0:06:46.113,0:06:48.440
What's biologically advantageous for me?

0:06:48.440,0:06:50.267
and then you get a visual image.

0:06:50.798,0:06:54.259
This is a visual illusion, [br]and vision's not about emotion,

0:06:54.259,0:06:56.411
vision's not necessarily about survival,

0:06:56.411,0:06:57.798
but pain is.

0:06:58.517,0:07:01.696
Now, some of you might not know, [br]if you're not medically trained,

0:07:01.696,0:07:03.888
but what's happening[br]at this guy's right leg,

0:07:03.888,0:07:05.558
that's not right, that's ...

0:07:05.558,0:07:06.911
(Laughter)

0:07:06.911,0:07:08.382
that's a dangerous situation,

0:07:08.382,0:07:10.658
and that danger message[br]arrives at the brain,

0:07:10.658,0:07:13.368
and the brain has to ask [br]exactly the same question.

0:07:14.078,0:07:16.292
What does this mean? [br]What should be done here?

0:07:16.295,0:07:22.271
And hopefully, the orchestra in this [br]person's brain will make your leg hurt.

0:07:23.143,0:07:25.518
In the work that[br]I've been doing for a long time,

0:07:25.518,0:07:30.098
we're trying our best to work out [br]how do we convince people in pain

0:07:30.601,0:07:32.589
that we understand they're in pain,

0:07:32.589,0:07:35.247
but it's not just about[br]the tissues of their body.

0:07:36.203,0:07:38.037
How do we convince them of that?

0:07:38.037,0:07:42.057
And a key conceptual shift[br]that we think is really important

0:07:42.358,0:07:45.017
is that you can understand [br]that pain is the end result.

0:07:45.017,0:07:48.139
Pain's an output of the brain [br]designed to protect you.

0:07:50.121,0:07:53.466
It's not something that comes[br]from the tissues of your body.

0:07:54.536,0:07:56.075
There's nothing there.[br]

0:07:56.075,0:07:58.102
We show patients a really sharp knife,

0:07:58.102,0:08:00.273
and we say this knife is sharp, yeah?

0:08:00.283,0:08:01.223
Yeah.

0:08:01.643,0:08:04.874
And it might be a bit cold;[br]it's hard; it's got all those properties.

0:08:04.874,0:08:07.007
This knife - painful as it sits out there.

0:08:07.011,0:08:10.862
No, it's not. That knife does not [br]have the properties of pain.

0:08:11.462,0:08:15.542
And when you stick it into their belly -[br]we do this regularly, straight through -

0:08:16.732,0:08:19.543
the belly doesn't adopt [br]the property of pain.

0:08:19.543,0:08:23.089
The brain has to do some [br]very rapid and groovy things

0:08:23.613,0:08:26.223
to project this illusion [br]that pain exists there.

0:08:26.572,0:08:30.906
100% of the time, [br]pain is a construct of the brain.

0:08:31.684,0:08:34.454
We can mess with pain easily [br]without touching the tissues.

0:08:34.454,0:08:36.374
This is an experiment we did a while ago

0:08:36.375,0:08:39.396
where we got supposedly 'normal'[br]healthy volunteers.

0:08:39.619,0:08:40.863
They're not normal people,

0:08:40.863,0:08:43.249
because they're volunteering[br]for a pain experiment,

0:08:43.249,0:08:44.178
(Laughter)

0:08:44.178,0:08:46.898
but let's say they are[br]reasonably normal, right,

0:08:46.898,0:08:50.228
and we put a very cold piece of metal [br]on the back of their hand,

0:08:50.954,0:08:52.890
and we just show them one of two lights.

0:08:52.897,0:08:56.115
One light is red, and one light is blue.

0:08:56.115,0:08:59.831
We don't tell anything about the lights, [br]we just show them the light.

0:09:02.563,0:09:04.223
I see that hand.

0:09:04.794,0:09:06.572
We ask them, 'How much does it hurt?'

0:09:06.572,0:09:10.315
And if they see the red light, it hurts[br]more than if they see the blue light.

0:09:10.315,0:09:11.890
The stimulus is exactly the same,

0:09:11.890,0:09:14.975
what's different is [br]the meaning of the stimulus.

0:09:14.975,0:09:18.199
Now there's a cue that says,[br]'This is really hot.'

0:09:18.199,0:09:20.329
Because red means hot.

0:09:21.059,0:09:23.689
So the sensible brain,[br]the clever brain should say,

0:09:23.689,0:09:28.517
'Well, I really don't want you to do it,[br]so I'm going to make it really hurt.'

0:09:30.680,0:09:34.349
There's people in the States that are[br]allowed to get their psychology students

0:09:34.349,0:09:37.215
to participate in experiments[br]in exchange for credit points -

0:09:37.215,0:09:39.399
or sex, or something -

0:09:39.916,0:09:43.775
anyway, they put their head inside what[br]they think is a stimulator for their head,

0:09:43.775,0:09:47.096
and they make sure that[br]the subject can see the intensity knob.

0:09:47.096,0:09:48.988
And as they turn up the intensity knob,

0:09:48.988,0:09:53.594
this little figure there showing[br]the lines going up at a steady rate,

0:09:53.594,0:09:55.598
that's their reported head pain,

0:09:55.598,0:09:57.578
and it matches the intensity knob.

0:09:57.578,0:09:59.908
But the stimulator's doing nothing.

0:09:59.908,0:10:02.533
It's just one of those[br]old-fashioned plastic hair dryers

0:10:02.533,0:10:03.759
that doesn't do anything.

0:10:03.759,0:10:05.389
You know those things?

0:10:05.389,0:10:08.229
You probably use one - yeah?

0:10:08.886,0:10:11.716
The trick is that they[br]have to see the intensity knob.

0:10:12.960,0:10:15.117
I always think it'd be fun[br]to do an experiment

0:10:15.117,0:10:18.886
based on that Spinal Tap film[br]where the intensity knob goes up to 11.

0:10:19.381,0:10:21.261
Remember that film?

0:10:21.878,0:10:24.305
What's really important[br]from a clinical perspective,

0:10:24.305,0:10:28.015
and I'm a clinical neuroscientist,[br]and I see patients in pain,

0:10:28.015,0:10:31.535
any piece of credible evidence[br]that they're in danger

0:10:31.535,0:10:33.055
should change their pain,

0:10:33.055,0:10:35.361
and they're all walking[br]into hospital departments

0:10:35.361,0:10:37.281
with models like this on the desk.

0:10:37.601,0:10:39.643
What does your brain say[br]when it sees a disc

0:10:39.643,0:10:42.391
that's slipped so far out[br]it's sitting on its own?

0:10:42.391,0:10:43.811
(Laughter)

0:10:44.681,0:10:49.564
If you've ever seen a disc in a cadaver,[br]you can't slip the suckers.

0:10:49.950,0:10:52.611
They're immobile, you can't slip a disc.

0:10:52.874,0:10:55.661
But that's our language,[br]and it messes with your brain.

0:10:55.661,0:10:58.611
It cannot not mess with your brain.

0:10:59.441,0:11:03.471
We can even modulate the location of pain.[br]We can do some groovy things.

0:11:03.894,0:11:06.171
It's quite well established[br]that referred pain

0:11:06.171,0:11:10.550
gives you pain in an area of your body[br]that might be physiologically normal.

0:11:11.080,0:11:13.230
Most of you would have heard[br]of referred pain.

0:11:13.230,0:11:14.250
(Sneezing)

0:11:14.250,0:11:15.290
Bless you.

0:11:15.290,0:11:18.420
We do experiments where we give you[br]pain in an artificial limb -

0:11:18.420,0:11:19.781
it's not even yours.

0:11:19.781,0:11:23.680
This is Meng, who was a postdoc[br]in my lab in Oxford in the UK,

0:11:23.680,0:11:25.402
and we stole a prosthetic limb,

0:11:25.406,0:11:28.168
which is a whole other story[br]which is really funny -

0:11:28.168,0:11:29.668
but I won't tell it to you -

0:11:29.668,0:11:32.638
[br]and we can do this manipulation

0:11:32.638,0:11:36.368
so that you start to feel like[br]the plastic limb in front of you is yours.

0:11:37.223,0:11:39.423
And we can make the rubber hand hurt.

0:11:39.423,0:11:44.663
And we can bring in a knife,[br]and run the knife across the rubber hand,

0:11:44.663,0:11:48.133
and you have your brain responses[br]to protect that rubber hand.

0:11:48.483,0:11:52.653
You're feeling pain[br]in a lump of plastic, effectively.

0:11:53.363,0:11:57.438
Here's a groovy experiment where[br]we take two Microsoft clipart people,

0:11:57.442,0:12:01.173
and we put a webcam[br]on the forehead of one of them

0:12:01.173,0:12:04.893
and a set of virtual reality glasses[br]on the other one.

0:12:06.153,0:12:08.436
And then we get them to shake hands.

0:12:08.436,0:12:10.126
And as they're shaking hands,

0:12:10.126,0:12:14.296
the person on your right,[br]who's wearing the goggles,

0:12:15.006,0:12:18.646
their visual field is coming[br]from the other person's forehead.

0:12:18.646,0:12:19.939
Have you got it?

0:12:20.009,0:12:24.161
So they are effectively looking[br]at the other person, thinking it's them

0:12:24.161,0:12:28.490
because they're shaking hands,[br]the motor command fits, everything's good.

0:12:28.490,0:12:32.980
And then we come in and put[br]a painful stimulus on that person's arm,

0:12:32.988,0:12:36.310
and they see it hit that arm[br]of the person over there,

0:12:36.310,0:12:40.550
with whom they're shaking hands,[br]and they say, 'Ouch! It really hurts.'

0:12:40.550,0:12:42.158
And we say, 'Where does it hurt?'

0:12:42.158,0:12:43.901
'On that man's arm.'

0:12:43.901,0:12:45.731
(Laughter)

0:12:45.731,0:12:48.511
They get it right every time,[br]pointing exactly where it is,

0:12:48.511,0:12:51.651
but if you were on the outside,[br]taking a photo, they're literally -

0:12:51.651,0:12:55.465
we've got the painful stimulus here,[br]and they're saying, 'It hurts there.'

0:12:55.880,0:12:59.751
So the brain is not only producing pain,

0:12:59.751,0:13:02.751
it's projecting it[br]to this location in mid-air.

0:13:03.211,0:13:04.846
We can mess with that.

0:13:04.846,0:13:07.292
This all becomes really important[br]when pain persists

0:13:07.297,0:13:09.998
because two things happen[br]when pain persists

0:13:09.999,0:13:12.560
that make the life[br]of someone in pain really difficult,

0:13:12.560,0:13:15.525
that costs our country[br]40 billion dollars a year.

0:13:15.672,0:13:17.645
It costs Australia more than cancer,

0:13:17.645,0:13:20.998
cardio-vascular disease[br]and diabetes combined.

0:13:21.981,0:13:25.979
Thanks for that facial expression,[br]I wanted someone to go ...

0:13:27.939,0:13:30.749
This is the problem,[br]that if we keep running the neurons,

0:13:30.749,0:13:34.739
the brain cells that produce pain,[br]they get better at producing pain.

0:13:35.076,0:13:36.795
They become more and more sensitive,

0:13:36.795,0:13:38.896
so we need a smaller[br]and smaller influence.

0:13:38.897,0:13:42.244
The illusion, if you like,[br]in increasing sensitivity

0:13:43.367,0:13:44.854
becomes very unhelpful.

0:13:44.854,0:13:48.634
It's trying to protect you from something[br]that's not needing protection.

0:13:49.114,0:13:50.224
It's very real.

0:13:50.734,0:13:53.488
The other thing that happens[br]is that all of these networks

0:13:53.488,0:13:57.986
lose their capacity to be specific[br]and precise, so the pain spreads.

0:13:58.296,0:14:02.752
The pain changes its quality.[br]Ultimately, it's not even informative.

0:14:02.752,0:14:05.502
It's both unhelpful and uninformative.

0:14:06.678,0:14:10.468
Maybe the next TED Talk ever[br]is the really important question,

0:14:10.468,0:14:12.208
'What do we do about it?'

0:14:13.112,0:14:14.532
Who knows?

0:14:14.997,0:14:15.997
No, we do know,

0:14:15.997,0:14:19.729
that's what we're really researching,[br]but that's the end of my 18 minutes.

0:14:19.729,0:14:21.869
Thank you very much for having me.

0:14:21.869,0:14:25.129
(Applause)