1
00:00:12,987 --> 00:00:15,237
... just as everyone goes,
'Great, quick nap.'

2
00:00:15,881 --> 00:00:17,131
Don't have a nap!

3
00:00:17,726 --> 00:00:20,926
Raise your hand - just squeeze
your left ear as hard as you can.

4
00:00:21,427 --> 00:00:23,007
Raise your hand if it hurt.

5
00:00:23,245 --> 00:00:25,035
Fantastic. Thanks for having me.

6
00:00:25,035 --> 00:00:26,035
(Laughter)

7
00:00:26,035 --> 00:00:27,481
No, no - it's not true.

8
00:00:27,481 --> 00:00:28,771
Let me tell you a story.

9
00:00:28,771 --> 00:00:31,351
I just want to take that
off the screen for the moment.

10
00:00:31,351 --> 00:00:33,744
I want to tell you a story
that will explain to you

11
00:00:33,744 --> 00:00:36,034
the first three years
of the Neurobiology of Pain

12
00:00:36,034 --> 00:00:38,242
that you would study
at university.

13
00:00:38,491 --> 00:00:40,741
Eight years ago, 
I was walking in the bush.

14
00:00:41,138 --> 00:00:42,621
I had a sarong on.

15
00:00:43,046 --> 00:00:44,116
(Laughter)

16
00:00:45,519 --> 00:00:47,639
Very cool. This is what happened.

17
00:00:50,653 --> 00:00:52,033
Did you see that?

18
00:00:52,384 --> 00:00:54,414
Hang on, this is what happened.

19
00:00:57,131 --> 00:01:00,141
Biologically, I'm going to tell you 
what happened just then.

20
00:01:00,141 --> 00:01:03,012
Something touched the outside 
of my left leg in the skin.

21
00:01:03,649 --> 00:01:05,046
That activates receptors

22
00:01:05,046 --> 00:01:08,236
on the end of big fat, myelinated,
fast-conducting nerve fibres,

23
00:01:08,572 --> 00:01:10,626
and they stream
straight up my leg - whizz -

24
00:01:10,626 --> 00:01:13,871
straight into my spinal cord - 
whizz - up to this part of my brain,

25
00:01:13,871 --> 00:01:14,881
and they say,

26
00:01:14,881 --> 00:01:18,301
'You've just been touched on the outside
of your left leg in the skin.'

27
00:01:18,301 --> 00:01:20,291
(Panting) (Laughter)

28
00:01:20,291 --> 00:01:22,478
Meanwhile, whatever it was

29
00:01:22,933 --> 00:01:26,143
is sufficiently intense
to activate free nerve endings;

30
00:01:26,143 --> 00:01:28,067
we call them 'nociceptors'.

31
00:01:28,067 --> 00:01:32,357
They're thin, unmyelinated, 
slow-conducting Lada Niva -

32
00:01:33,965 --> 00:01:35,663
someone knows
what a Lada Niva is -

33
00:01:35,663 --> 00:01:36,653
(Laughter)

34
00:01:36,653 --> 00:01:37,663
nerve fibres.

35
00:01:37,663 --> 00:01:40,515
And that message travels
up to my spinal cord,

36
00:01:40,515 --> 00:01:42,439
and that's as far as it goes.

37
00:01:42,439 --> 00:01:46,251
And it says to a fresh neuron
in my spinal cord,

38
00:01:46,810 --> 00:01:51,883
'Something dangerous has happened on
the outside of your left leg in the skin,

39
00:01:53,403 --> 00:01:54,471
mate.'

40
00:01:54,481 --> 00:01:55,660
(Laughter)

41
00:01:55,660 --> 00:01:58,960
And the spinal nociceptor
takes that message up to the thalamus,

42
00:01:58,960 --> 00:02:00,402
which sits in there somewhere,

43
00:02:00,402 --> 00:02:05,412
and says, 'There's danger on the outside
of your left leg in the skin, mate.'

44
00:02:06,434 --> 00:02:09,506
Now the brain has to evaluate 
how dangerous this really is.

45
00:02:09,821 --> 00:02:11,368
So it looks at everything.

46
00:02:11,663 --> 00:02:14,731
And the way that I make sense of this,
of what happened to me,

47
00:02:14,731 --> 00:02:18,739
is the brain thought, 'Frontal lobe,
have we been anywhere like this before?'

48
00:02:18,739 --> 00:02:21,795
Hang on, I'll just ask 
the posterior parietal cortex.

49
00:02:22,490 --> 00:02:24,502
Have we been in this environment before?

50
00:02:24,502 --> 00:02:25,552
Yes, we have.

51
00:02:26,068 --> 00:02:28,498
Has it happened at this stage
of the gait cycle?

52
00:02:28,498 --> 00:02:29,697
Yes it has.

53
00:02:29,929 --> 00:02:31,650
Is it coming from the same location?

54
00:02:31,650 --> 00:02:33,090
Yes it is.
What is it?

55
00:02:33,304 --> 00:02:37,222
Well your whole life growing up, 
you used to scratch your legs on twigs.

56
00:02:37,862 --> 00:02:39,508
This is not dangerous.

57
00:02:40,234 --> 00:02:42,714
I'm going to give you,
the organism, something

58
00:02:42,714 --> 00:02:45,899
so you can kick off the twig
and continue on your merry way.

59
00:02:46,246 --> 00:02:48,023
And that's what happened for me.

60
00:02:48,396 --> 00:02:50,752
I can't show you now, 
but I took off my sarong,

61
00:02:51,135 --> 00:02:53,346
got in the river, got out of the river,

62
00:02:53,354 --> 00:02:55,472
and that's the last thing I remember,

63
00:02:55,817 --> 00:02:58,107
having been bitten
by an eastern brown snake.

64
00:02:58,107 --> 00:02:59,397
(Mumbling)

65
00:02:59,515 --> 00:03:00,625
Survivor.

66
00:03:00,625 --> 00:03:01,859
(Laughter)

67
00:03:02,223 --> 00:03:03,873
Thank you very much.

68
00:03:03,873 --> 00:03:05,163
(Applause)

69
00:03:05,359 --> 00:03:06,404
Now, for some reason,

70
00:03:06,404 --> 00:03:10,008
the eastern brown snake
works by poisoning you - clearly -

71
00:03:10,391 --> 00:03:12,964
and one of the things it does is
activate nerve fibres.

72
00:03:12,964 --> 00:03:15,299
So actually my brain
would have got these messages

73
00:03:15,302 --> 00:03:17,635
saying, Danger! Danger! Danger! Danger!

74
00:03:17,644 --> 00:03:20,837
and, in its wisdom, it said, No. No. No.

75
00:03:21,927 --> 00:03:26,827
Six months later, I'm walking
in the bush with a boring talker.

76
00:03:27,430 --> 00:03:29,013
You know what a boring talker is?

77
00:03:29,013 --> 00:03:31,770
Those people, it doesn't matter
what they say, it's boring.

78
00:03:31,770 --> 00:03:32,770
(Laughter)

79
00:03:32,770 --> 00:03:36,743
It's irrelevant, but we'll call her Naomi

80
00:03:38,270 --> 00:03:40,072
because that is her name.

81
00:03:40,072 --> 00:03:41,340
(Laughter)

82
00:03:41,696 --> 00:03:43,666
Anyway, this is what happened, right?

83
00:03:45,400 --> 00:03:46,560
Ow! Wah!

84
00:03:46,730 --> 00:03:47,949
And I'm in agony.

85
00:03:47,949 --> 00:03:51,469
I have got a white-hot poke of pain
screaming up my leg.

86
00:03:52,392 --> 00:03:54,768
I'll tell you, biologically,
what's happened.

87
00:03:54,772 --> 00:03:57,493
Something touched the outside 
of my left leg in the skin.


88
00:03:57,493 --> 00:04:00,016
That activates big, fat, 
myelinated nerve fibres

89
00:04:00,016 --> 00:04:02,416
which send a message -
whizz - whizz - up to here.

90
00:04:02,416 --> 00:04:05,415
Just been touched on the outside 
of your left leg in the skin.

91
00:04:05,755 --> 00:04:08,753
It's sufficiently intense to activate
these free nerve endings.

92
00:04:08,753 --> 00:04:11,915
Danger receptors take
the message to my spinal cord:

93
00:04:11,919 --> 00:04:15,871
something dangerous has happened on
the outside of your left leg in the skin.

94
00:04:15,871 --> 00:04:16,871
(Audience) Mate.

95
00:04:16,871 --> 00:04:18,083
Yes!

96
00:04:18,083 --> 00:04:19,456
(Laughter)

97
00:04:19,835 --> 00:04:21,555
Well done, you weren't planted.

98
00:04:22,178 --> 00:04:24,582
That goes to the thalamus
and says the same thing:

99
00:04:24,588 --> 00:04:26,371
something dangerous has just happened

100
00:04:26,371 --> 00:04:28,441
on the outside
of your left leg in the skin.

101
00:04:28,441 --> 00:04:29,538
(Audience) Mate!

102
00:04:29,538 --> 00:04:33,286
So the brain says, thanks very much, 
Thalamus, kids alright? Good, anyway ...

103
00:04:33,286 --> 00:04:34,335
(Laughter)

104
00:04:34,335 --> 00:04:36,537
Frontal cortex,
anything to tell me about this?

105
00:04:36,537 --> 00:04:39,745
Hang on, I'll ask the posterior 
parietal cortex: where are we?

106
00:04:39,748 --> 00:04:41,326
We're walking in the bush.

107
00:04:44,934 --> 00:04:46,975
You're a bit 'mate' happy.

108
00:04:48,095 --> 00:04:49,645
At this stage of the gait cycle?

109
00:04:49,645 --> 00:04:51,947
Where's it coming from?
Have we been here before?

110
00:04:51,947 --> 00:04:53,408
Oh yes, we have.

111
00:04:53,807 --> 00:04:55,927
Last time we were here, you almost died.

112
00:04:56,679 --> 00:04:59,857
I'm going to make this hurt so much 
that you can do nothing else.

113
00:04:59,857 --> 00:05:03,360
And I was in absolute agony 
for what seemed like minutes.

114
00:05:03,700 --> 00:05:05,184
Screaming pain -

115
00:05:06,185 --> 00:05:10,162
until one of my mates looked at my leg,
and there's a little scratch from a twig.

116
00:05:10,162 --> 00:05:11,648
(Laughter)

117
00:05:12,284 --> 00:05:14,781
The pain in those situations 
was totally different

118
00:05:15,462 --> 00:05:16,796
because of meaning.

119
00:05:17,466 --> 00:05:20,526
I want to convince you that pain
is an illusion 100% of the time.

120
00:05:20,526 --> 00:05:22,178
Here's a visual illusion ...

121
00:05:22,363 --> 00:05:23,871
So have a look at this picture,

122
00:05:23,871 --> 00:05:26,961
you've got a square that's got A in it
and one that's got B in it.

123
00:05:27,437 --> 00:05:30,389
Raise your hand if you think 
that the square with A in it

124
00:05:30,393 --> 00:05:33,247
looks darker than the square with B in it.

125
00:05:34,346 --> 00:05:35,737
Thank goodness for that.

126
00:05:35,737 --> 00:05:40,178
None of you have a really socially
embarrassing neurological disorder.

127
00:05:40,498 --> 00:05:41,691
Except you.

128
00:05:41,691 --> 00:05:42,756
(Laughter)

129
00:05:42,756 --> 00:05:43,965
That's not true.

130
00:05:44,762 --> 00:05:47,186
Watch what happens 
if we have another look at this.

131
00:05:47,186 --> 00:05:50,226
These are those two squares
taken out of that picture.

132
00:05:50,831 --> 00:05:54,619
Hopefully you can see they're identical,
and some of you may not believe me.

133
00:05:54,624 --> 00:05:58,019
I'll just put A on top of that, 
and I'll put B on top of that.

134
00:05:59,221 --> 00:06:01,211
Some of you may still not believe me,

135
00:06:01,211 --> 00:06:04,331
so why don't we 
just move A over on top of B,

136
00:06:05,671 --> 00:06:07,751
or B over on top of A.

137
00:06:08,781 --> 00:06:12,011
No matter how long you look at this, 
A will look darker than B

138
00:06:12,011 --> 00:06:15,215
because your brain's doing 
some really groovy stuff,

139
00:06:15,760 --> 00:06:18,056
really quickly, outside of your awareness.

140
00:06:18,056 --> 00:06:19,159
Have a look at this.

141
00:06:19,159 --> 00:06:22,368
Turn your head on the side
and have a look at the same picture.

142
00:06:23,140 --> 00:06:24,627
Nothing changes.

143
00:06:24,634 --> 00:06:26,360
(Laughter)

144
00:06:27,133 --> 00:06:29,427
Fantastic. 100% take!

145
00:06:32,107 --> 00:06:33,926
So what really happens here,

146
00:06:34,739 --> 00:06:37,395
exactly the same frequency 
is hitting your retina,

147
00:06:38,013 --> 00:06:40,438
and that sends a message 
to the back of the brain,

148
00:06:40,707 --> 00:06:43,549
and then all of this groovy stuff
happens very quickly

149
00:06:43,549 --> 00:06:46,113
to ask the question,
What does this really mean?

150
00:06:46,113 --> 00:06:48,440
What's biologically advantageous for me?

151
00:06:48,440 --> 00:06:50,267
and then you get a visual image.

152
00:06:50,798 --> 00:06:54,259
This is a visual illusion, 
and vision's not about emotion,

153
00:06:54,259 --> 00:06:56,411
vision's not necessarily about survival,

154
00:06:56,411 --> 00:06:57,798
but pain is.

155
00:06:58,517 --> 00:07:01,696
Now, some of you might not know, 
if you're not medically trained,

156
00:07:01,696 --> 00:07:03,888
but what's happening
at this guy's right leg,

157
00:07:03,888 --> 00:07:05,558
that's not right, that's ...

158
00:07:05,558 --> 00:07:06,911
(Laughter)

159
00:07:06,911 --> 00:07:08,382
that's a dangerous situation,

160
00:07:08,382 --> 00:07:10,658
and that danger message
arrives at the brain,

161
00:07:10,658 --> 00:07:13,368
and the brain has to ask 
exactly the same question.

162
00:07:14,078 --> 00:07:16,292
What does this mean? 
What should be done here?

163
00:07:16,295 --> 00:07:22,271
And hopefully, the orchestra in this 
person's brain will make your leg hurt.

164
00:07:23,143 --> 00:07:25,518
In the work that
I've been doing for a long time,

165
00:07:25,518 --> 00:07:30,098
we're trying our best to work out 
how do we convince people in pain

166
00:07:30,601 --> 00:07:32,589
that we understand they're in pain,

167
00:07:32,589 --> 00:07:35,247
but it's not just about
the tissues of their body.

168
00:07:36,203 --> 00:07:38,037
How do we convince them of that?

169
00:07:38,037 --> 00:07:42,057
And a key conceptual shift
that we think is really important

170
00:07:42,358 --> 00:07:45,017
is that you can understand 
that pain is the end result.

171
00:07:45,017 --> 00:07:48,139
Pain's an output of the brain 
designed to protect you.

172
00:07:50,121 --> 00:07:53,466
It's not something that comes
from the tissues of your body.

173
00:07:54,536 --> 00:07:56,075
There's nothing there.


174
00:07:56,075 --> 00:07:58,102
We show patients a really sharp knife,

175
00:07:58,102 --> 00:08:00,273
and we say this knife is sharp, yeah?

176
00:08:00,283 --> 00:08:01,223
Yeah.

177
00:08:01,643 --> 00:08:04,874
And it might be a bit cold;
it's hard; it's got all those properties.

178
00:08:04,874 --> 00:08:07,007
This knife - painful as it sits out there.

179
00:08:07,011 --> 00:08:10,862
No, it's not. That knife does not 
have the properties of pain.

180
00:08:11,462 --> 00:08:15,542
And when you stick it into their belly -
we do this regularly, straight through -

181
00:08:16,732 --> 00:08:19,543
the belly doesn't adopt 
the property of pain.

182
00:08:19,543 --> 00:08:23,089
The brain has to do some 
very rapid and groovy things

183
00:08:23,613 --> 00:08:26,223
to project this illusion 
that pain exists there.

184
00:08:26,572 --> 00:08:30,906
100% of the time, 
pain is a construct of the brain.

185
00:08:31,684 --> 00:08:34,454
We can mess with pain easily 
without touching the tissues.

186
00:08:34,454 --> 00:08:36,374
This is an experiment we did a while ago

187
00:08:36,375 --> 00:08:39,396
where we got supposedly 'normal'
healthy volunteers.

188
00:08:39,619 --> 00:08:40,863
They're not normal people,

189
00:08:40,863 --> 00:08:43,249
because they're volunteering
for a pain experiment,

190
00:08:43,249 --> 00:08:44,178
(Laughter)

191
00:08:44,178 --> 00:08:46,898
but let's say they are
reasonably normal, right,

192
00:08:46,898 --> 00:08:50,228
and we put a very cold piece of metal 
on the back of their hand,

193
00:08:50,954 --> 00:08:52,890
and we just show them one of two lights.

194
00:08:52,897 --> 00:08:56,115
One light is red, and one light is blue.

195
00:08:56,115 --> 00:08:59,831
We don't tell anything about the lights, 
we just show them the light.

196
00:09:02,563 --> 00:09:04,223
I see that hand.

197
00:09:04,794 --> 00:09:06,572
We ask them, 'How much does it hurt?'

198
00:09:06,572 --> 00:09:10,315
And if they see the red light, it hurts
more than if they see the blue light.

199
00:09:10,315 --> 00:09:11,890
The stimulus is exactly the same,

200
00:09:11,890 --> 00:09:14,975
what's different is 
the meaning of the stimulus.

201
00:09:14,975 --> 00:09:18,199
Now there's a cue that says,
'This is really hot.'

202
00:09:18,199 --> 00:09:20,329
Because red means hot.

203
00:09:21,059 --> 00:09:23,689
So the sensible brain,
the clever brain should say,

204
00:09:23,689 --> 00:09:28,517
'Well, I really don't want you to do it,
so I'm going to make it really hurt.'

205
00:09:30,680 --> 00:09:34,349
There's people in the States that are
allowed to get their psychology students

206
00:09:34,349 --> 00:09:37,215
to participate in experiments
in exchange for credit points -

207
00:09:37,215 --> 00:09:39,399
or sex, or something -

208
00:09:39,916 --> 00:09:43,775
anyway, they put their head inside what
they think is a stimulator for their head,

209
00:09:43,775 --> 00:09:47,096
and they make sure that
the subject can see the intensity knob.

210
00:09:47,096 --> 00:09:48,988
And as they turn up the intensity knob,

211
00:09:48,988 --> 00:09:53,594
this little figure there showing
the lines going up at a steady rate,

212
00:09:53,594 --> 00:09:55,598
that's their reported head pain,

213
00:09:55,598 --> 00:09:57,578
and it matches the intensity knob.

214
00:09:57,578 --> 00:09:59,908
But the stimulator's doing nothing.

215
00:09:59,908 --> 00:10:02,533
It's just one of those
old-fashioned plastic hair dryers

216
00:10:02,533 --> 00:10:03,759
that doesn't do anything.

217
00:10:03,759 --> 00:10:05,389
You know those things?

218
00:10:05,389 --> 00:10:08,229
You probably use one - yeah?

219
00:10:08,886 --> 00:10:11,716
The trick is that they
have to see the intensity knob.

220
00:10:12,960 --> 00:10:15,117
I always think it'd be fun
to do an experiment

221
00:10:15,117 --> 00:10:18,886
based on that Spinal Tap film
where the intensity knob goes up to 11.

222
00:10:19,381 --> 00:10:21,261
Remember that film?

223
00:10:21,878 --> 00:10:24,305
What's really important
from a clinical perspective,

224
00:10:24,305 --> 00:10:28,015
and I'm a clinical neuroscientist,
and I see patients in pain,

225
00:10:28,015 --> 00:10:31,535
any piece of credible evidence
that they're in danger

226
00:10:31,535 --> 00:10:33,055
should change their pain,

227
00:10:33,055 --> 00:10:35,361
and they're all walking
into hospital departments

228
00:10:35,361 --> 00:10:37,281
with models like this on the desk.

229
00:10:37,601 --> 00:10:39,643
What does your brain say
when it sees a disc

230
00:10:39,643 --> 00:10:42,391
that's slipped so far out
it's sitting on its own?

231
00:10:42,391 --> 00:10:43,811
(Laughter)

232
00:10:44,681 --> 00:10:49,564
If you've ever seen a disc in a cadaver,
you can't slip the suckers.

233
00:10:49,950 --> 00:10:52,611
They're immobile, you can't slip a disc.

234
00:10:52,874 --> 00:10:55,661
But that's our language,
and it messes with your brain.

235
00:10:55,661 --> 00:10:58,611
It cannot not mess with your brain.

236
00:10:59,441 --> 00:11:03,471
We can even modulate the location of pain.
We can do some groovy things.

237
00:11:03,894 --> 00:11:06,171
It's quite well established
that referred pain

238
00:11:06,171 --> 00:11:10,550
gives you pain in an area of your body
that might be physiologically normal.

239
00:11:11,080 --> 00:11:13,230
Most of you would have heard
of referred pain.

240
00:11:13,230 --> 00:11:14,250
(Sneezing)

241
00:11:14,250 --> 00:11:15,290
Bless you.

242
00:11:15,290 --> 00:11:18,420
We do experiments where we give you
pain in an artificial limb -

243
00:11:18,420 --> 00:11:19,781
it's not even yours.

244
00:11:19,781 --> 00:11:23,680
This is Meng, who was a postdoc
in my lab in Oxford in the UK,

245
00:11:23,680 --> 00:11:25,402
and we stole a prosthetic limb,

246
00:11:25,406 --> 00:11:28,168
which is a whole other story
which is really funny -

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but I won't tell it to you -

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and we can do this manipulation

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so that you start to feel like
the plastic limb in front of you is yours.

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And we can make the rubber hand hurt.

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And we can bring in a knife,
and run the knife across the rubber hand,

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and you have your brain responses
to protect that rubber hand.

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You're feeling pain
in a lump of plastic, effectively.

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Here's a groovy experiment where
we take two Microsoft clipart people,

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and we put a webcam
on the forehead of one of them

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and a set of virtual reality glasses
on the other one.

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And then we get them to shake hands.

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And as they're shaking hands,

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the person on your right,
who's wearing the goggles,

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their visual field is coming
from the other person's forehead.

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Have you got it?

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So they are effectively looking
at the other person, thinking it's them

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because they're shaking hands,
the motor command fits, everything's good.

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And then we come in and put
a painful stimulus on that person's arm,

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and they see it hit that arm
of the person over there,

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with whom they're shaking hands,
and they say, 'Ouch! It really hurts.'

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And we say, 'Where does it hurt?'

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'On that man's arm.'

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(Laughter)

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They get it right every time,
pointing exactly where it is,

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but if you were on the outside,
taking a photo, they're literally -

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we've got the painful stimulus here,
and they're saying, 'It hurts there.'

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So the brain is not only producing pain,

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it's projecting it
to this location in mid-air.

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We can mess with that.

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This all becomes really important
when pain persists

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because two things happen
when pain persists

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that make the life
of someone in pain really difficult,

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that costs our country
40 billion dollars a year.

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It costs Australia more than cancer,

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cardio-vascular disease
and diabetes combined.

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Thanks for that facial expression,
I wanted someone to go ...

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This is the problem,
that if we keep running the neurons,

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the brain cells that produce pain,
they get better at producing pain.

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They become more and more sensitive,

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so we need a smaller
and smaller influence.

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The illusion, if you like,
in increasing sensitivity

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becomes very unhelpful.

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It's trying to protect you from something
that's not needing protection.

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It's very real.

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The other thing that happens
is that all of these networks

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lose their capacity to be specific
and precise, so the pain spreads.

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The pain changes its quality.
Ultimately, it's not even informative.

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It's both unhelpful and uninformative.

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Maybe the next TED Talk ever
is the really important question,

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'What do we do about it?'

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Who knows?

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No, we do know,

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that's what we're really researching,
but that's the end of my 18 minutes.

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Thank you very much for having me.

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(Applause)