Pawan Sinha on how brains learn to see

64,774 views ・ 2010-02-25

TED


Please double-click on the English subtitles below to play the video.

00:15
If you are a blind child in India,
0
15260
4000
00:19
you will very likely have to contend with
1
19260
3000
00:22
at least two big pieces of bad news.
2
22260
3000
00:25
The first bad news
3
25260
2000
00:27
is that the chances of getting treatment
4
27260
3000
00:30
are extremely slim to none,
5
30260
3000
00:33
and that's because most of the blindness
6
33260
2000
00:35
alleviation programs in the country
7
35260
2000
00:37
are focused on adults,
8
37260
2000
00:39
and there are very, very few hospitals
9
39260
3000
00:42
that are actually equipped to treat children.
10
42260
3000
00:46
In fact, if you were to be treated,
11
46260
4000
00:51
you might well end up being treated
12
51260
3000
00:54
by a person who has no medical credentials
13
54260
3000
00:57
as this case from Rajasthan illustrates.
14
57260
3000
01:00
This is a three-year-old orphan girl
15
60260
2000
01:02
who had cataracts.
16
62260
2000
01:04
So, her caretakers took her
17
64260
2000
01:06
to the village medicine man,
18
66260
2000
01:08
and instead of suggesting to the caretakers
19
68260
3000
01:11
that the girl be taken to a hospital,
20
71260
3000
01:14
the person decided to burn her abdomen
21
74260
2000
01:16
with red-hot iron bars
22
76260
2000
01:18
to drive out the demons.
23
78260
2000
01:20
The second piece of bad news
24
80260
3000
01:23
will be delivered to you
25
83260
2000
01:25
by neuroscientists, who will tell you
26
85260
3000
01:28
that if you are older than four or five years of age,
27
88260
3000
01:31
that even if you have your eye corrected,
28
91260
3000
01:34
the chances of your brain learning how to see
29
94260
3000
01:37
are very, very slim --
30
97260
2000
01:39
again, slim or none.
31
99260
3000
01:42
So when I heard these two things,
32
102260
2000
01:44
it troubled me deeply,
33
104260
2000
01:46
both because of personal reasons
34
106260
2000
01:48
and scientific reasons.
35
108260
2000
01:50
So let me first start with the personal reason.
36
110260
3000
01:53
It'll sound corny, but it's sincere.
37
113260
3000
01:56
That's my son, Darius.
38
116260
2000
01:58
As a new father,
39
118260
2000
02:00
I have a qualitatively different sense
40
120260
4000
02:04
of just how delicate babies are,
41
124260
3000
02:07
what our obligations are towards them
42
127260
3000
02:10
and how much love
43
130260
2000
02:12
we can feel towards a child.
44
132260
3000
02:15
I would move heaven and earth
45
135260
2000
02:17
in order to get treatment for Darius,
46
137260
3000
02:20
and for me to be told
47
140260
2000
02:22
that there might be other Dariuses
48
142260
2000
02:24
who are not getting treatment,
49
144260
2000
02:26
that's just viscerally wrong.
50
146260
3000
02:29
So that's the personal reason.
51
149260
2000
02:31
Scientific reason is that this notion
52
151260
3000
02:34
from neuroscience of critical periods --
53
154260
2000
02:36
that if the brain is older
54
156260
3000
02:39
than four or five years of age,
55
159260
2000
02:41
it loses its ability to learn --
56
161260
2000
02:43
that doesn't sit well with me,
57
163260
2000
02:45
because I don't think that idea
58
165260
2000
02:47
has been tested adequately.
59
167260
3000
02:50
The birth of the idea is from
60
170260
2000
02:52
David Hubel and Torsten Wiesel's work,
61
172260
2000
02:54
two researchers who were at Harvard,
62
174260
2000
02:56
and they got the Nobel Prize in 1981
63
176260
3000
02:59
for their studies of visual physiology,
64
179260
2000
03:01
which are remarkably beautiful studies,
65
181260
2000
03:03
but I believe some of their work
66
183260
2000
03:05
has been extrapolated
67
185260
2000
03:07
into the human domain prematurely.
68
187260
2000
03:09
So, they did their work with kittens,
69
189260
2000
03:11
with different kinds of deprivation regiments,
70
191260
2000
03:13
and those studies,
71
193260
2000
03:15
which date back to the '60s,
72
195260
2000
03:17
are now being applied to human children.
73
197260
3000
03:20
So I felt that I needed to do two things.
74
200260
3000
03:23
One: provide care
75
203260
3000
03:26
to children who are currently
76
206260
2000
03:28
being deprived of treatment.
77
208260
2000
03:30
That's the humanitarian mission.
78
210260
2000
03:32
And the scientific mission would be
79
212260
2000
03:34
to test the limits
80
214260
2000
03:36
of visual plasticity.
81
216260
2000
03:38
And these two missions, as you can tell,
82
218260
3000
03:41
thread together perfectly. One adds to the other;
83
221260
3000
03:44
in fact, one would be impossible without the other.
84
224260
3000
03:49
So, to implement
85
229260
2000
03:51
these twin missions,
86
231260
2000
03:53
a few years ago, I launched Project Prakash.
87
233260
3000
03:56
Prakash, as many of you know,
88
236260
2000
03:58
is the Sanskrit word for light,
89
238260
2000
04:00
and the idea is that
90
240260
2000
04:02
in bringing light into the lives of children,
91
242260
3000
04:05
we also have a chance
92
245260
2000
04:07
of shedding light on some of the
93
247260
2000
04:09
deepest mysteries of neuroscience.
94
249260
3000
04:12
And the logo -- even though it looks extremely Irish,
95
252260
3000
04:15
it's actually derived from
96
255260
2000
04:17
the Indian symbol of Diya, an earthen lamp.
97
257260
4000
04:21
The Prakash, the overall effort
98
261260
3000
04:24
has three components:
99
264260
2000
04:26
outreach, to identify children in need of care;
100
266260
4000
04:30
medical treatment; and in subsequent study.
101
270260
3000
04:33
And I want to show you a short video clip
102
273260
3000
04:36
that illustrates the first two components of this work.
103
276260
3000
04:41
This is an outreach station
104
281260
2000
04:43
conducted at a school for the blind.
105
283260
3000
04:46
(Text: Most of the children are profoundly and permanently blind ...)
106
286260
5000
04:51
Pawan Sinha: So, because this is a school for the blind,
107
291260
5000
04:56
many children have permanent conditions.
108
296260
2000
04:58
That's a case of microphthalmos,
109
298260
3000
05:01
which is malformed eyes,
110
301260
2000
05:03
and that's a permanent condition;
111
303260
2000
05:05
it cannot be treated.
112
305260
2000
05:07
That's an extreme of micropthalmos
113
307260
2000
05:09
called enophthalmos.
114
309260
2000
05:11
But, every so often, we come across children
115
311260
2000
05:13
who show some residual vision,
116
313260
3000
05:16
and that is a very good sign
117
316260
3000
05:19
that the condition might actually be treatable.
118
319260
2000
05:21
So, after that screening, we bring the children to the hospital.
119
321260
3000
05:24
That's the hospital we're working with in Delhi,
120
324260
2000
05:26
the Schroff Charity Eye Hospital.
121
326260
3000
05:29
It has a very well-equipped
122
329260
2000
05:31
pediatric ophthalmic center,
123
331260
3000
05:35
which was made possible in part
124
335260
2000
05:37
by a gift from the Ronald McDonald charity.
125
337260
4000
05:41
So, eating burgers actually helps.
126
341260
3000
05:45
(Text: Such examinations allow us to improve
127
345260
2000
05:47
eye-health in many children, and ...
128
347260
2000
05:54
... help us find children who can participate in Project Prakash.)
129
354260
3000
05:57
PS: So, as I zoom in to the eyes of this child,
130
357260
2000
05:59
you will see the cause of his blindness.
131
359260
3000
06:03
The whites that you see in the middle of his pupils
132
363260
3000
06:06
are congenital cataracts,
133
366260
3000
06:09
so opacities of the lens.
134
369260
2000
06:11
In our eyes, the lens is clear,
135
371260
3000
06:14
but in this child, the lens has become opaque,
136
374260
2000
06:16
and therefore he can't see the world.
137
376260
3000
06:19
So, the child is given treatment. You'll see shots of the eye.
138
379260
3000
06:22
Here's the eye with the opaque lens,
139
382260
2000
06:24
the opaque lens extracted
140
384260
2000
06:26
and an acrylic lens inserted.
141
386260
3000
06:29
And here's the same child
142
389260
2000
06:31
three weeks post-operation,
143
391260
3000
06:34
with the right eye open.
144
394260
3000
06:40
(Applause)
145
400260
6000
06:46
Thank you.
146
406260
2000
06:48
So, even from that little clip, you can begin to get the sense
147
408260
3000
06:51
that recovery is possible,
148
411260
2000
06:53
and we have now
149
413260
2000
06:55
provided treatment to over 200 children,
150
415260
3000
06:58
and the story repeats itself.
151
418260
2000
07:00
After treatment, the child
152
420260
2000
07:02
gains significant functionality.
153
422260
3000
07:05
In fact, the story holds true
154
425260
3000
07:08
even if you have a person who got sight
155
428260
2000
07:10
after several years of deprivation.
156
430260
2000
07:12
We did a paper a few years ago
157
432260
2000
07:14
about this woman that you see on the right, SRD,
158
434260
4000
07:18
and she got her sight late in life,
159
438260
2000
07:20
and her vision is remarkable at this age.
160
440260
4000
07:24
I should add a tragic postscript to this --
161
444260
3000
07:27
she died two years ago
162
447260
2000
07:29
in a bus accident.
163
449260
2000
07:31
So, hers is just a truly inspiring story --
164
451260
4000
07:35
unknown, but inspiring story.
165
455260
3000
07:38
So when we started finding these results,
166
458260
2000
07:40
as you might imagine, it created quite a bit of stir
167
460260
3000
07:43
in the scientific and the popular press.
168
463260
3000
07:46
Here's an article in Nature
169
466260
2000
07:48
that profiled this work,
170
468260
2000
07:50
and another one in Time.
171
470260
2000
07:52
So, we were fairly convinced -- we are convinced --
172
472260
2000
07:54
that recovery is feasible,
173
474260
2000
07:56
despite extended visual deprivation.
174
476260
3000
07:59
The next obvious question to ask:
175
479260
2000
08:01
What is the process of recovery?
176
481260
3000
08:04
So, the way we study that is,
177
484260
3000
08:07
let's say we find a child who has light sensitivity.
178
487260
2000
08:09
The child is provided treatment,
179
489260
2000
08:11
and I want to stress that the treatment
180
491260
2000
08:13
is completely unconditional;
181
493260
2000
08:15
there is no quid pro quo.
182
495260
2000
08:17
We treat many more children then we actually work with.
183
497260
3000
08:20
Every child who needs treatment is treated.
184
500260
3000
08:23
After treatment, about every week,
185
503260
2000
08:25
we run the child
186
505260
2000
08:27
on a battery of simple visual tests
187
507260
3000
08:30
in order to see how their visual skills
188
510260
2000
08:32
are coming on line.
189
512260
2000
08:34
And we try to do this for as long as possible.
190
514260
3000
08:37
This arc of development
191
517260
2000
08:39
gives us unprecedented
192
519260
2000
08:41
and extremely valuable information
193
521260
2000
08:43
about how the scaffolding of vision
194
523260
2000
08:45
gets set up.
195
525260
2000
08:47
What might be the causal connections
196
527260
2000
08:49
between the early developing skills
197
529260
2000
08:51
and the later developing ones?
198
531260
2000
08:53
And we've used this general approach to study
199
533260
2000
08:55
many different visual proficiencies,
200
535260
3000
08:58
but I want to highlight one particular one,
201
538260
4000
09:02
and that is image parsing into objects.
202
542260
3000
09:05
So, any image of the kind that you see on the left,
203
545260
2000
09:07
be it a real image or a synthetic image,
204
547260
3000
09:10
it's made up of little regions
205
550260
2000
09:12
that you see in the middle column,
206
552260
2000
09:14
regions of different colors, different luminances.
207
554260
3000
09:17
The brain has this complex task
208
557260
3000
09:20
of putting together, integrating,
209
560260
3000
09:23
subsets of these regions
210
563260
2000
09:25
into something that's more meaningful,
211
565260
2000
09:27
into what we would consider to be objects,
212
567260
2000
09:29
as you see on the right.
213
569260
2000
09:31
And nobody knows how this integration happens,
214
571260
2000
09:33
and that's the question we asked with Project Prakash.
215
573260
4000
09:37
So, here's what happens
216
577260
2000
09:39
very soon after the onset of sight.
217
579260
3000
09:42
Here's a person who had gained sight just a couple of weeks ago,
218
582260
3000
09:45
and you see Ethan Myers, a graduate student from MIT,
219
585260
3000
09:48
running the experiment with him.
220
588260
3000
09:51
His visual-motor coordination is quite poor,
221
591260
4000
09:55
but you get a general sense
222
595260
2000
09:57
of what are the regions that he's trying to trace out.
223
597260
3000
10:00
If you show him real world images,
224
600260
2000
10:02
if you show others like him real world images,
225
602260
3000
10:05
they are unable to recognize most of the objects
226
605260
2000
10:07
because the world to them is over-fragmented;
227
607260
3000
10:10
it's made up of a collage, a patchwork,
228
610260
3000
10:13
of regions of different colors and luminances.
229
613260
2000
10:15
And that's what's indicated in the green outlines.
230
615260
2000
10:17
When you ask them,
231
617260
2000
10:19
"Even if you can't name the objects, just point to where the objects are,"
232
619260
3000
10:22
these are the regions that they point to.
233
622260
2000
10:24
So the world is this complex
234
624260
2000
10:26
patchwork of regions.
235
626260
2000
10:28
Even the shadow on the ball
236
628260
2000
10:30
becomes its own object.
237
630260
3000
10:33
Interestingly enough,
238
633260
2000
10:35
you give them a few months,
239
635260
2000
10:37
and this is what happens.
240
637260
3000
10:43
Doctor: How many are these?
241
643260
2000
10:45
Patient: These are two things.
242
645260
2000
10:47
Doctor: What are their shapes?
243
647260
2000
10:49
Patient: Their shapes ...
244
649260
2000
10:51
This one is a circle,
245
651260
3000
10:54
and this
246
654260
2000
10:56
is a square.
247
656260
2000
10:58
PS: A very dramatic transformation has come about.
248
658260
3000
11:01
And the question is:
249
661260
2000
11:03
What underlies this transformation?
250
663260
2000
11:05
It's a profound question,
251
665260
2000
11:07
and what's even more amazing is how simple
252
667260
2000
11:09
the answer is.
253
669260
2000
11:11
The answer lies in motion
254
671260
2000
11:13
and that's what I want to show you in the next clip.
255
673260
3000
11:18
Doctor: What shape do you see here?
256
678260
2000
11:20
Patient: I can't make it out.
257
680260
3000
11:28
Doctor: Now?
258
688260
2000
11:31
Patient: Triangle.
259
691260
2000
11:35
Doctor: How many things are these?
260
695260
3000
11:48
Now, how many things are these?
261
708260
3000
11:51
Patient: Two.
262
711260
2000
11:53
Doctor: What are these things?
263
713260
2000
11:56
Patient: A square and a circle.
264
716260
2000
11:58
PS: And we see this pattern over and over again.
265
718260
3000
12:01
The one thing the visual system needs
266
721260
3000
12:04
in order to begin parsing the world
267
724260
2000
12:06
is dynamic information.
268
726260
2000
12:08
So the inference we are deriving from this,
269
728260
2000
12:10
and several such experiments,
270
730260
2000
12:12
is that dynamic information processing,
271
732260
2000
12:14
or motion processing,
272
734260
2000
12:16
serves as the bedrock for building
273
736260
2000
12:18
the rest of the complexity of visual processing;
274
738260
4000
12:22
it leads to visual integration
275
742260
2000
12:24
and eventually to recognition.
276
744260
3000
12:27
This simple idea has far reaching implications.
277
747260
3000
12:30
And let me just quickly mention two,
278
750260
3000
12:33
one, drawing from the domain of engineering,
279
753260
2000
12:35
and one from the clinic.
280
755260
2000
12:37
So, from the perspective of engineering,
281
757260
2000
12:39
we can ask: Goven that we know
282
759260
3000
12:42
that motion is so important for the human visual system,
283
762260
2000
12:44
can we use this as a recipe
284
764260
3000
12:47
for constructing machine-based vision systems
285
767260
3000
12:50
that can learn on their own, that don't need to be programmed
286
770260
3000
12:53
by a human programmer?
287
773260
2000
12:55
And that's what we're trying to do.
288
775260
2000
12:57
I'm at MIT, at MIT you need to apply
289
777260
3000
13:00
whatever basic knowledge you gain.
290
780260
2000
13:02
So we are creating Dylan,
291
782260
2000
13:04
which is a computational system
292
784260
2000
13:06
with an ambitious goal
293
786260
2000
13:08
of taking in visual inputs
294
788260
2000
13:10
of the same kind that a human child would receive,
295
790260
3000
13:13
and autonomously discovering:
296
793260
2000
13:15
What are the objects in this visual input?
297
795260
3000
13:18
So, don't worry about the internals of Dylan.
298
798260
3000
13:21
Here, I'm just going to talk about
299
801260
3000
13:24
how we test Dylan.
300
804260
2000
13:26
The way we test Dylan is by giving it
301
806260
2000
13:28
inputs, as I said, of the same kind
302
808260
3000
13:31
that a baby, or a child in Project Prakash would get.
303
811260
3000
13:34
But for a long time we couldn't quite figure out:
304
814260
3000
13:37
Wow can we get these kinds of video inputs?
305
817260
3000
13:41
So, I thought,
306
821260
2000
13:43
could we have Darius
307
823260
2000
13:45
serve as our babycam carrier,
308
825260
3000
13:48
and that way get the inputs that we feed into Dylan?
309
828260
3000
13:51
So that's what we did.
310
831260
2000
13:53
(Laughter)
311
833260
7000
14:00
I had to have long conversations with my wife.
312
840260
3000
14:03
(Laughter)
313
843260
5000
14:08
In fact, Pam, if you're watching this,
314
848260
2000
14:10
please forgive me.
315
850260
2000
14:13
So, we modified the optics of the camera
316
853260
4000
14:17
in order to mimic the baby's visual acuity.
317
857260
3000
14:20
As some of you might know,
318
860260
2000
14:22
babyies are born pretty much legally blind.
319
862260
4000
14:26
Their acuity -- our acuity is 20/20;
320
866260
3000
14:29
babies' acuity is like 20/800,
321
869260
3000
14:32
so they are looking at the world
322
872260
2000
14:34
in a very, very blurry fashion.
323
874260
3000
14:37
Here's what a baby-cam video looks like.
324
877260
3000
14:41
(Laughter)
325
881260
9000
14:50
(Applause)
326
890260
3000
14:53
Thankfully, there isn't any audio
327
893260
2000
14:55
to go with this.
328
895260
3000
14:58
What's amazing is that working with such
329
898260
2000
15:00
highly degraded input,
330
900260
2000
15:02
the baby, very quickly, is able
331
902260
2000
15:04
to discover meaning in such input.
332
904260
3000
15:07
But then two or three days afterward,
333
907260
2000
15:09
babies begin to pay attention
334
909260
2000
15:11
to their mother's or their father's face.
335
911260
2000
15:13
How does that happen? We want Dylan to be able to do that,
336
913260
3000
15:16
and using this mantra of motion,
337
916260
3000
15:19
Dylan actually can do that.
338
919260
2000
15:21
So, given that kind of video input,
339
921260
3000
15:24
with just about six or seven minutes worth of video,
340
924260
3000
15:27
Dylan can begin to extract patterns
341
927260
3000
15:30
that include faces.
342
930260
3000
15:33
So, it's an important demonstration
343
933260
2000
15:35
of the power of motion.
344
935260
2000
15:37
The clinical implication, it comes from the domain of autism.
345
937260
3000
15:40
Visual integration has been associated with autism
346
940260
2000
15:42
by several researchers.
347
942260
2000
15:44
When we saw that, we asked:
348
944260
2000
15:46
Could the impairment in visual integration
349
946260
3000
15:49
be the manifestation of something underneath,
350
949260
3000
15:52
of dynamic information processing deficiencies in autism?
351
952260
3000
15:55
Because, if that hypothesis were to be true,
352
955260
3000
15:58
it would have massive repercussions in our understanding
353
958260
3000
16:01
of what's causing the many different aspects
354
961260
2000
16:03
of the autism phenotype.
355
963260
3000
16:06
What you're going to see are
356
966260
2000
16:08
video clips of two children -- one neurotypical,
357
968260
3000
16:11
one with autism, playing Pong.
358
971260
2000
16:13
So, while the child is playing Pong, we are tracking where they're looking.
359
973260
3000
16:16
In red are the eye movement traces.
360
976260
3000
16:19
This is the neurotypical child, and what you see
361
979260
3000
16:22
is that the child is able to make cues
362
982260
2000
16:24
of the dynamic information
363
984260
2000
16:26
to predict where the ball is going to go.
364
986260
2000
16:28
Even before the ball gets to a place,
365
988260
3000
16:31
the child is already looking there.
366
991260
3000
16:34
Contrast this with a child
367
994260
2000
16:36
with autism playing the same game.
368
996260
2000
16:38
Instead of anticipating,
369
998260
2000
16:40
the child always follows where the ball has been.
370
1000260
3000
16:43
The efficiency of the use
371
1003260
2000
16:45
of dynamic information
372
1005260
2000
16:47
seems to be significantly compromised in autism.
373
1007260
3000
16:51
So we are pursuing this line of work
374
1011260
3000
16:54
and hopefully we'll have
375
1014260
2000
16:56
more results to report soon.
376
1016260
2000
16:58
Looking ahead, if you think of this disk
377
1018260
3000
17:01
as representing all of the children
378
1021260
2000
17:03
we've treated so far,
379
1023260
2000
17:05
this is the magnitude of the problem.
380
1025260
2000
17:07
The red dots are the children we have not treated.
381
1027260
3000
17:10
So, there are many, many more children who need to be treated,
382
1030260
2000
17:12
and in order to expand the scope of the project,
383
1032260
3000
17:15
we are planning on launching
384
1035260
2000
17:17
The Prakash Center for Children,
385
1037260
2000
17:19
which will have a dedicated pediatric hospital,
386
1039260
3000
17:22
a school for the children we are treating
387
1042260
2000
17:24
and also a cutting-edge research facility.
388
1044260
2000
17:26
The Prakash Center will integrate health care,
389
1046260
3000
17:29
education and research in a way
390
1049260
2000
17:31
that truly creates the whole
391
1051260
2000
17:33
to be greater than the sum of the parts.
392
1053260
3000
17:36
So, to summarize: Prakash, in its five years of existence,
393
1056260
3000
17:39
it's had an impact in multiple areas,
394
1059260
3000
17:42
ranging from basic neuroscience
395
1062260
2000
17:44
plasticity and learning in the brain,
396
1064260
2000
17:46
to clinically relevant hypotheses like in autism,
397
1066260
4000
17:50
the development of autonomous machine vision systems,
398
1070260
3000
17:53
education of the undergraduate and graduate students,
399
1073260
3000
17:56
and most importantly in the alleviation
400
1076260
2000
17:58
of childhood blindness.
401
1078260
2000
18:00
And for my students and I, it's been
402
1080260
2000
18:02
just a phenomenal experience
403
1082260
2000
18:04
because we have gotten to do interesting research,
404
1084260
4000
18:08
while at the same time
405
1088260
2000
18:10
helping the many children that we have worked with.
406
1090260
2000
18:12
Thank you very much.
407
1092260
2000
18:14
(Applause)
408
1094260
2000
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7