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Today I want to tell you

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about a project being carried out

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by scientists all over the world

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to paint a neural portrait of the human mind.

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And the central idea of this work

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is that the human mind and brain

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is not a single, general-purpose processor,

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but a collection of highly specialized components,

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each solving a different specific problem,

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and yet collectively making up

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who we are as human beings and thinkers.

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To give you a feel for this idea,

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imagine the following scenario:

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You walk into your child's day care center.

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As usual, there's a dozen kids there

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waiting to get picked up,

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but this time,

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the children's faces look weirdly similar,

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and you can't figure out which child is yours.

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Do you need new glasses?

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Are you losing your mind?

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You run through a quick mental checklist.

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No, you seem to be thinking clearly,

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and your vision is perfectly sharp.

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And everything looks normal

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except the children's faces.

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You can see the faces,

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but they don't look distinctive,

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and none of them looks familiar,

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and it's only by spotting an orange hair ribbon

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that you find your daughter.

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This sudden loss of the ability to recognize faces

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actually happens to people.

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It's called prosopagnosia,

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and it results from damage

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to a particular part of the brain.

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The striking thing about it

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is that only face recognition is impaired;

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everything else is just fine.

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Prosopagnosia is one of many surprisingly specific

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mental deficits that can happen after brain damage.

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These syndromes collectively

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have suggested for a long time

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that the mind is divvied up into distinct components,

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but the effort to discover those components

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has jumped to warp speed

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with the invention of brain imaging technology,

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especially MRI.

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So MRI enables you to see internal anatomy

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at high resolution,

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so I'm going to show you in a second

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a set of MRI cross-sectional images

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through a familiar object,

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and we're going to fly through them

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and you're going to try to figure out what the object is.

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Here we go.

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It's not that easy. It's an artichoke.

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Okay, let's try another one,

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starting from the bottom and going through the top.

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Broccoli! It's a head of broccoli.

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Isn't it beautiful? I love that.

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Okay, here's another one. It's a brain, of course.

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In fact, it's my brain.

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We're going through slices through my head like that.

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That's my nose over on the right, and now

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we're going over here, right there.

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So this picture's nice, if I do say so myself,

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but it shows only anatomy.

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The really cool advance with functional imaging

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happened when scientists figured out how to make

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pictures that show not just anatomy but activity,

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that is, where neurons are firing.

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So here's how this works.

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Brains are like muscles.

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When they get active,

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they need increased blood flow to supply that activity,

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and lucky for us, blood flow
control to the brain is local,

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so if a bunch of neurons, say, right there

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get active and start firing,

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then blood flow increases just right there.

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So functional MRI picks up
on that blood flow increase,

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producing a higher MRI response

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where neural activity goes up.

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So to give you a concrete feel

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for how a functional MRI experiment goes

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and what you can learn from it

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and what you can't,

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let me describe one of the first studies I ever did.

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We wanted to know if there was a special
part of the brain for recognizing faces,

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and there was already reason to
think there might be such a thing

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based on this phenomenon of prosopagnosia

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that I described a moment ago,

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but nobody had ever seen that part of the brain

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in a normal person,

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so we set out to look for it.

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So I was the first subject.

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I went into the scanner, I lay on my back,

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I held my head as still as I could

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while staring at pictures of faces like these

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and objects like these

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and faces and objects for hours.

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So as somebody who has
pretty close to the world record

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of total number of hours spent inside an MRI scanner,

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I can tell you that one of the skills

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that's really important for MRI research

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is bladder control.

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(Laughter)

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When I got out of the scanner,

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I did a quick analysis of the data,

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looking for any parts of my brain

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that produced a higher response
when I was looking at faces

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than when I was looking at objects,

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and here's what I saw.

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Now this image looks just awful by today's standards,

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but at the time I thought it was beautiful.

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What it shows is that region right there,

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that little blob,

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it's about the size of an olive

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and it's on the bottom surface of my brain

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about an inch straight in from right there.

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And what that part of my brain is doing

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is producing a higher MRI response,

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that is, higher neural activity,

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when I was looking at faces

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than when I was looking at objects.

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So that's pretty cool,

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but how do we know this isn't a fluke?

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Well, the easiest way

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is to just do the experiment again.

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So I got back in the scanner,

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I looked at more faces and I looked at more objects

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and I got a similar blob,

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and then I did it again

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and I did it again

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and again and again,

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and around about then

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I decided to believe it was for real.

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But still, maybe this is
something weird about my brain

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and no one else has one of these things in there,

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so to find out, we scanned a bunch of other people

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and found that pretty much everyone

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has that little face-processing region

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in a similar neighborhood of the brain.

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So the next question was,

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what does this thing really do?

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Is it really specialized just for face recognition?

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Well, maybe not, right?

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Maybe it responds not only to faces

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but to any body part.

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Maybe it responds to anything human

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or anything alive

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or anything round.

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The only way to be really sure that that region

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is specialized for face recognition

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is to rule out all of those hypotheses.

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So we spent much of the next couple of years

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scanning subjects while they looked at lots

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of different kinds of images,

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and we showed that that part of the brain

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responds strongly when you look at

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any images that are faces of any kind,

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and it responds much less strongly

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to any image you show that isn't a face,

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like some of these.

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So have we finally nailed the case

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that this region is necessary for face recognition?

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No, we haven't.

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Brain imaging can never tell you

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if a region is necessary for anything.

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All you can do with brain imaging

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is watch regions turn on and off

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as people think different thoughts.

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To tell if a part of the brain is
necessary for a mental function,

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you need to mess with it and see what happens,

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and normally we don't get to do that.

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But an amazing opportunity came about

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very recently when a couple of colleagues of mine

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tested this man who has epilepsy

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and who is shown here in his hospital bed

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where he's just had electrodes placed

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on the surface of his brain

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to identify the source of his seizures.

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So it turned out by total chance

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that two of the electrodes

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happened to be right on top of his face area.

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So with the patient's consent,

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the doctors asked him what happened

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when they electrically stimulated
that part of his brain.

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Now, the patient doesn't know

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where those electrodes are,

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and he's never heard of the face area.

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So let's watch what happens.

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It's going to start with a control condition

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that will say "Sham" nearly invisibly

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in red in the lower left,

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when no current is delivered,

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and you'll hear the neurologist speaking
to the patient first. So let's watch.

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(Video) Neurologist: Okay, just look at my face

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and tell me what happens when I do this.

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All right?

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Patient: Okay.

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Neurologist: One, two, three.

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Patient: Nothing.
Neurologist: Nothing? Okay.

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I'm going to do it one more time.

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Look at my face.

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One, two, three.

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Patient: You just turned into somebody else.

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Your face metamorphosed.

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Your nose got saggy, it went to the left.

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You almost looked like somebody I'd seen before,

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but somebody different.

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That was a trip.

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(Laughter)

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Nancy Kanwisher: So this experiment —

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(Applause) —

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this experiment finally nails the case

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that this region of the brain is not only

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selectively responsive to faces

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but causally involved in face perception.

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So I went through all of these details

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about the face region to show you what it takes

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to really establish that a part of the brain

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is selectively involved in a specific mental process.

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Next, I'll go through much more quickly

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some of the other specialized regions of the brain

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that we and others have found.

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So to do this, I've spent a lot of time

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in the scanner over the last month

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so I can show you these things in my brain.

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So let's get started. Here's my right hemisphere.

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So we're oriented like that.
You're looking at my head this way.

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Imagine taking the skull off

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and looking at the surface of the brain like that.

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Okay, now as you can see,

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the surface of the brain is all folded up.

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So that's not good. Stuff could be hidden in there.

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We want to see the whole thing,

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so let's inflate it so we can see the whole thing.

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Next, let's find that face area I've been talking about

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that responds to images like these.

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To see that, let's turn the brain around

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and look on the inside surface on the bottom,

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and there it is, that's my face area.

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Just to the right of that is another region

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that is shown in purple

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that responds when you process color information,

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and near those regions are other regions

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that are involved in perceiving places,

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like right now, I'm seeing
this layout of space around me

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and these regions in green right there

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are really active.

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There's another one out on the outside surface again

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where there's a couple more face regions as well.

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Also in this vicinity

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is a region that's selectively involved

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in processing visual motion,

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like these moving dots here,

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and that's in yellow at the bottom of the brain,

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and near that is a region that responds

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when you look at images of bodies and body parts

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like these, and that region is shown in lime green

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at the bottom of the brain.

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Now all these regions I've shown you so far

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are involved in specific aspects of visual perception.

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Do we also have specialized brain regions

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for other senses, like hearing?

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Yes, we do. So if we turn the brain around a little bit,

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here's a region in dark blue

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00:10:38,190 --> 00:10:40,536
that we reported just a couple of months ago,

270
00:10:40,536 --> 00:10:42,170
and this region responds strongly

271
00:10:42,170 --> 00:10:45,599
when you hear sounds with pitch, like these.

272
00:10:45,599 --> 00:10:47,742
(Sirens)

273
00:10:47,742 --> 00:10:49,823
(Cello music)

274
00:10:49,823 --> 00:10:51,740
(Doorbell)

275
00:10:51,740 --> 00:10:55,348
In contrast, that same region
does not respond strongly

276
00:10:55,348 --> 00:10:56,910
when you hear perfectly familiar sounds

277
00:10:56,910 --> 00:10:59,272
that don't have a clear pitch, like these.

278
00:10:59,272 --> 00:11:01,741
(Chomping)

279
00:11:01,741 --> 00:11:03,941
(Drum roll)

280
00:11:03,941 --> 00:11:06,708
(Toilet flushing)

281
00:11:06,708 --> 00:11:09,206
Okay. Next to the pitch region

282
00:11:09,206 --> 00:11:11,680
is another set of regions that
are selectively responsive

283
00:11:11,680 --> 00:11:14,445
when you hear the sounds of speech.

284
00:11:14,445 --> 00:11:16,285
Okay, now let's look at these same regions.

285
00:11:16,285 --> 00:11:18,753
In my left hemisphere, there's a similar arrangement —

286
00:11:18,753 --> 00:11:20,226
not identical, but similar —

287
00:11:20,226 --> 00:11:22,435
and most of the same regions are in here,

288
00:11:22,435 --> 00:11:24,437
albeit sometimes different in size.

289
00:11:24,437 --> 00:11:26,451
Now, everything I've shown you so far

290
00:11:26,451 --> 00:11:29,477
are regions that are involved in
different aspects of perception,

291
00:11:29,477 --> 00:11:31,310
vision and hearing.

292
00:11:31,310 --> 00:11:32,970
Do we also have specialized brain regions

293
00:11:32,970 --> 00:11:36,405
for really fancy, complicated mental processes?

294
00:11:36,405 --> 00:11:37,834
Yes, we do.

295
00:11:37,834 --> 00:11:41,223
So here in pink are my language regions.

296
00:11:41,223 --> 00:11:42,651
So it's been known for a very long time

297
00:11:42,651 --> 00:11:44,686
that that general vicinity of the brain

298
00:11:44,686 --> 00:11:46,879
is involved in processing language,

299
00:11:46,879 --> 00:11:48,611
but we showed very recently

300
00:11:48,611 --> 00:11:50,321
that these pink regions

301
00:11:50,321 --> 00:11:52,526
respond extremely selectively.

302
00:11:52,526 --> 00:11:55,338
They respond when you understand
the meaning of a sentence,

303
00:11:55,338 --> 00:11:58,176
but not when you do other complex mental things,

304
00:11:58,176 --> 00:12:00,355
like mental arithmetic

305
00:12:00,355 --> 00:12:02,751
or holding information in memory

306
00:12:02,751 --> 00:12:05,406
or appreciating the complex structure

307
00:12:05,406 --> 00:12:07,690
in a piece of music.

308
00:12:09,664 --> 00:12:12,553
The most amazing region that's been found yet

309
00:12:12,553 --> 00:12:15,860
is this one right here in turquoise.

310
00:12:15,860 --> 00:12:18,050
This region responds

311
00:12:18,050 --> 00:12:22,318
when you think about what another person is thinking.

312
00:12:22,318 --> 00:12:23,962
So that may seem crazy,

313
00:12:23,962 --> 00:12:27,830
but actually, we humans do this all the time.

314
00:12:27,830 --> 00:12:30,023
You're doing this when you realize

315
00:12:30,023 --> 00:12:31,654
that your partner is going to be worried

316
00:12:31,654 --> 00:12:34,161
if you don't call home to say you're running late.

317
00:12:34,161 --> 00:12:37,630
I'm doing this with that region of my brain right now

318
00:12:37,630 --> 00:12:39,911
when I realize that you guys

319
00:12:39,911 --> 00:12:41,509
are probably now wondering about

320
00:12:41,509 --> 00:12:44,056
all that gray, uncharted territory in the brain,

321
00:12:44,056 --> 00:12:46,020
and what's up with that?

322
00:12:46,020 --> 00:12:47,705
Well, I'm wondering about that too,

323
00:12:47,705 --> 00:12:50,100
and we're running a bunch of
experiments in my lab right now

324
00:12:50,100 --> 00:12:52,113
to try to find a number of other

325
00:12:52,113 --> 00:12:54,145
possible specializations in the brain

326
00:12:54,145 --> 00:12:57,513
for other very specific mental functions.

327
00:12:57,513 --> 00:13:00,134
But importantly, I don't think we have

328
00:13:00,134 --> 00:13:01,698
specializations in the brain

329
00:13:01,698 --> 00:13:04,444
for every important mental function,

330
00:13:04,444 --> 00:13:07,853
even mental functions that may be critical for survival.

331
00:13:07,853 --> 00:13:09,955
In fact, a few years ago,

332
00:13:09,955 --> 00:13:11,072
there was a scientist in my lab

333
00:13:11,072 --> 00:13:12,481
who became quite convinced

334
00:13:12,481 --> 00:13:14,230
that he'd found a brain region

335
00:13:14,230 --> 00:13:16,142
for detecting food,

336
00:13:16,142 --> 00:13:18,060
and it responded really strongly in the scanner

337
00:13:18,060 --> 00:13:20,788
when people looked at images like this.

338
00:13:20,788 --> 00:13:23,700
And further, he found a similar response

339
00:13:23,700 --> 00:13:25,639
in more or less the same location

340
00:13:25,639 --> 00:13:27,640
in 10 out of 12 subjects.

341
00:13:27,640 --> 00:13:29,934
So he was pretty stoked,

342
00:13:29,934 --> 00:13:31,194
and he was running around the lab

343
00:13:31,194 --> 00:13:33,196
telling everyone that he was going to go on "Oprah"

344
00:13:33,196 --> 00:13:35,214
with his big discovery.

345
00:13:35,214 --> 00:13:38,236
But then he devised the critical test:

346
00:13:38,236 --> 00:13:41,419
He showed subjects images of food like this

347
00:13:41,419 --> 00:13:44,160
and compared them to images with very similar

348
00:13:44,160 --> 00:13:47,970
color and shape, but that weren't food, like these.

349
00:13:47,970 --> 00:13:50,101
And his region responded the same

350
00:13:50,101 --> 00:13:52,050
to both sets of images.

351
00:13:52,050 --> 00:13:53,377
So it wasn't a food area,

352
00:13:53,377 --> 00:13:56,148
it was just a region that liked colors and shapes.

353
00:13:56,148 --> 00:13:58,709
So much for "Oprah."

354
00:14:00,483 --> 00:14:02,708
But then the question, of course, is,

355
00:14:02,708 --> 00:14:04,834
how do we process all this other stuff

356
00:14:04,834 --> 00:14:07,804
that we don't have specialized brain regions for?

357
00:14:07,804 --> 00:14:09,615
Well, I think the answer is that in addition

358
00:14:09,615 --> 00:14:13,169
to these highly specialized components
that I've been describing,

359
00:14:13,169 --> 00:14:16,848
we also have a lot of very general-
purpose machinery in our heads

360
00:14:16,848 --> 00:14:18,342
that enables us to tackle

361
00:14:18,342 --> 00:14:20,448
whatever problem comes along.

362
00:14:20,448 --> 00:14:22,503
In fact, we've shown recently that

363
00:14:22,503 --> 00:14:24,571
these regions here in white

364
00:14:24,571 --> 00:14:27,982
respond whenever you do any difficult mental task

365
00:14:27,982 --> 00:14:29,083
at all —

366
00:14:29,083 --> 00:14:32,654
well, of the seven that we've tested.

367
00:14:32,654 --> 00:14:34,823
So each of the brain regions that I've described

368
00:14:34,823 --> 00:14:36,129
to you today

369
00:14:36,129 --> 00:14:38,896
is present in approximately the same location

370
00:14:38,896 --> 00:14:40,638
in every normal subject.

371
00:14:40,638 --> 00:14:42,261
I could take any of you,

372
00:14:42,261 --> 00:14:43,487
pop you in the scanner,

373
00:14:43,487 --> 00:14:45,772
and find each of those regions in your brain,

374
00:14:45,772 --> 00:14:47,677
and it would look a lot like my brain,

375
00:14:47,677 --> 00:14:49,747
although the regions would be slightly different

376
00:14:49,747 --> 00:14:53,311
in their exact location and in their size.

377
00:14:53,311 --> 00:14:55,676
What's important to me about this work

378
00:14:55,676 --> 00:14:58,645
is not the particular locations of these brain regions,

379
00:14:58,645 --> 00:15:01,232
but the simple fact that we have

380
00:15:01,232 --> 00:15:03,800
selective, specific components of mind and brain

381
00:15:03,800 --> 00:15:05,448
in the first place.

382
00:15:05,448 --> 00:15:07,459
I mean, it could have been otherwise.

383
00:15:07,459 --> 00:15:09,900
The brain could have been a single,

384
00:15:09,900 --> 00:15:11,395
general-purpose processor,

385
00:15:11,395 --> 00:15:12,867
more like a kitchen knife

386
00:15:12,867 --> 00:15:14,550
than a Swiss Army knife.

387
00:15:14,550 --> 00:15:17,661
Instead, what brain imaging has delivered

388
00:15:17,661 --> 00:15:21,507
is this rich and interesting picture of the human mind.

389
00:15:21,507 --> 00:15:23,970
So we have this picture of very general-purpose

390
00:15:23,970 --> 00:15:25,040
machinery in our heads

391
00:15:25,040 --> 00:15:27,397
in addition to this surprising array

392
00:15:27,397 --> 00:15:30,832
of very specialized components.

393
00:15:31,712 --> 00:15:33,865
It's early days in this enterprise.

394
00:15:33,865 --> 00:15:36,641
We've painted only the first brushstrokes

395
00:15:36,641 --> 00:15:39,568
in our neural portrait of the human mind.

396
00:15:39,568 --> 00:15:42,650
The most fundamental questions remain unanswered.

397
00:15:42,650 --> 00:15:46,450
So for example, what does each
of these regions do exactly?

398
00:15:46,450 --> 00:15:48,592
Why do we need three face areas

399
00:15:48,592 --> 00:15:50,057
and three place areas,

400
00:15:50,057 --> 00:15:52,925
and what's the division of labor between them?

401
00:15:52,925 --> 00:15:55,618
Second, how are all these things

402
00:15:55,618 --> 00:15:57,330
connected in the brain?

403
00:15:57,330 --> 00:15:58,917
With diffusion imaging,

404
00:15:58,917 --> 00:16:01,096
you can trace bundles of neurons

405
00:16:01,096 --> 00:16:03,671
that connect to different parts of the brain,

406
00:16:03,671 --> 00:16:05,302
and with this method shown here,

407
00:16:05,302 --> 00:16:08,999
you can trace the connections of
individual neurons in the brain,

408
00:16:08,999 --> 00:16:11,717
potentially someday giving us a wiring diagram

409
00:16:11,717 --> 00:16:13,783
of the entire human brain.

410
00:16:13,783 --> 00:16:15,830
Third, how does all of this

411
00:16:15,830 --> 00:16:18,979
very systematic structure get built,

412
00:16:18,979 --> 00:16:21,935
both over development in childhood

413
00:16:21,935 --> 00:16:24,747
and over the evolution of our species?

414
00:16:24,747 --> 00:16:26,647
To address questions like that,

415
00:16:26,647 --> 00:16:28,430
scientists are now scanning

416
00:16:28,430 --> 00:16:30,587
other species of animals,

417
00:16:30,587 --> 00:16:35,973
and they're also scanning human infants.

418
00:16:36,931 --> 00:16:40,582
Many people justify the high
cost of neuroscience research

419
00:16:40,582 --> 00:16:43,336
by pointing out that it may help us someday

420
00:16:43,336 --> 00:16:46,793
to treat brain disorders like Alzheimer's and autism.

421
00:16:46,793 --> 00:16:48,740
That's a hugely important goal,

422
00:16:48,740 --> 00:16:51,961
and I'd be thrilled if any of my work contributed to it,

423
00:16:51,961 --> 00:16:54,959
but fixing things that are broken in the world

424
00:16:54,959 --> 00:16:57,760
is not the only thing that's worth doing.

425
00:16:57,760 --> 00:17:00,988
The effort to understand the human mind and brain

426
00:17:00,988 --> 00:17:03,806
is worthwhile even if it never led to the treatment

427
00:17:03,806 --> 00:17:05,483
of a single disease.

428
00:17:05,483 --> 00:17:07,520
What could be more thrilling

429
00:17:07,520 --> 00:17:10,661
than to understand the fundamental mechanisms

430
00:17:10,661 --> 00:17:12,957
that underlie human experience,

431
00:17:12,957 --> 00:17:15,883
to understand, in essence, who we are?

432
00:17:15,883 --> 00:17:19,332
This is, I think, the greatest scientific quest

433
00:17:19,332 --> 00:17:22,045
of all time.

434
00:17:22,045 --> 00:17:27,515
(Applause)