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The word concussion evokes a fear
these days more so than it ever has,
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and I know this personally.
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I played 10 years of football,
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was struck in the head
thousands of times,
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and I have to tell you, though,
what was much worse than that
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was a pair of bike accidents I had
where I suffered concussions,
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and I'm still dealing with the effects
of the most recent one
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today as I stand in front of you.
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There is a fear around concussion
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that does have some evidence behind it.
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There is information that a repeated
history of concussion
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can lead to early dementia,
such as Alzheimer's,
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and Chronic Traumatic Encephalopathy.
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That was the subject
of the Will Smith movie "Concussion."
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And so everybody is caught up in football
and what they see in the military,
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but you may not know
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that bIke-riding is the leading cause
of concussion for kids,
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sports-related concussion, that is.
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And so another thing
that I should tell you
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that you may not know
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is that the helmets that are worn
in bicycling and football
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and many activities,
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they're not designed or tested
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for how well they can protect
your children against concussion.
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They're in fact designed and tested
for their ability to protect
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against skull fracture.
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And so I get this question
all the time from parents,
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and they ask me,
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"Would you let your own child
play football?"
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Or, "Should I let my child play soccer?"
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And I think that as a field,
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we're a long way from giving an answer
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with any kind of confidence there.
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So I look at that question
from a bit of a different lens,
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and I want to know,
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how can we prevent concussion?
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Is that even possible?
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And most experts think that it's not,
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but the work that we're doing in my lab
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is starting to reveal more of the details
around concussion
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so that we can have
a better understanding.
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The reason we're able
to prevent skull fracture with helmets
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is because it's pretty simple.
We know how it works.
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Concussion has been
much more of a mystery.
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So to give you a sense of what might
be happening in a concussion,
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I want to show you the video here
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that you see when you type in to Google,
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"What is a concussion?"
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The CDC website comes up,
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and this video essentially
tells the whole story.
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What you see is the head moves forward,
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the brain lags behind,
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then the brain catches up
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and smashes into the skull,
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it rebounds off the skull,
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and then proceeds to run into
the other side of the skull.
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And what you'll notice is highlighted
in this video from the CDC,
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which I'll note was funded by the NFL,
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is that the outer surfaces of the brain,
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where it was to have
smashed into the skull,
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looks like it's been damaged or injured,
so it's on the outer surface of the brain.
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And what I'd like to do with this video
is to tell you that there are
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some aspects that are probably right,
indicative of what the scientists
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think happens with concussion,
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but there's probably more
that's wrong with this video.
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So one thing that I do agree with,
and I think most experts would,
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is that the brain does
have these dynamics.
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It does lag behind the skull
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and then catch up and move
back and forth and oscillate.
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That we think is true.
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However, the amount of motion
you see in the brain in this video
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is probably not right at all.
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There's very little room
in the cranial vault,
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only a few millimeters,
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and it's filled entirely
with cerebral spinal fluid,
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which acts as a protective layer.
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And so the brain as a whole
probably moves very little
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inside the skull.
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The other problem with this video
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is that the brain is shown
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as a kind of rigid whole
as it moves around,
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and that's not true either.
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Your brain is one of the softest
substances in your body,
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and you can think of it
kind of like jello.
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So as your head is moving back and forth,
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your brain is twisting and turning
and contorting,
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and the tissue is getting stretched,
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and so most experts I think would agree
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that concussion is not likely to be
something that's happening
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on this outer surface of the brain,
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but rather it's something
that's much deeper
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towards the center of the brain.
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Now, the way that we're
approaching this problem
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to try to understand
the mechanisms of concussion
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and to figure out if we can prevent it
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is we are using a device like this.
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It's a mouthguard.
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It has sensors in it that are
essentially the same
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that are in your cell phone:
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accelerometers, gyroscopes,
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and when someone is struck in the head,
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it can tell you how their head moved
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at a thousand samples per second.
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The principle behind
the mouthguard is this:
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it fits onto your teeth.
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Your teeth are one of the hardest
substances in your body.
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So it rigidly couples to your skull
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and gives you the most precise
possible measurement
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of how the skull moves.
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People have tried other
approaches with helmets.
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We've looked at other sensors
that go on your skin,
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and they all simply move around too much,
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and so we found that this is
the only reliable way
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to take a good measurement.
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So now that we've got this device,
we can go beyond studying cadavers,
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because you can only learn so much
about concussion
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from studying a cadaver,
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and we want to learn
and study live humans.
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So where can we find
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a group of willing volunteers
to go out and smash their heads
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into each other on a regular basis
and sustain concussion?
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Well, I was one of them,
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and it's your local friendly
Stanford football team.
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So this is our laboratory,
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and I want to show you
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the first concussion we measured
with this device.
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One of the things that I should point out
is the device has this gyroscope in it,
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and that allows you to measure
the rotation of the head.
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Most experts think that that's
the critical factor
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that might start to tell us
what is happening in concussion.
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So please watch this video.
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Announcer: Cougars bring
extra people late, but Luck has time,
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and Winslow is crushed.
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Announcer: I hope he's all right.
(Audience roars)
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Announcer: Top of your screen,
you'll see him come on
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just this little post route,
get separation,
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the safety.
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There it comes at you in real speed.
You'll hear this.
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Announcer: The hit delivered by --
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David Camarillo: Sorry, three times
is probably a little excessive there.
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But you get the idea.
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So when you look at just the film here,
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pretty much the only thing
you can see is he got hit really hard
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and he was hurt.
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But when we extract the data
out of the mouthguard
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that he was wearing, we can see
much more detail,
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much richer information.
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And one of the things that we noticed here
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is that he was struck
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in the lower left side of his face mask.
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And so that did something first
that was a little counterintuitive.
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His head did not move to the right.
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In fact, it rotated first to the left.
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Then as the neck began to compress,
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the force of the blow caused it
to whip back to the right,
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so this left-right motion
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was sort of a whiplash type phenomenon
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and then we think that is probably
what led to the brain injury.
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Now, this device is only limited in such
that it can measure the skull motion,
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but what we really want to know
is what's happening inside of the brain.
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So we collaborate with
Svein Kleiven's group in Sweden.
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They've developed a finite element
model of the brain.
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And so this is a simulation
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using the data from our mouthguard
from the injury I just showed you,
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and what you see is the brain,
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this is a cross-section right in the front
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of the brain twisting and contorting
as I mentioned,
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so you can see this doesn't
look a lot like the CDC video.
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Now, the colors that you're looking at
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are how much the brain tissue
is being stretched,
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and so the red is 50 percent.
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That means the brain has been stretched
to 50 percent of its original length,
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the tissue in that particular area.
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And the main thing I want to draw
your attention to is this red spot.
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So this red spot is very close
to the center of the brain,
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and relatively speaking,
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you don't see a lot of colors like that
on the exterior surface
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as the CDC video showed.
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Now, to explain a little more detail
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about how we think concussion
might be happening,
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one thing I should mention
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is that we and others have observed
that a concussion is more likely
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when you're struck and your head
rotates in this direction.
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This is more common
in sports like football,
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but this seems to be more dangerous.
So what might be happening there?
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Well, one thing that you'll notice
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in the human brain
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that is different than other animals
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is we have these two very large lobes.
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We have the right brain
and the left brain.
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And the key thing to notice
in this figure here
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is that right down the center
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of the right brain and the left brain
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there's a large fissure that goes
deep into the brain.
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And in that fissure, what you
can't see in this image,
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you'll have to trust me,
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there is a fibrous sheet of tissue.
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It's called the falx, and it runs
from the front of your head
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all the way to the back of your head,
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and it's quite stiff.
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And so what that allows for
is when you're struck
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and your head rotates
in this left-right direction,
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forces can rapidly transmit
right down to the center of your brain.
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Now, what's there
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at the bottom of this fissure?
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It's the wiring of your brain,
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and in fact this red bundle
here at the bottom of that fissure
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is the single largest fiber bundle
that is the wiring that connects
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the right and left sides of your brain.
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It's called the corpus callosum,
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and we think that this might be
one of the most common mechanisms
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of concussion,
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and as the forces move down,
they strike the corpus callosum,
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it causes a dissociation
between your right and your left brain
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and could explain some of
the symptoms of concussion.
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This finding is also consistent
of what we've seen
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in this brain disease that I mentioned,
Chronic Traumatic Encephalopathy.
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So this is an image
of a middle-aged
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ex-professional football player,
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and the thing that I want to point out
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is if you look at the corpus callosum,
and I'll page back here so you can see
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the size of a normal corpus callosum
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and the size of the person here who
who has Chronic Traumatic Encephalopathy,
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it is greatly atrophied.
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And the same goes for all of the space
in the ventricles.
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These ventricles are much larger.
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And so all of this tissue
near the center of the brain
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has died off over time.
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So what we're learning
is indeed consistent.
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Now there is some good news here,
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and I hope to give you a sense
of hope by the end of this talk.
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One of the things that we've noticed,
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specifically about
this mechanism of injury,
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is though there's a rapid transmission
of the forces down this fissure,
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it still takes a defined amount of time,
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and what we think is if we can
slow the head down just enough
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so that the brain does not
lag behind the skull
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but instead it moves in synchrony
with the skull,
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then we might be able to prevent
this mechanism of concussion.
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So how can we slow the head down?
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(Laughter)
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A gigantic helmet.
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So with more space, you have more time,
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and this is a bit of a joke,
but some of you may have seen this.
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This is bubble soccer,
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and it's a real sport.
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In fact I saw some young adults
playing this sport down the street
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from my house the other day,
and as far as I know there have been
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no reported concussions.
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(Laughter)
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But in all seriousness,
this principle does work,
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but this has gone too far.
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This isn't something that's practical
for bike riding or playing football,
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and so we are collaborating
with a company in Sweden called Hövding.
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Some of you may have seen their work,
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and they're using the same principle
of air to give you some extra space
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to prevent concussion.
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Kids, don't try this at home please.
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This stuntman does not have a helmet.
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He instead has a neck collar,
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and this neck collar has sensors in it,
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the same type of sensors
that are in our mouthguard,
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and it detects when he's likely
to have a fall,
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and there's an airbag
that explodes and triggers,
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the same way that an airbag
works in your car, essentially.
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And in the experiments we've done
in my lab with their device,
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we found that it can greatly reduce
the risk of concussion in some scenarios
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compared to a normal bicycle helmet.
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So it's a pretty exciting development,
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but in order for us to actually realize
the benefits of technology
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that can prevent concussion,
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it needs to meet regulations.
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That's a reality,
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and this device is for sale in Europe
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but is not for sale in the US,
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and probably won't be any time soon.
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So I wanted to tell you why.
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There are some good reasons and then
there are some not so good reasons.
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Bike helmets are federally regulated.
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The Consumer Product Safety Commission
has been given jurisdiction
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to approve any bike helmet for sale,
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and this is the test they use.
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This is back to what I was telling you
at the beginning of the talk
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about skull fracture.
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That's what this test is for.
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And that's an important thing to do.
It can save your life,
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but it's not sufficient, I would say.
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So for example, one thing
this test doesn't evaluate
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is it doesn't tell you is that airbag
going to trigger
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at the right time and place,
and not trigger when it doesn't need to?
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Similarly, it's not going to tell you,
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is this helmet likely
to prevent concussion or not?
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And if you look at football helmets,
which aren't regulated,
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they still have a very similar test.
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They're not regulated
by the government, anyway.
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They have an industry body,
which is the way most industries work.
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But this industry body, I can tell you,
has been quite resistant
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to updating their standards.
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So in my lab, we are working on not only
the mechanism of concussion,
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but we want to understand
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how can we have better test standards?
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And we hope that the government
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can use this type of information
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to encourage innovation
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by letting consumers know
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how protected are you
with a given helmet.
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And I want to bring this back finally
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to the original question I asked,
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which is, would I feel comfortable
letting my child play football
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or ride a bicycle?
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And this might be just a result
of my own traumatic experience.
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I'm much more nervous
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about mike daughter Rose
riding a bicycle.
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So she's a year and a half old,
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and she's already, well,
wants to anyway, race down
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the streets of San Francisco.
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This is the bottom
of one of these streets.
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And so my personal goal
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is to, and I believe this is possible,
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is to further develop these technologies,
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and in fact we're working on
something in my lab in particular
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that really makes optimal use
of the given space of the helmet,
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and I am confident that we will
be able to, before she's ready
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to ride a two-wheeler,
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have something available
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that can in fact really reduce
the risk of concussion
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and comply with regulatory bodies.
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And so what I'd like to do,
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and I know that this is for some of you
of more immediate nature,
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I've got a couple years here,
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is to be able to tell parents
and grandparents when I'm asked,
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it is safe and healthy for your children
to engage in these activities.
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And I'm very fortunate to have
a wonderful team at Stanford
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that's working on hard on this.
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So I hope to come back in a few years
with the final story,
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but for now I will tell you that
please don't just be afraid
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when you hear the word concussion.
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There is hope.
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Thank you.
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(Applause)