Kind: captions
Language: en
foreign
is one of the most complex objects that
we know of in the universe
there are more Connections in your brain
than there are stars in the Milky Way
galaxy
so we literally walk around with about
10 000 galaxies worth of neuronal
Connections in one of our brains that
vast web of connections creates you but
how figuring out how the brain
implements the mind is a massive
challenge
it seems as though the world just pours
itself into the Mind through the
transparent Windows of the eyes and the
ears and all our other senses
hear and feel real you might think that
the reality outside is actually what
you're perceiving and the answer is no
it really isn't almost like the very
first moment we are transforming reality
it feels so real because we don't know
better think about the Illusions do you
remember the dress of course it's like a
celebrity the dress a polarizing debate
that took over the Internet
Illusions are fascinating they're like
fractures in The Matrix oh isn't that
interesting they reveal to us that the
way we perceive things isn't necessarily
the way they are
could you the biggest illusion of all
you're saying stuff who you are is an
illusion as everything else you're no
exception your brain perception
deception
right now on Nova
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thank you
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okay rolling
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take three
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have you ever thought about what's real
what's real what's real
somehow the whole world out there gets
inside my head
how do I know what I see what I hear
what I feel is right it's a question
that's fascinated me ever since I was a
little girl
I couldn't sleep one night and I had
this thought for the first time
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and then I thought well even if I don't
have a body can I at least keep my own
inner thoughts
so I asked my dad the next day Dad where
do my thoughts come from and he said
they come from your brain
your brain I was hooked
bag of jelly between my ears how does it
work I think it's one of the ultimate
Mysteries how matter becomes sold
to answer that question would be perhaps
the highest human achievement today
I mean forget about scientific because
it's a human question
foreign
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answers I became a neuroscientist and a
psychologist
I'm Heather Berlin and my journey to
understand my brain begins with a
question
how does the world out there with all
its beauty and complexity get inside our
heads
thank you
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think about it imagine for a second your
brain sealed inside your skull
there's no light no sound
your massive collection of billions and
billions of cells that are living in
this weird Pond that is entirely devoid
of all of the sensations and that
somehow Through Chemistry and
electricity all of these perceptions and
memories of the world originate in our
brains
all brains from the tiny fish to the
enormous elephant
microscopic cells called neurons and one
of their jobs is to translate input from
the external World whether that's light
heat sound or pressure for instance into
electrochemical signals the organism can
use to act what might be surprising to
you is that as neurons process sensory
signals they create an edited version of
reality e even on the most basic level
deciding to throw away 99 of the world
almost at the very first moment we are
transforming reality into something we
can use neurons transform Reality by
competing with each other when a
creature touches smell sees or hears
something its sensory neuronspire some a
little some a lot depending on where the
physical signal is strongest but follow
those signals down towards its brain
you'll see that the weaker ones get
Stamped Out
for simple brains say the brain of a
crab
a diffuse light to the eye becomes a
sharp beam
for more complex brains like ours
it's in part what makes you think that
these two squares are completely
different colors but actually they're
identical
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think about Illusions first they're a
lot of fun but as a neuroscientists
Illusions are very important to us
because of these discrepancy between
objective reality and subjective
perception we can use the solutions as a
handle to try to understand what the
brain is doing all the time
Susanna Martinez Conde along with her
partner and collaborator Stephen magnic
are among the world's preeminent experts
on Illusions and perception and what
they tell us about how the brain works
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to give a different example edelson's
checkerboard illusion this is so
striking because you see some of the
checks as dark and others are bright but
you realize that it is exactly the same
shade of gray
don't believe it look at the squares
labeled A and B A looks darker right
wrong that's the illusion that's because
your brain is adjusting for the shadow
what's happening is that your brain is
considering the light source and
basically subtracting that light source
from your resulting perception your
brain is performing an interpretation a
shortcut if you will to arrive at a
perception
the brain's shortcuts to short reality
this much how much of the world are we
really seeing
what you need to understand is that we
really can't see most of the world
around us we're effectively blind to
99.9 percent of the world around us at
any given time if you hold out your
thumb at arm's length and you straighten
your elbow and you look at your
thumbnail your thumbnail is about one
degree of visual angle here and it turns
out that that's the only place we can
actually see with 2020 Vision wow and
everywhere else we're legally blind it
might sound hard to believe but human
vision is really like this you actually
only see detail in about one percent of
your visual field that's because only a
tiny portion of the world can be
processed in detail by the retina
it feels like I'm seeing the whole world
in 2020 vision and it's almost all
completely made up in your brain based
on assumptions and models of how the
world works and just a tiny bit of high
quality visual information let me
demonstrate this to you I know it's kind
of hard to believe because you've been
having your whole life where you feel
like everything's continuous yeah show
me the data show me the evidence let's
look at an eye tracker and look at your
eyes and how they actually work and if
you put your head in this headrest we'll
point the camera at your eyeballs and
we'll actually be able to see where your
eyeballs point during this demonstration
Feels Like Clockwork Orange
Buck lived at a big house and the
sun-kissed Santa Clara Valley
first up a reading demo
though most of your screen may be filled
with x's to me it just feels like normal
reading I barely see the x's and that's
because the display of letters is tied
to my eye movements
wait it's just the words are being
revealed depending on where I look
that's right so as you move your eyes
the words are revealed to you but we
don't move our eyes in the same way you
do so we just see a bunch of x's most of
the time what turns out to be critical
is my eye movements so our eye movements
program what part of this high quality
piece of visual real estate we're going
to put where and at what time the human
eye moves about three times per second
we take it for granted but without these
movements we'd be basically blind as
Steve is about to show me in this
demonstration it's the opposite here
we're blocking what you could possibly
see right though you may see a whole
scene with a square moving around all I
see is the square I can tell something
is around the edges but it's blurry
whenever I try to look the square moves
with my eyes and it's blocked this is so
frustrating this one who has their hand
up in this image
I think that guy down there
that's right but it's very hard for you
to see right every time I look at him
yeah
disappears because this block it blocks
it
this actually is interesting because
it's in high quality Vision wherever you
look but it's blurry in the surround
now the theme looks normal to me but
mostly blurry to you because your eye
movements don't match mine
wherever you happen to look you have
high quality image processing happening
and the surround is completely blurry
this kind of represents exactly what
your visual system looks like all the
time anyway
so why would our brains be built this
way well think about what the
alternative is what if we didn't have
eye movements well we didn't have eye
lifts and we just wanted to see the
entire world we'd need to have our
retina see everything in very high
quality our brains would be 600 times
bigger and you got to remember the
visual systems are best sense this is
our richest sense so our other senses
are are even more impoverished
here's how your brain really sees the
world it's easy to think it's like this
you open your eyes and the whole world
pours in but really it's like this
your eyes sample tiny pieces of the
world and brain fills in the rest
constantly all the time
we feel like we have this incredibly
Rich wide full detailed percept of
what's going on moment to moment and
that's probably pretty illusory but
we're actually aware of is a tiny subset
of the information that comes in through
our eyes
don't believe it consider this your
optic nerve is what connects your eye to
your brain and its location near the
center of your retina effectively
creates a blind spot near the center of
your visual field and yet you don't
experience the blind spot why the brain
samples the area near the blind spot and
fills in the Gap with its best guess
it's probably not fair to say that we
completely confabulate the world it's
just that we probably represent one
percent of it at any particular moment
in time so it's a constant updating
between what I see versus what I
remember versus what I expect and it's
that dance between those three that
actually gives us our sense of reality
and amazingly that edited reality
despite its limitations serves us quite
well you might ask if I'm just keeping
track of one percent of the information
in the world how can I drive a car and
it turns out that first one percent of
the information that comes in from the
world is actually an enormous amount of
information if we had to actually pay
attention to everything on the road at
the end at one particular time it would
take minutes maybe even longer before I
decide to turn the wheel right or to
turn the wheel left
by understanding how my senses really
work I'm getting a peek behind the
curtain what my brain is really up to
outside of my awareness
based on these very tiny amount of
information we construct this Grand
simulation of the visual world around us
feels so real because we don't know
better
and most of the time we all agree on
that simulation it's when we don't that
we can learn something
so do you remember the dress of course
did you see this dress or this one it's
a simple question but the answer has
divided friends and family
remember it caused quite the stir right
massive stir a polarizing debate that
took over the internet
people had existential crises over this
image people tweeted things like if
that's not white and gold my life has
been a lie swear on your mother's brain
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massive arguments I watched videos of
people screaming at each other this is
white dude white that is dark blue it's
purple blue I bet there was a divorce
here or there over this image
so when you first saw that dress as a as
a vision scientist what did you think
well when I first saw the dress I
thought it was blue and black and I
thought that the internet was yanking my
chain right to get the goat of vision
neuroscientists sure but in the morning
when I looked at my phone
I saw white and gold
and now of course I was obsessed so I
said well if this is an ambiguous image
all I have to do is disambiguate it so I
set to work I got into Photoshop cut out
the dress put it into a scene with lots
of Rich cues and all of a sudden boom
you can see the dress is white and gold
wow now the pixels the pixels that make
up the dress there are identical to the
original image now this doesn't work for
everybody but for most the visual
context can make all the difference
what's different here is her skin is
tinted blue
the background has blue light cast on it
she's standing in the shadow of that
Cube and so your brain says aha I need
to ignore some amount of blue light that
is in this signal that's hitting my eye
and render this as white and gold
and if we flip things around same dress
pasted it into this other scene her skin
is tinted yellow the background has a
yellow cast she's standing no longer in
the shadow but in the light Boom blue
and black amazing that's really amazing
so again the dress the pixels are
exactly the same identical the dress is
a powerful example of how color really
works in the brain does that mean we're
creating color in our minds or does
color actually exist in the world color
takes place in the brain and I've
prepared a little illusion for you that
should convince you of this
so I have a picture of four cars here I
want you to tell me what color are these
cars let's start in the top left okay so
the one on the left looks red then the
one next to it looks blue I'd say the
one the bottom there bottom left looks
green and then in one next to it looks
orange okay what if I told you that all
of those pixels are not only gray they
are the same Gray
how is this possible
because the light that enters your eyes
contrary to what you might have learned
in school is not color color is an
interpretation of your brain
here's how it works
light shines on the world and bounces
off objects this part you know
and light comes in different wavelengths
each corresponding to a different color
what you might not have heard in school
is how those wavelengths change when
they hit different surfaces rough smooth
wet Etc this signal that gets into your
eye is actually a product of the
reflective properties of the object and
the wavelength of light hitting it then
that signal is focused on the retina the
back of the eye where we have about 130
million light sensitive cells three
types called cones are involved in color
each sensitive to different wavelengths
of light long medium and short but that
light still isn't color for that to
happen our brain has to take that
three-piece code from the retina and use
the relative response of the cones to
encode color it's not until that signal
gets to an area called V4 that we get a
neural representation of color that
corresponds to our perceptual experience
so why would our brains be built this
way
well if our brains weren't Built This
Way objects would appear to change in
color all the time and that would render
color pretty useless signal in the world
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that's because objects reflect different
wavelengths into your eye depending on
the lighting conditions
if your brain didn't compensate for this
a red berry would appear gray in a cave
blue it Dawn and orange dust but instead
your brain carefully calibrates your
experience to hold color constant
similarly color vision in other animals
is tuned to their needs
different species have very different
kinds of color vision that are suited to
their particular environment to their
particular challenges for Staying Alive
dogs rely on smell so they have fewer
types of cones and thus see the world
like this
Birds need to recognize tiny color
differences from great distances so they
have an extra type of cone that allows
them to see more colors than we do and
bees need to find flowers rich in nectar
so they see ultraviolet light that's
invisible to us
color provides a lot of valuable
information about the world but only if
we can Faithfully extract something
about the object so we don't actually
see color as it is in the real world we
just see it in terms of how it's useful
for us absolutely and the dress is
probably the best example of that it's a
really powerful demonstration of how our
color Machinery works so why do people
see this image of the dress differently
it comes down to your brain's
assumptions about the lighting
conditions
seems that the more time you spend
working indoors under artificial light
which is predominantly yellow the more
likely you are to say the dress is black
and blue because your brain assumes it
is lit by artificial light and subtracts
out the yellow conversely if you spend
more time in natural light which is
Bluer you're more likely to see it as
white and gold
so then what is the actual color of the
dress well Heather I happen to have
brought it with me
so what color is it uh it's obviously I
was right blue and black team blue and
black for the win yes I can't believe
this is the actual dress I feel like I'm
holding like it's like a celebrity the
dress I know it should be in a museum
not my closet
before the dress people hadn't really
realized would differ so much between
individuals we're now quite used to the
idea that we all differ on the outside
we all have differences in skin color
and height and shape but just as we all
differ on the outside we all differ on
the inside too
and this inner diversity is very
important it gives us a certain humility
about our own ways of seeing
lucians give us a ringside seat to watch
how the brain creates our world and it's
not just the visual domain
try listening to this
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brainstorm right simple enough now
listen to this
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green needle okay so you're thinking
what's the big deal but what if I tell
you that the two audio clips I just
played were exactly identical for most
people what you hear depends on which
label you read sounds unbelievable here
try it again but this time just read one
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okay now read the other and listen again
now when I first encountered this I was
floored too even though I know what's
going on when your brain encounters
uncertainty it fills in the gaps with
its best guess in this case we have a
degraded audio clip and when you're
primed with a certain word to go with it
your brain automatically jumps to the
best fit
for most of us we literally hear what we
want to hear and it gets even worse
let's try one more
another internet Sensation that Lit Up
debates across the country
yummy yummy yummy once and for all is it
Yani is it Laurel it's not yet
did you hear yanny
who heard Laurel
it is Laurel and not Yeti
it's like that stupid dress again all
over but an audio form this is not
saying Laurel this is only saying Annie
exactly it's moral
now about half of you hear yanny and the
other Laurel and unlike the first
illusion I can't get most of you to
experience this one any other way you're
locked into your version of reality
aren't exactly sure why but
Yanni The Divide stems from the fact
that the audiophile is an ambiguous
signal made up of both high and low
frequencies but by manipulating the
frequencies I might be able to change
what you hear
hi
Laura hello Laurel
Laurel all of this goes to show how much
the brain is an active interpreter of
sensory input our perception of the
external world is actually much less
objective than we'd like to believe most
of the world around us is very real but
never lived there
okay
you lived in your mind which is a
perception of that world that's being
filtered through a bunch of salt water
sacks of proteins and electrochemical
signals which can't possibly be making
completely accurate determinations of
what's actually in the outside world
not convinced or maybe you're just
asking why
Green Dot flashes
does it line up with the Red Dot
if you're like most people the red one
always seems just a little bit ahead
now try again
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the Red Dot and the Green Dot are
actually perfectly aligned that's
because some neuroscientists would say
that it's not your brain's job to
perceive the world accurately rather its
job is to predict what happens next
to a certain extent you see what you
expect to see a predicted path of motion
and this is what helps us hit a home run
or Flinch from a punch at just the right
moment
the brain is a predicting machine
given a set of circumstances in this
story at this moment
what are the likely plausible next
events in the story
the brain is using sensory information
to calibrate update to fine-tune these
predictions so they remain tied to
reality in ways that are not constrained
by accuracy but that are constrained by
how useful the brain's perceptual
predictions are in the business of
staying alive
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and to Keep Us Alive the brain has
evolved to look for signals of potential
danger one of the most important is pain
and as neuroscientist thean Griffith is
about to show me sometimes that can be a
kind of Illusion as well so what is this
this is a thermal Grill okay this is a
machine that could give us some insight
as to how pain works in your brain all
right this is making me nervous already
as I'm getting strapped in don't worry
it's all an illusion actually okay
and it's comprised of these different
metal bars that are either set to a cold
or warm temperature so why don't you go
ahead and touch that first bar
it's warm right and then the next bar
cold and then the next one warm you see
so they're alternating cold warm cold
warm now you want to see what happens
when you put your hand down
not necessarily
okay
okay here we go
ow right isn't that interesting yeah
what is going on there it sort of feels
cold at first but then then it gets this
kind of burning sensation right yes very
much so it feels super hot like I'm
getting burnt so it's not a hundred
percent clear exactly how this is
happening but what we think might be
going on is that basically your brain is
getting a little bit confused okay
that's feeling cold and it's also
feeling warmth and somehow it's
interpreting these two signals as pain
here's what neuroscientists think is
going on
in your hands you have separate sensors
for heat cold and pain foreign
normally when you touch something
slightly cold both your cold and pain
sensors are activated but the cold ones
override the signals from the pain
sensors telling your brain there's
nothing to worry about
unless In This Very unnatural scenario
with the thermal Grill you happen to be
touching something warm at the same time
here the heat signals cancel out the
cold ones leaving you with just the pain
ones activated telling your brain ouch
so in that respect is pain real or is it
just an illusion or a construct of the
brain that's a really good question so
noxious stimuli is is a real thing right
if you stick your hand in boiling water
that's an aversive stimulus the
perception of a noxious stimuli is real
pain is more of a construct right and it
can vary from Individual to individual
pain is a construct of the brain
how do we know that you touch a needle
right prick your finger we can draw the
anatomy what just happened
we have very well-defined Pathways
saying this is pain information we don't
interpret it as pain until it hits your
brain
pain not unlike the experience of color
is a construct of the mind
but just because pain is in your brain
doesn't make it any less critical for
survival
pain is a very important learning
mechanism for children they learn what
behaviors they can engage in that are
safe and what behaviors will they should
not engage in because they could cause
them bodily harm and there's different
mutations that people can have in
certain proteins that make them
completely insensitive to pain and so
kids do things like bite on their lips
or on their fingers when they're very
young and as they get older can engage
in Risky Behavior so pain is extremely
important for us to feel
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Illusions are fascinating
they're like fractures in The Matrix
they reveal to us that the way we
perceive things
isn't necessarily the way they are
Illusions help us find the cracks in the
mortar of that world we've built for
ourselves and understand what it is our
world is actually made out of and what
the brain is actually doing so most
people think of the brain reconstructing
the world more or less verbatim but
that's just not true what it's actually
doing is it's getting very little
information and it's using that very
little information to make a big Grand
model of the world
we cannot process the vast amount of
information that is constantly
bombarding our senses Illusions you can
think of them as shortcuts shortcuts
make us faster more efficient with less
resources based on these Snippets of
information we build this more complex
simulation of reality and that
simulation of the world is what we
consciousness
we take it for granted but every time
you wake up your brain stitches together
all your sensory inputs
sound of a distant train
smell of coffee
warmth of the Sun
to an experience of the world and that
experience that awareness of the world
is what scientists call Consciousness in
Neuroscience Consciousness is the Holy
Grail humans have been fascinated by
Consciousness for thousands of years
probably much longer than that I agree
now of course the word Consciousness
means a lot of things to different
people to some Consciousness means being
awake as opposed to a sleep or
self-aware or the contents of my
thoughts but that's not how we
neuroscientists think about it
we think of it as something much more
basic it's just internal experience
it feels like something to see the color
red
taste a strawberry
hear the crack of thunder
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we are complicated biological creatures
but the most Central feature of Our
Lives is that we are conscious creatures
too when I open my eyes it's not just
that my brain does some sophisticated
processing of the visual information I
have an experience
during the course of my journey I've
seen how our experience of reality is
not what it seems if my conscious
awareness is built from my perceptions
flawed as they may be
how does that work and what does it mean
so please take a seat some of the first
clues trickled in from people like this
put your chin on the chin rest a lot of
very valuable information comes from
patients who've had part of the brain
damage by piecing these various parts
together of seeing what was lost we've
come to appreciate the role that these
various brain readers play in the
creation of Consciousness we're going to
calibrate your eyes first and Powerful
example of this is the phenomenon of
Blind Side
this is a patient who had a stroke in
her visual areas in the back of the
brain and this stroke is affecting your
visual field three years ago she felt a
pounding in her head I had what I
thought was a migraine I actually went
to the emergency room because I'm
walking around with this area where I
can't see the stroke damaged a piece of
the brain devoted to Vision leaving her
with an apparent total blind spot that
blind spot it's enough that if you're
driving an oncoming car disappears into
it
takes a little anxiety producing and
things like that
in everyday tasks her eye movements make
up the difference
but what happens when she
neuroscientist laurella batelli wants to
find out
so she developed a clever series of
experiments to pin down just how blind
is she really in that spot
we're using i-link which is the eye
tracking system to make sure she doesn't
move the eyes she keeps her eyes focused
on the center spot every time she hears
a beep she has to save those little dots
inside the circle are moving to the left
or to the right left the eye tracker
checks that she's not shifting her gaze
when you're doing tests like this
that blind area what does that kind of
look like for you what does it feel like
for you when that Target pops up in my
blind area I don't see it
left strangely even though she says she
doesn't see anything in the blind spot
she gets it right more often than not
right
so that some information is getting in
but they're not consciously seeing it
but they can respond to it in different
ways exactly
even if they say I didn't see anything
but you tell them please just tell me
whether you saw it or not then the
response would be above chance so just
keep your eyes closed okay
what's going on
to probe deeper Lorella lets me give the
patient a different version of The
Challenge I put a miniature screwdriver
in her blind spot
okay I'm gonna have you open your eyes
and fixate okay
see nothing you see nothing nothing okay
even though she says she sees nothing
look at which tool she picks I'll turn
over there and look at the objects tell
me what you think you saw a screwdriver
yep
I'm gonna try another one
next I display a tiny wrench
did you see anything no no okay look
over there and guess what you think he's
was there
I think the wrench yeah
I'm gonna guess the scissors good job
all right scissors time and time again
she makes the right choice amazing so
you know it seems to be that you're
saying you're not seeing anything yet
when I'm asking you to choose you're
pretty much getting it correct so
something is getting in how is this
possible
it's as if she sees the tools but
doesn't know it they actually saw
something but they're not entirely aware
of it information is getting in
affecting our behavior and how we're
responding to the world around us
without there being a conscious
perception of that piece of visual
information correct I'm gonna go with
the hammer again until patients like
this we scientists had never seen
perception separate from conscious
experience and this tells us that
perception and Consciousness are
separate things in the brain
but it also has me wondering if someone
can still use visual information without
awareness of it why do we have
Consciousness at all
what is consciousness for
blue might come from babies
everything we know suggests that they're
born conscious they're certainly taking
in information from the time they're
born
they are making rational choices about
what they learn from extremely early on
and they are forming memories of their
specific surroundings of their parents
of their important relationships
we can see that in their behavior
and all that behavior brings a lot of
fuel
brains are expensive Computing gadgets
so while you're just sitting here your
brain is using up about 20 of all the
calories that you have so it's using up
quite a bit but if you think about a
two-year-old his brain is using 60 of
his calories
so almost all that food is just going to
keep his brain going
to understand why young brains might
need so much more fuel check out the
connections in a toddler's brain versus
in adults a two-year-old's brain has
about two quadrillion synapses by the
time they had adulthood that number is
cut in half so think about the
difference between the baby brain the
child's brain and the adult brain the
child's brain is more like a back
Country Roads where you have little tiny
roads that are going from one Village to
the nest none of them are very efficient
there's not a lot of traffic and the
traffic doesn't go very quickly but they
connect lots and lots of different
places
and the adult brain is more like super
highways that get you from one place to
another very quickly and take a lot of
traffic but don't connect as many
different places as we age in the
interest of efficiency we strengthen the
connections that are useful to us and
prune the rest
you basically take neurons you don't
need to get rid
and what you have now is a very lean
machine that does certain things
and it does them very well
you see this early brain that's very
exploratory that has lots and lots of
potential lots of possibilities not very
good at putting on your jacket and
getting out to preschool in the morning
and then we have this later brain that's
very good at doing things not so good at
changing not so good at taking in new
information not so good at doing
something new what this suggests is that
maybe what Consciousness is for is
choosing what's important for us to be
aware of at any given moment kind of
like a spotlight
for the adults it's a Consciousness it's
this bright Spotlight in one place and
everything around it is dark
well for children and babies it would be
more like a floodlight where nearly
everything is illuminated
you're conscious of a lot more that's
going on
Consciousness may be like an amplifier
boosting the important signals over the
noise is there any evidence
this is where fmri comes in a special
tool in Neuroscience that takes pictures
of the brain while it's doing something
it's a map where blood flow is in high
demand the result is a map of brain
activity
so where is consciousness in the brain
and how does it work
to find out if neuroscientists designed
a clever series of experiments that go
like this
they start by flashing a word on a
screen for about 30 milliseconds
you flush this word and the person is
not able to see the word at all she says
there was no word but in the fmri
scanner the visual cortex is activated
even though people say they don't see
anything
so the trick here is to find the
threshold find the timing where
sometimes people consciously see the
image
so if you make now the word a little bit
longer
suddenly the person says oh well there
is a word obviously and it's completely
visible there is really a sort of all or
non-phenomenon either you see it or you
don't and once you've done
got a really powerful window onto the
neural correlates of conscious
perception
when that happens suddenly a suite of
different parts of the brain shows a
surge in activity the parietal cortex
which integrates the senses the anterior
cingulate which modulates drive and
decision making and the prefrontal
cortex which handles reasoning and
higher order cognition
an ignition of distributed bin areas
that come online together speak to each
other and broadcast this information to
the rest of the brain and this is what
we think is occurring during conscious
perception
According to some experts this
communication between brain regions is
the signature of consciousness
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this discovery could have real-world
applications and matters of life and
death but that would take one more step
figuring out how to measure
consciousness
in science When we struggle to
understand a phenomenon that seems quite
mysterious it's often really important
to be able to measure it
so a few hundred years ago this happened
with heat it was the development of
thermometers that catalyzed that
understanding
could something work for Consciousness
the same way could we have a
Consciousness amateur that will lead us
to a deeper understanding of what
Consciousness is
that deeper understanding could
transform the treatment of people with
brain injuries so every year over a
million people worldwide will come into
an intensive care unit unresponsive
comatose the challenge that we face is
that our bedside exam asking the person
to open their eyes pinching them and
seeing if they'll respond seeing if they
move their arms and their legs that
bedside exam is fundamentally limited
limited because it often misses people
who are actually conscious
in this case we have a healthy volunteer
from the Nova team but what if she were
unresponsive how would we ever know if
she was conscious Brian edlow's team at
Mass General Hospital is testing a new
technique to find out
so tell me what are you doing here we
are pinging the brain with a magnetic
pulse and looking for an electrical Echo
ing is
cranial magnetic stimulation or
the echo is the key if it dies out
quickly the patient is unconscious they
might be in a coma deep sleep or under
anesthesia
If instead the echo rings out across the
brain and becomes more complex the
patient is likely to be conscious and
aware even if they appear unresponsive
the analogy that we like to use is
throwing a pebble on a lake so the
pebble represents the TMS pulse to
stimulate the brain and the brain waves
the electrical ripples that emanate from
that pulse represent the waves in the
lake
the more complex those waves are and the
longer duration the more likely that
person is to be conscious
those brain waves at Lowe's team
that measures electrical activity in the
brain to quantify the amount of
complexity a patient's brain bounces
back here's how it works
all neurons when poked by a magnet will
kick back an electrical signal that
looks like this a brain wave but if the
surrounding neurons aren't healthy those
brain waves won't get very far it turns
out that in conscious people even those
who appear unresponsive not only do
those brain waves spread all over the
brain but they become more complex too
it's as if to use music as the analogy
what starts as a single repeated note by
a few neurons eventually turns into a
coordinated Symphony of Millions
that there is this explosion of
complexity only when the person is
conscious this complexity the way
different brain areas speak to each
other is a signature of a marker of
consciousness
studies of hundreds
hundredth coma have enabled scientists
to develop a complexity scale a score
above a certain threshold means your
conscious or have the capacity for
consciousness
multiple Studies have now shown that 15
to 20 percent of patients who appear
unresponsive they don't express
themselves on our behavioral exam they
are actually conscious so you know will
this be able to help people in those
States when we speak to families about
what matters to them most
it is that patient's current level of
Consciousness and their potential for
future recovery of consciousness
if families were to have that
information it could fundamentally
affect the decisions they make about
whether to continue life-sustaining
therapy
focus in the clinic is extremely real
and fast and people realize that the
problem of Consciousness is starting to
be solved
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starting to be solved
while we have several Clues
Clues might work in the brain this is
only the beginning
how all of those pieces of brain
activation add up to you A distinct
individual with a sense of self is still
a mystery I know my brain creates an
internal experience by knitting together
bits of sensory information filling in
the gaps with its best guess of what's
out there in the world but what are
those guesses based on
memory
each of us has a life rich with
experiences to draw from where we were
born went to school who we fell in love
with memories are the Cornerstone of our
identities but as it turns out they have
a very shaky Foundation I could swear by
it and would pass every lie detector
test that I had met Mother Teresa but I
hadn't something that I wanted to happen
but it never did happen
the stories we tell ourselves or what we
consider our memory is a construction we
create these representations
and they're very dynamic they constantly
change you're kind of living a revision
of the story of your life constantly
the more often we recall things the less
objectively accurate our memories become
it turns out that every time you recall
a memory your first kiss
graduating from college the death of a
loved one the very Act of recollection
makes it vulnerable to change
so when you're experience a new event it
has to be stored in the brain and then
we used to think that whenever you think
about that event you retrieve the same
original
memory but what we got to realize in the
last few decades is that whenever you
retrieve a memory it goes back to an
unstable state
in 2000 memory scientist Eric kandell
won the Nobel Prize for showing that
each memory creates new synapses
connections that store the memory
what happens when you recall it every
time you remember it
bring it up into your working memory and
you perceive it and you destroy the
long-term memory
and you actually have to recast it into
long-term memory when you re-remember it
so every single time you remember
something you actually add more noise to
it so that it's more and more and more
false
throughout time
this mechanism called reconsolidation
was first discovered in rodents where
neuroscientists witnessed what happens
when a memory gets recollected for the
memory to return to long-term storage
the connections between neurons actually
have to get rebuilt
recent experiments have suggested this
is likely a mechanism in human brains as
well because certain drugs known to
disrupt reconsolidation have been shown
to alter human memories
we're stuck with the problem of how do
we know what is true how do we know
what's real and maybe part of the
recognition is some of those things
don't matter as much as we think they do
if we think about the fact that maybe
our memories are not as they originally
happened could be a scary thought
because and who are we I think you need
to think about it as something more
liberating
because if you're stuck with original
representations you're kind of stuck in
the past
just like our perceptions our sense of
self is dynamic built to serve Us in the
present
our experience of of self as a
construction at all sorts of different
levels what the brain is doing is
interested in is weaving together a kind
of story the brain is a storytelling
machine right it's a machine that's
designed to make predictions the
narratives that we tell ourselves are
the biggest illusions that we ever
participate in your sense of who you are
is an illusion as everything else you're
no exception
but even if our sense of self is an
illusion where does that leave us
trust the illusion
that's the only thing that we can be
sure of that would we perceive is not
what's there
so all these years later in my quest to
understand where my thoughts come from
and how my brain works I've learned that
my brain is an Exquisite machine that
perceives reality in the service of
survival not accuracy the world I carry
inside of my head is a construction of
my brain built on bits of sensory
information woven together with memory
to create a conscious experience
now to some this might sound scary but
to me it's inspiring
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a simple Act of opening our eyes and
seeing a world
we should not take that for granted and
in realizing
what a miracle of neural computation is
going on under the hood to give us even
the simplest experiences I think this
adds value it adds meaning it adds depth
to our lives
I think it's liberating to understand
that we arise from this organization of
matter it means that we can be a little
bit more humble we are gorgeous machines
designed by Evolution as well as by our
environment education friends families
all of that is inscribed in our brains
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sometimes when I wonder
what I'm doing with my life I think how
is it that a spatial and temporal
pattern of electrical signals passing
between cells in our brains makes us who
we are
that just being a part of the team
asking that question
is worth keeping going for
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thank you
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thank you
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all right
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