The Secret Life of the Brain (1 of 5) The Baby's Brain (2002)

[Music] the brain is wider than the sky for put

them side by side the one the other will contain with ease and you [Music]

beside the brain is deeper than the sea for hold them blue to Blue the one the other will absorb as sponges

buckets do the brain is just the weight of God for heft them pound for pound and they

will differ if they do a syllable from sound a baby's brain less than one pound of gelatinous

tissue and within its milky convoluted folds a universe of meaning emotions ideas memories dreams

all will somehow find a home here evolving and changing over a lifetime the Ultimate machine and the ultimate source of

everything we understand the world the way we do because of the brains we have we will understand the brain itself the way we will because of the brains we

[Music] have the brain is the most complex thing on earth even the brain of a baby is wildly

complicated a piece of the brain the size of a grain of rice contains about 10,000 nerve cells just in that little piece you can just imagine how many

pieces you have in your head within that 10,000 nerve cells each nerve cell can make anywhere between 1 to 10,000 connections with other nerve

cells so they're something like a trillion connections it's almost overwhelming to think about the whole thing if you think about how the whole brain and nervous system gets assembled you know you just

want to throw up your hands and say it's way too complicated we're never going to understand [Music]

it the brain is the seat of our consciousness of who we are and in understanding where it comes

from we understand where we come from [Music] Elizabeth traphagen was born less than two weeks ago 3 months before she was

expected 3 months before she was ready to meet the [Music]

world she was 28 weeks and 6 days she weighed 3 lb and she was 14 in long it was somewhat frightening not

knowing what a pry would look like here we go there we go it's something you don't expect you're suddenly in this medical world rather than the world of taking your baby home

and trying to figure out how to dress it and change its diaper Elizabeth is a healthy premature baby her lungs actively suck in the air

her heart beats on its own but the one organ Central to all the others is not fully prepared her brain the miracle Technologies of modern

medicine can help keep Elizabeth alive but 12 critical weeks of brain development must now continue outside the protective walls of the

womb when the baby comes out of the womb Everything Changes suddenly light suddenly sharp

sounds the brain reacts to the stimulation it can't filter it can't stop it can't shut it

out they survive and make the best of it yet what's the [Music] cost the brain of a baby born through 3

months premature is vulnerable many precious weeks of development still [Music]

remain billions of brain cells are not done forging links with billions of other brain cells eventually there will be trillions and trillions of connections between

cells charged with electrical pulses Rippling like lightning storms across the Hills and Valleys of the brain's deeply furrowed [Music]

tissue every cell in its place every link between cells carefully organized nothing random nothing

arbitrary what we would really love to understand is how the brain during development generates millions and millions ions of neurons sends them to

the right position in the brain and then somehow instructs each of those individual nerve cells to form very very specific connections with one

another you can think about development like a play a play that follows a script that is written down by the genetic code but it has no director it has no

producer and it has a bunch of actors that have never spoken their lines before despite all this you pull the play off to me that's a

[Music] miracle egg and sperm their Union forms a single cell

which will divide and divide and divide again within 3 weeks the multiplying cells have curled into a quivering oval ball

[Music] inside lies a cluster of cells that have begun to fold themselves into the shape of a garden hose the neural

tube from the bottom will come the spinal cord from the top the

brain here lies the Primitive beginning of all our thoughts and feelings by four weeks just as a woman is discovering she is pregnant the first

brain cells the neurons are already forming at an astonishing rate 500,000 neurons every minute neurons that will never reproduce

themselves and rarely be replaced and that's amazing because if you think about it most cells in your body turn over if you think about your skin you're constantly it's sort of

disgusting you're constantly sloughing off dead skin cells and someone calculated once that if you look at the turnover of skin across a lifetime

you're probably generating and shedding about 90 pounds of skin so most cells in the body do their thing and then they die and they're

replaced neurons are born in fetal life and then those very cells are the ones that are still functioning all the way into old

[Music] age as the tiny fetus grows the neurons make their way out from inside the neural tube to build the brain layer

upon layer like an onion the neurons follow a cellular pathway as if they were traveling down a highway they just grab hold of

supporting cells called glea and Propel themselves along they put their nucleus in the back of the cell which makes them sort of fat in the back and then they hold on to the

guide wire this G fiber so it's kind of like an inchworm as it moves along and each little cell goes all by itself and what is a very very

vulnerable process no other kind of cell has to do that and it's just an amazing

thing neurons travel in waves Millions every day embarking on a daunting Expedition that scientists call migration it's an amazing phenomena

because it's as if they're going across the country I mean in terms of the distances relative to their size they're they're making a huge Odyssey through all kinds of foreign territory and the

most amazing thing about this migration is that they generally do it without mistakes they're following cues along the way that are telling them exactly where to

go for years scientists wondered how the migrating neurons find their place in the brain do the neurons simply travel in herds gliding down a GLE Highway which

takes them to their final destination or do neurons do their own driving each neuron genetically programmed to fulfill its own predetermined

purpose we used to think that migration was just like delivering cells out a conveyor belt and you just dump out the cells at the end but now we know that's

not the case there's evidence that shows that young neurons have an idea about where

they're migrating to and that they can recognize their position within the brain in her laboratory at Stanford University neurobiologist Susan

McConnell devised a series of experiments to track the destiny of a migrating neuron neurons are born from the division of stem cells the seeds from

which the tissues of the body grow some stem cells can transform themselves into any kind of cell blood

skin heart bone or brain cell McConnell took a descendant of a stem cell and before it morphed into a

neuron transplanted it into a developing brain then watched it [Music]

migrate she found that the fate of the soon to become neuron was determined by the neurons that were its neighbors it traveled beside them and

took on the same function they did that cell is plastic it's still listening to signals from the outside it gets the instructions from the new new neighbors and it resets its fate it says

yeah sure I can do that too but when McConnell transplanted a neuron it was true to its own genetic Destiny it followed its own path and

took on an entirely different function from the cells surrounding it what this result tells us is that by the time a young neuron begins its

migration it has already received instructions about what to become it knows it goes into a new environment and even though everyone else in the brain all these other young neurons are going

to position a it says no no I'm supposed to go to position B and that's exactly what it does by 24 weeks the vital organs of the fetus are well

formed the Primitive heart can beat on its own the once powerless lungs are now prepared to fill with air and the brain has near nearly its full complement of

billions and billions of neurons reaching out to each other building connections with mindboggling speed nearly 2 million every second until the

brain has become a tightly packed network of trillions of crisscrossing wires with more connections than stars in the

sky you can imagine the size of the wiring problem how is that problem solved how is that achieved during development how is it that each one of those trillion connections is made

appropriately you might think oh what a mess it's just going to be a jumble of connections and wires all over the place but in fact the nervous system seems to have a

strategy the strategy is in the genes the brain begins to wire Itself by following a precisely specified genetic blueprint

the connections are following very defined rules you know go out of the eye turn right at the optic kaym cross the

kaym head toward the lateral geniculate nucleus grow into the lateral geniculate nucleus don't grow into the medial geniculate nucleus because that's an auditory structure so you can imagine

the first stage of brain wiring is kind of like solving the problem of connecting phones in New York to phones in Boston making sure that you're making connections between Boston and New York

and not Boston and Washington DC and that's all specified genetically now then there's a second phase of brain wiring let's say you want to place a phone call to your

grandmother in New York and you want that phone to ring you know on Park Avenue and 47th or whatever you don't want the phone to ring up at the wall

door Historia okay how do you get that precise phone to ring that's the second phase of brain wiring if you place a phone call to your

grandmother early in development her phone will ring but so will a lot of other phones so there are a lot of connections

that are made if the connections are correct and being used they get strengthened if they're not being used or they're only being used occasionally they're

lost we could call it use it or lose [Music] it so the F brain is really a dynamic structure that's constantly changing in

response to this process of strengthening appropriate connections and pruning inappropriate connections getting the circuits all

tuned up takes a long time so it can't happen overnight because you have literally billions of connections to

[Music] check when a child is born prematurely the process is only partly

[Music] over so a huge amount of rain wiring is having to happen in the [Music]

nursery at briam and Women's Hospital in Boston 2 wee old Elizabeth traphagen born 3 months premature must cope with

the world before her brain is ready for more than two decades developmental psychologist hiidel Al has been studying creamies like Elizabeth to

learn how their fragile brains accustomed to the muffled darkness of the womb adapt to the Dazzle and Buzz of the

world how does the difference of inputs of sound of light shape how the brain grows itself

Al those cells haven't yet laid down their their connective tissue they are telephone wires if you will but it's

much more active than that it's like a wire that grows itself so it's it's Dynamic it's biological it's not like the hardware in your computer that you

put in but it depends on what it's experiencing on the way it grows [Music] 299 thanks to the technological wonders

of the modern intensive care unuse most premature babies survive to 4.7 but nearly half will have

difficulties later in life difficulty paying attention difficulty learning they will have trouble with

planning imposing structure prioritizing as they grow up they appear as very bright children and they are yet they can't hold their own in the second

grade classroom Al and her research team believe that the glare and clamor of the Intensive Care Unit itself is part of the

problem another down below 5.7 over7 in the early days just having these children survive was a miracle we referred to children who made it on their own as Miracle babies and now

Miracles are becoming more common in fact it's more or less an expectation that a premature infant will live then we've discovered that that may not be

enough we've got to go a step further and ask ourselves despite our very best efforts medically they aren't quite comparable to full-term

infants why does premature birth shape the brain in ways that nature never intended for the next 8 years Elizabeth

will be part of an unprecedented [Music] study eegs will record her brain's electrical impulses magnetic resonance images

reveal her brain's hidden structures yeah it's bright in here for you I know we may be able to do something

about that Elizabeth doesn't know it yet but hiidel Al has now become part of her [Music] life the brain is faced with more

challenges than the brain would be faced in the womb yeah life to be ight yes in the womb she doesn't get food directly

into her stomach she gets food via the digestive system of the mother and she isn't lying in the bed

she has all that support and she doesn't have to breathe on her own the mother's whole body takes care of it

the pre terms can see they hear yet they can manage themselves in the same way that a full-time child

does now if I move you a little bit you won't like that over they will be much more hyp sensitive more easily

overstimulated few Impressions get can be managed easily they all go in and flood yeah so you have these big overreactive

responses that cost the baby tremendously so then you say well can I do something about it think I can't really see where you

are how you doing there as I can't see her face can you see your face yeah okay all right your nose isn't covered up or anything so make you warm again Al's

demonstrated that a carefully controlled environment tuned to a pre's special needs will help them better manage the world around them as they grow Elizabeth has spent her short life

in an intensive care unit specially designed by Al everything is gentle and slow trying to be quiet with the

[Music] baby trying to emulate the womb where she'd hear muffled sounds and it would be dark and then the the skin to skin

contact she can hear my heart um and that she's close to me and and she and it's nice because she does does seem to recognize me she settles

down and finds her spot and settles in and and that's a great feeling when you're leaving her care up to people who are much more qualified for for most of

her daily life it's nice to know that she knows who mom is the mother or father can do so much

better in helping her be relaxed yeah you get your fingers now good the mother has the baby on the breast that's what the brain that's what

the body of the baby the nervous system has been promised the womb the breast the closeness of holding the body of the

parent and the family the social group that makes that family feel confident Elizabeth was strong enough to go home when she was 6 weeks old

now it's up to her parents to continue the gental care begun in the hospital all right welcome

home she'll be going back to see Dr Al in 2 months just after she was supposed to have been born Al wants to compare Elizabeth's

brain to the brains of other premature babies pries who spent the first days of their lives in a standard Hospital intensive care

unit will the special treatment Elizabeth received make a difference how much influence does the world around us have on the developing

[Music] brain to help answer that question

neuroscientists turned to a small animal immortalized in a portrait by Leonardo da Vinci over 500 years ago the feret

the most fundamental question in understanding how the brain develops has to be the interaction between nature and [Music]

nurture we know that the brain has different areas that do different things such as the visual cortex at the back of the

brain or the auditory cortex in the middle of the brain how do these areas get to be where they are and how do they do what they end up doing in the

[Music] adult how plastic is the brain how flexible can nurture Trump what nature

intended in a series of elegant experiments neuroscientist maranka Sur restructured the brains of newborn ferrets [Music]

in the normal feret light striking the eye creates electrical waves that travel to the visual cortex Sur rewired the ferret's brain

hooking up the eyes to the auditory cortex showering the hearing parts of the brain with electric waves generated by the

Light we reasoned that if we can make visual inputs from the eye go to the auditory cortex that normally processes

hearing would the hearing cortex now become like a visual cortex or a seeing cortex if it grew up with vision uh rather than with

audition would the hearing cortex now come to have the same circuits and connections that Mark the visual cortex

if it doesn't then nature or the genetic endowment is of the essence if it does then the inputs are important or nurtured is important than the animal

would [Music] see by recording a series of images directly from the brains of his rewired

ferrets sir provided evidence that the ferrets could see with normal ferrets the activity of the neurons in the visual cortex takes

on a characteristic pin wheel shape with the rewired ferrets the auditory cortex describes a similar pin wheel design the brain has been transformed

but not entirely instead of 2020 Vision they will have let's say 26 division meaning that they see at 20 ft what a normal fad

would see at 60 ft the characteristic pin wheel is still there but it is less orderly slurred

environment shapes the brain but can't completely change genetic Destiny our experiments demonstrate beautifully I think the interaction of

Nature and nurture I believe that the environment writes on a developing brain but does not write on a blank

slate there is a structure that comes about due to genes which then is is influenced further by the environment

that the brain is developing in our experiments provide very clear evidence of the remarkable plasticity of the brain 3 weeks after the day she was

supposed to have been born Elizabeth's parents brought her back to see hi highle leals at Children's Hospital in Boston does the brains remarkable plasticity

make pries like Elizabeth especially vulnerable does an intensive care unit that mimics the womb have a demonstrable effect on the brain once again AL observed Elizabeth

carefully hi beautiful girl did we wake you up out of your sleep

[Music] that was great that was

[Music] great the toy really captured her attention

she just brightened right up to it and her eyebrows up and her eyes curious and her face shaped forward and she followed

very smoothly in all directions and up and to the side and in the full Ark so that's wonderful for just about 3

weeks after due date and she did very nicely with the light so although that kept coming she shut it out with just a

little bit of breathing adjustment on her part uh in terms of her strength and all her reflex repertoire she's

symmetrical she's strong and she came to alertness I mean she's really come together it's impressive so

overall you've done a remarkable job in supporting her yeah it's not trivial a little baby Elizabeth appeared to be doing

well but she was enlisted in another round of tests to learn if her behavior corresponded to measurable changes in her brain

no one has really done this before it's only been recently that we've had the experience to say is it possible that our intervention may actually be visible in terms of a change in physical

development of brain parameters can we actually see it in the brain it's still too early to draw conclusions but we do know something

about Elizabeth pictures from from the MRI reveal normal brain maturation and as for the results of her

EEG oh she's surpassed caught up and surpassed what I would expect it's a very nice normal exemplary fullterm EEG that I could put in a

textbook as an example to what can we attribute this this will be the result of our

study as scientists we have to be very cautious not to overinterpret individual cases uh it's entirely possible that her

Improvement was through her own internal fortitude and that we were bit players in this in this great game of growing up on the other hand we might have been very crucial and we'll never know

because we can't wind the clock back and not do the intervention on her so what we have to do is have a population where there is no intervention population with an intervention and compare them as a

group there'll always be a star in the non-intervened group who comes through well and there'll always be someone that we we just couldn't help but on the average is what we're looking for and

that's what the scientific method is all about Elizabeth whatever the reason Elizabeth

is improving every day hi how's my girl and for her parents that's enough there's a great possibility for

Elizabeth to have uh normal brain development and that's just such a huge gift my hope when she was born was that by the time she reached kindergarten age

people she would just blend in with her class um but there seems to be a very good chance that on her first birthday she will be starting to toddle like any

other one-year-old and that that would be great [Music]

premature or fullterm every baby is faced with the same [Music]

challenge a wash in novel sights and sounds babies must begin to learn how to navigate a roing sea of Sensations there's a huge task in

organizing the world it must be difficult but the babies seem to do it they act like little scientists they

actively explore and construct uh a view of the world and in that sense they are parallel to what we as scientists uh do

our entire lives and what uh all of us do as we try to negotiate a very complicated world that's constantly under

[Music] change babies are exquisitly sensitive a newborn can identify his

mother's whispered coups respond to the fragrance of her body and the Sweet Taste of her milk even recognize her face when you're holding your baby and

rocking him in your arms and peering down at him your face happens to be the distance that babies like to look at most of

all and in fact even by two days of age a newborn baby can recognize his mother from sight alone now that's quite a

remarkable ability for a baby that has a poorly developed eye and for a baby that has a poorly developed brain vision is the last of the senses to

develop with an imature eye sending wobbly signals to a still developing brain it's no surprise that a baby looks out on a different world than an

[Music] adult what the baby is seeing then we think looks something like a faded photograph if you you take a photograph

and sort of fade it out so that it's all washed out and if you're looking at The Faded photograph through a tube then that is what the world would look like

to a newborn baby the fact that the baby doesn't see very well in a sense is very good for an immature brain and that's because this

immature brain cannot handle excess stimulation so what the eye is doing is dampening down that external stimulation making it something that the brain can

handle much better but it's also important to remember that no matter how damp and down that stimulation is that's going into this very immature brain that

stimulation is critical what happens if the brain doesn't get the stimulation it needs what if light falls upon the eye but never reaches its

destination hly McMillan is just 5 weeks old a healthy normal baby but her right eye is clouded by a faulty lens a

cataract that must be removed at once or she will never see like a normal child on the day that she was born we noticed that her eye her right eye

didn't open as wide as uh her left eye but in my family I have a sister and my father that have an eye that's a little bit just a little bit smaller than the other so we didn't really think anything

of it but we were informed that we would have to have surgery to remove the lens from what we hear the sooner the better for the surgery

so hopefully it's soon enough basically this is after all our discussions that we had before this is the final form that just gives me permission to go ahead and do the right

eye that way I won't forget for a baby it's really urgent that we get in there because if a baby has a cataract uh there the images that are

supposed to be getting in those images which are critical for the brain to be able to develop its Vision uh those images aren't getting there and as a result the brain is not getting the

opportunity to experience vision and go through its normal visual development which allows it to eventually create the healthy normal vision that we all know when Grandma has a cataract all of her

connections between eye and brain have been formed years ago and they remain stable over time so even if they're not

used they don't go away but when your child has a cataract it's the use it or lose it game that's being played during development it's still a period of

decision- making and pruning of Connections in fact even just one or two months of missing visual experience from

birth can have permanent consequences on the way that brain is wired up and on what that brain can do later on okay cutie

pie you see her soon okay take good care of excuse me [Music] [Music]

okay so there's the Cataract right there inside the [Music] I've just got a little bit piece left here that I need to get rid of thank

[Music] you okay m how we're just going to slip this in the old days we used to do this under general anesthesia but the nice thing about this lens is that allows us to do

it this way within a week of the operation Holly's eye has healed and Dr lvin inserts a contact lens which Holly will need for the rest of her

life for the first time Holly's right eye is sending clear images to her brain the key is if you just put your hand right underneath so you can feel the eyeball underneath you'll be [Music]

fine all of a sudden as if the eye was open to the brain it's the same as if the baby came out of that dark jet black womb and all of a sudden opens their

eyes in a deliver room somewhere but Holly's vision is still in danger for at least 5 years until her visual development stabilizes she will

have to wear a patch for most of her waking hours over her good left eye or else her brain will never learn to use the right eye to see if the good eye was not patched there is no point in having

the surgery at all there's no point in having the contact lens you have this weak eye that has to fight for cortical connections with a totally normal strong

good eye and that totally normal strong good eye if allowed will take over all the brain space leave nothing for the deprived eye and the deprived eye will

get weaker and weaker sounds a little counterintuitive patching the good eye should cause the same problem that the Cataract did but in fact it doesn't and we really don't understand why that is

and you can patch that good eye intensely and virtually never see any adverse effect of that that's one of our Mysteries now daddy if you'll just shut

your eyes as I show you each one of these cards Holly's cataract has been removed but how well can Holly see

okay we got one beautiful look over there just minutes after Holly receives her contact lens psychologist Terry Lewis examines her vision by watching

whether a finely calibrated series of patterns captures her attention you can't play the game with your eyes closed no you can't we find that even

within 10 minutes of first being able to see the baby can see as well as a normal newborn that tells us that the brain can

mature up to some point without any visual experience up to the newborn levels because certainly there's no visual experience while the baby's in utero although cataract babies like

Holly see as well as newborn babies they don't see as well as babies their own age here we go Holly but they catch up quickly it's shocking how quickly Vision

improves after that contact lens is put in we found that Within one hour we have a significant Improvement in how well the babies can

see now why this is so exciting is because it tells us that although the brain is no better than that of a normal newborn in the absence of visual

experience once it gets that visual experience it's ready to go it's champing at the bit because that first little bit even that first hour of visual experience is going to send that

brain into action faster than it would in normal [Music] development in a series of carefully controlled studies comparing normal

babies to cataract babies Lewis has found that as cataract babies grow their Vision continues to improve until they reach their first birthday

[Music] the children do begin falling behind after a year but on average with cly treatment

and complying with doctor's instructions the eye can end up being a totally good functioning [Music] eye it is has been 7 months since

Holly's surgery and her parents have been diligently patching her good eye let's see how you're doing this time Holly here we

go are you ready looking at me that's a good girl that was a nice good luck for me Holly's vision is

improving her cataract was removed early in time for her developing brain to learn to see Hello Hol the visual tapestry of the world will be fully hers

for the rest of her life oh good girl yes that was really good [Music]

looking when we are babies our brains are more open to the shaping hand of experience than any time in our lives in response to the demands of the

World the baby's brain sculpts [Music] itself I think the brain of a baby is like a work in

progress we're not really building circuits from scratch anymore we've done that but now a baby's experience with the environment can refine the circuit

and influence which connections are stabilized and which connections are lost we really think of brain development as a

Continuum although large sections of wiring are permanent development doesn't stop it's not over it keeps on going as

we grow older it doesn't ever stop and in fact at the end of this program your brain is going to be different from the way it was in the beginning because you've learned something and remembered

something hopefully or you've forgotten but whatever you've done it's different from the way it was before our brains are plastic as babies grow and develop their

brains adapt to the world with a flexibility that is the Hallmark of Being [Music] Human there's great mystery

left our memory and our hopes and our aspirations and who we love and all of that is in there encoded in the circuits and we only have the bearest

beginnings of an understanding about how all of these things really work the brain is just the weight of God

for heft them pound for pound and they will differ if they do as syllable from

[Music] sound join us for the next four episodes of The Secret Life of the brain and follow the brain's remarkable journey

through a lifetime childhood can be one of the most wonderful periods of all of life because we have everything to discover

the child's brain and the mirac of language o w how does a child learn to talk no if me we how about this one and

to read what happens if something goes wrong I have this um this thing in my brain that's called

xxia we clap our hands in theu we clap our hands adolescence is the last great time of enormous Brain

Change and brain development the teenage brain is vulnerable to the dangers of drugs I'm an addict and I need I need

[Music] help and the chaos of schizophrenia I spent 19 years with the same personality and all of a sudden it was

taken away [Music] we are not thinking machines we are feeling machines that

think the adult brain a fragile balance between thinking and feeling why do we have these emotions what are they

for there's no empathy or sympathy he just can't get that feeling deadness Terror distorted time I

did not want to live one weekend our daughter was here and he walked into the kitchen and he said who are

you in its final decades the brain is faced with a new set of challenges 63 years old and can't tie your own shoes isn't that

ridiculous but it Marshalls surprising powers of renewal what makes the engine go desire desire

desire take a 3D animated tour of the brain at PBS online find brain teasers take a cognitive test and more at

pbs.org

[Music]

major funding for the secret life of the brain is provided by the National Science Foundation America's investment in the future

funding is also provided by at fizer we're spending nearly 5 billion looking for the cures of the future we have 12,000 scientists and health experts who

firmly believe the only thing incurable is our passion fizer life is our life's work the medronic foundation on behalf of

medronic providing lifelong solutions for people with chronic disease medronic when life depends on medical technology

[Music] ology the park Foundation dedicated to education and quality television The Dana Foundation The

Corporation for Public Broadcasting and by contributions to your PBS station from viewers like you thank you

[Music]