Incredible Human Machine Page #2

this is the retina,

where more than 1 20 million photoreceptors

convert light into electrical impulses,

before processing

and shipping them off to the brain.

ln a mind-boggling feat that soaks up

about a third of our brain power,

our brains continually compare new data with

information processed a split second before.

Combine that with

what they already expect to be there

and vision is born.

At least, that's how it's supposed to work.

When it doesn't,

the world can look more like this.

62-year-old Linda Morfoot has a genetic disease

called retinitis pigmentosa.

which has been gradually degrading her

eyes'photoreceptors for the past 40 years.

They haven't turned light into sight

for the last ten.

lt's frustrating to lose your sight

because you run into things,

you run into people.

And it can be depressing.

Just open up real wide.

Very good.

Now, thanks to Dr Mark Humayun

of the University of Southern California,

she may see again.

All along we've been told it's impossible,

it's science fiction, it can't happen.

Look up.

Humayun has implanted an ingenious

little device at the back of Linda's eye.

Just 1 6 electrodes

that should act as a simple retina,

turning light into impulses

that can be sent to the brain.

We lay it right on the retina

and the current stimulates

the underlying nerve cells.

When this information is received by the brain,

you see a spot of light.

To perceive those spots, Linda had to first wear

a special pair of sunglasses that capture light,

convert it into electrical signals,

and fire up the implants in her eyes.

As the doctors activated the electrodes

one by one,

it started to work.

lt was crude,

but Linda could now see light and movement.

As they turned more and more electrodes on,

l could see the lights on

or the doorway.

l could tell the difference

between black and white.

lt was exciting. Yes, it was.

1 6 signals hardly compares to the million or so

a working retina transmits.

But with each passing day,

her brain compensates,

and Linda sees more detail.

We thought that 1 6 electrodes would never ever

give Linda or any other patients

the level of vision they have been able to attain.

The brain fills in the missing gaps.

From simple flashes of light

our brains can somehow conjure

meaningful images.

So, now, after 1 0 years of blindness,

Linda can see the grandchildren

she never saw before.

They like to run in front of me.

''Where am l, Grandma? Where am l?''

l'm more connected to them,

a little more part of their lives, you know.

Even for those of us lucky enough

to see 20/20

the sense of sight does not work alone

in the incredible human machine.

On either side of our heads

are the body's microphones - ears.

But ears do much more than hear.

They give us balance, telling us

where we are in space at any given moment.

Riding a bike, landing,

perfecting a dive,

even taking a baby step,

all would be impossible without

the intricate gadgetry deep inside our ears.

Here, three fluid-filled tubes work like

carpenters'levels to help keep us balanced.

When we turn our heads, the fluids move,

stimulating nerve cells,

and orienting the brain in three dimensions.

Up-down, left-right,

forward-backward.

lt's a powerful little mechanism

that we can stimulate artificially.

Welcome to the weird world of tomorrow.

With a special electrified headset,

scientists in Japan have taken hold of

our balancing centres.

By sending current down to those nerves

in our inner ears

they've created remote-controlled

human beings.

TRANSLATOR:
l've never experienced

such a sensation.

lt was like being drunk on the deck of a boat

rocking in the waves.

The current is low voltage,

just enough to throw people off balance

and compel them to walk left, right,

even trace the shape of a giant pretzel.

TRANSLATOR:
My body was out of control.

lt was swaying to the left and to the right.

We can even remote control ourselves.

We're not trying to control people

or manipulate their actions.

Rather, we want to help them,

help guide them.

Especially people with balance problems

or dizziness.

The researchers say one day it may even help

navigational devices, like GPS,

to physically guide us to our destinations,

or make a video game

feel more like a rollercoaster.

Our ears provide another powerful sensation

to enrich our day.

Every time we, or anything else for that matter,

make a move or vibrate,

we create ripples in the air.

Distinct waves all travelling at

different frequencies,

which waft into our ears at some 750mph

and produce sound.

Like radar dishes, our ears channel

the sound waves deep into our skulls.

Our eardrums vibrate in tune to the frequencies,

moving three tiny bones,

each about as long as a grain of rice.

Magnified 20 times we can see the ear

hear,

inside...

..and out.

Love in an elevator

Livin' it up when l'm going down

Love in an elevator

Turnin' it up till l'm upside down...

The bones'movements get converted to pulses

of pressure

which vibrates fluid

which disturbs tiny hairs

which excite nerve cells

which translate all of this to the brain.

One sound perhaps more than any other

is music to our ears -

the human voice.

lt's an astonishingly versatile instrument,

but it's vulnerable.

As lead singer for Aerosmith,

Steven Tyler's work depends on his vocal cords.

l need a girl like an open book

To read between the lines

Few of us think about the trauma we generate

in our voice boxes when we talk, sing, laugh

or scream.

But if you were to look down the gullet

of Steven Tyler,

it would show why he,

and millions of others,

are wreaking havoc on a delicate instrument.

Thank you!

Tonight, as Aerosmith perform,

Dr Steven Zeitels and his team

from Massachusetts General Hospital

will get a rare treat.

With the help of special

monitoring equipment

they'll see how this famous pair of vocal cords

holds up to such extremes.

Dr Zeitels, one time for my kids,

what is this monitoring?

What we're going to be doing is looking at

the vibrations on the skin of your neck,

which is going to pick up the intensity

of your voice,

it's going to be picking up the loudness

of your voice.

Thank you, Doctor.

lnto the abyss.

lnto the great beyond with Dr Zeitels.

Backstage throughout tonight's concert,

Zeitels will use an endoscope

to examine Tyler's voice box up close.

Try not to touch the sides.

Stick your tongue out for me.

Just breathe. Say ''Ah''.

Ahhh!

lt's a rare insight into what goes on

in a high-performance singer.

Real time measures of a performer

who is at the top of his game

doing a live performance

in front of thousands of people -

that's a first, hasn't been done before.

(Sings high note)

(Laughs)

To produce these kinds of sounds,

Tyler's vocal cords are slamming together

an average of 1 70 times a second.

That's more than half a million times

during the course of a concert

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