Download Script - Making Neuroscience Fun

MAKING NEUROSCIENCE FUN
SIGHT & SOUND
(Grade 4)
♥SLIDE #1: INTRODUCTION
Good Morning (Afternoon)!
My name is __________ and I am (a Neuroscience student -- or you can say you study Neuroscience – or you
are a Neuroscientist) at Johns Hopkins University.
Question: Does anyone know or can anyone guess what neuroscience is (or what a Neuroscientist studies?
Let’s look at this guy up here.
Question: Do you know what this is a picture of?
This is a cartoon of a brain. This is a brain that is having fun – because this little brain is
skateboarding.
Neuroscience is the study of the nervous system – which includes your brain. If you study the nervous system
you are a Neuroscientist.
(Next, tells the students why you are visiting them. I usually say something like this…..)
I am here because I LOVE NEUROSCIENCE and I wanted to share some things I know about the nervous
system with you.
♥SLIDE #2: NERVOUS SYSTEM
Question: OK – so, what is the nervous system?
The nervous system is made up of your brain, your spinal cord, and all of your nerves. Here is a drawing
of what your nervous system would look like if we removed all of your skin, muscles, bones and organs.
Your nervous system is connected to every part of your body. It is what makes your body work. Your brain
helps you to do all of the behaviors that you do. The brains most important job is helping to keep you alive
– as an animal and as part of a species.
There is so much to know about the nervous system…..
♥SLIDE #3: NEURONS
Inside of your brain are little pieces – like a puzzle. These little pieces are called neurons.
Neurons talk to each other by sharing chemicals with one another. One neuron spits out their chemicals and
another neuron catches it. Then they become friends and make a connection. They tell your brain what it
needs to know, and then your brain tells your body what it needs to know.
♥SLIDE #4: TODAY’S TALK
Today I am going to talk to you about SIGHT & SOUND. Or, more specifically about how your brain allows you
to see and hear things.
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In order to understand how your brain lets you see and hear things, we need to understand how the brain
processes information from the electromagnetic spectrum.
SLIDE #5: WHAT IS THE ELECTROMAGNETIC SPECTRUM?
The electromagnetic spectrum describes different energy sources that are out there in the world. Our brain
converts energy that is in the world into something that our neurons can understand.
When I first started to think about how sight and sound go together, I realized that both our auditory system
and our visual system process the same kind of energy – electromagnetic. They just process different
wavelengths of electromagnetic energy.
Different kinds of information is transmitted using different wavelengths.
Light energy – that we can see - is transmitted using wavelengths between 400 and 700 nanometers.
Sounds – that we can hear – are transmitted using wavelengths between 1.7 centimeter and 17 meters or
20 – 20,000 Hz (waves per second).
Now, there are other wavelengths of energy on the electromagnet spectrum, such as X-rays, radio waves, etc.
But we can’t see the bones inside of our friends without an x-ray machine and we can’t hear the music in the
air without a radio…Why???
Well, let’s see if we can answer this question.
SLIDE #6: SENSORY RECEPTORS & TRANSDUCTION
In order for your nervous system to get information that is transmitted along the electromagnetic spectrum – we
need to change that information into something the nervous system can understand.
Your brain has specialized cells – called sensory receptors – that help translate the electromagnetic energy
into information the neurons understand – chemical information.
The sensory receptors that help you see are called rods and cones. Your visual system uses rods and
cones to tell your neurons that there is a rainbow out in the world.
The sensory receptors that help you hear sounds are called hair cells. Your auditory system uses hair cells
to tell your neurons that you hear people singing.
The rods and cones and hair cells translate the electromagnetic energy into chemical energy because that is
what the neurons understand. This process is called transduction.
Inside of our bodies the sensory receptors are in charge of the transduction.
So, why can’t see the bones inside of our friends without an x-ray machine and why can’t we hear the music in
the air without a radio??? Because we don’t have sensory receptors in our bodies that can translate those
wavelengths of electromagnetic energy.
If we had sensory receptors that could translate the electromagnetic energy that allows us to see inside our
friends – we would have x-ray vision.
If we had sensory receptors that could translate the electromagnetic energy that allows us to hear the
radiowaves in the air – we would have superhero hearing.
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We don’t have those sensory receptors in our body to translate those wavelengths of energy – but, humans
are smart and they go to school to learn things – so they can build machines that can help us translate energy
from the electromagnetic spectrum that our bodies cannot.
Let’s look into how our sensory receptors translate electromagnetic energy into chemical energy for our
neurons.
SLIDE #7: VISUAL SYSTEM
Our visual system detects electromagnetic energy in the range of 400 to 700 nanometers.
♥SLIDE #8: RETINA
The sensory receptors that translate visual energy – our rods and cones – are in the back of our eyeball in a
place called the retina.
Your retina is in the back of your eyeball.
Our eyes are designed to focus light on the retina.
Things that you see get turned around and flipped upside down before they reach the retina.
This is because of all the stuff that is in front of the retina, like your cornea, lens, and the fluid that fills up
your eyeball – the vitreous humor.
♥SLIDE #9: RODS AND CONES
The rods and cones in the retina actually translate different wavelengths of light.
The rods tell our brain about light and dark and the cones tell our brain about colors.
Inside of your rods and cones is a chemical, called a photopigment.
Inside of the rods, the photopigment is called rhodopsin.
When the rods “catch” the light, the photopigment breaks apart and sends information to the brain.
There are 3 different photopigments inside of the cones, one for red, green and yellow.
♥SLIDE #10: AFTER-IMAGE DEMO
The photopigments help to “trick” our brain by making us see things that are not there.
Demo: After-image
I am going to show you a picture and then I am going to make it disappear.
I want everyone to stare at the yellow cross in the middle of the blue box.
When it disappears, I want you to stare at the white screen.
Question: What did you see?
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(If they do indeed stare at the yellow cross, they should see a blue cross in a yellow box.)
♥SLIDE #11: AFTER-IMAGE
If you did see a blue cross in the middle of a yellow box, you saw an after-image. This happens when your
cones get “tired”.
When you stare at something, you put that light energy onto one part of your retina.
The light breaks apart all of the photopigments in the rods and cones in that part of your retina.
So….those rods and cones are “tired”, they don’t have anymore photopigment – so they can’t send
information to your brain.
BUT….the rods and cones for the other color – still have photopigments and they send the wrong
information to your brain.
♥SLIDE #12: INFO OUT OF THE EYE
Neurons in the retina, called ganglion cells, have axons that bring information into the brain.
The axons all meet and leave the eyeball in the optic nerve.
The optic nerve is a big bundle of axons that lies on the bottom of your brain.
Information from the optic nerve contains information from one of your eyes.
At the optic chiasm information from your nasal retina crosses over. Information from your temporal retina
does not cross.
The optic tract carries information from both of your eyes.
Information from our optic nerve is carried from our eyes to the back of our brain by cells called neurons, to a
place called the occipital lobe.
The occipital lobe is also part of our visual system.
On the way to the occipital lobe, the information stops and is passed to other neurons.
Now remember because of the “stuff” in our eye in front of our retina that information gets turned around and
upside down, well as the information passes from one neuron to another it gets turned right side up.
In our occipital lobe, information about color, size, movement, shape is all put together like a puzzle.
Our brain “sees” what is in the world outside. The neurons in the occipital lobe “talk” to other parts of our
brain.
That is how we know if we recognize the person, place or thing that we are seeing.
SLIDE #13: AUDITORY SYSTEM
Our auditory system detects electromagnetic energy in the range of 1.7 centimeter and 17 meters or 20 –
20,000 Hz (waves per second).
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SLIDE #14: INNER EAR & HAIR CELLS
Our ears are ears are designed to catch moving air molecules which ultimately causes fluid in our inner ear to
move.
The anatomy of the outer ear enhances the reception of sounds in the range of 2,000 to 5,000 Hz – which
is the range important for speech – speech is about 3,000.
The hair cells – the sensory receptors that transduce sound – are found in the inner ear.
Your inner ear is actually found high above your cheek in your temporal bone.
♥SLIDE #15: HOW DO THE HAIR CELLS WORK?
The hair cells actually have “hair” on the ends called cilia.
The hair on the hair cells can move – just like the hair on your head – when the fluid in your inner ear
moves.
The hair on the hair cells are connected by tip links. When the hair moves it pulls on a structure called a “tip
link”.
♥SLIDE #16: TIP LINKS
A tip link is like a trap door. When you open up the trap door this allows little molecules called ions to flow from
the outside of the hair cell to the inside of the hair cell.
Show how bending the “cilia” open up the tip links channel.
♥SLIDE #17: TRANSDUCTION
So…bending the hair on the hair cells in the inner ear passes along a chemical which singles to our neurons in
auditory system that there is a sound.
The hair cells are responsible for the transduction of the sounds into chemical energy that the neurons
understand.
So, let’s see how this works…
DEMO: TIP LINK
♥SLIDE #18: AUDITORY PATHWAY
The information from the hair cells then goes to the brainstem and finally in the cortex of the temporal lobe.
When it reaches the cortex, you “know” about the sound – perception occurs.
♥SLIDE #19: SUMMARY
Because we have specialized sensory receptors that can transduce the energy from the electromagnetic
spectrum we are able to see and hear.
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Our biology allows us to see and hear things that are important to us and our brain uses that information so
that we can live in the world we live in….but, the way we see and hear things is different than the way other
animals see and hear things.
We have 3 types of cones and one type of rod, but dogs only have 2 types of cones – so they see the
world in shades of blue and yellow. We see the entire rainbow. Chickens have 4 types of cones – so they
see more colors in their rainbow!!!
But, when it comes to hearing – dogs rule!!! They hear sounds between 40 and 60,000 Hz while humans
and chickens hear between 20 and 20,000 Hz.
♥SLIDE #20: CONCLUSION
I have enjoyed talking to you today, and I hope that you have enjoyed hearing about the neat things that your
nervous systems can do.
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