JOAN CARTAN-HANSEN, HOST: A neurosurgeon is a doctor who cares for your brain when it needs special medical treatment.

Dr. Derek Martinez is a neurosurgeon and also a dad.

We found him and his daughter at the park the other day talking about the brain and the five senses.

And guess what?

He says there are more than five senses.

[MUSIC] DAUGHTER: Dad, I have a book report.

Could you tell me more about the brain?

DR. MARTINEZ: Of course.

I have a brain right here and we can look at it.

What do you want to know?

DAUGHTER: Tell me, how does the brain know what you're doing?

DR. MARTINEZ: That's a great question.

Well, it gets different information from different parts of your body, so it knows where your arms and legs are because of a couple of areas in the brain.

One is here on the top and it lets you know if your arm is bent or straightened, and you can tell the difference between pushing on something hard or pushing something light.

All that information comes into the brain and the brain knows if something is soft or if it's sharp.

It knows if you are moving quickly or very slowly or standing still.

DAUGHTER: Those the five senses?

DR. MARTINEZ: That's sort of touch.

And it's also something else called proprioception, which means sensing yourself because it knows where your body is.

That's why you can close your eyes and know exactly where your foot is or if your knee is bent or straight because the brain knows.

CARTAN-HANSEN: Proprioception is one of those extra senses we have.

It's an automatic process, one you do without even recognizing it.

Say, you're walking along an uneven surface, your body adjusts the muscles in your legs and your feet to maintain your balance.

Or, if you have an itch on your nose, your body and brain move your arm and hand to scratch it Without you ever having to look and see where the itch is.

There's also kinesthesia.

This extra sense allows you to use proprioception to learn physical skills.

Like playing the piano without looking at the keys, or riding a bike, or gymnasts keeping track of where they are as the flip or spin in the air, so they know where to land.

Different body parts are used for the extra senses.

Mechanoreceptors are in the skin, muscles, ligaments, tendons and near your bones and joints.

These receptors detect things like pressure, vibration and motion.

They also sense forces acting on your body, like gravity, and sends that information to your brain.

You also have five organs in your inner ear called the peripheral vestibular system.

These help your brain maintain things like posture, position and movement.

And according to Dr. Martinez, there's more than you might think to even our regular five senses.

DR. MARTINEZ: So, touch is more than just touching it.

You can tell the difference between pressure and vibration, right?

You can tell if something is shaking or not.

DAUGHTER: What about taste?

DR. MARTINEZ: Taste is a great one.

So, taste comes from your tongue, and it comes from a couple of different nerves that again, go into this bottom part of the brain and there's a little spot in the brain that recognizes the pattern of stimulation from the tongue.

And then you can tell if something is sweet or sour.

So, you can tell the difference between eating cinnamon candy or eating a mint candy because the brain remembers the pattern.

And did you know that the smell is really closely connected to that part of the brain that I talked about with memory.

So, smells sometimes if you have something really, really important happen and there's a smell with it, then you remember the experience you had.

It goes straight to the front of your mind When you smell that smell again, it's pretty cool.

DAUGHTER: How can we protect our brain?

DR. MARTINEZ: There are lots of ways.

So, one important way is if you're doing something where you could fall and get hurt, like mountain biking.

You should wear a helmet or skiing.

It's also good to eat healthily and get lots of sleep.

That's very good for our brain.

And so is exercise.

All those things help protect our brain.

DAUGHTER: What does a brain surgeon do?

DR. MARTINEZ: We do a few different things when it comes to the brain.

So sometimes we can put in brain stimulators to help people who have things like Parkinson's disease or other causes of tremor so that they can control their bodies better.

Sometimes we have to take out tumors that aren't supposed to be there so that the brain can work again.

And sometimes we have to help people who unfortunately were in an accident or fell and injured their brain and sometimes they need surgery to allow the brain to recover.

And so we do all those sorts of things to help people.

And sometimes it's surgery and sometimes it's not.

DAUGHTER: What's a piece of advice I should put in my book report?

DR. MARTINEZ; I think you should put in your book report that it is our privilege and responsibility to protect our brain and make it healthy.

And so, anything that you can do to help your brain will help you have a more full life.

So, eat healthy, protect your brain.

Exercise.

Our brain thrives on learning patterns, so learning new things.

Our brain is excellent at that, especially when you're a kid.

DR. MARTINEZ: OK well, we answer all the questions you had one more thing to show you.

Want a scoop?

DAUGHTER: Okay, woah!

DR. MARTINEZ: There's a spoon!

Let's see if your senses work.

DAUGHTER: Mmm, it tastes good.

DR. MARTINEZ: Good.

DAUGHTER: The brain tastes good.

Who knew brain could be so delicious?

CARTAN-HANSEN: If you want the recipe for Jello-brain, send me an email.

If you want to learn more about the five senses, check out the science trek website.

You'll find it at ScienceTrek.org.

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