The VOR Is Fast

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From the course by The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

868 ratings

The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

868 ratings

Learn how the nervous system produces behavior, how we use our brain every day, and how neuroscience can explain the common problems afflicting people today. We will study functional human neuroanatomy and neuronal communication, and then use this information to understand how we perceive the outside world, move our bodies voluntarily, stay alive, and play well with others.

From the lesson

The Vestibular Sense & Gaze

The vestibular system and gaze control give us so much but are grossly under appreciated. They are so fundamental that we discount them, assuming that they will always be there. When the vestibular system fails us, its importance dominates our lives. Living with either a vestibular or an eye movement disorder is very disruptive to everyday life. In this module, you will learn how the inner ear is designed to detect and respond to head movements. You will learn about the circuit that connects the inner ear to the motoneurons that control the location of your eyes, allowing us to reflexively maintain our view of an object even as we move about in the world. Finally, we will talk about how you can modify this reflexive control of the eyes and how you can control where you are looking.

The VOR Is Fast4:46

Horizontal VOR Circuitry4:44

Adapting the VOR4:56

Meet the Instructors

Peggy Mason
Professor
Neurobiology

[MUSIC]

Okay, so, we've gone to all this trouble to figure out how our head is moving.

Why, what's so bloody important about it?

Well, one is to keep us upright, to keep our balance.

But another big piece that we're going to look in

at some detail is to keep our gaze steady.

And when I say gaze, what I mean is where we're looking.

And where we're looking is a function of two feature, two properties.

One is where our head is oriented, and where our eyes are oriented.

So if my he, my eyes are stra, looking straight ahead and

my head is this way, I'm looking there.

But if my eyes are straight ahead and I'm, and my head is oriented this way,

I'm looking there.

But I can also look there by simply moving my eyes.

Gaze is head plus eyes.

But we're going to consider, and it is a reasonable approximation,

that most of gaze especially for, for

moving gaze within a limited point of view.

We, for instance, as your reading a book,

most of gaze involves just moving the eyes.

Okay, so as I'm walking down the street and

my head is bopping around, why don't I see the world bopping around too?

Well, because I have this lovely reflex called the vestibuloocular reflex.

So, the vestibulo ocular reflex,

also affectionately known as the VOR.

The VOR prevents me from messing up my gaze even before I have a chance to.

It keeps my gaze steady

immediately as all of these ex, head accelerations are occurring.

And it's fast, and it's fast in large part because it uses the vestibular system.

Remember that the vestibular system is really, it's, it's really instantaneous.

Those tip links are just opening the channels stuff, ions are rushing in.

There's a very quick response out in the inner ear.

And then information gets right to the vestibular nucleus.

And from the vestibular nucleus, as we'll see in the next segment,

information is already sent to motor neurons.

Okay.

That are going to change your eye position.

So one way to, to, to think about this to,

to see the effect of the VOR is to look at your finger.

Now, I want all of you to do this at home.

You're going to look at your finger and

you're going to turn your head from side to side.

Does your finger stay in focus?

Do you still see your finger in focus?

And the answer is yes.

Now, what you're going to do is instead of turning your head,

you're going to move your finger back and forth.

And you're going to try and follow that.

Does it stay in focus?

Not so much.

That's because your visual system is very slow.

And that's why we don't have a visual ocular reflex.

We have a vestibuloocular reflex.

We depend on the vestibular system, not the visual system.

So here is here is just an example.

This is actually me, trying to take a picture of this bird as I'm on a boat.

But we can consider this in a metaphor for me without a vestibular system.

If I didn't have a vestibular system and

I just depended on realizing that I'm not looking,

I'm not aiming my camera at the right place, this would be how slow things are.

And I, and I don't have a steady picture.

I'm, I'm all over the place.

I go from here, to here, to there.

In contrast when I use my VOR,

what happens is that as the head moves, the eyes move in opposition.

When we add head plus eyes, we get gaze.

And gaze equals steady.

It's not moving.

That's the VOR.

Okay, in the next segment,

we're going to see how the nervous system actually produces the VOR.

It's a pretty simple circuit and we're going to look at that.

[MUSIC]

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