Nystagmus

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來自 The University of Chicago 的課程

了解大脑：日常生活中的神经生物学

822 個評分

The University of Chicago

了解大脑：日常生活中的神经生物学

822 個評分

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.

從本節課中

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

與講師見面

Peggy Mason
Professor
Neurobiology

[MUSIC]

Okay, so let's look at an example of nystagmus and

the example that we're going to look at is called post-rotatory nystagmus.

And I do this every year with students in the medical school class that I teach.

And what we do is we rotate somebody in a chair.

So rotate them for about 30, 60 seconds and then we stop.

And what you're going to see is that their eyes are going to move like this.

It's a beating nystagmus.

And so let's just take it apart.

What are we doing when we're rotating?

We are setting it up so let's say that we're doing a clockwise rotation.

So, the person is turning this direction, that bends the cupula like this.

And then when we stop, now the, the,

the relative motion of on the cupula is actually in the other direction.

So we stop bending.

This stuff comes back.

And it excites this this horizontal canal.

So now this horizontal canal is excited, which elicits a VOR.

So we know that if the if this horizontal canal is excited

the, there's going to be a VOR in that direction.

And the interesting thing here, is, that, at,

after the VOR occurs there's a reset back to the, to the center and

then the VOR occurs again and there's a reset.

So, so there is a VOR in this direction and then a reset in this direction.

So if we took the position of the eye,

horizontal position of the eye across time,

what you would see is that there's a gradual

movement in this direction, and then a fast reset.

And then a gradual movement, and then a fast reset.

Now I'm going to show you a video in a moment.

But the, the fact of the matter is that this fast reset is the thing that you see.

This is easy to see.

It looks like the mo, the a quick eye movement.

And so the nystagmus is named for this direction.

So in this case it would be a left beating nystagmus.

So now we're going to look at a video, this is one of my medical students,

he's been rotated in a chair clockwise, clockwise rotation.

And here we go.

And then he's been stopped and you can see that is beating,

he's beating that way.

He's beading to his left.

There's a slow movement to the right followed by a fast reset, and

this post auditory nystagmus will last approximately 30 seconds.

Nothing you can do about it.

And, and what is he experiencing?

You can try this.

What you'll experience is that the, the visual world is moving.

So, in a person with nystagmus the world is going to move.

Gaze is not held steady.

Now this is an example of a very, a healthy nystagmus,

it's a sign of, of brain health.

Another example is the nystagmus that you get,

which is called optokinetic the optokinetic response,

which is if you're traveling along in a vehicle and

you see a repeating pattern, such as a fence, a picket fence.

What you'll do is you'll follow it and then you'll, you'll reset.

You'll follow it and reset.

And that's another healthy ver, healthy sign.

It's a healthy version of a nystagmus.

Okay, so what we're going to do in the final segment of this

of this module is look at how the VOR may change across different conditions.

[MUSIC]

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