Eye Movements

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From the course by The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

621 ratings

The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

621 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.

Eye Movements5:05

Saccade Circuits4:47

Controlling Saccades6:03

Meet the Instructors

Peggy Mason
Professor
Neurobiology

[MUSIC]

Okay, so now, we're, we're going to shift gears and talk about eye movements.

Eye movements beyond the VOR.

And one of the first ones one can think about is the, is cancellation of the VOR.

In other words, if I, if I move my head and

I still stay looking over there, I'm using a VOR.

But let's say I want to look at something over there.

What I do is I move my head and I keep my eyes focused or fixated forward.

And therefore, I have shifted not only my gaze, but

I've shifted my gaze using a head movement and no-eye movement.

I've cancelled the VOR.

I've prevented my VOR from taking my gaze back to its original position.

And so we need to be able to maintain gaze maintain fixation.

But we also need to be able to switch, and look at new and different things.

And so the whole field of,

of study of how we move our eyes is, is the ocular motor field.

And it may sound one of the reasons it's important

is because there's a lot of neural architecture.

Both in the periphery and

in the central nervous system that goes to making your eye movements work.

And as we saw in vision, just being off by just a degree or two degrees

will impact visual acuity and impact the person's life.

So we need to be able to move our eyes, and we need to be able to move our eyes

exceptionally well in order to to see things in fine focus.

Now, if that were all that there were to it,

it would be a very nuts and bolts kind of, of study.

But in fact there, there's a lot more to it.

So, this is Toula.

She's very intent on looking at something.

Her gaze is tightly controlled.

We can do that too.

But there's, there's more to eye movements than,

than than just how they, they come about and

what they mean about the health or the, or the lack of health of, of a brain.

And that is that they tell us something about a person.

So, a person who is shifty eyed has a different we react to a person who's

shifty eyed very differently from we, how we react to somebody who looks us in

the eye and tells us as they maintain their gaze X, Y, or Z.

So we, we derive a lot of implications from how a person interacts with us.

And a large chunk of that is how they view us.

What's happening with their eyes?

That tells us a ton.

And there are, there is essentially no, I can't think of a neuropsychiatric

disease where eye movements are not at least somewhat effected.

So for instance in a clinically depressed person,

there, it's very difficult for them.

It maybe very difficult for them to make eye contact.

They may have a downward gaze.

I, for there have been a number of

studies showing that in au, autism spectrum disorder,

autistic spectrum disorder people have changes in how they move their eyes.

And I just want to show you one example of this.

Wha, what is this of?

Well, most people what is this image?

And most people will respond and say that this is an H.

And indeed that's how I responded.

That's how many people responded.

But what you see here is that it is indeed the form of an H.

But each component that it's made up of is an E.

So another way to say is it's a lot of Es.

Both are correct, neither is incorrect.

And it, they simply depend on what pattern of eye movements you use.

Are you using this kind of an eye movement, or

you're looking at the global picture?

Or are you looking very locally at each of these individual components?

And so this global versus local processing is something that I,

that can be different across different people.

In the next segment, what we're going to do is look at the primary

type of eye movement that we use to change our gaze.

And that is a saccade, okay?

Saccade eye movements.

[MUSIC]

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