Posture

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En provenance du cours de The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

585 notes

The University of Chicago

Understanding the Brain: The Neurobiology of Everyday Life

585 notes

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.

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Voluntary Movements

"Voluntary movements are how we interact with the world. The organization of the motor system has implications for how we move, and the types of movements we can make. This module we'll start to explore the organization of the motor system, from neurons to muscles. This module contains a lot of material, so be sure to start early so that you have time to finish!"

Postural Control5:32

Central Pattern Generator7:37

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Peggy Mason
Professor
Neurobiology

[MUSIC]

So now we're gonna talk about automatic movements and

the automatic movement that we're gonna focus on initially at least is posture.

And posture is the position of the body with respect to gravity,

and in general once we adopt a posture we can maintain that posture.

So if I'm standing, postural control would mean that I keep on standing.

In order to do that, one way to think

about the challenge is to keep the center

of mass over the support surface.

So the support surface is that part of the body that is in contact with the ground.

In this person standing here, it's the footprints.

That's the support surface.

The envelope that is described by those footprints.

And the center of mass, not the center of pass.

The center of mass is located right about here in the middle.

Right about the belly button, in the middle.

If I'm standing like this and my center of mass is above my support surface,

then the challenge of postural control is pretty minimal.

Now if I move my center of mass, so

if I go like this, now my center of mass has shifted,

I have to use something to keep me upright.

And so in fact what we are really keeping over the support surface is not so

much the center of mass, but remember that force equals mass times acceleration,

so what we are really keeping over the support surface is the center of force.

And what's the force that we use?

The force that we use is muscle force, muscle contraction,

the force of muscle contraction.

And so let's just think about this.

If I reduce my support surface by standing on one leg,

it is now more challenging to keep me upright,

to keep my center of force over my support surface.

Another way to think about this is that if I have a small support surface and

I elevate my center of mass, it's also harder.

So, if I had weights and I were holding them up, that would be harder to stand.

If I stand like this,

with one foot in front of another, so from the side

one foot in front of the other, that's also harder to stand.

Your center of mass is not above your support surface,

you have to use muscle force in order to keep yourself upright.

So this is essentially the entire

framework for which Pilates and

other exercise regimens are based.

So in Pilates what you are trying to do is to force your core muscles to contract,

and the way you do that is to make sure that you

really are testing those core muscles.

It's the core muscles that enable you to stay upright when your center of mass is

really displaced from

your support surface.

And for many of us, we're very impressed by

looking at people that do amazing things with their bodies,

gymnasts and dancers and so on, who can put their center of

mass really off to the side from their support surface.

And that takes a lot of muscle strength to do it.

So, in the next segment what we're gonna look at is,

what are the brain mechanisms that allow us to control posture,

that allow us to do this?

[MUSIC]

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