The Four Functions (6:15)

From Professor Peggy Mason's "Understanding the Brain: The Neurobiology of Everyday Life" course. See https://www.transifex.com/projects/p/coursera-neurobio/

[MUSIC]

Okay, so what locked-in syndrome, the

locked-in syndrome that, that Jean
Dominique Bauby suffered from.

It tells us about the four basic functions

of the brain, of the central nervous
system.

And those are; voluntary movement,
perception, homeostasis and

something that is oddly described as
abstract or higher functions, cognition.

There are a lot of words for this, none of
them exactly perfect.

Okay.

So, let's just go through what these
various functions mean.

So, voluntary movement is everything that
we do.

And, when I say voluntary, I kind of mean
voluntary, and I kind of don't.

What I mean is something that is driven by
the brain.

And that can be something that

I do completely volitionally, completely
deliberately.

Like I say, I'm going to raise my hand,
and I raise my hand.

That's a voluntary volitional movement.

But, if I step on something and I wince in
pain.

That's an emotional movement.

Both of them, are, we're classifying for
right now as voluntary movements.

They're self generated.

They are, they come from ourselves.

And these voluntary movements are the only
way that we have to express ourselves.

I know that in the popular press there

is a difference between words and, and,
and actions.

Sticks and stones can break my bones but
words can never hurt me.

Well actions and, and talk, talk and

actions, they're, they're all, they're all
one action.

[LAUGH] So talk is an action, and we use
are laryngeal muscles.

Our diaphragm our the, the muscles of the

upper airway including their tongue, and
pharyngeal muscles.

These are all muscles that we use to
actually express ourselves.

So, talking, writing.

Having a facial expression.

Raising your hand.

Jumping up and down.

Doing a new da, dance step.

All of these are voluntary movements, and
these were

definitely lost in Bauby, all he could do
and

all many of people in, with locked-in
syndrome

can do is, is move their eyelid.

Okay.

So that's voluntary movement.

Perception, is distinct from sensation.

And that's a very important, concept.

Perception is what we consciously
appreciate about sensation.

So, what, I sense all sorts of stuff that
I have no perception about.

So, for instance.

My brain senses how much CO2 there is in
my blood.

Well, I have no idea how much
CO2 there is in my blood.

I mean, I could take a guess.

But, that's because I'm a scientist, and I
kind of know how much there should be.

but, but there's all the, there, there's
sensors that tell

us how long our muscles are, where our,
our joints are.

None of that actually reaches conscious
perception.

The perceptions that we have
include vision and hearing,

smell and taste, the sense of balance, the
sense of position in the world.

Where are we?

Where is our head in the world?

A sense of equilibrium.

All of those are perceptions that we have.

They actually reach conscious, a conscious
level.

The third function, major function, that
we're going to talk about, is homeostasis.

And homeostasis is what we use to keep our
body in physiological limits.

To make sure that we have enough oxygen to
our brain, and to the rest of our body.

We are going to focus very much on brain
[LAUGH] in this course.

so, we have to make sure that the, that,
that there's enough oxygen

delivered to the body, that there's enough
blood pressure that keeps us upright.

We have to make sure that our body
temperature stays within limits.

The physiological limits that the body
will tolerate.

We -- there are life cycle events that are
challenges to our, our being.

And these include giving birth, and
nursing a newborn, suckling from a mother.

All of these things are part of
homeostasis.

They're part of the package that keeps us
alive.

Another part of homeostasis is a rhythm.

The rhythm of our lives.

The daily rhythm.

The wake and the sleep.

And the seasonal rhythm.

Rhythm, the seasonal rhythm that has a
little bit less

of an obvious influence on us than, the
daily rhythm.

And then, the cycle of life.

So we go from infancy, to childhood, to
adolescence.

To early adulthood, to middle age, to
being older.

And so, these are all part of homeostasis.

It's all part of the challenge of staying
alive, and as far as abstract functions,

these are things like thinking, and
feeling emotions, and motivation.

And language, and memory, and learning.

All of these are part of our higher
abstract functions.

Another incredibly important abstract
function, is how we interact.

How, how do we play well with others?

How do we get in that sandbox and, and,
and survive it?

So these are all part of abstract
functions.

And they're a very important part of being
a, a human.

So, in the next segment, what we're
going to do is, we're going to

assign each one of these functions to a
part

of the central nervous system.

[MUSIC]