But, here's something we haven't learned about together...LEARNING.

The ways in which we acquire and retain knowledge

(which is the very definition of learning)

is really a science in itself. And like any other discipline that involves the study

of the human brain is practically still in its infancy.

Just twenty years ago most scientists believed

that once we reached adulthood our brains were pretty much fixed

not that we were incapable of learning anything new exactly,

but the assumption was that our brains development phase was over...

and now it's pretty much there to remind our hearts keep beating.

And occasionally let us remember where we left our phone.

But thanks to huge advances in things

like functional brain imaging we have a clearer picture than ever of

how our brains work and we're beginning to observe some wonderful things.

For one we now know that the process of learning

actually alters the structure of our brains at the cellular level

and once more it turns out that our brains

never stop changing to make room for new information.

People often compare the human brain to a computer, but

imagine a computer that can actually grow new circuits,

as it acquires new facts and associations

(and you have a much more awesome comparison)

-this is the gift known as neural plasticity.

You might think of plastic is being stiff in cheap,

but biology plasticity refers to the capacity of living things to mold themselves to new conditions

and our brains are great at it.

For one thing your brain cells (or neurons)

are always changing their connections to one another,

to meet changing demands.

Each of your neurons consists of a central body,

with spindly dendrites and a long axon stemming from it.

The neuron transmits electrical signals to other

brain cells through its axon, and receives signals through its dendrites

-via connections where the cells meet called synapses.

When you're born, each neuron in your brain has about

2,500 synapses connecting it to other cells.

But by the time you're 3

and you've become just a sponge of fascinating new information like

what sound a piggy makes & where your mom's face goes when she hides behind her hands

...you have 6 times as many (up to 15,000 synapses)

for each neuron in your brain!

In this regard it's kinda true that brain hit its peak when you're young,

because by the time you're an adult your brain cells have about half as many synapses as when you were 3

but it turns out that's okay because we now know that

synapses just shrink up when they're no longer needed.

Like you know now that pigs go oink and that people still exist when you can't see their faces

so you don't need to keep those connections to remind you.

This process of winnowing down of unused connections

is known as syntactic pruning.

Meanwhile, your neurons experience all kinds of new growth as you continue to

soak up new information,

like how to drive, how to solve for x, and how to get through that one really hard

level in your favorite castles matching game.

Here...the key to learning is memory

because you need to retain that information in order to apply it in the future.

So your brain cells can change in different ways

depending on how long you've remembered what you learned.

As you stockpile data in your short term memory, for example:

the structure of your existing synapses has been found to change

with more and stronger dendrites growing to reinforce them.

So for info that you retain for just a short time like,

how to destroy digital castles using rocks and fire

you don't need to sprout whole new connections -just beefing up the existing ones

you've used so far will help you master the game just fine.

But when it comes to important stuff like the learning we do at school

or hopefully the stuff you learn here on SciShow

your neurons actually forge entirely new synapses over time

as you re-learn, re-remember, and reuse the information.

This is how your brain builds the long-term memory you need

to retain the learning you're doing right now at work and at school

and turn it into a lifetime of applied knowledge.

So I said it before and I'll say it again

take care of your brain and odds are...it'll take care of you!

Thanks for watching this SciShow.

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