Transcriber: Deans The Reviewer: Maria Pericleous
I am feeling really stressed.
And it’s not just because I’m up here in front of this large audience.
I never, ever in my wildest dreams, imagined living through a global pandemic.
I was already anxious
about climate change,
cost of living,
politics,
I have twin teenaged daughters
and then Covid.
I’m a Neuroscientist and I study how our brain changes what we learn.
And I’m worried about what all the stress is doing to our brain health.
Now, I have to be honest,
I was really, really concerned about agreeing to give this talk.
I’m already really busy.
And it felt, it felt stressful to take something like this on.
But a conversation with my mom
changed my mind.
We were talking, and I was sharing my concerns
about stress and brain health with her.
And the topic really resonated.
She was so concerned about stress and learning and brain health
of her grandchildren,
you know, of course not herself,
that I felt like I should start this conversation.
I’m worried,
because high levels of stress for long periods of time
can interfere with our ability to learn.
When feel stressed,
our body releases a hormone called cortisol.
Cortisol does a lot of really important things in our bodies.
We all woke up this morning because our cortisol levels went up.
They either went up naturally and you woke up on your own,
or they may have gone up rather unkindly when your alarm went off.
Cortisol is normally at its highest concentration
early in the day.
It slowly decreases until we go to sleep at night.
The cycle repeats the next day.
Cortisol regulates
a number of important functions in our body.
It regulates blood pressure and blood glucose.
It helps our immunity.
It can decrease our sensitivity to pain.
And it gives us that little edge if we’re gonna take a test,
run a race, maybe give a TEDxTalk.
But what happens when we’re stressed such that our cortisol levels go up
and they stay high for a long period of time?
High levels of cortisol can cause us to lose
bone density and muscle mass.
They raise inflammation, lower immunity
and they increase abdominal fat.
But maybe most concerning is that
high levels of cortisol can interfere with our ability to think.
You know, this feeling of just being so stressed out
you can’t even form a thought.
And when this happens,
cortisol is interfering with our ability to learn.
The bottom line is that all of this stress is making all of us worse learners.
So how does stress affect learning exactly then?
So you need to understand that we are, simply put, learning machines.
Everything we do, everything we experience
is causing us to learn and it’s changing your brain.
So brain change in response to learning is called neuroplasticity.
And it doesn’t just happen in school,
you’re doing this all the time.
Have you changed your golf swing?
Well, you learned.
Can you sing along to your new favorite song?
Well, you learned.
Do you know where to go in the grocery store
to find that favorite item?
And for me, it’s coffee.
And you learn that, too.
When we learn, we change brain cells,
and our brains are made up of billions of individual cells
called neurons.
They communicate with one another by sending chemical signals
that pass across through the brain.
When we learn something new,
the chemical concentration in our brain can change very rapidly.
And this is the mechanism
that supports the formation of a short term memory.
So short term memory, it’s just what it sounds like.
It’s a newly formed memory.
It’s fragile.
It’s easily forgotten.
To be remembered and to persist across time and different situations,
that short term memory has to be converted into a long term memory.
Have you ever crammed for an exam?
You maybe even studied
as you walked into the room you were going to take the test in.
You might have gotten a really good grade.
Do you remember any of that information now?
(Laughter)
You made a short term memory when you cram,
but you didn’t study long enough to convert that into a long term memory.
To really learn something, you must create a long term memory.
And long term memories require that the structure of the brain is changed.
And this happens as neurons add or move contacts with other neurons.
This takes time.
But long term memories are relatively permanent.
Once you learn to ride a bike,
you never forget.
And you can ride any bike,
you don’t have to continue to ride the little one that you learned on.
But creating that long term memory is going to take a lot of practice or study
and it also requires sleep.
So, what happens when we’re really stressed?
High levels of cortisol interfere with the transformation
of short term memories into long term memories.
To create long term memories, there’s other chemicals in the brain
called growth factors.
These growth factors facilitate the formation of long term memories.
They make it easier to add and remove those contacts
on neurons.
Growth factors directly support learning.
But in the brain,
growth factors and cortisol compete.
Imagine a mall parking lot,
every parking spot is full.
It’s a total nightmare.
You drive in circles and there’s no parking.
A similar thing happens in your brain.
For chemicals to bind to your neurons,
there has to be a receptor where they can attach.
The receptors are the parking spots.
And if they’re all full of cortisol,
there’s no place for growth factor to park.
And this impairs learning.
There is good news, though.
The single largest driver of neuroplasticity is our behavior.
That means that we can adopt different behaviors,
we can do things that will help our brain learn.
So what on earth should we do?
There’s a number of ways that we can help our brain learn.
One of the most powerful is exercise.
So we already knew that exercise was really good
for our heart and our muscles.
But it turns out that it has incredible effects on the brain.
Work for my research lab at the University of British Columbia
has shown that even a single session of intense exercise
can change cortical excitability,
alter the function of your brain,
and promote learning.
So in these studies, we had people exercise
and then practice learning something new.
And in the short term, within the same session,
there’s no effect of exercise.
But we had people come back the next day,
and we compared people who exercised to a group that didn’t exercise,
we found a huge advantage for the exercise group.
It appears that exercise facilitates the transformation
of a short term memory into a long term memory.
And the best part, exercise reduces cortisol.
It’s the tow truck that comes in and pulls cortisol out
and makes room for growth factors to park in our neurons.
Importantly, it doesn’t matter how you exercise.
You can walk, run, garden, dance, hike, cycle, ski.
They all have amazing effects on the brain.
So what else can we do?
Well, I don’t know about you,
but I did not sleep eight hours last night.
We are a population of chronically sleep deprived people.
Yet sleeping eight vs six hours a night lowers your cortisol by 50%.
And it also reduces your blood pressure.
And sleep is essential
to convert short term memories into long term memories.
In other research from my lab,
we studied people who practice yoga
just recreationally, two to three times a week,
and we compared them to runners.
We tested their physical fitness, their levels of stress
and we mapped their brain activity
when we put them into stressful situations.
Now, I’m going to admit that when we started this study,
I was absolutely convinced that the runners would be healthier.
And that’s because I’m a lifelong distance runner.
And I was right.
(Laughter)
But I was only a little bit right.
(Laughter)
So the runners showed higher physical fitness
and that’s not really a surprise.
But people who practiced yoga showed lower levels of stress
and a much more adaptive pattern of brain activity
when we put them into these stressful situations.
What is so special about yoga?
Well, it’s not likely the poses that are affecting the brain,
as much as it is the practice of mindfulness
that’s associated with yoga.
Other research in children has shown
that practicing mindfulness, and that’s just sitting still
for short periods of time through the day and focusing on how you feel,
lowered cortisol and improved performance in school.
Mindfulness simply just seems to allow the brain the opportunity
to rest and reset.
And in our crazy technology driven lives, we rarely let our brains rest.
We rarely give our mind the opportunity to just wander.
It seems though that our brains need these kinds of breaks,
and providing them can lower cortisol,
reduce stress and improve learning.
Life is stressful and it’s full of change,
but we can intentionally affect how that stress alters our brains.
Exercise.
Sleep.
Practice being mindful.
These all open up parking spots for learning.
Each one reduces cortisol, lowers your stress
and improves your brain health.
They help learning,
no matter how old you are or what it is you’re trying to learn.
And each one has important implications for brain health,
and we really need to take care of our brains.
We each only get one.
And who knows?
Maybe on your next Walker Run, you’ll pass by me and my mom.
We’ll see you out there.
Thank you.
(Applause)