Welcome to the Huberman Lab Podcast,

where we discuss science

and science-based tools for everyday life.

My name is Andrew Huberman,

and I’m a professor of neurobiology and ophthalmology

at Stanford School of Medicine.

This podcast is separate

from my teaching and research roles at Stanford.

It is, however, part of my desire and effort

to bring zero cost to consumer information

about science and science-related tools

to the general public.

In keeping with that theme,

I want to thank the first sponsor of today’s podcast.

Our first sponsor is Athletic Greens.

Athletic Greens is an all-in-one

vitamin mineral probiotic drink.

I’ve been taking Athletic Greens since 2012,

so I’m delighted that they’re sponsoring the podcast.

The reason I started taking Athletic Greens

and the reason I still take Athletic Greens

once or twice a day

is that it helps me cover

all of my basic nutritional needs.

It makes up for any deficiencies that I might have.

In addition, it has probiotics,

which are vital for microbiome health.

I’ve done a couple of episodes now

on the so-called gut microbiome

and the ways in which the microbiome interacts

with your immune system, with your brain to regulate mood,

and essentially with every biological system

relevant to health throughout your brain and body.

With Athletic Greens, I get the vitamins I need,

the minerals I need,

and the probiotics to support my microbiome.

If you’d like to try Athletic Greens,

you can go to athleticgreens.com slash Huberman

and claim a special offer.

They’ll give you five free travel packs

plus a year supply of vitamin D3 K2.

There are a ton of data now showing that vitamin D3

is essential for various aspects

of our brain and body health.

Even if we’re getting a lot of sunshine,

many of us are still deficient in vitamin D3.

And K2 is also important

because it regulates things like cardiovascular function,

calcium in the body, and so on.

Again, go to athleticgreens.com slash Huberman

to claim the special offer of the five free travel packs

and the year supply of vitamin D3 K2.

Today’s episode is also brought to us by Element.

Element is an electrolyte drink

that has everything you need and nothing you don’t.

That means the exact ratios of electrolytes are an element,

and those are sodium, magnesium, and potassium,

but it has no sugar.

I’ve talked many times before on this podcast

about the key role of hydration and electrolytes

for nerve cell function, neuron function,

as well as the function of all the cells

and all the tissues and organ systems of the body.

If we have sodium, magnesium, and potassium

present in the proper ratios,

all of those cells function properly

and all our bodily systems can be optimized.

If the electrolytes are not present and if hydration is low,

we simply can’t think as well as we would otherwise,

our mood is off, hormone systems go off,

our ability to get into physical action,

to engage in endurance and strength

and all sorts of other things is diminished.

So with Element, you can make sure

that you’re staying on top of your hydration

and that you’re getting the proper ratios of electrolytes.

If you’d like to try Element, you can go to drinkelement,

that’s element.com slash Huberman,

and you’ll get a free Element sample pack

with your purchase.

They’re all delicious.

So again, if you want to try Element,

you can go to elementlmnt.com slash Huberman.

Today’s episode is also brought to us by Thesis.

Thesis makes what are called nootropics,

which means smart drugs.

Now, to be honest, I am not a fan of the term nootropics.

I don’t believe in smart drugs in the sense that

I don’t believe that there’s any one substance

or collection of substances that can make us smarter.

I do believe based on science, however,

that there are particular neural circuits

and brain functions that allow us to be more focused,

more alert, access creativity, be more motivated, et cetera.

That’s just the way that the brain works,

different neural circuits for different brain states.

Thesis understands this.

And as far as I know, they’re the first nootropics company

to create targeted nootropics for specific outcomes.

I’ve been using Thesis for more than six months now,

and I can confidently say that their nootropics

have been a total game changer.

My go-to formula is the clarity formula,

or sometimes I’ll use their energy formula before training.

To get your own personalized nootropic starter kit,

go online to takethesis.com slash Huberman,

take a three-minute quiz,

and Thesis will send you four different formulas

to try in your first month.

That’s takethesis.com slash Huberman,

and use the code Huberman at checkout

for 10% off your first order.

I’m pleased to announce that the Huberman Lab Podcast

is now partnered with Momentus Supplements.

We partnered with Momentus for several important reasons.

First of all, they ship internationally

because we know that many of you are located

outside of the United States.

Second of all, and perhaps most important,

the quality of their supplements is second to none,

both in terms of purity and precision

of the amounts of the ingredients.

Third, we’ve really emphasized supplements

that are single ingredient supplements,

and that are supplied in dosages

that allow you to build a supplementation protocol

that’s optimized for cost,

that’s optimized for effectiveness,

and that you can add things and remove things

from your protocol in a way

that’s really systematic and scientific.

If you’d like to see the supplements

that we partner with Momentus on,

you can go to livemomentus.com slash Huberman.

There you’ll see those supplements,

and just keep in mind that we are constantly expanding

the library of supplements available through Momentus

on a regular basis.

Again, that’s livemomentus.com slash Huberman.

Today, we’re talking about neuroplasticity,

which is this incredible feature of our nervous systems

that allows it to change in response to experience.

Neuroplasticity is arguably one of the most important

aspects of our biology.

It holds the promise for each and all of us

to think differently, to learn new things,

to forget painful experiences,

and to essentially adapt to anything that life brings us

by becoming better.

Neuroplasticity has a long and important history,

and we’re not going to review all of it in detail,

but today what we are going to do

is discuss what is neuroplasticity,

as well as the different forms of neuroplasticity.

We’re going to talk about how to access neuroplasticity,

depending on how old you are,

and depending on the specific types of changes

that you’re trying to create.

This is a topic for which there are lots of tools,

as well as lots of biological principles

that we can discuss.

So let’s get started.

Most people are familiar with the word neuroplasticity.

It’s sometimes also called neuroplasticity.

Those are the same thing.

So if I say neuroplasticity or neuroplasticity,

I’m referring to the same process,

which is the brain and nervous system’s ability

to change itself.

And there are a lot of reasons

why the nervous system would do this.

It could do it in response to some traumatic event.

It could, for instance, create a sense of fear

around a particular place,

or a fear of automobiles or planes.

It could also occur when something positive happens,

like the birth of our first child,

or when our puppy does something amusing,

or we see an incredible feat of performance in athleticism.

The word neuroplasticity means so many things

to so many different people

that I thought it would be important

to just first put a little bit of organizational logic

around what it is and how it happens.

Because nowadays, if you were to go online

and Google the word neuroplasticity,

you would find hundreds of thousands of references,

scientific references, as well as a lot of falsehoods

about what neuroplasticity is and how to access it.

As I mentioned before,

we’re going to talk about the science of it,

and we’re going to talk about the tools

that allow you to engage this incredible feature

of your nervous system.

And that’s the first point,

which is that all of us were born with a nervous system

that isn’t just capable of change,

but was designed to change.

When we enter the world,

our nervous system is primed for learning.

The brain and nervous system of a baby

is wired very crudely.

The connections are not precise.

And we can see evidence of that

in the fact that babies are kind of flopping there

like a kind of a little potato bug with limbs.

They can’t really do much in terms of coordinated movement.

They certainly can’t speak,

and they can’t really do anything with precision.

And that’s because we come into this world overconnected.

We have essentially wires.

Those wires have names like axons and dendrites.

Those are the different parts of the neurons

discussed in episode one.

But those little parts and those wires and connections

are everywhere.

Imagine a bunch of roads

that are all connected to one another in kind of a mess,

but there are no highways.

They’re all just small roads.

That’s essentially what the young nervous system is like.

And then as we mature,

as we go from day one of life to 10 years old,

20 years old, 30 years old,

what happens is particular connections get reinforced

and stronger and other connections are lost.

So that’s the first important principle

that I want everyone to understand,

which is that developmental plasticity,

the neuroplasticity that occurs from the time we’re born

until about age 25 is mainly a process

of removing connections that don’t serve our goals well.

Now, of course, certain events happen

during that birth to 25 period

in which positive events and negative events

are really stamped down into our nervous system

in a very dramatic fashion

by what we call one trial learning.

We experienced something once

and then our nervous system is forever changed

by that experience.

Unless of course we go through some work

to undo that experience.

So I want you to imagine in your mind

that when you were brought into this world,

you were essentially a widely connected web of connections

that was really poor at doing any one thing.

And that through your experience,

what you were exposed to by your parents

or other caretakers, through your social interactions,

through your thoughts,

through the languages that you learn,

through the places you traveled or didn’t travel,

your nervous system became customized

to your unique experience.

Now, that’s true for certain parts of your brain

that are involved in what we call representations

of the outside world.

A lot of your brain is designed to represent the visual world

or represent the auditory world

or represent the gallery of smells

that are possible in the world.

However, there are aspects of your nervous system

that were designed not to be plastic.

They were wired so that plasticity

or changes in those circuits is very unlikely.

Those circuits include things like

the ones that control your heartbeat,

the ones that control your breathing,

the ones that control your digestion.

And thank goodness that those circuits

were set up that way

because you want those circuits to be extremely reliable.

You never want to have to think about

whether or not your heart will beat

or whether or not you will continue breathing

or whether or not you’ll be able to digest your food.

So many nervous system features like digestion

and breathing and heart rate are hard to change.

Other aspects of our nervous system

are actually quite easy to change.

And one of the great gifts of childhood,

adolescence and young adulthood

is that we can learn through almost passive experience.

We don’t have to focus that hard

in order to learn new things.

In fact, children go from being able to

speak no language whatsoever

to being able to speak many, many words

and comprise sentences,

including words they’ve never heard before,

which is remarkable.

It means that the portions of the brain

involved in speech and language

are actually primed to learn and create new combinations.

What this tells us is that the young brain

is a plasticity machine,

but then right about age 25,

plus or minus a year or two,

everything changes.

After age 25 or so,

in order to get changes in our nervous system,

we have to engage in a completely different

set of processes in order to get those changes to occur.

And for them more importantly, to stick around.

And this is something that I think is vastly overlooked

in the popular culture discussion about neuroplasticity.

People always talk about fire together, wire together.

Fire together, wire together is true.

It is the statement of my colleague at Stanford,

Carla Schatz,

and it’s an absolute truth

about the way that the nervous system

wires up early in development.

But fire together, wire together

doesn’t apply in the same way after age 25.

And so we have these little memes

and these little quotes that circulate on the internet,

like fire together, wire together,

or there’s a famous quote

from the greatest neurobiologist of all time, Ramon y Cajal.

I think it goes something like,

should somebody wish to change their nervous system,

they could be the sculptor of their nervous system

in any way they want, something like that.

And that sounds great.

I mean, who wouldn’t want to change their nervous system

any way they want?

But what’s lost in those statements

is how to actually accomplish that.

And we’re going to cover that today.

But please understand that early in development,

your nervous system is connected very broadly

in ways that make it very hard to do anything well.

From birth until about age 25,

those connections get refined,

mainly through the removal of connections

that don’t serve us,

and the incredible strengthening of connections

that relate to either powerful experiences

or that allow us to do things like walk and talk

and do math, et cetera.

And then after age 25,

if we want to change those connections,

those super highways of connectivity,

we have to engage in some very specific processes.

And those processes, as we’ll soon learn, are gated,

meaning you can’t just decide to change your brain.

You actually have to go through a series of steps

to change your internal state

in ways that will allow you to change your brain.

I just want to acknowledge

that Costello is snoring particularly loud today.

Some of you seem very keen at picking up on his snoring.

Others of you can’t hear his snoring.

It’s very low rumbling sound.

And whether or not you can or you can’t

probably relates to the sensitivity of your hearing.

We’re actually going to talk about perfect pitch today

and a range of auditory detection.

And so if you can hear Costello’s snoring, enjoy.

If you can’t, enjoy.

I want to talk about how the nervous system changes.

What are these changes?

Many of us have been captivated

by the stories in the popular press

about the addition of new neurons.

This idea, oh, if you go running or you exercise,

your brain actually makes new neurons.

Well, I’m going to give you the bad news first,

which is that after puberty,

so after about age 14 or 15,

the human brain and nervous system adds very few,

if any, new neurons.

The idea that new neurons could be added to the brain

is one that has a rich history in experimental science.

It’s clear that in rodents and in some non-human primates,

new neurons, a process called neurogenesis,

can occur in areas of the brain,

such as the olfactory bulb,

which is of course involved in smell,

as well as a region of our hippocampus,

a center of the brain involved in memory

called the dentate gyrus of the hippocampus.

And there is strong evidence that new neurons

can be added to those structures throughout the lifespan.

In humans, the evidence is a little bit more controversial.

It’s clear that we can add new neurons

to our olfactory bulb.

In fact, if any of you have ever had

the unfortunate experience of being hit on the head too hard,

the wires called axons from those olfactory neurons

that live in your nose can get sheared off

because they have to pass through a bony plate

called the cribriform plate.

And the cribriform plate can shear those axons

and people can become what’s called anosmic.

They won’t be able to smell.

But over time, those neurons,

unlike most all central nervous system neurons,

can grow those connections back

and even reestablish new neurons

added to the olfactory bulb.

They come from elsewhere deep in the brain

and they migrate through a pathway

called the rostral migratory stream.

You can Google these words

and look up some of the descriptions of this

if you’d like to learn more.

So indeed, there’s some evidence

that the neurons responsible for smell

can be replaced throughout the lifespan,

certainly in very young individuals

from birth till about age 15 or so.

Whether or not there are new neurons

added to the hippocampus,

the memory center of the human brain isn’t clear.

Many years ago, Rusty Gage’s lab at the Salk Institute

did a really important study

looking at terminally ill cancer patients

and injecting them with a label,

a dye that is incorporated only into new neurons.

And after these patients died,

their brains were harvested,

the brains were looked at,

and there were new neurons there.

There was evidence for new neurons.

Those results, I think, stand over time,

but what was not really discussed

in the popular press discussion around those papers

was that it was very few cells that were being added.

And a number of papers have come along over the years,

mainly from labs at UCSF, although from others as well,

showing that if there are new neurons

added to the adult brain,

it’s an infinitesimally small number of new neurons.

So that’s the depressing part.

We don’t get new neurons.

After we’re born, we pretty much have the neurons

that we’re going to use our entire life.

And yes, as we get older

and we start to lose certain functions in our brain,

we lose neurons.

But all is not lost, so to speak,

because there are other ways in which neural circuits

can create new connections and add new functions,

including new memory, new abilities,

and new cognitive functions.

And those are mainly through the process

of making certain connections,

which of course are those things we call synapses,

between neurons, making those connections stronger

so they’re more reliable, they’re more likely to engage,

as well as removing connections.

And the removal of connections is vital

to say moving through a grieving process

or removing the emotional load of a traumatic experience.

So even though we can’t add new neurons

throughout our lifespan,

at least not in very great numbers,

it’s clear that we can change our nervous system,

that the nervous system is available for change,

that if we create the right set of circumstances

in our brain, chemical circumstances,

and if we create the right environmental circumstances

around us, our nervous system will shift into a mode

in which change isn’t just possible, but it’s probable.

As I mentioned before,

the hallmark of the child nervous system is change.

It wants to change.

The whole thing, everything from the chemicals

that are sloshing around in there,

to the fact that there’s a lot of space between the neurons,

a lot of people don’t know this,

but early in development,

there’s a lot of space between the neurons,

and so the neurons can literally move around

and sample different connections very easily,

removing some and keeping others.

As we get older, the so-called extracellular space

is actually filled up by things called extracellular matrix

and glial cells, glia means glue,

those cells are involved in a bunch of different processes,

but they start to fill in all the space,

kind of like pouring concrete between rocks,

and when that happens,

it becomes much harder to change the connections

that are there.

One of the ways in which we can all get plasticity

at any stage throughout the lifespan

is through deficits and impairments

in what we call our sensory apparati,

our eyes, our ears, our nose, our mouth,

and there are some very dramatic

and somewhat tragic examples of people,

for instance, who have genetic mutations

where they are born without a nose

and without any olfactory structures in the brain,

so they cannot smell.

In that case, areas of the brain

that normally would represent smell

become overtaken by areas of the brain

involved in other things like touch and hearing and sight.

In individuals that are blind from birth,

the so-called occipital cortex,

the visual cortex in the back,

becomes overtaken by hearing.

The neurons there will start to respond to sounds

as well as braille touch,

and actually, there’s one particularly tragic incident

where a woman who was blind since birth

and because of neuroimaging studies,

we knew her visual cortex was no longer visual,

it was responsible for braille reading and for hearing,

she had a stroke that actually took out

most of the function of her visual cortex,

so then she was blind, she couldn’t braille read or hear.

She did recover some aspect of function.

Now, most people, they don’t end up

in that highly unfortunate situation,

and what we know is that, for instance,

blind people who use their visual cortex

for braille reading and for hearing

have much better auditory acuity and touch acuity,

meaning they can sense things with their fingers

and they can sense things with their hearing

that typical sighted folks wouldn’t be able to.

In fact, you will find a much greater incidence

of perfect pitch in people that are blind,

and that tells us that the brain,

and in particular, this area we call the neocortex,

which is the outer part,

is really designed to be a map

of our own individual experience.

So these, what I call experiments of impairment or loss

where somebody is blind from birth or deaf from birth

or maybe has a limb development impairment

where they have a stump instead of an entire limb

with a functioning hand,

their brain will represent the body plan that they have,

not some other body plan.

But the beauty of the situation

is that the real estate up in the skull, that neocortex,

the essence of it is to be a customized map of experience.

Now, it is true, however, that if,

let’s say I were to be blind when I’m 50,

I’m 45 right now, I’ve always been sighted.

If I was blind at 50,

I’ll probably have less opportunity

to use my formerly visual cortex

for things like braille reading and hearing

because my brain has changed.

It’s just not the same brain I had when I was a baby.

So there’s actually a principle of biology.

Not many people know this.

It’s actually a principle of neurology,

which is called the Kennard principle,

which says if you’re going to have a brain injury,

you want to have it early in life.

Of course, better to not have a brain injury at all,

but if you’re going to have it,

you want to have it early in life.

And this is based on a tremendous number of experiments

examining the amount of recovery

and the rate of recovery in humans

that had lesions to their brain

either early in life or later in life.

So the Kennard principle says

better to have injuries early in life.

Now, that’s reassuring for the young folks.

It’s not so reassuring for the older folks,

but there are aspects of neuroplasticity

that have nothing to do with impairments.

I mean, earlier I said,

we’re all walking around with this map,

this representation of the world around us.

So we can see edges, we can see colors,

except for folks that are colorblind, of course.

And we also have a map of emotional experience.

We have a map of whether or not

certain people are trustworthy,

certain people aren’t trustworthy.

A few years ago, I was at a course

and a woman came up to me and she said,

I wasn’t teaching the course, I was in the course.

And she said, I just have to tell you

that every time you speak, it really stresses me out.

And I said, well, I’ve heard that before,

but do you want to be more specific?

And she said, yeah, your tone of voice

reminds me of somebody

that I had a really terrible experience with.

I said, well, okay, well, I can’t change my voice,

but I really appreciate that you acknowledge that.

And it also will help explain

why you seem to cringe every time I speak,

which I hadn’t noticed until then.

But after that, I did notice she had a very immediate

and kind of visceral response to my speech.

Perhaps some of you are having that right now.

But in any event, over the period of this two-week course,

she would come back every once in a while and say,

you know what, I think just by telling you

that your voice was really difficult for me to listen to,

it’s actually becoming more tolerable to me.

And by the end, we actually became pretty good friends

and we’re still in touch.

And so what this says is that the recognition of something,

whether or not that’s an emotional thing

or a desire to learn something else,

is actually the first step in neuroplasticity.

And that’s because our nervous system

has two broad sets of functions.

Some of those functions are reflexive,

things like our breathing, our heart rate, our obvious ones.

But other aspects are reflexive, like our ability to walk.

If I get up out of this chair and walk out of the door,

I don’t think about each step that I’m taking.

And that’s because I learned how to walk during development.

But when we decide that we’re going to shift

some sort of behavior or some reaction

or some new piece of information that we want to learn

is something that we want to bring into our consciousness,

that awareness is a remarkable thing

because it cues the brain and the rest of the nervous system

that when we engage in those reflexive actions going forward,

that those reflexive actions

are no longer fated to be reflexive.

Now, if this sounds a little bit abstract,

we’re going to talk about protocols for how to do this.

But the first step in neuroplasticity

is recognizing that you want to change something.

And you should immediately say,

well, kids don’t go into school and say,

oh, I want to learn language

or I want to learn social interactions.

And that’s the beauty of childhood.

The whole brain has this switch flipped

that is making change possible.

But after that, we have to be deliberate.

We have to know what it is exactly that we want to change.

Or if we don’t know exactly what it is

that we want to change,

we at least have to know

that we want to change something

about some specific experience.

In this case, I believe that she came and told me

that my voice was really awful for her to listen to,

not to make me feel bad or for any other reason,

except that she wanted it to not be the case.

And she knew I wasn’t going to stop talking.

So she decided to call it

to her consciousness and mine as well.

So that’s important.

If you want to learn something

or you want to change your nervous system in any way,

whether or not it’s because of some impairment

or because of something that you want to acquire,

a cognitive skill, a motor skill, an emotional skill,

the first thing is recognizing what that thing is.

And that often can be the hardest thing to identify.

But the brain has these self-recognition mechanisms.

And those self-recognition mechanisms are not vague,

spiritual, or mystical, or even psychological concepts.

They are neurochemicals.

We’re going to talk next about the neurochemicals

that stamp down particular behaviors

and thoughts and emotional patterns

and tell the rest of the nervous system,

this is something to pay attention to,

because this is in the direction of the change

that I want to make.

So I’ll repeat that.

There are specific chemicals

that when we are consciously aware

of a change we want to make,

or even just that we want to make some change,

chemicals are released in the brain

that allow us the opportunity to make those changes.

Now, there are specific protocols

that science tells us we have to follow

if we want those changes to occur.

But that self-recognition is not a kind of murky concept.

What it is, is it’s our forebrain,

in particular, our prefrontal cortex,

signaling the rest of our nervous system

that something that we’re about to do, hear, feel,

or experience is worth paying attention to.

So we’ll pause there, and then I’m going to move forward.

One of the biggest lies in the universe

that seems quite prominent right now

is that every experience you have changes your brain.

People love to say this.

They love to say,

your brain is going to be different after this lecture,

that your brain is going to be different

after today’s class than it was two days ago.

And that’s absolutely not true.

The nervous system doesn’t just change

because you experience something,

unless you’re a very young child.

The nervous system changes

when certain neurochemicals are released

and allow whatever neurons are active in the period

in which those chemicals are swimming around

to strengthen or weaken the connections of those neurons.

Now, this is best illustrated

through a little bit of scientific history.

The whole basis of neuroplasticity

is essentially ascribed to two individuals,

although there were a lot more people

that were involved in this work.

Those two individuals go by the name

David Hubel and Torsten Wiesel.

David Hubel and Torsten Wiesel

started off at Johns Hopkins,

moved to Harvard Medical School.

And in the 70s and 80s,

they did a series of experiments

recording electrical activity in the brain.

They were in the visual cortex,

meaning they put the electrodes in the visual cortex.

And they were exploring how vision works

and how the visual brain organizes

all the features of the visual world

to give us these incredible things

we call visual perceptions.

But Hubel was a physician

and he was very interested in what happens

when, for instance, a child comes into the world

and they have a cataract.

The lens of their eye isn’t clear, but it’s opaque.

Or when a kid has a lazy eye

or the eyes have what’s called strabismus,

which is when the eyes either deviate outward or inward.

These are very common things of childhood,

especially in particular areas of the world.

And what David and Torsten did is they figured out

that there was a critical period

in which if clear vision did not occur,

the visual brain would completely rewire itself

basically to represent

whatever bit of visual information was coming in.

So they did these experiments

that kind of simulate a droopy eye or a deviating eye

where they would close one eyelid.

And then what they found is that the visual brain

would respond entirely to the open eye.

There was sort of a takeover of the visual brain

representing the open eye.

Many experiments in many different sensory systems

followed up on this.

There are beautiful experiments, for instance,

from Greg Rechenzone’s lab up at UC Davis

and Mike Merzenich’s labs at UCSF

showing that for instance,

if two fingers were taped together early in development,

so they weren’t moving independently,

the representation of those two fingers

would become fused in the brain

so that the person couldn’t actually distinguish

the movements and the sensations

of the two fingers separately.

Pretty remarkable.

All of this is to say that David and Torsten’s work

for which they won a Nobel prize,

they shared it with Roger Sperry,

their work showed that the brain is in fact

a customized map of the outside world,

we said that already,

but that what it’s doing is it’s measuring

the amount of activity for a given part of our body,

one eye or the other,

or our fingers, this finger or that finger,

and all of those inputs are competing

for space in the brain.

Now, this is fundamentally important

because what it means is that

if we are to change our nervous system in adulthood,

we need to think about not just what we’re trying to get,

but what we’re trying to give up.

We can’t actually add new connections

without removing something else.

And that might seem like kind of a stinger,

but it actually turns out to be a great advantage.

One of the key experiments that David and Torsten did

was an experiment where they closed both eyes,

where they essentially removed all visual input

early in development.

Now, this is slightly different than blindness

because it was transient,

it was only for a short period of time,

but what they found is when they did that,

there was no change.

However, if they closed just one eye,

there was a huge change.

So when people tell you,

oh, at the end of today’s lecture,

or at the end of something,

your brain is going to be completely different,

that’s simply not true.

If you’re older than 25,

your brain will not change

unless there’s a selective shift in your attention

or a selective shift in your experience

that tells the brain it’s time to change.

And those changes occur

through the ways I talked about before,

strengthening and weakening of particular connections.

They have names like long-term potentiation,

long-term depression,

which has nothing to do with emotional depression,

by the way, spike timing dependent plasticity.

I threw out those names not to confuse you,

but for those of you that would like

more in-depth exploration of those,

please, you can go Google those and look them up.

There are great Wikipedia pages for them

and you can go down the paper trail.

I might even touch on them in some subsequent episodes.

But the important thing to understand

is that if we want something to change,

we really need to bring an immense amount of attention

to whatever it is that we want to change.

This is very much linked to the statement I made earlier

about it all starts with an awareness.

Now, why is that attention important?

Well, David and Tornstein won their Nobel prize

and they certainly deserved it.

They probably deserve two

because they also figured out how vision works.

And I might be biased

because they’re my scientific great-grandparents,

but I think everybody in the field of neuroscience agrees

that Hubel and Wiesel, as they’re called,

H and W for those in the game,

absolutely deserved a Nobel prize for their work

because they really unveiled the mechanisms

of brain change, of plasticity.

David passed away a few years ago.

Tornstein’s still alive.

He’s in his late nineties.

He’s still at the Rockefeller University.

He’s sharp as a tack.

He still jogs several miles a day.

He’s really into art and a number of other things.

He’s also a super nice guy.

Hubel was a really nice guy as well.

Also, he was a great Frisbee player, I discovered,

because he beat me in a game of ultimate

when he was like 80,

which still has me a little bit irked.

But anyway, Hubel and Wiesel did an amazing thing

for science that will forever change the way

that we think about the brain.

However, they were quite wrong

about this critical period thing.

The critical period was this idea

that if you were to deprive the nervous system of an input,

say closing one eye early in development

and the rest of the visual cortex is taken over

by the representation of the open eye,

that you could never change that unless you intervened early.

And this actually formed the basis

for why a kid that has a lazy eye or a cataract,

why even though there’s some issues

with anesthesia in young children,

why now we know that you want to get in there early

and fix the cataract or fix the strabismus,

that’s what ophthalmologists do.

However, their idea that you had to do it early

or else there was no opportunity

to rescue the nervous system deficit later on,

turned out wasn’t entirely true.

In the early 90s, a graduate student

by the name of Greg Reckonzone was in the laboratory

of a guy named Mike Merzenich at UCSF.

And they set out to test this idea

that if one wants to change their brain,

they need to do it early in life

because the adult brain simply isn’t plastic,

it’s not available for these changes.

And they did a series of absolutely beautiful experiments.

By now, I think we can say proving

that the adult brain can change

provided certain conditions are met.

Now, the experiments they did are tough.

They were tough on the experimenter

and they were tough on the subject.

I’ll just describe one.

Let’s say you were a subject in one of their experiments.

You would come into the lab and you’d sit down at a table

and they would record from or image your brain

and look at the representation of your fingers,

the digits as we call them.

And there would be a spinning drum,

literally like a stone drum in front of you

or metal drum that had little bumps.

Some of the bumps were spaced close together,

some of them were spaced far apart.

And they would do these experiments

where they would expect their subjects to press a lever

whenever, for instance, the bumps got closer together

or further apart.

And these were very subtle differences.

So in order to do this,

you really have to pay attention

to the distance between the bumps.

And these were not braille readers

or anyone skilled in doing these kinds of experiments.

What they found was that as people paid

more and more attention to the distance between these bumps,

and they would signal when there was a change

by pressing a lever,

as they did that, there was very rapid changes,

plasticity in the representation of the fingers.

And it could go in either direction.

You could get people very good

at detecting the distance between bumps

that the distance was getting smaller

or the distance was getting greater.

So people could get very good at these tasks

that are kind of hard to imagine

how they would translate to the real world

for a non-braille reader.

But what it told us is that these maps of touch

were very much available for plasticity.

And these were fully adult subjects.

They’re not taking any specific drugs.

They don’t have any impairments that we’re aware of.

And what it showed,

what it proved is that the adult brain is very plastic.

And they did some beautiful control experiments

that are important for everyone to understand,

which is that sometimes they would bring people in

and they would have them touch these bumps

on this spinning drum,

but they would have the person pay attention

to an auditory cue.

Every time a tone would go off

or there was a shift in the pitch of that tone,

they would have to signal that.

So the subject thought they were doing something

related to touch and hearing.

And all that showed was that it wasn’t just the mere action

of touching these bumps.

They had to pay attention to the bumps themselves.

If they were placing their attention

on the auditory cue on the tone,

well, then there was plasticity

in the auditory portion of the brain,

but not on the touch portion of the brain.

And this really spits in the face of this thing

that you hear so often,

which is every experience that you have

is going to change the way your brain works.

Absolutely not.

The experiences that you pay super careful attention to

are what open up plasticity.

And it opens up plasticity to that specific experience.

So the question then is why?

And Merzenich and his graduate students and postdocs

went on to address this question of why.

And it turns out the answer

is a very straightforward neurochemical answer.

And inside of that answer is the opportunity

for any of us to change our brain at any point

throughout our lifespan,

essentially for anything that we want to learn.

That could be subtracting an emotion

from an experience we’ve had.

It could be building a greater range of emotion.

It could be learning new information,

like learning a new language.

It could be learning new motor skill,

like dance or sport,

or it could be some combination of cognitive motor.

So for instance, an air traffic controller

has to do a lot with their mind

in addition to a lot with their hands.

So it’s not just cognitive,

it’s not just motor, but combined.

So we’re going to talk about what that chemical is,

but to just give you an important hint,

that chemical is the same chemical of stress.

This is not a discussion about stress per se.

In a future podcast episode,

we’ll talk all about stress and tools to deal with stress.

It’s something my lab works on quite extensively.

And it’s a topic that I enjoy discussing.

But this is a topic about brain change.

And what I just told you is that

in order to change the brain,

you have to pay careful attention.

And the immediate question should be, well, why?

Well, the answer is that when we pay careful attention,

there are two neurochemicals,

neuromodulators as they’re called,

that are released from multiple sites in our brain

that highlight the neural circuits

that stand a chance of changing.

Now, it’s not necessarily the case

that they’re going to change,

but it’s the first gate that has to open

in order for change to occur.

And the first neurochemical is epinephrine, also adrenaline.

We call it adrenaline when it’s released

from the adrenal glands above our kidneys.

That’s in the body.

We call it epinephrine in the brain,

but they are chemically identical substances.

Epinephrine is released from a region in the brainstem

called locus coeruleus.

Fancy name, you don’t need to know it unless you want to.

Locus coeruleus sends out these little wires we call axons

such that it hoses the entire brain essentially

in this neurochemical epinephrine.

Now, it’s not always hosing the brain with epinephrine.

It’s only when we are in high states of alertness

that this epinephrine is released.

But the way this circuit is designed,

it’s very nonspecific.

It’s essentially waking up the entire brain.

That’s because the way that epinephrine works

by binding particular receptors

is to increase the likelihood that neurons will be active.

So no alertness, no neuroplasticity.

However, alertness alone is not sufficient.

As we would say, it’s necessary

but not sufficient for neuroplasticity.

We know this is true also from the work of Hubel and Wiesel

where they looked at brain plasticity

in response to certain experiences

in subjects that were either awake or asleep.

And I hate to break it to you,

but you cannot just simply listen to things in your sleep

and learn those materials.

Later, I’ll talk about how you can do certain things

in your sleep that you’re unaware of

that can enhance learning of things

that you were aware of while you were awake.

But that is not the same as just listening to some music

or listening to a tape while you sleep

and expecting it to sink in, so to speak.

Epinephrine is released when we pay attention

and when we are alert.

But the most important thing for getting plasticity

is that there be epinephrine, which equates to alertness,

plus the release of this neuromodulator acetylcholine.

Now, acetylcholine is released from two sites in the brain.

One is also in the brainstem,

and it’s named different things in different animals,

but in humans, the most rich site of acetylcholine neurons

or neurons that make acetylcholine

is the parabigeminal nucleus or the parabrachial region.

There are a number of different names

of these aggregates of neurons.

You don’t need to know the names.

All you need to know

is that you have an area in your brainstem

and that area sends wires, these axons,

up into the area of the brain that filters sensory input.

So we have this area of the brain called the thalamus,

and it is getting bombarded

with all sorts of sensory input all the time.

Costello’s snoring off to my right,

the lights that are in the room,

the presence of my computer to my left.

All of that is coming in.

But when I pay attention to something,

like if I really hone in on Costello’s snoring,

I create a cone of attention.

And what that cone of attention reflects

is that acetylcholine is now amplifying the signal

of sounds that Costello is making with his snoring

and essentially making that signal greater

than all the signal around it.

What we call signal-to-noise goes up.

So those of you with an engineering background

will be familiar with signal-to-noise.

Those of you who do not have an engineering background,

don’t worry about it.

All it means is that one particular shout

in the crowd comes through,

Costello’s snoring becomes more salient,

more apparent relative to everything else going on.

Acetylcholine acts as a spotlight.

But epinephrine, for alertness,

acetylcholine spotlighting these inputs,

those two things alone are not enough to get plasticity.

There needs to be this third component.

And the third component is acetylcholine released

from an area of the forebrain called nucleus basalis.

If you really want to get technical,

it’s called nucleus basalis of my nert.

For any of you that are budding physicians

or going to medical school, you should know that.

If you have acetylcholine released from the brainstem,

acetylcholine released from nucleus basalis and epinephrine,

you can change your brain.

And I can say that with confidence

because Merzenich and Reckinzone,

as well as other members of the Merzenich lab,

Michael Kilgard and others,

did these incredible experiments

where they stimulated the release of acetylcholine

from nucleus basalis, either with an electrode

or with some other methods that we’ll talk about.

And what they found was when you stimulate

these three brain regions, locus coeruleus,

the brainstem source of acetylcholine,

and then the basal forebrain source of acetylcholine,

when you have those three things,

whatever you happen to be listening to,

doing or paying attention to,

immediately in one trial takes over the representation

of a particular area of the brain.

You essentially get rapid, massive learning in one shot.

And this has been shown again and again and again

in a variety of papers,

also by a guy named Norm Weinberger from UC Irvine.

And it is now considered a fundamental principle

of how the nervous system works.

So while Hubel and Wiesel talked about critical periods

in developmental plasticity,

it’s very clear from the work of Merzenich

and Weinberg and others,

that if you get these three things,

if you can access these three things

of epinephrine, acetylcholine from these two sources,

not only will the nervous system change, it has to change.

It absolutely will change.

And that is the most important thing

for people to understand if they want to change their brain.

You cannot just passively experience things.

And repetition can be important,

but the way to use repetition to change your brain

is fundamentally different.

So now let’s talk about how we would translate

all the scientific information and history

into some protocols that you can actually apply,

because I think that’s what many of you are interested in.

And I’m willing to bet that most of you

are not interested in lowering electrodes

into your nucleus basalis, and frankly, neither am I.

In episode one of the Huberman Lab podcast,

I described the various ways that people can monitor

and change their nervous system.

Those ways include brain machine interface,

pharmacology, behavioral practices,

and those behavioral practices, of course,

can include some dos, do this, and some don’ts,

don’t do that, et cetera.

In thinking about neuroplasticity,

I want to have a very frank conversation

about what one can do,

but also acknowledge this untapped capacity

that I’m just not hearing about out there,

which is one can also combine behavioral practices

with pharmacology.

One can combine behavioral practices

with brain machine interface.

And you don’t have to do that.

In fact, I’m not recommending you do anything in particular.

As always, I’ll say it again, I’m not a physician,

so I don’t prescribe anything.

I’m a professor, so I profess a lot of things.

What you do with your health and your medical care

is up to you.

You’re responsible for your health and wellbeing.

So I’m not going to tell you what to do or what to take.

I’m going to describe what the literature tells us

and suggests about ways to access plasticity.

We know we need epinephrine.

That means alertness.

Most people accomplish this through a cup of coffee

and a good night’s sleep.

So I will say you should master your sleep schedule

and you should figure out how much sleep you need

in order to achieve alertness when you sit down to learn.

All the tools and more science

than probably you ever wanted to hear about sleep

and how to get better at sleeping and timing your sleep,

et cetera, and naps, and all of that

is in episodes two, three, four, and five

of the Huberman Lab Podcast.

So I encourage you to refer to those

if your sleep is not where you would like it to be.

Your ability to engage in deliberate focused alertness

is in direct proportion to how well you are sleeping

on a regular basis.

I think that’s kind of an obvious one.

So get your sleep handled.

But once that’s in place,

the question then is how do I access this alertness?

Well, there are a number of ways.

Some people use some pretty elaborate

psychological gymnastics.

They will tell people that they’re going to do something

and create some accountability.

That could be really good.

Or they’ll post a picture of themselves online

and they’ll commit to losing a certain amount of weight

or something like this.

So they can use either shame-based practices

to potentially embarrass themselves

if they don’t follow through.

They’ll write checks to organizations that they hate

and insist that they’ll cash them

if they don’t actually follow through.

Or they’ll do it out of love.

They’ll decide that they’re going to run a marathon

or learn a language or something

because of somebody they love

or they want to devote it to somebody.

The truth is that from the standpoint of epinephrine

and getting alert and activated,

it doesn’t really matter.

Epinephrine is a chemical

and your brain does not distinguish

between doing things out of love or hate, anger, or fear.

It really doesn’t.

All of those promote autonomic arousal

and the release of epinephrine.

So I think for most people,

if you’re feeling not motivated to make these changes,

the key thing is to identify not just one

but probably a kit of reasons,

several reasons as to why you would want

to make this particular change.

And being drawn toward a particular goal

that you’re excited about can be one.

Also being motivated to not be completely afraid,

ashamed, or humiliated for not falling through

on a goal is another.

Just want to briefly mention one little aside there

because I’ve got a friend who’s a physician.

He’s a cardiologist who has a really interesting theory.

This is just theory,

but I think it will resonate with a lot of people,

which is that you’ve all heard of this molecule dopamine

that gives us this sense of reward

when we accomplish something.

Well, we also want to be able to access dopamine

while we’re working towards things.

Enjoy the process, as they say,

because it has all sorts of positive effects.

It gives us energy, et cetera.

With my friend, what he says is,

there’s many, many instances where someone will come to him

and say, you know what, I’m going to write a book.

And he says, oh, that’s great.

I’m sure the book’s going to be terrific

and you really should write a book.

And then they never go do it.

And his theory is if you get so much dopamine

from the reward of people saying,

oh yeah, you’re absolutely going to be able to do that,

you might not actually go after the reward

of the accomplishment itself.

So beware these positive reinforcements also.

Not saying people should flagellate themselves

to the point of victory in whatever they’re pursuing,

but motivation is a tricky one.

So I suggest that everyone asks themselves,

what is it that I want to accomplish?

And what is it that’s driving me to accomplish this?

And come up with two or three things,

fear-based perhaps, love-based perhaps,

or perhaps several of those,

in order to ensure alertness,

energy, and attention for the task.

And that brings us to the attention part.

Now, it’s one thing to have an electrode

embedded into your brain

and increase the amount of acetylcholine.

It’s another to exist in the real world

outside the laboratory and have trouble focusing,

having trouble bringing your attention

to a particular location in space for a particular event.

And there’s a lot of discussion nowadays

about smartphones and devices

creating a sort of attention deficit,

almost at a clinical level for many people,

including adults.

I think that’s largely true.

And what it means, however,

is that we all are responsible for learning

how to create depth of focus.

There are some important neuroscience principles

to get depth of focus.

I want to briefly talk about the pharmacology first,

because I always get asked about this.

People say, what can I take

to increase my levels of acetylcholine?

Well, there are things you can take.

Nicotine is called nicotine

because acetylcholine binds to the nicotinic receptor.

There are two kinds of acetylcholine receptors,

muscarinic and nicotinic,

but the nicotinic ones are involved

in attention and alertness.

I have colleagues, these are not my,

you know, kind of like bro science buddies.

I have those friends too.

This is a Nobel prize winning colleague

who chews Nicorette while he works.

He used to be a smoker.

He quit smoking because of fear of lung cancer.

So like a smart choice,

but he missed the level of focus

that he could bring to his work.

This is somebody who’s had a very long career.

And if you ever meet with him,

unfortunately I can’t name him.

If you ever meet with him,

what you realize is he chews

about five pieces of Nicorette an hour,

which I am not suggesting people do.

But when I asked him, why are you doing this?

He said, well, increases my alertness and focus.

And also his theory,

and I want to really underscore that it’s theory

not scientifically supported yet

is that it offsets Parkinson’s and Alzheimer’s.

It is true that nucleus basalis is the primary site

of degeneration in the brain

in people that have dementia and Parkinson’s.

And it’s what leads to a lot of their inability

to focus their attention,

not just deficits in plasticity.

So he might be onto something.

Now I’ve tried chewing Nicorette.

It makes me super jittery.

I don’t like it because I can’t focus very well.

It kind of takes me too far up

the level of autonomic arousal.

I’ve got friends that dip Nicorette all day,

some of whom are scientists,

writers and artists and musicians

are familiar with the effects of nicotine

from the era where a lot of people smoked

and fortunately fewer people smoke now.

So if you’re interested in the pharmacology,

there are supplements and things

that can increase cholinergic transmission in the brain.

I’m not suggesting you do this,

but if you’re going to go down that route,

you want to be very careful

how much you rely on those all the time,

because the essence of plasticity

is to create a window of attention and focus

that’s distinct from the rest of your day.

That’s what’s going to create a mark in your brain

and the potential for plasticity.

Things that increase acetylcholine besides nicotine

or Nicorette, the nicotine could come

from a variety of sources,

or things like alpha-GPC or choline.

There are a number of these things.

I would encourage you to go to examine.com, the website,

and just put in acetylcholine,

and it will give you a list of supplements

as well as some of the dangers of these supplements

that are associated with cholinergic transmission.

But I would be remiss and I would be lying

if I didn’t say that there are a lot of people out there

who are using cholinergic drugs

in order to increase their level of focus.

And since we’re coming up on the Olympics,

I don’t want to get anyone in trouble,

but I’m well aware that the fact that the sprinters

are really into cholinergic drugs

because not only is acetylcholine important

for the focus that allows them to hear the gun

and be first out the blocks on the sprints.

That’s a lot of where the race is won.

Hearing that gun and being quickest on reaction time.

So they take cholinergic agents for that.

As well as acetylcholine is the molecule

that controls nerve to muscle contraction.

So your speed of reflexes is actually controlled

by this nicotinic transmission as well.

So lots to think about in terms of acetylcholine in sport

and mental acuity, not just plasticity.

Now, for most of you,

you probably don’t want to chew Nicorette,

definitely don’t want to smoke cigarettes

or take supplements for increasing acetylcholine.

So what are some ways that you can increase acetylcholine?

And there it’s going to sound like a bit

of a circular argument, but you want to increase focus.

How do you increase focus?

You know, people are so familiar with sitting down,

reading a couple of pages of a book

and realizing that none of it sunk in.

We’re talking to someone and seeing their mouth move,

maybe even nodding your head subconsciously

and go, mm-hmm, mm-hmm.

And none of it sinks in.

This can be very damaging for school,

work performance and relationships, as many of you know.

Costello, incidentally, never seems to pay attention

to anything I say while looking directly at me,

which contradicts what I’m about to say,

which is that the best way to get better at focusing

is to use the mechanisms of focus that you were born with.

And the key principle here is that mental focus

follows visual focus.

We are all familiar with the fact that our visual system

can be unfocused, blurry, or jumping around,

or we can be very laser focused on one location in space.

What’s interesting and vitally important

to understanding how to access neuroplasticity

is that you can use your visual focus

and you can increase your visual focus

as a way of increasing your mental focus abilities

more broadly.

So I’m going to explain how to do that.

Plasticity starts with alertness.

And as I mentioned before,

that alertness can come from a sense of love,

a sense of joy, a sense of fear, doesn’t matter.

There are pharmacologic ways to access alertness too.

The most common one is, of course, caffeine,

which if you watch the sleep episodes,

you know reduces this molecule that makes us sleepy

called adenosine.

I drink plenty of caffeine.

I’m a heavy user of caffeine.

I don’t think abuser of caffeine.

I think in reasonable amounts,

provided we can still fall asleep at night,

caffeine can be a relatively safe way

to increase epinephrine.

Now, many people are now also using Adderall.

Adderall chemically looks a lot like amphetamine.

And basically it is amphetamine.

It will increase epinephrine release from locus coeruleus.

It will wake up the brain.

And that’s why a lot of people rely on it.

It does have a heavy basis for use

in certain clinical syndromes prescribed,

such as attention deficit.

However, it also has a high probability of abuse,

especially in those who are not prescribed it.

Adderall will not increase focus.

It increases alertness.

It does not touch the acetylcholine system.

And if those of you that are taking Adderall say,

well, it really increases my focus overall,

that’s probably because your autonomic nervous system

is just veering towards what we call parasympathetic.

You’re really just very sleepy.

And so it’s bringing your levels of alertness up.

As I mentioned, Adderall is very problematic

for a number of people.

It can be habit forming.

Learning on Adderall does not always translate

to high performance off or on Adderall at later times.

And the Adderall discussion is a broader one

that perhaps we should have

with a psychiatrist in the room at some point

because it is a very widely abused drug

at this point in time.

The acetylcholine system and the focus that it brings

is available, as I mentioned, through pharmacology,

but also through these behavioral practices.

And the behavioral practices that are anchored

in visual focus are going to be the ones

that are going to allow you to develop great depth

and duration of focus.

So let’s think about visual focus for a second.

When we focus on something visually, we have two options.

We can either look at a very small region of space

with a lot of detail and a lot of precision,

or we can dilate our gaze and we can see big pieces

of visual space with very little detail.

It’s a trade-off.

We can’t look at everything at high resolution.

This is why we have the pupil more or less relates

to the fovea of the eye, which is the area

in which we have the most receptors,

the highest density of receptors that perceive light.

And so our acuity is much better in the center

of our visual field than in our periphery.

It’s a simple experiment you can do right now.

If you’re listening to this, you can still do it.

You can hold your hands out in front of you,

provided that you’re sighted, you should be able

to see how many fingers you have in front of you.

For me, it’s five, still got all five fingers,

amazingly enough.

If I move my hand off to the side,

I can’t see them with precision, but as I move them back

into the center of my visual field,

I can see them with precision.

And that’s because the density, the number of pixels

in the center of my visual field is much higher

than it is in the periphery.

When we focus our eyes, we do a couple things.

First of all, we tend to do that in the center

of our visual field, and our two eyes tend to align

in what’s called a vergence eye movement

towards a common point.

The other thing that happens is the lens of our eye moves

so that our brain now no longer sees the entire visual world

but is seeing a small cone of visual imagery.

If it, that was the dog bumping into the wall, forgive me.

That small cone of visual imagery

or soda straw view of the world has much higher acuity,

higher resolution than if I were to look at everything.

Now you say, of course, this makes perfect sense,

but that’s about visual attention, not mental attention.

Well, it turns out that focus in the brain

is anchored to our visual system.

I’ll talk about blind people in a moment,

but assuming that somebody is sighted,

the key is to learn how to focus better visually

if you want to bring about higher levels

of cognitive or mental focus,

even if you’re engaged in a physical task.

Now, there’s a remarkable phenomenon in animals

where animals that have their eyes on the side of their head

are scanning the entire visual environment all the time.

They’re not focused on anything.

Think you’re grazing animals, your cows, your sheep,

your birds, et cetera.

But think about a bird picking up seeds on the beach

or on concrete.

That bird’s head is up here.

It’s up about a foot off the ground,

or if it’s a small bird, about six inches off the ground,

and its eyes are on the side of its head,

and yet it has this tiny beak that can quickly pick up

these little seeds off the ground with immense precision.

Now, if you try to do that

by staring off to the sides of the room

and picking up items in front of you with high precision

at that tiny scale, little tiny objects,

you will miss almost every time.

They do it perfectly,

and they don’t smash their beak into the ground

and damage it.

They do it with beautiful movement acuity also.

So how do they do it?

How do they create this focus

or this awareness of what’s in front of them?

It turns out as they lower their head,

their eyes very briefly move inward

in what’s called a virgin’s eye movement.

Now, their eyes can’t actually translocate in their head.

They’re fixed in the skull, just like yours and mine are.

But when we move our eyes slightly inward,

maybe you can tell that I’m doing it like so,

basically shortening or making the interpupillary distance,

as it’s called, smaller, two things happen.

Not only do we develop a smaller visual window

into the world,

but we activate a set of neurons in our brainstem

that trigger the release of both norepinephrine,

epinephrine, and acetylcholine.

Norepinephrine is kind of similar to epinephrine.

So in other words, when our eyes are relaxed in our head,

when we’re just kind of looking

at our entire visual environment,

moving our head around, moving through space,

we’re in optic flow, things moving past us,

or we’re sitting still,

we’re looking broadly at our space, we’re relaxed.

When our eyes move slightly inward

toward a particular visual target,

our visual world shrinks,

our level of visual focus goes up,

and we know that this relates

to the release of acetylcholine and epinephrine

at the relevant sites in the brain for plasticity.

Now, what this means is that

if you have a hard time focusing your mind

for sake of reading or for listening,

you need to practice,

and you can practice, focusing your visual system.

Now, this works best

if you practice focusing your visual system

at the precise distance from the work

that you intend to do for sake of plasticity.

So how would this look in the real world?

Let’s say I am trying to concentrate

on something related to, I don’t know, science.

I’m reading a science paper,

and I’m having a hard time, it’s not absorbing.

I might think that I’m only looking

at the paper that I’m reading.

I’m only looking at my screen,

but actually, my eyes are probably darting around a bit.

Experiments have been done on this.

Or I’m gathering information

from too many sources in the visual environment.

Now, presumably, because it’s me,

I’ve already had my coffee, I’m hydrated,

I’m well-rested, I slept well,

and I still experience these challenges in focusing.

Spending just 60 to 120 seconds

focusing my visual attention on a small window of my screen,

meaning just on my screen with nothing on it,

but bringing my eyes to that particular location

increases not just my visual acuity for that location,

but it brings about an increase in activity

in a bunch of other brain areas that are associated

with gathering information from this location.

So put simply, if you want to improve your ability to focus,

practice visual focus.

Now, if you wear contacts or you wear corrective lenses,

that’s fine.

You, of course, would want to use those.

You don’t want to take those off and use a blurry image.

The finer the visual image,

and the more that you can hold your gaze

to that visual image,

the higher your levels of attention will be.

Many times on Instagram and here,

I’ve been teased for not blinking very often.

That’s actually a practiced thing.

We blink more as we get tired, which, as you hear it,

you’ll probably just say, duh.

As we get tired, the neurons in the brainstem

that are responsible for alertness

and that hold the eyelids open start to falter

and our eyelids start to close.

This is why it’s hard.

The words, I could barely keep my eyes open,

which may be how you feel right now.

But assuming that you’re paying attention and you’re alert,

when you’re very alert, your eyes are wide.

Your eyes are open.

And as you get tired, your eyelids start to close.

Blinks actually reset our perception of time and space.

This was shown in a beautiful paper in Current Biology.

I’ll be sure to post the reference in the notes.

And blinking, of course, is necessary to lubricate the eyes.

People blink because their eyes might get dry.

But if you can keep focus by blinking less

and by focusing your eyes to a particular location,

it’s probably pretty creepy for you to experience

as I’m doing this.

But the more that you can do this,

the more that you can maintain a kind of a cone

or a tunnel of mental focus.

And so I’m sort of revealing my practice,

which is that I’ve worked very hard

through blinking contests with my 14-year-old niece

who still beats me every time and it really bothers me,

but also just through my own self-practice

of learning to blink less and focus my visual attention

on a smaller region of space.

Now, for me, that’s important

because I’m mainly learning things on a computer screen.

If you’re going to be doing sport,

it’s quite a bit different.

And we can discuss how you might translate that to sport.

In fact, in the next episode,

I’m going to talk all about how plasticity

and the focus mechanisms relate

to learning of movement practices and coordinated movements.

It’s an entire discussion unto itself,

but the same principle holds.

So we need alertness.

You can get that through mental tricks of motivation,

fear or love, whatever it is.

Pharmacology, please do it healthfully.

Caffeine, if that’s in your practice.

Certainly want to be well hydrated.

That actually will increase alertness.

Having a very full bladder will increase alertness,

although you don’t want your alertness to be so high.

Do that.

All you can think about is the fact

that you have to go urinate a bit

because that’s very distracting.

You don’t want your alertness to go through the roof.

You need focus and visual focus is the primary way

in which we start to deploy these neurochemicals.

Now, you may ask, well, what about the experiment

where people were feeling this rotating drum

or listening to the auditory cue?

That doesn’t involve vision at all.

Ah, if you look at people

who are learning things with their auditory system,

they will often close their eyes.

And that’s not a coincidence.

If somebody is listening very hard,

please don’t ask them to look you directly in the eye

while also asking that they listen to you.

That’s actually one of the worst ways

to get somebody to listen to you.

If you say, now, listen to me and look me in the eye,

the visual system will take over

and they’ll see your mouth move,

but they’re going to hear their thoughts

more than they’re going to hear what you’re saying.

Closing the eyes is one of the best ways

to create a cone of auditory attention.

And this is what low vision or no vision folks do.

They have tremendous capacity to focus their attention

in particular locations.

Incidentally, does anyone know the two animals

that have the best hearing in the world?

The absolute best hearing,

many orders of magnitude better than humans.

Turns out it’s the elephant.

That might not surprise you.

They have huge ears.

And the moth, which probably will surprise you.

I didn’t even know that moths could hear,

but now it explains why they’re so hard to catch.

If you are not sighted,

you learn how to do this with your hearing.

If you’re somebody who braille reads,

you learn how to do this with your fingers.

If you look at great piano players like Glenn Gould,

they oftentimes will turn their head to the side.

You think about some of the great musicians

that like Stevie Wonder that were blind, right?

He would look away

because he had no reason to look at the keys,

but oftentimes they’ll orient an ear

or one side of their head to the keys on the piano.

As I mentioned before,

people who are non-sighted have better pitch.

So we have these cones of attention that we can devote.

And for most people, vision is the primary way

to train up this focus ability and these cones of attention.

So you absolutely have to focus on the thing

that you’re trying to learn.

And you will feel some agitation

because of the epinephrine in your system.

If you’re feeling agitation and it’s challenging to focus

and you’re feeling like you’re not doing it right,

chances are you’re doing it right.

And you can practice this ability to stare

for long periods of time without blinking.

I know it’s a little eerie for people to watch,

but if your goal is to learn how to control

that visual window for sake of controlling your focus,

it can be an immensely powerful portal

into these mechanisms of plasticity

because we know it engages things like nucleus basalis

and these other brainstem mechanisms.

I get a lot of questions

about attention deficit hyperactivity disorder, ADHD,

and attention deficit disorder.

Some people actually have clinically diagnosed ADD and ADHD.

And if you do, you should certainly work

with a good psychiatrist to try and figure out

the right pharmacology and or behavioral practices for you.

Many people, however, have given themselves

a low-grade ADHD or ADD because of the way

that they move through their world.

They are looking at their phone a lot of the time.

It’s actually very easy to anchor your attention

to your phone for the following reason.

First of all, it’s very restricted in size.

It’s very easy to limit your visual attention

to something about this big.

It’s one of the design features of the phone.

The other is that just as you’ve probably heard,

a picture is worth a thousand words.

Well, a movie is worth 10,000 pictures.

Anytime we’re looking at things that have motion,

visual motion, our attentional system

will naturally gravitate towards those movies.

It’s actually much harder to read words on a page

than it used to be for many people

because we’re used to seeing things spelled out for us

in YouTube videos or videos where things move

and are very dramatic.

It is true that the more that we look

at those motion stimuli,

the more that we’re seeing movies of things

and things that are very dramatic and very intense,

the worse we’re getting at attending to things

like text on a page or to listening to something

like a podcast and extracting the information.

So much so that I think many people have asked me,

hey, why aren’t you providing intense visuals

for us to look at?

Well, frankly, it’s because a lot of people

are consuming this content through pure auditory,

through just by listening.

And I want them to be able to digest all the material.

But in addition to that,

if you think about the areas of life

that dictate whether or not we become successful,

independent, healthy individuals,

most of those involve the kind of boring practices

of digesting information on a page.

Boring because it’s not as exciting in the moment perhaps

as watching a movie or something being spoon-fed to us.

But the more attention that we can put to something,

even if it’s fleeting and we feel like

we’re only getting little bits and pieces,

shards of the information as opposed to the entire thing,

that has a much more powerful effect

in engaging this cholinergic system for plasticity

than does, for instance, watching a movie.

And that’s because when we watch a movie,

the entire thing can be great.

It can be awesome.

It can be this overriding experience.

But I think for all those experiences,

if you’re somebody who’s interested in building your brain

and expanding your brain

and getting better at various things,

feeling better, doing better, et cetera,

one has to ask how much of my neurochemical resources

am I devoting to the passive experience

of letting something just kind of overwhelm me

and excite me versus something

that I’m really trying to learn and take away.

And now there’s another,

I enjoy movie content and TV content all the time.

I scroll Instagram often,

but we are limited in the extent

to which we can grab a hold

of these acetylcholine release mechanisms or epinephrine.

And I think that we need to be careful

that we don’t devote all our acetylcholine and epinephrine,

all our dopamine for that matter,

to these passive experiences of things

that are not going to enrich us and better us.

So that’s a little bit of an editorial on my part,

but the phone is rich with movies.

It’s rich with information.

The real question is,

is the information rich for us in ways that grow us

and cultivate smarter, more emotionally,

you know, emotionally evolved people,

or is it creating,

what’s it doing for our physical wellbeing for that matter?

So I don’t want to tell people what to do or not to do,

but think carefully about

how often you’re focusing on something

and how good you are or poor you are

at focusing on something that’s challenging.

So once you get this epinephrine, this alertness,

you get the acetylcholine released

and you can focus your attention,

then the question is for how long?

And in an earlier podcast,

I talked about these ultradian cycles

that last about 90 minutes.

The typical learning bout should be about 90 minutes.

I think that learning bout will no doubt include

five to 10 minutes of warmup period.

I think everyone should give themselves permission

to not be fully focused in the early part of that bout,

but that in the middle of that bout,

for the middle hour or so,

you should be able to maintain focus for about an hour or so.

So that for me means eliminating distractions.

That means turning off the Wi-Fi.

I put my phone in the other room.

If I find myself reflexively getting up to get the phone,

I will take the phone and lock it in the car outside.

If I find myself going to get it anyway,

I am guilty of giving away the phone for a period of time

or even things more dramatic.

I’ve thrown it up on my roof before,

so I can’t get to it till the end of the day.

That thing is pretty compelling

and we come up with all sorts of reasons

why we need it to be in contact with it.

But I encourage you to try experiencing what it is

to be completely immersed in an activity

where you feel the agitation

that your attention is drifting,

but you continually bring it back.

And that’s an important point,

which is that attention drifts, but we have to re-anchor it.

We have to keep grabbing it back.

And the way to do that, if you’re sighted,

is with your eyes.

That as your attention drifts and you look away,

you want to try and literally maintain visual focus

on the thing that you’re trying to learn.

Feel free to blink, of course,

but you can greatly increase your powers of focus

and the rates of learning,

which is anchored in all the work of Merz

and Eccles and Wiesel and others.

Now, that’s the trigger for plasticity.

But the real secret is that neural plasticity

doesn’t occur during wakefulness.

It occurs during sleep.

We now know that if you focus very hard on something

for about 90 minutes or so,

maybe you even do several bouts of that per day,

if you can do that.

Some people can,

some people can only do one focused bout of learning.

That night and the following nights while you sleep,

the neural circuits that were highlighted, if you will,

with acetylcholine transmission will strengthen

and other ones will be lost,

which is wonderful because that’s the essence of plasticity.

And what it means is that when you eventually wake up

a couple of days or a week later,

you will have acquired the knowledge forever,

unless you go through some process to actively unlearn it.

And we will talk about unlearning in a later episode.

So mastering sleep is key

in order to reinforce the learning that occurs.

But let’s say you get a really poor night of sleep

after a bout of learning.

Chances are if you sleep the next night

or the following night,

that learning will occur.

There’s a stamp in the brain

where this acetylcholine was released.

It actually marks those synapses neurochemically

and metabolically so that those synapses

are more biased to change.

Now, if you don’t ever get that deep sleep,

then you probably won’t get those changes.

There’s also a way in which you can bypass the need

for deep sleep, at least partially,

by engaging in what I call non-sleep deep rest,

these NSDR protocols.

But I just want to discuss the science of this.

There was a paper that was published

in Cell Reports last year

that shows that if people did,

it was a spatial memory task,

actually quite difficult one,

where they had to remember the sequence of lights

lighting up.

And if there are just two or three lights

in a particular sequence, it’s easy.

But as you get up to 15 or 16 lights

and numbers in the sequence,

it actually gets quite challenging.

If immediately after,

and it was immediately after the learning,

the actual performance of this task,

people took a 20-minute non-sleep deep rest protocol

or took a shallow nap,

so lying down, feet slightly elevated perhaps,

just closing their eyes, no sensory input.

The rates of learning were significantly higher

for that information

than were to just had a good night’s sleep

the following night.

So you can actually accelerate learning

with these NSDR protocols or with brief naps,

90 minutes or less.

So the key to plasticity in childhood is to be a child.

The key to plasticity in adulthood

is to engage alertness, engage focus,

and then to engage non-sleep deep rest

and deep sleep while you’re in your typical bout of sleep.

I always get asked,

how many bouts of learning can I perform?

Well, I know people that train up

these visual focus mechanisms

to the point where they can do

several 90-minute bouts throughout the day,

as many as three or four.

And some of them are also inserting

non-sleep deep rest as well.

Now that can get pretty tricky.

A lot of people find that they can recover best

from these intense bouts of focused learning

by doing some motor activity,

where you get into self-generated optic flow.

And that should make sense

if you’ve ever heard me lecture about stress,

which I’ve done a little bit in various podcasts.

When we are in a mode of self-generated optic flow,

like walking or running or cycling,

and things are just floating past us on our retina,

we’re not really looking anywhere in particular.

So this is the opposite of a tight window of focus.

When we do that,

there are areas of the brain like the amygdala,

which are involved in releasing epinephrine

and create alertness.

At the extremes, it creates fear, but certainly alertness.

Those all shut down.

So it’s its own form of non-sleep deep rest.

So some people find it much more pleasurable and practical

to engage in a focused bout of learning,

and then go do some activity

that involves what we would essentially call wordlessness,

where you’re not really thinking about much of anything.

And so for those of you that listen to audio books

or podcasts while you run,

you may want to consider whether or not

that’s how you want to spend your time.

I’d love it if you were listening to this podcast

while you run or cycle,

but I’m much more interested in you

actually getting the benefits of neuroplasticity

than just listening to me for sake of listening to me.

So for many people, letting the mind drift

where it’s not organized in thought

after a period of very deliberate focused effort

is the best way to accelerate learning

and depth of learning.

And there are good scientific data

to support these sorts of things,

including the Cell Reports paper

that I mentioned a few moments ago.

I want to synthesize some of the information

that we’ve covered up until now.

This entire month is about neuroplasticity.

Today’s episode has covered a lot,

but by no means has it covered all of the potential

for neuroplasticity and protocols for plasticity.

We will get into all of it,

but today I want to make sure that these key elements

that form the backbone of neuroplasticity

are really embedded in people’s minds.

First of all, plasticity occurs throughout the lifespan.

Early from birth until 25,

mere exposure to a sensory event can create plasticity.

That could be a good thing or a bad thing.

We’re going to talk about unlearning the bad stuff,

traumas, et cetera, in a subsequent episode this month.

If you want to learn as an adult, you have to be alert.

It might seem so obvious,

but I think a lot of people don’t think about

when in their 24-hour cycle they’re most alert.

There are four episodes devoted to that 24-hour cycle

and the cycles of alertness and sleep.

I encourage you to listen to those

if you haven’t had the opportunity to yet,

or just ask yourself, when during the day

do you typically tend to be most alert?

That will afford you an advantage

in learning specific things during that period of time.

So don’t give up that period of time

for things that are meaningless, useless,

or not aligned with your goals.

It’ll be a terrible time to get into passive observance

or just letting your time get soaked away by something.

That is a valuable asset.

That epinephrine released from your brainstem

is going to occur more readily at particular phases

of your 24-hour cycle than others

during the waking phase, of course.

You should know when those are.

And then you could start to think about

the behavioral practices,

maybe the pharmacologic practices

like caffeine, hydration, et cetera,

that will support heightened levels of alertness.

Attention is something that can be learned,

and attention is critical for creating that condition

where whatever it is that you are engaging in

will modify your brain in a way

that you won’t have to spend so much attention on it

going forward.

That’s the essence of plasticity,

that things will eventually become reflexive,

the language that you’re learning,

the motor movement, the cognitive skill,

the ability to suppress an emotional response

or to engage in emotional response,

depending on what your goals are

and what’s appropriate for you.

Increasing acetylcholine can be accomplished

pharmacologically through nicotine.

However, there are certain dangers

for many people to do that,

as well as a cost, a financial cost.

Learning how to engage the cholinergic system

through the use of the visual system,

practicing how long can you maintain focus

with blinks as you need them,

but how long can you maintain visual focus on a target,

just on a piece of paper set a few feet away in the room

or at the level of your computer screen?

These are actually things that people do in communities

where high levels of visual focus are necessary.

Now, the other way to get high levels of visual focus

and alertness is to have a panic

or to have a situation that’s very, very bad.

You will be immediately focused on everything

related to that situation, but that’s unfortunate.

What we’re really talking about here

is trying to harness the mechanisms of attention

and get better at paying attention.

You may want to do that with your auditory system,

not with your visual system,

either because you’re low vision or no vision,

or because you’re trying to learn something

that relates more to sounds than to what you see.

But for most people,

they’re trying to learn information, cognitive information,

or they’re trying to learn how to hear the nuance

in their partner’s explanations

of their emotionally challenging events, et cetera.

And just remember, by the way, what I said earlier,

which is that if you really want somebody to listen to you

and really hear what you’re saying and what’s underlying it,

you should not and cannot expect them

to look directly at you while you do that.

That’s actually going to limit their ability to focus.

I’m trying to rescue a few folks out there

who might be in this struggle.

I, of course, have never been in this struggle.

And that was supposed to be a joke.

I’m very familiar with that struggle.

But I know that one can get better at listening,

one can get better at learning,

one can get better at all sorts of things

by anchoring in these mechanisms.

Now, of course, you can also combine protocols.

You can decide to combine pharmacology

with these learning practices.

Many people in communities do that.

Many people are doing that naturally

by drinking their coffee right before they do their learning.

But I would also encourage you

to think about how long those learning bouts are.

If you think you have ADD or ADHD, see a clinician,

but you should also ask yourself,

are you giving up the best period of focus

that you have each day naturally

to some other thing like social media

or some other activity that doesn’t serve you well,

or are you devoting that period to the opportunity to learn?

You should also ask yourself

whether or not you’re trying to focus too much

for too long during the day.

I know some very high-performing individuals,

very high-performing in a variety of contexts,

and none of them are focused all day long.

Many of them take walks down the hallway,

sometimes mumbling to themselves

or not paying attention to anything else.

They go for bike rides, they take walks.

They are not trying to engage their mind

at maximum focus all the time.

Very few people do that

because we learn best in these 90-minute bouts

inside of one of these ultradian cycles.

And I should repeat again that within that 90-minute cycle,

you should not expect yourself to focus

for the entire period of one 90-minute cycle.

The beginning and end are going to be a little bit flickering

in and out of focus.

How do you know when one of these 90-minute cycles

is starting?

Well, typically when you wake up

is the beginning of the first 90-minute cycle,

but it’s not down to the minute.

You’ll be able to tap into your sense

of these 90-minute cycles

as you start to engage in these learning practices

should you choose.

And then, of course, getting some non-sleep deep rest

or just deliberate disengagement,

such as walking or running or just sitting,

eyes closed or eyes open, kind of mindlessly,

it might seem, in a chair,

just letting your thoughts move around

after a learning about will accelerate

the rate of plasticity that’s been shown

in quality peer-reviewed studies.

And then, of course, deep sleep.

And so what we can start to see

is that plasticity is your natural right early in life,

but after about age 25,

you have to do some work in order to access it.

But fortunately, these beautiful experiments

of Hubel and Wiesel and Merzenich and Weinberger

and others point in the direction

of what allows us to achieve plasticity.

It points to the neurochemicals and the circuits,

and we now have behavioral protocols

that allow us to do that.

I also really want to emphasize

that there’s an entire other aspect of behavioral practices

that will allow us to engage in plasticity

that don’t involve intense focus and emotionality,

but involve a lot of repetition.

So there’s another entire category of plasticity

that involves doing what seem like almost mundane things,

but doing them over and over again repeatedly

and incorporating the reward system that involves dopamine.

So today I talked about the kind of plasticity

that comes from extreme focus.

You would get that extreme focus and alertness naturally

through a hard or difficult event that you didn’t want.

That’s the kind of stinger,

but your brain is designed to keep you safe.

So it wants to get one trial learning

from things like touching a hot stove

or engaging with a really horrible person.

You can get incredible plasticity of positive experiences

of things that you want by engaging this high focus regime

and then rest, non-sleep, deep rest, and sleep.

And there’s another aspect of plasticity

which we will explore next episode,

as well as when we explore movement-based practices

for enhancing plasticity and plasticity of movement itself.

And those are not of the high attention

kind of high emotionality

or the intensity of the experiences that I described today.

Those are more about repetition and reward and repeat,

repetition, reward, repeat.

And they are used for a distinctly different category

of behavioral change, more of which relate to habits

as opposed to learning of particular types of information

that allow us to perform physically, cognitively,

or adjust our emotional system.

So I’m going to stop there.

I’m sure there are a lot of questions.

Please put your questions in the comment section below.

And please remember that this entire month

we’re going to be exploring neuroplasticity.

So this discussion slash lecture,

I wish it was more of a back and forth,

but this is what the format offers us.

So please do put your questions in the comment section

and I will address them in the other episodes coming soon

on neuroplasticity.

As I say that, I’m reminded that many of you

are listening to this on Apple or Spotify,

and therefore there isn’t an opportunity to leave comments

aside from the rating section on Apple.

So if you have specific topics related to neuroplasticity

that you would like me to cover

in the subsequent episodes this month,

please go to the YouTube, subscribe,

but as well, please put your question

in the comment section for this episode

and I’ll be sure to read them and respond.

Many of you have very graciously asked

how you can help support the Huberman Lab podcast.

Best way to do that is to subscribe on YouTube.

You might want to also hit the notification button

so that you don’t miss any upcoming episodes.

Leave a comment.

As well, if you go to Apple,

you can give us a five-star rating

and there’s a place there

where also you can leave a comment.

And if you prefer to listen on Spotify,

subscribe and download on Spotify.

In addition, it’s always helpful if you recommend the podcast

to your friends and family and others

who you think might benefit from the information.

And as well, please check out our sponsors.

That’s a great way to help us.

And as mentioned at the beginning of today’s episode,

we are now partnered with Momentous Supplements

because they make single ingredient formulations

that are of the absolute highest quality

and they ship international.

If you go to livemomentous.com slash Huberman,

you will find many of the supplements

that have been discussed on various episodes

of the Huberman Lab podcast,

and you will find various protocols

related to those supplements.

Thanks so much for your time and attention.

And as always, thank you for your interest in science.

♪♪