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- Welcome to the Huberman Lab Podcast,
where we discuss science
and science-based tools
for everyday life.
I'm Andrew Huberman,
and I'm a Professor of
Neurobiology and Ophthalmology
at Stanford School of Medicine.
Today, my guest is Dr. Jack Feldman.
Dr. Jack Feldman
is a distinguished
Professor of Neurobiology
at the University of
California, Los Angeles.
He is known for his pioneering work
on the neuroscience of breathing.
We are all familiar with breathing
and how essential breathing is to life.
We require oxygen, and
it is only by breathing
that we can bring oxygen to all the cells
of our brain and body.
However, as the work from Dr. Feldman
and colleagues tells us,
breathing is also fundamental
to organ health and function
at an enormous number of other levels.
In fact, how we breathe,
including how often we breathe,
the depth of our breathing and the ratio
of inhales to exhales actually
predicts how focused we are,
how easily we get into sleep,
how easily we can exit from sleep.
Dr. Feldman gets credit for the discovery
of the two major brain
centers that control
the different patterns of breathing.
Today, you'll learn
about those brain centers
and the patterns of
breathing they control,
and how those different
patterns of breathing influence
all aspects of your
mental and physical life.
What's especially wonderful
about Dr. Feldman and his work
is that it not only points
to the critical role
of respiration in disease,
in health and in daily life,
but he's also a practitioner.
He understands how to
leverage particular aspects
of the breathing process
in order to bias the brain
to be in particular states
that can benefit us all.
Whether or not you are a person
who already practices breathwork,
or whether or not you're somebody
who simply breathes to stay alive,
by the end of today's discussion
you're going to understand
a tremendous amount
about how the breathing system works
and how you can leverage
that breathing system
toward particular goals in your life.
Dr. Feldman shares with us
his own particular breathing
protocols that he uses,
and he suggests different
avenues for exploring respiration
in ways that can allow you, for instance,
to be more focused for work,
to disengage from work
and high stress endeavors
to calm down quickly.
And indeed, he explains
not only how to do that,
but all the underlying science
in ways that will allow
you to customize your own
protocols for your needs.
All the guests that we bring
on The Huberman Lab Podcast
are considered at the
very top of their fields.
Today's guest, Dr. Feldman,
is not only at the top of his
field, he founded the field.
Prior to his coming into neuroscience
from the field of physics,
there really wasn't much information
about how the brain controls breathing.
There was a little bit of information,
but we can really credit Dr. Feldman
and his laboratory for identifying
the particular brain areas
that control different
patterns of breathing
and how that information can
be leveraged towards health,
high performance and
for combating disease.
So, today's conversation you're going
to learn a tremendous amount
from the top researcher in this field.
It's a really wonderful
and special opportunity
to be able to his knowledge with you,
and I know that you're not
only going to enjoy it,
but you are going to
learn a tremendous amount.
Before we begin, I'd like to
emphasize that 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'd like to thank the
sponsors of today's podcast.
Our first sponsor is Thesis.
Thesis as a company that makes nootropics.
Now, I've talked before on
the podcast and elsewhere
about the fact that I don't
really like the term nootropics,
which means smart drugs,
because smart means many different things
in many different contexts.
You've got creativity, you've got focus,
you've got task switching.
So, the idea that there will
be one pill or one formula
that could make us smarter and better
at all those things at once,
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In fact, different chemicals
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And that's the basis of Thesis.
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In other words, specific
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Thesis uses very high quality ingredients,
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I talked about those in the ADHD podcast.
Those are some of the ingredients
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There's a lot of research
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However, I can't take it.
When I take it, I get really bad headaches
and I know some people who do
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This is a great example
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Thesis gives you the ability
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So, they have a formulation for instance,
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In addition to that detailed
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I've been using Thesis for
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My favorite of the formulations
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Today's episode is also brought
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Today's episode is also
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Headspace is a meditation
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I've long been a believer in meditating.
There is so much data
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to reduced stress levels,
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It just goes on and on.
I mean, there are literally thousands
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The reason for that is
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One quick mention before we dive
into the conversation with Dr. Feldman.
During today's episode,
we discuss a lot of breathwork practices
and by the end of the episode,
all those will be accessible to you.
However, I'm aware that there are a number
of people out there that
want to go even further
into the science and
practical tools of breathwork.
And for that reason, I want
to mention a resource to you.
There is a cost associated
with this resource,
but it's a terrific platform
for learning about breathwork practices
and for building a number
of different routines
that you can do, or that you could teach.
It's called Our Breathwork Collective.
I'm not associated with
the Breathwork Collective,
but Dr. Feldman is an advisor to the group
and they offer daily live
guided breathing sessions
and an on-demand library
that you can practice any time
free workshops on breathwork.
And these are really developed
by experts in the field,
including Dr. Feldman.
So, as I mentioned, I'm not
on their advisory board,
but I do know them and their work
and it is of the utmost quality.
So anyone wanting to
learn or teach breathwork
could really benefit from
this course, I believe.
If you'd like to learn more,
you can click on the
link in the show notes
or visit ourbreathcollective.com/huberman,
and use the code Huberman at checkout.
And if you do that,
they're offering you
$10 off the first month.
Again, it's
ourbreathcollective.com/huberman
to access the Our Breath Collective.
And now for my conversation
with Dr. Jack Feldman.
Thanks for joining me today.
- It's a pleasure to be here, Andrew.
- Yeah, it's been a long time coming.
You're my go-to source for
all things respiration.
I mean, I breathe on my own,
but when I want to
understand how I breathe
and how the brain and breathing interact,
you're the person I call.
- Well, I'll do my best.
As you know, there's a lot
that we don't understand,
which still keeps me employed and engaged,
but we do know a lot.
- Why don't we start off by just talking
about what's involved
in generating breath.
And if you would, could
you comment on some
of the mechanisms for rhythmic breathing
versus non rhythmic breathing?
- Okay, so on the mechanical side,
which is obvious to everyone,
we want to have air flow in, inhale,
and we need to have air flow out
and the reason we need to do this
is because for body
metabolism, we need oxygen.
And when oxygen is utilized through
the aerobic metabolic process,
we produce carbon dioxide.
And so, we have to get
rid of the carbon dioxide
that we produce in particular
because the carbon dioxide affects
the acid base balance
of the blood, the pH,
and all living cells are very sensitive
to what the pH value is,
so your body is very interested
in regulating that pH.
So we have to have enough oxygen
for our normal metabolism,
and we have to get rid of
the CO2 that we produce.
So, how do we generate this air flow?
Well, the air comes into the lungs.
We have to expand the lungs
and as the lungs expand,
basically, it's like a balloon
that you would pull apart.
The pressure inside that balloon drops
and the air will flow into the balloon.
So we expand, put pressure on
the lungs to pull it apart,
that lowers the pressure in
the air sacks called alveoli
and air will flow in because
pressure outside the body
is higher than pressure inside the body
when you're doing this
expansion, when you're inhaling.
What produces that?
Well, the principle
muscle is the diaphragm,
which is sitting inside the
body just below the lung,
and when you want to inhale,
you basically contract the
diaphragm and it pulls it down.
And as it pulls it down,
it's inserting pressure
forces on the lung,
the lung wants to expand.
At the same time, the rib cage
is going to rotate up and out,
and therefore expanding the
cavity, the thoracic cavity.
At the end of inspiration,
under normal conditions
when you're aggressed,
you just relax and it's
like pulling on a spring.
You pull down a spring
and you let go and relax.
So, you inhale and you exhale.
Inhale, relax, and exhale.
- So, the exhale is passive?
- At rest it's passive.
We'll get into what happens
when you need to increase
the amount of air you're bringing in
because your ventilation,
your metabolism goes up
like during exercise.
Now the muscles themselves,
skeletal muscles don't do anything unless
the nervous system tells
them to do something.
And when the nervous system tells
them to do something, they contract.
So, there are specialized
neurons in the spinal cord,
and then above the spinal cord,
the region called the brainstem,
which go to respiratory muscles,
in particular for
inspiration in the diaphragm
and the external intercostal
muscles in the rib cage.
And they contract.
So, these respiratory muscles
these inspiratory muscles
become active and they become
active for a period of time,
then they become silent and
when they become silent,
the muscles then relax back to
their original resting level.
Where does that activity in these neurons
that innovate the muscle,
which are called motor neurons,
where does that originate?
Well, this was a question
that's been bandied around
for thousands of years,
and when I was a beginning
assistant professor,
it was fairly high priority for me
to try and figure that out,
because I wanted to understand
where this rhythm of
breathing was coming from
and you couldn't know
where it was coming from
until you knew where it was coming from.
And I didn't phrase that properly.
You couldn't understand
how it was being done
until you know where to look.
So, we did a lot of experiments,
which I can go into
detail and finally found,
there was a region in the brainstem,
that's once again this region
sort of above the spinal cord,
which was critical for
generating this rhythm.
It's called the pre-Botzinger complex.
And we can talk about how that was named.
This small site, which contains in humans,
a few thousand neurons,
it's located on either
side and works in tandem
and every breath begins with neurons
in this region beginning to be active,
and those neurons then connect ultimately
to these motor neurons
going to the diaphragm
and to the external
intercostals causing them
to be active and causing
this inspiratory effort.
When the neurons in the
pre-Botzinger complex finish
their burst of activity,
then inspiration stops and then you begin
to exhale because of this passive recoil
of the lung and rib cage.
- Could I just briefly
interrupt you to ask
a few quick questions
- Of course.
- before we move forward in
this very informative answer.
The two questions are,
is there anything known
about the activation
of the diaphragm and
the intercostal muscles
between the ribs as it relates
to nose versus mouth breathing,
or are they activated
in the equivalent way,
regardless of whether or not someone
is breathing through their nose or mouth?
- I don't think we fully
have the answer to that.
Clearly there are differences
between nasal and mouth breathing.
At rest the tendency is
to do nasal breathing
because the air flows that are necessary
for normal breathing as easily managed
by passing through the nasal cavities.
However, when your
ventilation needs to increase
like during exercise, you
need to move more air,
you do that through your
mouth because the airways
are much larger then,
and therefore you can move much more air,
but at the level of the
intercostals and the diaphragm,
their contraction is not,
is almost agnostic to whether or not
the nose and mouth are open.
- Okay, so if I understand correctly,
there's no reason to suspect
that there are particular,
perhaps even non
overlapping sets of neurons
in pre-Botzinger area of the brainstem
that triggered nasal versus mouth inhales?
- No, I would say that it's not
that the pre-Botzinger
complex is not concerned
and cannot influence that,
but it does not appear as
if there's any modulation
of whether or not it's where
the air is coming from,
whether it's coming through
your nasal passages or through your mouth.
- Great. Thank you.
And then the other question I have
is that these intercostal muscles
between the ribs then
move the ribs up and out
if I understand correctly,
and the diaphragm,
are those skeletal or
as the Brits would say,
skeletal muscles or smooth muscles?
What type of muscle are
we talking about here?
- As I said earlier, these are skeletal,
I didn't say there was skeletal muscles,
but they're muscles that need neural input
in order to move.
You talked about smooth muscles.
They are specialized muscles like we have
in the gut and in the heart,
and these are muscles that are capable
of actually contracting
and relaxing on their own.
So, the heart beats,
it doesn't need neural
input in order to beat.
The neural inputs modulate the strength
of it and the frequency,
but they beat on their own.
The skeletal muscles involved
in breathing need neural input.
Now, there are smooth muscles
that have an influence on breathing,
and these are muscles that
are lining the airways.
And so, the airways have smooth muscle
and when they become activated,
the smooth muscle can contract or relax,
and when they contract inappropriately
is when you have problems
breathing like in asthma.
Asthma is a condition
where you get inappropriate constriction
of the smooth muscles of the airways.
- So, there's no reason
to think that in asthma
that the pre-Botzinger or
these other neuronal centers
in the brain that activate breathing,
that they are involved or
causal for things like asthma?
- As of now, I would say the
preponderance of evidence
is that it's not involved,
but we've not really
fully investigated that.
- Thank you.
Sorry to break your flow,
but I was terribly
interested in knowing answers
to those questions and you
provided them, so thank you.
- Now, remind me again, where I was in my-
- We were just landing in pre-Botzinger
and we will return to the naming
of pre-Botzinger because it's a wonderful
and important story really,
that I think people should be aware of.
But maybe you could march
us through the brain centers
that you've discovered
and others have worked
on as well that control breathing,
pre-Botzinger as well
as related structures.
- Okay.
So, when we discovered the pre-Botzinger,
we thought that it was the primary source
of all rhythmic respiratory movements,
both inspiration and expiration.
Their notion of a single
source is like day or night.
It's like they're all coming,
they all have the same origin
that the Earth rotates
and day follows night
and we thought that the
pre-Botzinger complex
would be inhalation, exhalation.
And then in a series of experiments
we did in the early part of 2000,
we discovered that there
seemed to be another region
which was dominant in
producing expiratory movements,
that is the exhalation.
We had made a fundamental mistake
with the discovery of the pre-Botzinger,
not taking into account
that at rest expiratory muscle activity
or exhalation is passive.
So, if that's the case,
a group of neurons that might
generate active expiration,
that is to contract
the expiratory muscles,
like the abdominal muscles
or the internal intercostals
are just silent.
We just thought it wasn't,
the air was coming from one place,
but we got evidence that in fact,
it may have been coming
from another place.
And following up on these experiments,
we discovered that there
was a second oscillator
and that oscillator is involved
in generating what we
call active expiration.
That is this act of-
- If I go [exhales].
- Yeah [exhales], or when
you begin to exercise,
you have to go [panting], and
actually move that air out.
This group of cells,
which is silent at rest
suddenly becomes active
to drive those muscles,
and it appears that it's an
independent oscillator when-
- Maybe you could just clarify
for people what an oscillator is.
- Okay, an oscillator is
something that goes in a cycle.
So, you can have a pendulum
as an oscillator going back and forth.
The Earth is an oscillator
because it goes around
and it's day and night.
- Some people's moods are oscillating.
- Oscillating.
And it depends how regular they are.
You can have oscillators
that are highly regular
or that are in a watch,
or you can have those that
are sporadic or episodic.
Breathing is one of those oscillators
that for life has to be
working continuously 24/7.
It starts late in the third trimester
because it has to be
working when you're born,
and basically works throughout
life and if it stops,
if there's no intervention
beyond a few minutes,
it will likely be fatal.
- What is this second oscillator called?
- Well, we found that in a
region around the facial nucleus,
so we initially,
when this region was initially identified,
we thought it was involved
in sensing carbon dioxide.
It was what we call a
central chemo receptor.
That is, we want to keep
carbon dioxide levels,
particularly in the brain
at a relatively stable level
'cause the brain is
extraordinarily sensitive
to changes in pH.
If there's a big shift in carbon dioxide
there'll be a big shift in brain pH,
and that'll throw your brain,
if I can use the technical
term, out of whack.
And so, you want to regulate that
and the way to regulate
something in the brain
is you have a sensor in the brain.
And others basically identified
that the ventral surface of the brainstem,
that is the part of the
brainstem that's on this side,
was critical for that
and then we identified
a structure that was near
the trapezoid nucleus.
It was not named in any of
these noranatomical atlases,
so we just picked the name out of the hat
and we called it the
retro trapezoid nucleus.
- I should clarify for people.
When Jack is saying trapezoid,
it doesn't mean the trapezoid muscles.
Trapezoid refers to the
shape of this nucleus,
this cluster of neurons.
Parafacial makes me think
that this general area
is involved in something
related to mouth or face.
Is it an area rich with
neurons controlling other parts
of the face, eye blinks,
nose twitches, lip curls, lip smacks?
- If you go back in an evolutionary sense
and a lot of things that
are hard to figure out
begin to make sense when you look
at the evolution of the nervous system.
When control of facial muscles,
going back to more primitive creatures
because they had to take things
in their mouth for eating,
so we call that the
face sort of developed,
the eyes were there, the mouth is there,
these nuclei, the modem that
contained the motor neurons,
a lot of the control
systems for them developed
in the immediate vicinity.
So, if you think about the face,
there's a lot of sudden
nuclei around there
that had various roles
at various different times in evolution.
And at one point in evolution,
the facial muscles were
probably very important
in moving fluid in and out of the mouth
and moving air in and out of the mouth,
and so part of these
many different sub nuclei
now seems to be in mammals to be involved
in the control of expiratory muscles.
But we have to remember that mammals
are very special when
it comes to breathing,
because we're the only
class of vertebrates
that have a diaphragm.
If you look at amphibians and reptiles,
they don't have a diaphragm.
And the way they breathe is
not by actively inspiring
and passively expiring.
They breathe by actively
expiring and passively inspiring
because they don't have a
powerful inspiratory muscle.
And somewhere along the line,
the diaphragm developed,
and there are lots of theories
about how it developed.
I don't think it's particularly clear.
There was something that
you can find in alligators
and lizards that could
have turned into a muscle
that was the diaphragm.
The amazing thing about the diaphragm
is that it's mechanically
extremely efficient.
And what do I mean by that?
Well, if you look at how oxygen gets
from outside the body
into the bloodstream,
the critical passage is across
the membrane in the lung.
It's called the alveolar
capillary membrane.
The alveolus is part of the lung
and the blood runs through capillaries,
which are the smallest tubes
in the circulatory system.
And at that point,
oxygen can go from the air
filled alveolus into the blood.
- Which is amazing.
I find that amazing,
even though it's just purely mechanical,
the idea we had these
little sacks in our lungs,
we inhale and the air
goes in and literally
the oxygen can pass into the bloodstream-
- Passes into the bloodstream.
But the rate of which
it passes will depend
on the characteristics of the membrane,
what the distance is between the alveolus
and the blood vessel, the capillary.
But the key element is the surface area.
The bigger the surface area,
the more oxygen that can pass through,
it's entirely a passive process.
There's no magic about
making oxygen go in.
Now, how do you get a pack,
a large surface area in a small chest?
Well, you start out with one
tube, which is the trachea,
the trachea expands.
Now you have two tubes.
Then you have four tubes
and it keeps branching.
At some point, at the
end of those branches,
you put a little sphere,
which is an alveolus,
and that determines what the
surface area is going to be.
Now, you then have a mechanical problem.
You have the surface area,
you have to be able to pull it apart.
So, imagine you have a little
square of elastic membrane,
it doesn't take a lot of
force to pull it apart,
but now if you increase it by 50 times,
you need a lot more
force to pull it apart.
So, amphibians who were breathing,
not by compressing the lungs
and then just passively expanding it
weren't able to generate a lot of force,
so they have relatively few branches.
So, if you look at the surface area
that they pack in their lungs
relative to their body size,
it's not very impressive.
Whereas when you get to mammals,
the amount of branching that you have
is you have four to 500,000,000 alveoli.
- If we were to take
those four to 5,000,000-
- 100,000,000, four to 500,000,000.
- 100,000,000, excuse me,
and lay those out flat,