Welcome to Huberman Lab Essentials,

[music] where we revisit past episodes

for the most potent and actionable

science-based tools for mental health,

physical health, and performance.

I'm Andrew Huberman, and I'm a professor

of neurobiology and ophthalmology at

Stanford School of Medicine. Today we

are going to discuss your brain

chemistry and how to control and

optimize your brain chemistry for all

aspects of mental health, physical

health, and performance. The important

thing to know is that your brain and

your spinal cord and the rest of your

so-called nervous system

control all the organs of your body and

that all the organs of your body feed

back, meaning they communicate through

chemicals and other means to your

nervous system.

And vitally important is the fact that

which neural circuits are active and

which neural circuits are likely to be

less active at any given moment depends

on two major categories of chemicals. It

depends on hormones and it depends on

so-called neuromodulators.

And the four neuromodulators that we're

going to talk about today that are of

the utmost importance for your goals are

dopamine,

epinephrine, also called adrenaline,

serotonin, and acetylcholine. There are

many features of how neuromodulators

work, but for sake of today's

discussion, we only need to focus on two

of those features. And those are

fast-acting features and longer, slower

features or what we call baseline

features. Now, perhaps surprisingly, I'd

like to focus on the slow actions of the

neuromodulators first because those slow

actions of the neuromodulators are

happening in you and in me and in

everyone right now, and they set the

backdrop, the context in which the

various tools to manipulate dopamine,

epinephrine, serotonin, or acetylcholine

will work.

What do I mean by the context or the

backdrop, or the baseline? Well,

it's fair to say that most people are

awake during the daytime and asleep at

night. So, schedules of sleep and

wakefulness will vary, but in general,

everybody, regardless of whether or not

you're nocturnal, or you're so-called

diurnal, you're awake during the day,

pretty much everybody follows a schedule

in which from 0 to 9 hours after waking,

that is, from the time you wake up until

about 9 hours later,

the neuromodulators dopamine and

epinephrine tend to be at their highest

levels that they will be at any point in

the 24-hour period, in any period of the

day.

So, we can call this 0 to 9 hour period

phase one of the day, just for

simplicity. And I've referred to this

before in a previous episode, but not in

this exact context. From 9 to about 16

hours is what we will call phase two,

and that's when dopamine and epinephrine

levels tend to subside a bit compared to

the earlier phase one part of the day,

and serotonin levels start to increase.

And then, phase three of the 24-hour

cycle, which is from about, and again,

about, these are approximates, from

about 17 hours after waking until about

24 hours after waking, is phase three of

the day. We're not going to focus too

much on phase three today, because phase

three of the 24-hour cycle, that 17 to

24-hour period, is one in which you

ought to be deeply asleep, whether or

not you're nocturnal or diurnal. So,

we're mainly going to focus on

what we're calling phase one and phase

two. Phase one being this dopamine,

epinephrine dominated phase of our day,

and phase two being this more

serotonergic, or serotonin dominated

portion of the day. And then, you might

say, "Well, what about acetylcholine?"

Forgot about acetylcholine? Well, we

didn't forget about acetylcholine.

Acetylcholine is under control more in

terms of what we happen to be doing at

any given moment, whether or not we're

focusing or not focusing, whether or not

we're learning or not learning.

And here I'm referring to acetylcholine

specifically in the context of the brain

and thinking because as some of you are

probably shouting out there, right? If

you're exercise physiologist or you know

anything about how the brain controls

movement,

acetylcholine is used at the nerve to

muscle synapse, right? So, neurons don't

just control other neurons electrically.

The way you're able to move in fact is

because neurons are controlling the

electric activity of muscles,

literally the contraction of muscle

fibers, and that

control is exerted through the release

of acetylcholine. So, acetylcholine is

working at muscles as well, but we're

not focused on that today. We're focused

on

what we can do during phase one of the

day and what we can do during phase two

of the day to control the specific

neuromodulators, dopamine, epinephrine,

serotonin, and acetylcholine toward

particular end goals. So, again, it's

really important to understand what the

backdrop of these neuromodulators is,

the so-called baseline, and that they

vary across the day if you're going to

be able to leverage tools to optimize

your brain chemistry. Before we dive

into the more pointed directed effects

of specific tools on neuromodulators,

I'd like to have just briefly mention

hormones because they are also important

for understanding the background and the

context and these baseline levels of

neuromodulators. Hormones have many

different effects on the brain and body,

and not unlike neuromodulators, some of

those effects are very fast, some of

them are very slow. Today we want to

think about hormones as they relate to

these neuromodulators, the dopamine,

serotonin, epinephrine, and

acetylcholine. And in general,

testosterone tends to collaborate with

and increase the action of dopamine.

That's not always the case, but in

general, when testosterone goes up,

dopamine goes up.

In general, when corticosteroids like

cortisol and some related steroid

hormones increase, epinephrine levels go

up. And in general, when hormones like

oxytocin or prolactin are increased,

levels of serotonin go up. And then we

have poor old lonely acetylcholine off

on its own. But it's not poor and

lonely, it actually has incredibly

potent effects on its own. So it's

really that it just doesn't need much

help from the hormone systems, or at

least not the steroid hormone systems,

in order to have its tremendous effects.

If you understand these four

neuromodulators and you understand that

while there are many tools ranging from

pharmacologic to behavioral that can tap

into these neuromodulator systems that

can kind of press on the gas of

dopamine, pull back on serotonin, and so

on. Well, then you can create a sort of

kit, a grab bag of things that you can

use in any context, or I should say that

you can look to depending on the context

you're in, and create the states of body

and mind that you want. Now, once again,

painting with a somewhat broad brush,

but nonetheless an accurate brush, we

can say that dopamine, when elevated

above baseline,

tends to increase states of motivation,

both mental and physical motivation,

drive, and to some extent focus.

Epinephrine and a closely related

molecule called norepinephrine,

and again, I want to emphasize that

epinephrine is adrenaline and adrenaline

is epinephrine. Norepinephrine is

noradrenaline and noradrenaline is

norepinephrine, but today we're going to

just simply talk about epinephrine and

norepinephrine.

That category of neuromodulator is

mainly responsible for generating our

energy, our level of fuel and baseline

level of forward center of mass, as I

like to call it. When epinephrine levels

are high, we tend to feel agitated, we

tend to feel like we want to move, we

tend to feel like we can't shut down our

thinking and our anticipation of what's

going to happen next. And when

epinephrine levels are very, very low,

we actually have less physical energy,

we tend to have less mental energy in

terms of generating thoughts very

quickly, and so on and so forth. Now,

the neuromodulator serotonin

creates a number of different states in

the brain and body, but for sake of

today's discussion, we're going to think

about the predominant states that it

creates, and those are states of

contentness, being happy, feeling fairly

relaxed, feeling soothed, and to some

extent even some relief from pain or

lack of pain.

Serotonin is associated with a feeling

of satiety, of having enough of what we

already have. And acetylcholine, we can

say, is mainly

associated with states of focus.

And we can go a step further and say

that it's mainly associated with steps

of focus as they relate to learning and

encoding new information, so-called

neuroplasticity.

So, let's say you want to be more

motivated, you want to be more in

pursuit of goals, and you want to have

more energy and to be more focused.

There are many ways to go about that, in

fact, there's a near infinite cloud of

opportunities, everything from

prescription drugs to illicit drugs,

which I certainly do not recommend,

supplements, nutrition,

you can listen to particular music, you

can do all sorts of cognitive,

behavioral, nutritional supplementation

tricks, or

you can just understand that what you're

really after are increases in dopamine

above baseline that you control,

and there are ways to control them that

are quite potent and science tells us

which tools are going to be the most

potent and the most versatile for you.

So, I'm going to share those tools with

you now with the caveat that each one of

those tools

could be its own entire podcast episode

and that we've done near entire episodes

on each of these tools or small

collections of these tools. So, I'm

going to cover these in somewhat

superficial manner. Let's say you want

to increase dopamine for sake of

increasing motivation.

The first thing to do is to understand

what the natural behavioral tools are

for increasing dopamine and to do those

as consistently as possible. Again,

these are tools that you'll want to do

nearly every day if not every day.

And I know I'm sounding like a broken

record on this one, but here again we

come to sunlight and

I should say not just the desire to but

really the need for viewing the maximum

amount of sunlight that one can

reasonably get given schedules and

locations in the world, time of year, et

cetera. In the early part of the day.

Within the first hour of waking,

ideally, but certainly in the first 3

hours of your day, you're going to want

to maximize sunlight exposure to your

eyes. Never look at the sun or any other

light so bright that it's painful to

look at and yes, of course, blinking is

fine, but no, take sunglasses off, go

outside once the sun is out and get some

natural light in your eyes. So, if you

get sunlight exposure to your eyes and

it does have to be to your eyes in the

early part of the day, you increase the

amount of dopamine receptor that you

have, which allows whatever circulating

dopamine happens to be there to have a

greater effect on motivation and I

should say also on mood and feelings of

being in pursuit and generally in

craving and pursuit of things in life.

Now, there's another way to increase the

effect of whatever dopamine happens to

be circulating in your brain and body.

And this again relates to increasing the

number or the efficacy of the receptors

for dopamine. How do you do that? Well,

it turns out that regular ingestion of

caffeine at safe and appropriate levels

of about 100 to 250 mg

is going to increase the number of D2

and D3 dopamine receptors. When you

drink caffeine, it's going to increase

your levels of adrenaline and so-called

epinephrine, which will increase your

energy levels. It's going to decrease

levels of something called adenosine,

which builds up while you're sleepy.

It's going to make you feel less sleepy,

more alert, more energetic. That's sort

of obvious. But, what's less obvious is

that it's increasing the number and

efficacy of dopamine receptors, so that

whatever dopamine happens to be around

in your system is going to have more of

a potent effect. So, these are ways of

modulating more or less the baseline of

dopamine that you are able to produce

and the ways that dopamine can have its

action by way of binding to receptors

more potently.

Now, there are other ways to increase

dopamine in a more acute or directed

way. There ways to spike your dopamine,

to enhance your state of motivation,

mood, focus, and so on. If you're

somebody who has

or is taking drugs for depression or

mania, please be very cautious about

manipulating your dopamine in any case.

I don't just say that to protect us, I

say that to protect you.

But, if we were to look at the

supplement landscape and ask which

supplements increase dopamine, there are

a vast number of them.

But,

the three main ones, the most effective

ones that are readily available out

there without a prescription, are mucuna

pruriens. This is actually the outside

of a velvety bean that has been

extracted and put into a supplement.

Mucuna pruriens is actual L-DOPA. It's

99% L-DOPA, which is a prescription drug

that is given for Parkinson's and for

other purposes where increasing dopamine

is important.

I don't recommend mucuna pruriens. I'm

not saying that no one should take it,

but I don't take it and I don't

recommend it because it tends to so

potently and acutely increase dopamine

that there's a pretty substantial crash

afterwards. The other two supplements

that can increase dopamine in a

short-term way, but in a significant way

are L-tyrosine. So, you can buy that as

a supplemented amino acid. People vary

tremendously in their sensitivity to

supplementing L-tyrosine. I know people

that can take 2 g. I know people that

can barely take 100 mg. I know people

that the best dose for them is 0 mg. So,

there's a lot of variation there

depending on sensitivity and their

natural baseline levels of dopamine and

whether or not they're doing a lot of

other things to support dopamine. But

nonetheless, taking L-tyrosine will lead

to fairly substantial increases in

dopamine within about 15 to 45 minutes

and it lasts for about 30 minutes to 2

hours and then there's kind of a

tapering off. Some people experience a

little bit of an emotional or and/or I

should say energetic crash. Some people

don't. Then the other supplement that I

certainly use and that I know a number

of other people use is more fast-acting

but more potent, which is

phenylethylamine.

This relates to the so-called PEA

molecule.

P P E A

and

phenylethylamine increases dopamine and

some metabolites related to dopamine in

ways that really increase energy and

feelings of well-being and motivation.

And again, it's fast-acting. So, my

particular protocol, the one I use is

I'll take phenylethylamine at dosages of

about 300 to 600 mg along with some

L-tyrosine or I'll take it on its own

with a molecule or I should say a

compound that we'll talk about a little

bit later as it relates to

acetylcholine, alpha-GPC. But tyrosine

and phenylethylamine taken alone or

together will make you feel more

motivated and more alert, more willing

and able to lean into particular

motivated behaviors, whether or not

they're physical or cognitive. But

leaving that aside, there are certain

behavioral protocols that are unrelated

to your overall goals and motivations

that can increase dopamine in a very

sustained way. And without question, the

most potent behavioral tool for doing

that is going to be deliberate cold

exposure.

Deliberate cold exposure has been talked

about a lot here and elsewhere in terms

of its

ability to do things like reduce

inflammation

as a way to test and improve resilience

because uncomfortable cold, uh, provided

it's applied safely, is a great way to

learn to be more resilient because

you're essentially staying or forcing

yourself to stay in a circumstance where

your system is flooded with adrenaline.

As I mentioned before, dopamine tends to

collaborate with epinephrine and vice

versa. Many people will ask which

protocols to follow. Please see the

episode on the use of deliberate cold

for health and performance. You'll find

that hubermanlab.com. So,

the use of cold water for increasing

dopamine is a real tool. It's, I would

say, a power tool. I want to just

briefly return to the fact, however,

that all of that is riding on that phase

one, phase two background, meaning it's

probably going to take less cold water

exposure, or I should say, less time

doing cold water exposure early in the

day to get a big increase in dopamine

than it would later in the day. Because

later in the day, your baseline levels

of dopamine are lower and you've got

more serotonin circulating.

That should make sense to you now as to

why that's the case. And does that mean

that you should really modify your

protocols dramatically? Probably not,

but you might keep that in mind that if,

for instance, you need to be in a highly

motivated, focused state in the late

part of the day for whatever reason, it

might take a few or more of these tools

in combination in order to accomplish

that. Whereas if you're somebody who

feels pretty good during the day, but

you're kind of lacking motivation, you

want to increase dopamine levels and you

don't yet need to or want to resort to

prescription drugs or supplementation,

well then you might layer in and

behavioral protocols, paying attention

to, of course, the things that you might

be doing that would also potentially

suppress dopamine. So, again, that kit

of tools is designed for you to play

with if you choose, if it's safe for you

to apply them, then do that. Consider

doing them individually, not trying to

hit all the tools all at once, right? I

mean, why throw all those tools at your

dopamine system at once?

Better would be to have those tools in

your kit and be able to deploy them

depending on whether or not you're on

travel, whether or not you're eating

well or less well, whether or not you're

sleeping well or less well.

That's highly individual, and I like to

think that in having those tools in

hand, you'll be able to adjust them and

apply them in the ways that allow you to

access the dopamine increases that

you're after. So, next I'd like to talk

about epinephrine, also called

adrenaline.

I want to point out that epinephrine is

released both in the brain and the body.

In fact, there's a barrier between brain

and body that prevents the epinephrine

that's released from your adrenal glands

from crossing the blood-brain barrier.

So, your brain has a separate site

called the locus coeruleus. This is a

collection of neurons in the back of the

brain that kind of sprinkle the rest of

the brain with epinephrine

and essentially wakes up

whatever neural circuits happen to see,

or I should say, uh,

wake up any circuits where that

epinephrine happens to arrive, right?

And generally increase the excitability

of those networks. That's why we say

epinephrine

increases energy. I'm not talking about

caloric energy, although that's

distantly related to this, but really

energy and the desire to move. For many

people, increasing

adrenaline or epinephrine might seem

like a crazy idea. Most people probably

associate this molecule with stress, and

they would like to be less stressed.

But,

there are people, including me, that

want to increase our levels of

epinephrine at least early in the day.

I'm somebody who wakes up rather slowly.

In fact, I tend to be kind of thinking

about thinking about maybe being in

action early in the day, but I try and

push myself to get into action, which

itself can increase epinephrine. I

should mention that any physical

activity, any physical activity,

walking, running, weightlifting,

swimming,

even talking for that matter, is going

to increase levels of epinephrine. Locus

coeruleus is a brain structure that is

tightly coupled with behaviors in a

bidirectional way. That is, when you are

in action, you increase the amount of

epinephrine released from locus

coeruleus, you wake up the brain.

And conversely, when locus coeruleus is

active, the brain wakes up. So, it's

reciprocal, it goes both directions. So,

keep that in mind. Exercise does indeed

give you energy. It burns caloric

energy, but it gives you neural energy

by way of increasing epinephrine

transmission from locus coeruleus. So,

we have exercise and we have caffeine as

potent tools for increasing epinephrine

and thereby energy.

Another potent tool that's purely

behavioral, but it is known to work

based on excellent studies in humans, is

so-called cyclic hyperventilation. Some

of you may be familiar with Wim Hof

breathing. There's also Tummo breathing,

which is very similar, Kundalini

breathing.

All of those styles of breathing involve

cyclic hyperventilation. Deep inhales

and either passive exhales or active

exhales, but repeating inhale, exhale,

inhale, exhale in a very deep and

repetitive way. If you did that for 25

repetitions, 25 inhales and exhales, you

would feel more alert. You'd also feel

more warm. Why? Because you increased

epinephrine adrenaline release in the

brain and body. It works the first time

and it works every time to increase

epinephrine and thereby energy. If you

do that over and over, you're going to

be very alert. You're going to have more

energy, you're going to feel like you

want to move around a lot more. In fact,

you might even feel agitated. So, people

with a lot of anxiety or prone to panic

attack might want to be cautious in how

they train and embark on that type of

breathing, might want to approach it a

little more carefully or avoid it

altogether. But, for most people, cyclic

hyperventilation is simply going to get

you more energized and feeling like you

want to move, feeling like you can think

more clearly, and you will be more

wide-eyed and alert because you are

releasing adrenaline. And the cold water

exposure protocol that I talked about

earlier and that's covered in our

episode on cold and in the newsletter on

cold, well, that, as I mentioned

earlier, potently increases dopamine,

but also epinephrine. Now, we can't

really say that there are foods to

increase epinephrine. There are, of

course, prescription drugs that will

increase epinephrine.

And, of course, there are all sorts of

so-called beta blockers that will block

the receptors for epinephrine to make

you feel calm for public speaking or for

various heart conditions, etc. That's

really the domain of physicians and

should really be worked out with your

cardiologist, with a physician, etc. I

think the tools of exercise and, should

you want very potent increases in

adrenaline, high-intensity exercise, as

well as the tools of caffeine, cyclic

hyperventilation, and deliberate cold

exposure really combine to give you a

nice little kit, I would say a versatile

kit, of ways to increase epinephrine for

sake of having more physical and mental

energy. So, next is the neuromodulator

acetylcholine. And, as I mentioned

earlier, acetylcholine is associated

with states of focus. And those states

of focus can be high-energy states of

focus. So, the ones that are accompanied

by high levels of dopamine and

epinephrine, and where we're really

excited about and really lasered in on

something, or they can be the calmer,

more relaxed states of focus, like

reading a book or practicing music or

listening very carefully to somebody in

a way that's relaxed and calm. Now, ways

to increase acetylcholine in a potent

way include, again, nutrition and

supplementation. It is important to have

baseline levels of acetylcholine be

sufficiently high as well. And for that,

the ideal situation is to regularly

ingest foods that provide enough of the

precursors for acetylcholine to be made.

Eggs contain a lot of choline, beef

contains choline, soybeans contain

choline. So, there are vegan or non-meat

sources. Chicken, fish, mushrooms,

kidney beans, these sorts of things

contain a lot of choline. And there are

other vegetables that contain choline.

So, depending on your dietary

preferences and needs, you can um select

certain foods uh to ingest to get enough

choline to synthesize enough baseline

acetylcholine.

In the realm of supplementation, there

are some excellent tools for increasing

acetylcholine in the acute short-term,

meaning over the course of about 30

minutes out to about 2 hours or maybe

even 4 hours. The most common of those

molecules is actually nicotine.

Nicotinic acetylcholine receptors are

abundant throughout the body and brain.

They're in various brain circuits. They

are on muscle. And yes,

smoking nicotine either by vaping or

cigarette will activate those nicotinic

receptors.

But, of course, smoking is a terrible

thing. It will also activate things like

lung cancer. So, I definitely don't

recommend that. It also activates

addiction because of the ways that it

triggers activation of the dopamine

circuits. However, some people will chew

Nicorette or other nicotine type gums.

Some people are very sensitive to

ingested nicotine. Some people take it

and feel absolutely terrible. But, some

people do use them as a cognitive

enhancers. Supplements that I have used

and do use for increasing acetylcholine

are things like Alpha-GPC

or Huperzine.

Alpha-GPC

is in the choline pathway such that more

acetylcholine is synthesized after you

ingest it. That's the general logic or

framework of how it works. Whereas

Huperzine is mainly in the enzymatic

pathway. It tends to adjust how much

acetylcholine is broken down and lead to

net increases in acetylcholine.

I will often take 300 mg of Alpha-GPC

prior to workouts or prior to cognitive

work bouts. I tend to take it alongside

caffeine and phenylethylamine, so I take

that in combination either before

workouts or work bouts. It really

sharpens my focus and again, I'm doing

that three, maybe four times per week

and I'm careful to do that in the early

part of the day so that it does not

disrupt my sleep. So let's discuss

serotonin.

Serotonin, as I mentioned earlier, is

associated with brain and body states of

well-being, of comfort, of satiety and

therefore it should come as no surprise

that a lot of the prescription drug

treatments for things like depression

involve increasing levels of serotonin

in the brain and body.

That said, anytime you talk about

prescription drugs for serotonin,

we also want to acknowledge that there

are often side effects associated with

increasing serotonin. In particular, if

serotonin levels go too high, that is if

the dosages of those treatments go too

high, people will, for instance, feel

reduced appetite, reduced libido,

increased lethargy, etc.

And there's a so-called serotonergic

syndrome. That said, there are

behavioral tools, nutritional tools and

supplementation tools that can tap into

the serotonin system, not to the same

degree and potency, but nonetheless, in

ways that can still impact our feelings

of well-being in positive ways. What

sorts of things? Well, for instance,

physical contact, things like holding

hands, believe it or not, hugs,

cuddling, etc. can increase serotonin

transmission and they make people feel

good. This shouldn't really come as a

surprise. There's also gratitude and we

did an entire episode about gratitude.

There's a lot of misunderstanding about

gratitude. Turns out, first of all, that

receiving, not giving gratitude, is what

has the most potent effects on

increasing serotonin and activity of the

brain circuits that involve serotonin

and that lead to increases in feelings

of well-being. So, this is interesting.

Receiving

much more than giving gratitude

is what activates those serotonergic

pathways. The other thing about

gratitude that's somewhat

counterintuitive is that observing

others giving and receiving gratitude is

immensely powerful for evoking serotonin

and the activity of serotonergic

circuits in you, the observer. So,

receiving and observing gratitude turns

out to be the most potent way to

increase serotonin in the brain and

body. Now, what about

nutritional approaches to increasing

serotonin? Well, just as we have

tyrosine as an amino acid precursor

upstream of dopamine synthesis,

we have

the amino acid tryptophan, which is

upstream of serotonin synthesis. And one

simply has to go online and put in

tryptophan-containing foods, and you

will discover that there are a lot of

foods that are enriched in tryptophan

that can lead to net increases in the

amount of serotonin available in the

brain and body. Now, one molecule that I

found to be particularly interesting and

useful, and this is one that I haven't

talked about yet on this podcast, is

inositol, in particular myo-inositol.

Myo-inositol can have the effect of

increasing serotonin and other

neurochemicals, but primarily, at least

in terms of the neuromodulators

discussed today, serotonin. I've been

taking 900 mg of myo-inositol

every third night or so as a test of its

ability to improve sleep, and I have to

say

the depth and quality of sleep that I've

been obtaining on myo-inositol is pretty

remarkable. And of course, I should

mention that no supplement, either added

or withdrawn from your protocol, should

ever be used as a direct replacement for

prescription drug treatments that your

physician has given you. You should

always talk to your physician anytime

you remove or add something to your drug

protocol or prescription protocol, of

course. And again, this is a general

theme of all four of these

neuromodulators, dopamine, epinephrine,

acetylcholine, and serotonin.

You want to make sure that you have

sufficient baseline levels of those

things through things like diet, regular

behaviors, and then you have the

opportunity to use supplementation and

if it's appropriate for you,

prescription drugs, and certain

behavioral protocols to try and get

these potent increases, these acute

increases in whichever the

neuromodulators you happen to want to

leverage for your particular goals. So,

that brings us to the end of at least

this exploration of the neuromodulators,

dopamine, epinephrine,

acetylcholine, and serotonin.

Whether or not you're using nutritional

tools or supplementation or prescription

drugs or any other sort of protocol to

try and create a desired effect of focus

or energy, motivation, relaxation,

you're playing with the same

neurochemical ingredients. So, what I'm

hoping is that rather than decide that

anyone tool is the most useful or that

anyone neurochemical is most useful for

that matter,

that the information that I've provided

today allows you a kit of versatile

tools that allows you to figure out what

levels of dopamine and augmentation of

dopamine are appropriate and necessary

for you. What levels of acetylcholine

and tools for manipulating acetylcholine

are going to be most useful for you and

so on and so forth. So, I'd like to

thank you once again for joining me

today in our discussion about these

incredibly powerful molecules we call

neuromodulators

and the things we can do and take in

order to control them so that we can

enhance our mental health, physical

health, and performance. And last but

certainly not least, thank you for your

interest in science.

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