Learn. Share. Evolve…

0:00:05 Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life.
0:00:14 I’m Andrew Huberman, and I’m a professor of neurobiology and ophthalmology at Stanford School of Medicine.
0:00:17 Today we’re discussing the vagus nerve.
0:00:24 The vagus nerve, or what neuroanatomists call cranial nerve 10, is an extremely interesting nerve
0:00:30 because when we hear the word nerve, we often think of a small, you know, connection between one thing and another,
0:00:33 the wires of the nerve, which of course we call axons.
0:00:36 If you didn’t know that, now you know they’re called axons.
0:00:40 But actually, the cranial nerve is an extensive pathway.
0:00:43 It’s a whole set of connections that link the brain and body.
0:00:48 In fact, in many respects, it looks kind of like its own nervous system
0:00:52 within the traditional nervous system of the brain and the spinal cord,
0:00:54 the connections between spinal cord and muscle.
0:00:59 The vagus nerve is so vast, it spreads out through so much of the body.
0:01:04 And as you’ll learn today, it’s connected to so many interesting different brain areas
0:01:10 and has so many interesting different functions that it deserves, well, an entire episode of this podcast.
0:01:15 The other great thing about the vagus nerve is it is highly actionable,
0:01:19 meaning what you will learn today, if you already know something about the vagus nerve,
0:01:22 the vagus nerve is going to change what you know and believe about the vagus nerve.
0:01:28 What you hear today will also, if you don’t know or you’re not familiar with the vagus nerve,
0:01:31 is going to educate you on the latest about the vagus nerve.
0:01:35 We’ve learned a lot about the vagus nerve and ways to control the vagus nerve in the last few years.
0:01:41 And finally, and perhaps most importantly, the information that you’re going to learn today includes actionable tools
0:01:48 that will, for instance, allow you to make yourself more alert when you want to, without the use of pharmacology.
0:01:56 It will allow you to calm yourself down quickly when you want to, on demand and quickly, without the use of pharmacology or devices.
0:02:04 And it will also allow you to alter your mood for the better and, indeed, to improve your ability to learn.
0:02:06 The vagus nerve is that important.
0:02:07 It’s involved in that many different things.
0:02:13 And the pathways of the vagus nerve, as I mentioned, have been charted in more detail in recent years.
0:02:18 And the ways that we can get into the vagus nerve and stimulate its actions in specific ways
0:02:25 to achieve those endpoints of improved mood, deeper relaxation, fast relaxation, elevated levels of alertness,
0:02:28 and on and on, are now very well understood.
0:02:32 So, as you can probably tell, I’m extremely excited about today’s episode
0:02:36 because the vagus nerve is just one of the most fascinating aspects to our nervous system.
0:02:38 You have one, I have one.
0:02:42 So, let’s figure out how they work and how to put it to work for the better.
0:02:47 Before we begin, I’d like to emphasize that this podcast is separate from my teaching and research roles at Stanford.
0:02:53 It is, however, part of my desire and effort to bring zero-cost-to-consumer information about science
0:02:55 and science-related tools to the general public.
0:02:59 In keeping with that theme, today’s episode does include sponsors.
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0:05:43 Okay, let’s get familiar with the vagus nerve.
0:05:46 The vagus nerve is cranial nerve 10.
0:05:49 The vagus nerve is very different than the other cranial nerves
0:05:54 because whereas it does have connections with areas on the face, head, and neck,
0:05:57 and deep to those areas too, so throat, et cetera,
0:06:03 it also has connections, or I should say it receives and provides connections
0:06:05 to areas within the body.
0:06:10 In fact, it has connections with the head area, the neck area, the chest area,
0:06:14 the abdomen, and even a bit lower into the lower intestines.
0:06:20 So the vagus nerve is super extensive in terms of its outputs and its inputs.
0:06:23 And I’ll explain what I mean by outputs and inputs in just a moment.
0:06:27 But what’s very useful to understand and visualize in your mind a bit,
0:06:29 anytime we’re talking about the vagus nerve,
0:06:33 is we’re talking about a nerve of many, many different pathways
0:06:36 that both receives and provides information
0:06:40 from essentially all areas of the body down to the base of your pelvis.
0:06:44 And that stands in stark contrast from the other cranial nerves,
0:06:48 which tend to receive information from restricted areas of the body,
0:06:51 most typically the head and neck area,
0:06:56 and that tend to provide connections to the head and neck area.
0:07:01 The word vagus actually translates more or less to vagabond, which means wandering.
0:07:04 So early neuroanatomists saw that this nerve, cranial nerve 10,
0:07:09 had connections to large areas of the body and head and neck
0:07:12 and received inputs from lots of areas of the body
0:07:16 and decided to call it essentially the vagabond nerve or the vagus nerve.
0:07:19 Now, even though the word vagabond means essentially wandering,
0:07:22 and the word wandering kind of suggests random,
0:07:25 there is nothing random about the wiring of the vagus nerve.
0:07:31 The vagus nerve is incredibly precise in terms of where it receives information from
0:07:33 and where it provides information to.
0:07:37 Now, I want to be very clear what I mean about information, okay?
0:07:40 If you’re a biologist, you’ll probably understand some of this.
0:07:43 If you’re not, and I have to assume most of you are not,
0:07:46 it’s still very important that you understand,
0:07:47 and it’s very easy to understand,
0:07:50 that your nervous system, your brain, spinal cord,
0:07:53 and of course your nervous system includes all these cranial nerves,
0:07:56 including the vagus nerve, are carrying different types of information
0:07:59 along different pathways, different neurons or different nerve cells
0:08:01 within the vagus nerve, for instance,
0:08:06 are receiving or giving different types of information for different purposes.
0:08:11 For instance, there is sensory information carried by neurons,
0:08:13 nerve cells in your nervous system.
0:08:16 Sensory information is the kind of information that, for instance,
0:08:22 converts light into electrical signals at the level of your eyes.
0:08:24 Then your eyes are providing information to the brain
0:08:26 about what’s out in the visual world.
0:08:27 That’s sensory information.
0:08:31 The same could be said for sound waves.
0:08:34 That’s sensory information that your auditory system converts to,
0:08:38 basically, your understanding of speech and sound and music, etc.
0:08:41 Other neurons control motor functions,
0:08:43 literally the movement of your limbs
0:08:45 by controlling contraction of your muscles
0:08:46 or the movement of your lips
0:08:50 or the closing or opening of your airways, for instance.
0:08:56 So motor information, of course, can be seen on the surface of the body.
0:08:57 I’m moving my hands now.
0:08:58 I’m moving my mouth.
0:09:00 You don’t even need to see me do that to know that I’m doing that.
0:09:05 But within our body, we have organs that also need motor control.
0:09:07 For instance, our gut.
0:09:11 Our gut is not just a passive tube through which food moves.
0:09:13 The gut is contracting and relaxing.
0:09:17 It’s moving food through from one end to the other, okay?
0:09:19 We have our pancreas.
0:09:20 We have our liver.
0:09:21 We have our spleen.
0:09:22 And you might think,
0:09:23 oh, well, those are sort of vegetative organs.
0:09:24 They just kind of sit there.
0:09:27 Maybe the cells do stuff, but they don’t move much.
0:09:30 But actually, your spleen even has a contractile ability.
0:09:33 So it can contract to release red blood cells
0:09:35 or immune cells into circulation and so on and so forth.
0:09:39 Different organs, including your muscles,
0:09:40 but other organs as well,
0:09:44 need instructions as to when they should move,
0:09:46 when they should contract, when they should relax.
0:09:47 So we have sensory information
0:09:50 that’s carried by essentially one set of neurons
0:09:51 in our nervous system.
0:09:54 So carrying light information or sound information,
0:09:56 or as you’ll see in a few minutes,
0:09:58 chemical information about the acidity of the gut,
0:09:59 for instance.
0:10:04 And we have neurons that are considered motor neurons.
0:10:05 They control the contraction of muscles
0:10:07 or the contraction of these different organs
0:10:11 or the encouragement for different aspects
0:10:13 of the digestive tract to contract or relax,
0:10:14 to move food along, okay?
0:10:17 So we’ve got sensory neurons and we have motor neurons.
0:10:19 And then there are a lot of other neurons as well
0:10:21 that we call modulatory neurons
0:10:22 that kind of adjust the balance
0:10:25 between the sensory information and motor information.
0:10:26 We aren’t going to talk so much today
0:10:28 about modulatory neurons,
0:10:30 but they are an important third category
0:10:31 of neuron in the nervous system.
0:10:33 Now, why am I telling you all this stuff
0:10:34 about sensory and motor?
0:10:37 Because the vagus nerve is also unique
0:10:41 in that it is both a sensory pathway and a motor pathway.
0:10:44 And this is something that most discussions
0:10:45 about the vagus nerve,
0:10:48 in fact, I would say 99% of discussions
0:10:50 about the vagus nerve that you see online
0:10:52 or when you hear about,
0:10:53 forgive me, in your yoga classes,
0:10:55 by the way, I’m going to touch on
0:10:57 how yoga and ancient yogic practices
0:10:59 actually managed to tease apart
0:11:01 some very important functions of the vagus nerve
0:11:03 without knowing any of the underlying mechanisms.
0:11:05 But it is the case that most of the time
0:11:07 when you hear about the vagus nerve
0:11:09 out there in the general world or in the media,
0:11:12 it’s about the vagus nerve being a calming pathway
0:11:15 that’s involved in transmitting information
0:11:17 about the sensory milieu of the body.
0:11:21 So, you know, heart rate, acidity of the gut,
0:11:24 you know, how comfortable we are in our body to our brain.
0:11:27 And people will say you want to activate the vagus nerve
0:11:29 because you want to calm down.
0:11:31 Well, that is true,
0:11:33 but that is just one small fraction
0:11:34 of the functions of the vagus nerve.
0:11:35 Why?
0:11:38 Because the vagus nerve includes both sensory
0:11:40 and motor neurons within it.
0:11:44 And while it is true that a ton of sensory information
0:11:46 is coursing up from the organs of the body
0:11:49 into the brain through what we call the vagus nerve,
0:11:53 there’s also motor information coming from the brain
0:11:54 to the body.
0:11:56 So if we are going to have an accurate,
0:11:58 meaningful, actionable conversation
0:11:59 about the vagus nerve,
0:12:00 it’s very important that you know
0:12:03 that the vagus nerve contains sensory neurons
0:12:05 as well as motor neurons.
0:12:07 And I want to be clear that I’m not just telling you
0:12:09 about sensory versus motor neurons in the vagus nerve
0:12:11 to just overload you with nomenclature.
0:12:13 It turns out that if you want to access
0:12:17 the calming aspects of vagus nerve activation
0:12:21 versus the energizing effects of vagus nerve activation
0:12:24 versus the immune enhancing effects
0:12:27 of vagus nerve activation versus the ways
0:12:30 that you can improve learning using vagus nerve activation,
0:12:32 you need to know whether or not you’re trying
0:12:36 to activate a sensory pathway or a motor pathway
0:12:38 within this vast set of connections
0:12:39 that we call the vagus nerve.
0:12:42 Okay, so I want to just briefly describe
0:12:44 the sensory pathways within the vagus nerve.
0:12:47 And by the way, if you’re a yoga teacher,
0:12:50 if you are a therapist, if you are a teacher,
0:12:52 if you are a human being on earth,
0:12:54 this information is going to be very useful to you
0:12:56 because this is the information
0:12:59 that will allow you to understand why it is
0:13:01 that when your body is in a certain comfortable
0:13:03 or uncomfortable state,
0:13:07 it has a particular effect on your mind and your brain
0:13:10 to feel, well, in general, comfortable or uncomfortable.
0:13:13 Your vagus nerve includes very interesting
0:13:15 and kind of unusually shaped neurons.
0:13:18 Okay, the neurons of the vagus nerve
0:13:20 are not like the ones that you see in the typical picture
0:13:22 if you were to look up neuron online.
0:13:24 If you were to look up neuron online,
0:13:26 what you would find is you’d see a picture
0:13:29 of what’s called a cell body where the nucleus, the DNA is.
0:13:30 You’d see what are called dendrites,
0:13:33 which typically are the area where neurons receive input.
0:13:36 And then you’d see the wire-like extension
0:13:38 that we call the axon out to the area
0:13:40 that that neuron communicates with.
0:13:41 And then you might see a little picture
0:13:44 of some little blobs or what we call vesicles
0:13:46 being released at the end of that axon.
0:13:50 That is not at all what vagal nerve neurons look like.
0:13:53 Some of them do, but the vast majority,
0:13:56 about 85% of the neurons in the vagus nerve
0:13:58 have a cell body with that DNA,
0:14:00 with the nucleus in it,
0:14:03 sitting in an area kind of near your neck
0:14:05 and back of your head,
0:14:07 sort of what we call the brainstem.
0:14:09 And it’s called the nodose ganglion.
0:14:11 Now, the nodose ganglion is a collection
0:14:13 of cell bodies of neurons.
0:14:15 So you can think of it kind of like a cluster of grapes.
0:14:19 And they do indeed have an axon extending from them,
0:14:22 a wire that goes out to the body, okay?
0:14:25 That wire looks for all the world,
0:14:27 like the axons on any other neurons.
0:14:29 And that little axon can be very short
0:14:32 if it terminates, as we say, in an area of the neck.
0:14:34 It can be slightly longer
0:14:35 if it terminates in the chest area,
0:14:38 and even longer if it goes to what we call our viscera,
0:14:42 our lungs, our pancreas, our liver,
0:14:45 down to any number of different organs
0:14:49 within our major abdominal body compartment, okay?
0:14:51 You also see an axon, a little wire
0:14:55 from a vagal sensory neuron out to the spleen.
0:14:56 Now, what I just described,
0:14:59 a cell body with an axon extending from it
0:15:01 out to the organs of the body,
0:15:02 different organs of the body,
0:15:05 tend to be innervated by different neurons,
0:15:07 not always, but in general.
0:15:11 But here’s what’s different about these vagal neurons.
0:15:15 These vagal neurons have another axon
0:15:16 that goes from the cell body.
0:15:18 So they’re what we call a bipolar neuron.
0:15:21 They have another axon that extends up into the brainstem
0:15:25 and terminates in generally one of three different,
0:15:26 what we call brainstem nuclei,
0:15:28 which are just areas of the brainstem.
0:15:31 So this is very important to embed in your mind, right?
0:15:34 Because in reality, embedded in your head and neck
0:15:37 or in your brain and neck are these neurons,
0:15:38 which are kind of like a cluster of grapes
0:15:41 that have, each one is going to have two branches,
0:15:44 one that goes out to a particular organ of the body
0:15:47 and another branch that goes up into your brainstem.
0:15:50 Now, this visual understanding,
0:15:52 which hopefully is starting to take place in your mind,
0:15:55 is extremely important to understand
0:15:57 how 85% of the vagus nerve works.
0:16:01 85% of the vagus nerve works by having these neurons
0:16:05 that have axons in say the spleen or around the lungs
0:16:07 or that innervate the heart
0:16:09 or that innervate any number of different organs
0:16:10 in your body.
0:16:14 And they collect sensory information
0:16:17 about what’s going on in each
0:16:18 and every one of those organs.
0:16:21 That information goes up the axon.
0:16:23 Remember, there’s a cell bodies in the nodos ganglion
0:16:26 and then it goes further up past the cell body
0:16:28 into the brainstem, okay?
0:16:30 So when people talk about the vagus nerve,
0:16:33 cranial nerve 10 as being a sensory pathway,
0:16:36 it is mostly a sensory pathway.
0:16:38 It’s collecting information through these axons.
0:16:39 Why is that weird?
0:16:41 Well, it’s not weird,
0:16:42 but it’s different than the way
0:16:43 we normally talk about neurons
0:16:45 where the axon is the output end, right?
0:16:47 Where it’s dumping stuff onto the next neuron
0:16:48 to make things happen.
0:16:52 The neurons in the nodos ganglion of the vagus nerve,
0:16:53 I know that’s a lot of language,
0:16:56 but these neurons that send an axon branch
0:16:58 out to the organs of the body
0:17:00 are collecting information about what’s happening,
0:17:03 what sensory information is occurring
0:17:05 out at those organs.
0:17:08 And that information goes up those wires,
0:17:10 past the cell body and into the brainstem,
0:17:13 and then that’s communicated to the brain.
0:17:18 So basically we can think of 85% of the vagus nerve,
0:17:21 this huge superhighway from the body to the brain
0:17:22 as being sensory.
0:17:24 And when we talk about sensory,
0:17:26 it’s important that you understand
0:17:28 that two types of sensory information
0:17:30 are coming in through these wires,
0:17:31 through these axons,
0:17:33 and that are delivered to the brain.
0:17:35 And in response to that sensory information,
0:17:36 as you’ll soon learn,
0:17:39 your brain will change its levels of alertness.
0:17:40 Sometimes it gets more alert,
0:17:41 sometimes it gets calmer.
0:17:44 Sometimes it primes you to learn better.
0:17:46 Sometimes it will turn on a fever.
0:17:48 It will literally heat up your entire body
0:17:54 based on what those axons are sensing out in the periphery.
0:17:55 The periphery, of course,
0:17:57 being the organs and tissues of your body
0:17:59 outside your brain and spinal cord.
0:18:01 So I realize that’s a bit of neuroanatomy.
0:18:03 For those of you that aren’t familiar with neuroanatomy,
0:18:05 it might seem like an overwhelming amount of neuroanatomy,
0:18:08 but it’s extremely important to have that idea in your mind
0:18:11 of sensory information flowing up into the brain
0:18:15 from your organs because anatomically speaking
0:18:16 and functionally speaking,
0:18:20 it runs exactly opposite to how we typically see neurons
0:18:22 when they’re drawn in diagrams for us
0:18:23 and how we talk about neurons
0:18:25 as just putting stuff out at the level of the axon
0:18:26 at the end of those wires.
0:18:29 Information is coming up those wires
0:18:30 in the case of the vagus.
0:18:30 Okay.
0:18:34 So whereas for the visual system or the auditory system
0:18:37 or for the smell system or the taste system,
0:18:41 typically we have one type of sensory information coming in.
0:18:41 So for instance,
0:18:42 in the visual system,
0:18:46 light photons of energy are converted into electrical signals
0:18:49 that the rest of the visual system unpacks
0:18:50 to give you visual perceptions,
0:18:52 to control your circadian rhythms.
0:18:54 Or in the case of the auditory system,
0:18:55 you have sound waves,
0:18:56 which are transduced
0:18:59 by this beautiful mechanism of your inner ear
0:19:01 that then gets converted
0:19:04 into your understanding of speech or music, et cetera.
0:19:06 In the case of the vagus nerve,
0:19:09 the sensory information coming from your organs,
0:19:10 from your lungs,
0:19:12 from your gut.
0:19:12 And by the way,
0:19:13 your gut,
0:19:13 when I say that,
0:19:15 I don’t just mean your stomach.
0:19:17 I also mean the large and small intestine
0:19:18 and all the stuff above your stomach as well.
0:19:22 The sensory information that’s coming from the body
0:19:24 includes both chemical information
0:19:27 and mechanical information.
0:19:29 Now the mechanical information
0:19:30 is pretty straightforward to understand.
0:19:33 If your gut is full of food or air or water
0:19:34 and it’s very distended,
0:19:36 you can feel that.
0:19:37 The reason you can feel that
0:19:39 is because you have mechanoreceptors
0:19:43 that sense stretch in the lining of the gut
0:19:45 and send that information
0:19:47 by way of those axons up
0:19:50 to and past the nodos ganglion.
0:19:51 There’s some processing of that information
0:19:52 in the nodos ganglion,
0:19:55 but then it goes up and into your brain stem.
0:19:56 Okay.
0:19:57 Now also within the gut,
0:19:59 you have chemical information.
0:20:01 There’s information about,
0:20:01 for instance,
0:20:02 and we’ll talk more about this later,
0:20:05 how much serotonin is in the gut.
0:20:07 You may have heard that 90% of the serotonin
0:20:10 in your body is manufactured in the gut.
0:20:12 And indeed it’s manufactured in your gut.
0:20:13 It plays an important role
0:20:16 in gut motility and gut health.
0:20:18 The serotonin in your gut
0:20:20 is distinct from the serotonin
0:20:21 released in your brain.
0:20:22 Later, we’ll talk about
0:20:24 how the levels of serotonin in your gut
0:20:26 are conveyed to the brain
0:20:27 by way of, you guessed it,
0:20:28 the vagus nerve.
0:20:30 And your brain in turn
0:20:32 makes different levels of serotonin
0:20:34 to impact your mood.
0:20:35 Super interesting,
0:20:36 super important pathway
0:20:37 has relevance for depression
0:20:39 and just for everyday mood and wellbeing.
0:20:40 We’ll talk about it.
0:20:41 It’s a highly actionable pathway.
0:20:42 Super cool.
0:20:45 So you have mechanical information
0:20:47 and you have chemical information
0:20:48 coming from, for instance,
0:20:50 your gut up through the sensory
0:20:52 in the technical nomenclature.
0:20:53 It’s called afferents.
0:20:55 Afferents is a technical language.
0:20:56 Feel free to ignore this.
0:20:57 But for those of you that want to know,
0:20:59 you aficionados already know this,
0:21:01 the afferents are the inputs to a structure.
0:21:04 Efferents are the inputs from a structure.
0:21:07 But what we’ve got in the case of the gut
0:21:09 is mechanical and chemical information
0:21:11 being sensed by different neurons
0:21:12 with different receptors
0:21:15 that pay attention to different things.
0:21:17 Meaning those receptors are activated
0:21:18 by either mechanical stretch
0:21:20 or by the presence or absence
0:21:21 of particular chemicals in the gut,
0:21:23 how acidic the gut is.
0:21:25 And that information goes up,
0:21:26 processed a bit in the no-dose ganglion,
0:21:28 and then relayed up to the brainstem.
0:21:29 And we’ll talk in a moment
0:21:30 about what happens to that information
0:21:33 after it lands in the brainstem.
0:21:35 Now, chemical and mechanical information
0:21:37 is also being conveyed
0:21:38 from other structures in the body.
0:21:40 You can probably imagine what some of these are,
0:21:42 and we don’t have to go through each and every one,
0:21:44 but as one additional example to the gut,
0:21:46 I’ll just use, for instance, the lungs.
0:21:50 When your lungs expand and contract as you breathe,
0:21:54 that information is relayed up through
0:21:56 and past the no-dose ganglion
0:21:57 and up into the brainstem.
0:21:59 And as you can imagine, your lungs,
0:22:01 because you’re inhaling oxygen
0:22:03 and you’re also offloading carbon dioxide,
0:22:06 your lungs are expanding and contracting.
0:22:09 Your lungs are also communicating mechanical
0:22:12 and chemical oxygen-carbon dioxide ratio
0:22:13 information up to the brain.
0:22:14 Now, if we wanted to,
0:22:15 we could explore and discuss
0:22:16 every single organ of your body
0:22:19 that gets axon input from the vagus nerve
0:22:21 and therefore can carry sensory information
0:22:22 up the vagus.
0:22:24 And again, there’s going to be information
0:22:26 about the chemical environment
0:22:29 and the mechanical status of each of those organs
0:22:31 carried up to your brainstem.
0:22:33 We’re not going to do that now for sake of time,
0:22:36 but it’s very important that you now take a step back
0:22:37 and you realize,
0:22:39 hmm, I understand what sensory information is.
0:22:41 I understand that it’s different than motor information.
0:22:44 It’s carried by different neurons in the nervous system.
0:22:48 The vagus nerve has both sensory and motor neurons.
0:22:50 The sensory neurons are collecting information
0:22:51 from all these bodily organs.
0:22:52 And by the way,
0:22:54 those bodily organs don’t just stop
0:22:55 at the level of the lungs.
0:22:56 It includes the heart,
0:22:58 it includes some stuff that’s happening in the neck,
0:23:00 some of the muscles that are controlling
0:23:02 the constriction of the airways.
0:23:04 We’ll get into this a little bit more in a few minutes,
0:23:07 but you now also know that when we talk about
0:23:09 collecting sensory information from the body
0:23:12 and sending it to the brain by these vagal pathways,
0:23:15 that the types of sensory information
0:23:18 include both chemical and mechanical information.
0:23:19 And the reason that’s important
0:23:21 is not just academic and intellectual.
0:23:24 it’s not just to fill the airspace with nomenclature.
0:23:27 It’s because if you’re going to think about ways
0:23:30 to change the activity of the vagus system,
0:23:33 the ways to, for instance, calm down,
0:23:35 or the ways to improve your immune system function,
0:23:38 or to improve your mood in the short and long term,
0:23:39 you need to ask yourself,
0:23:43 am I going to do that through a mechanical change,
0:23:45 or am I going to do that by making a change
0:23:48 to the chemical milieu of a given organ or set of organs?
0:23:50 So to drive the point I just made home,
0:23:53 let’s take an example that we see a lot out there,
0:23:56 which is that if you want to increase the activity
0:23:59 of your vagus nerve, you want to calm down.
0:24:00 Why am I saying calm down?
0:24:02 I neglected to say earlier that, by the way,
0:24:04 every medical student and pre-med student should know,
0:24:07 which is that cranial nerve 10, the vagus nerve,
0:24:09 is classified as a parasympathetic nerve.
0:24:12 Parasympathetic refers to one branch
0:24:14 of the so-called autonomic nervous system.
0:24:17 The autonomic nervous system controls your levels of alertness
0:24:18 and your levels of calm.
0:24:19 It has two major branches.
0:24:22 One branch is called the sympathetic nervous system.
0:24:24 It has nothing to do with emotional sympathy.
0:24:27 The sympathetic nervous system is generally responsible
0:24:30 for increasing our levels of alertness.
0:24:32 Everything from being alert, like I am now,
0:24:35 all the way up to full-blown panic attack,
0:24:37 which fortunately I’m not right now.
0:24:40 The parasympathetic nervous system is often referred to
0:24:42 as the rest and digest system.
0:24:45 And indeed, it has roles in rest and digestion,
0:24:47 but it controls a lot more than just that.
0:24:49 The parasympathetic branch of the autonomic nervous system
0:24:52 controls, for instance, digestion.
0:24:55 It controls our ability to fall asleep at night.
0:24:58 If the parasympathetic nervous system is overly activated,
0:25:01 it can make us sleepy when we don’t want to be sleepy.
0:25:04 It can make us pass out when we don’t want to pass out.
0:25:07 It can be responsible for putting people into a state of coma.
0:25:10 So it’s not good to think about the sympathetic nervous system
0:25:12 simply as fight or flight, how it’s often referred to,
0:25:15 because it’s also responsible for generating healthy,
0:25:18 wakeful, non-anxious, non-stress levels of alertness,
0:25:21 as well as stressed out panic states.
0:25:24 And the parasympathetic nervous system is responsible
0:25:26 for putting us into a calm and relaxed state,
0:25:29 or a deep sleep state,
0:25:32 or a coma state if it were to be hyperactivated.
0:25:34 The autonomic nervous system is a seesaw
0:25:37 where the levels of alertness and calm
0:25:39 that we experience at any one moment
0:25:42 reflect the relative balance of sympathetic nervous system
0:25:44 and parasympathetic nervous system activity.
0:25:46 They’re sort of in a push-pull with one another.
0:25:48 Increase the parasympathetic nervous system activity
0:25:49 a little bit, you get a bit calmer.
0:25:52 Increase the sympathetic nervous system activity a little bit,
0:25:53 you get a bit more alert,
0:25:55 but they’re always both active.
0:25:59 The vagus nerve is classified as a parasympathetic nerve.
0:26:02 However, it’s a bit of a misnomer,
0:26:04 because as you’ll soon realize,
0:26:06 there are pathways within the vagus nerve
0:26:09 that were you to activate these pathways
0:26:10 within the vagus nerve,
0:26:13 you would become more alert, not less alert.
0:26:16 This is one of the things that I’m hoping to dispel
0:26:17 through the course of this episode,
0:26:20 which is this very common myth out there.
0:26:23 It’s almost pervasive that when you activate the vagus nerve,
0:26:25 you’re going to calm down.
0:26:27 it is simply not true, okay?
0:26:29 There are instances where that is true.
0:26:32 There are instances where the opposite is true,
0:26:34 depending on which branch of the vagus nerve
0:26:36 you happen to activate or suppress.
0:26:38 One example, however,
0:26:41 where activating a particular branch of the vagus nerve
0:26:43 does indeed lead to more relaxation,
0:26:48 is the branch of the vagus nerve that, again, is sensory, okay?
0:26:51 So it’s taking information about mechanical phenomenon,
0:26:54 in this case, pressure or touch,
0:26:58 and it’s sending that information down into the brainstem areas
0:27:00 that are going to interpret that information.
0:27:05 This branch of the vagus nerve that is carrying sensory information
0:27:08 doesn’t come from the viscera or the neck,
0:27:09 it comes from the head.
0:27:10 And it’s the branch of the vagus nerve
0:27:14 that essentially goes behind the ear
0:27:16 and in some of the deeper components of the ear.
0:27:17 Remember, they tell you,
0:27:18 don’t put anything into your ear
0:27:21 that’s smaller than your elbow.
0:27:23 Well, I’m breaking that rule right now
0:27:25 and I’m putting my index finger into my ear
0:27:27 and kind of rubbing in a circular way
0:27:31 that kind of the area right outside the hole of the ear.
0:27:32 There’s a branch of the vagus nerve there.
0:27:33 There’s also, as I mentioned,
0:27:35 a branch of the vagus nerve behind the ear.
0:27:38 And were you to rub behind the ear just gently
0:27:40 or with a little bit of pressure,
0:27:41 indeed, you’re going to activate
0:27:42 that branch of the vagus nerve.
0:27:44 That branch of the vagus nerve
0:27:45 is carrying sensory information.
0:27:47 So that mechanical pressure is being conveyed
0:27:49 into the brainstem.
0:27:52 And indeed, that pathway satisfies all the criteria
0:27:56 of being a parasympathetic or calming inducing pathway.
0:27:58 Now you can find all over the internet
0:27:59 that rubbing behind the ears
0:28:01 is really going to calm us down
0:28:03 and really bring our level
0:28:05 of overall autonomic arousal way, way down.
0:28:08 In reality, it doesn’t bring our overall level
0:28:10 of autonomic arousal way, way down.
0:28:13 It brings our level of autonomic arousal down a bit
0:28:15 depending on how active
0:28:18 our sympathetic nervous system happens to be.
0:28:19 Why do I tell you this?
0:28:22 Well, I’m not trying to rain on any parties out there,
0:28:25 but the truth is, if you’re super stressed,
0:28:26 if you’re in a panic attack,
0:28:28 rubbing behind your ears might help a little bit,
0:28:30 but it’s not going to suddenly bring you
0:28:31 into a state of calm.
0:28:32 Soon, we’re going to talk about things
0:28:35 that can bring you into a state of calm very fast,
0:28:37 and I will explain exactly how they work
0:28:38 and why they work so quickly
0:28:39 and why they are so robust.
0:28:41 I don’t want to be disparaging
0:28:42 of the area behind the ear
0:28:43 or the area within their ear.
0:28:45 Some people really like their ears rubbed.
0:28:47 I certainly like the area behind my ears rubbed
0:28:47 like I’m doing now
0:28:49 or the areas within my ears gently rubbed.
0:28:50 Who doesn’t like that?
0:28:51 And indeed, it’s calming.
0:28:54 But it’s one minor branch
0:28:57 of the vagus nerve carrying sensory information.
0:28:59 It’s not going to suddenly shift
0:29:00 your autonomic nervous system.
0:29:01 It’s not going to suddenly tilt that seesaw
0:29:04 into parasympathetic dominance, as it were.
0:29:06 To do that, you need to leverage
0:29:09 some of the other more robust branches
0:29:10 of the vagus nerve.
0:29:11 And I’ll teach you how to do that
0:29:12 in just a moment here.
0:29:15 The point is that the vagus nerve does carry
0:29:18 sort of classic parasympathetic information.
0:29:21 If you’re asked on an exam, students, med students,
0:29:22 I don’t want to be responsible
0:29:23 for you getting this wrong.
0:29:25 I’d love to be responsible for you getting it right.
0:29:27 I teach neuroanatomy to medical students.
0:29:28 If you are asked,
0:29:32 is cranial nerve 10, the vagus nerve,
0:29:33 parasympathetic or sympathetic,
0:29:35 you should answer parasympathetic.
0:29:37 If you’re asked if it’s sensory or motor,
0:29:39 you should say it’s mixed, it’s both.
0:29:40 So it’s mixed parasympathetic.
0:29:42 However, for everybody out there,
0:29:43 med student or not,
0:29:45 just understand that when you activate
0:29:46 certain branches of the vagus nerve,
0:29:49 you’re either going to get an elevation in alertness,
0:29:51 that is an increase in sympathetic nervous system activity,
0:29:54 or a decrease in alertness,
0:29:56 that is an elevation in parasympathetic activity,
0:29:58 depending on which branch you activate
0:30:00 and the context matters.
0:30:02 So if you want to relax,
0:30:03 you can rub behind your ears,
0:30:05 you can rub inside your ears.
0:30:06 If you have permission,
0:30:07 you can do that to the person next to you
0:30:09 if they like it.
0:30:12 But it’s not the case
0:30:14 that activating any branch of the vagus nerve
0:30:16 is going to calm us down.
0:30:17 That’s simply not the case.
0:30:18 And in a moment,
0:30:19 I’ll tell you why.
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0:33:39 Okay, so we’ve talked about
0:33:41 all the sensory information
0:33:42 coming in from behind the ear,
0:33:44 from deep in the ear,
0:33:44 from the body,
0:33:47 coursing up past no-dose ganglion
0:33:48 into the brainstem.
0:33:50 I told you earlier
0:33:51 and it’s still true now
0:33:55 that 85% of the vagus nerve pathways
0:33:57 are sensory in nature,
0:33:59 carrying chemical and mechanical information.
0:34:02 So what about this other 15% of the vagus nerve
0:34:04 that is not carrying sensory information
0:34:06 from the body,
0:34:07 from the head
0:34:09 into these brainstem nuclei?
0:34:10 By the way,
0:34:11 when I say brainstem nuclei,
0:34:14 I don’t mean nuclei
0:34:15 in the context of one neuron.
0:34:16 This can be a little bit confusing,
0:34:19 but when we hear about the nucleus of a neuron,
0:34:20 we mean the area
0:34:22 that generally contains the DNA
0:34:24 and we’re distinguishing it
0:34:26 from the axon and the other parts.
0:34:28 When we hear about a nucleus in the brain,
0:34:29 these neuroanatomists
0:34:30 should have been more creative,
0:34:31 but when we’re hearing
0:34:32 about a nucleus in the brain,
0:34:35 it means a collection of different neurons,
0:34:36 so a big group of neurons.
0:34:38 So when I say brainstem nuclei,
0:34:39 I mean a lot of neurons,
0:34:40 thousands of neurons
0:34:42 in little clumps there
0:34:43 that we call nuclei.
0:34:45 So the vagus nerve
0:34:47 includes different nuclei,
0:34:49 different collections of neurons,
0:34:50 and these neurons
0:34:52 have what we call efferents,
0:34:53 outputs to,
0:34:55 as you might’ve guessed,
0:34:56 the body,
0:34:59 back to the various organs of the body.
0:35:00 They also have connections
0:35:04 to things within the head and face area,
0:35:05 but for the time being,
0:35:06 I’m mostly going to talk about
0:35:09 the motor outputs of the vagus nerve
0:35:11 that come from these brainstem nuclei.
0:35:12 So these motor outputs
0:35:15 are not themselves paying attention
0:35:17 to mechanical or chemical information.
0:35:19 they are going to control
0:35:19 they are going to control
0:35:21 the organs of the body.
0:35:23 This is extremely important
0:35:24 if you want to be able
0:35:25 to understand and leverage
0:35:26 your vagus nerve
0:35:27 for health and wellbeing,
0:35:28 mental health,
0:35:28 physical health,
0:35:29 performance,
0:35:31 and even for accelerated learning.
0:35:32 I guess that would fall
0:35:33 under performance
0:35:34 or for recovery
0:35:35 from different diseases.
0:35:36 There are really nice papers
0:35:37 starting to emerge
0:35:39 that if you can selectively activate
0:35:40 these motor pathways,
0:35:41 you can accelerate
0:35:43 and increase the recovery
0:35:44 from stroke.
0:35:46 So this is of serious significance.
0:35:48 But for those of us
0:35:49 that fortunately don’t have strokes,
0:35:51 it’s still of serious significance.
0:35:51 And in fact,
0:35:53 right now I’m going to tell you
0:35:54 about an actionable tool
0:35:55 whereby you can leverage
0:35:56 one of these motor pathways
0:35:58 to a very specific endpoint
0:35:59 anytime you want.
0:36:00 So let’s talk about
0:36:01 how you can leverage
0:36:02 these motor pathways
0:36:03 of the vagus
0:36:04 in order to what’s called
0:36:05 auto-regulate.
0:36:07 Auto-regulation is not just
0:36:08 a fancy word
0:36:09 for calming down.
0:36:10 We are going to talk
0:36:11 about calming down.
0:36:12 But auto-regulation
0:36:13 is the way
0:36:14 in which your vagus nerve
0:36:15 makes sure
0:36:16 that that seesaw
0:36:18 of sympathetic nervous system
0:36:19 to parasympathetic nervous system
0:36:20 balance
0:36:21 doesn’t get tilted
0:36:22 too far
0:36:23 to the side
0:36:24 of sympathetic
0:36:25 nervous system activation.
0:36:26 That your levels
0:36:27 of alertness,
0:36:28 your heart rate,
0:36:29 your breathing rate,
0:36:29 et cetera,
0:36:31 don’t get too high.
0:36:32 And the reason
0:36:33 it’s called auto-regulation
0:36:34 and not just calming down
0:36:35 is that auto-regulation
0:36:36 is something
0:36:37 that’s always happening
0:36:38 in the background
0:36:39 as you’re going
0:36:40 about your daily activities.
0:36:40 In fact,
0:36:41 it’s also happening
0:36:42 while you sleep.
0:36:43 In fact,
0:36:44 now we’re going
0:36:44 to talk about things
0:36:45 that you can do
0:36:46 deliberately
0:36:48 to indeed calm down
0:36:49 but to also increase
0:36:51 the amount of auto-regulation
0:36:51 that occurs
0:36:53 during your entire day
0:36:54 when you’re not focusing
0:36:54 on doing these
0:36:55 particular protocols
0:36:57 as well as during sleep
0:36:58 and that will result
0:36:58 in elevated
0:37:00 what’s called HRV
0:37:02 or heart rate variability.
0:37:03 Now I realize
0:37:04 that’s a tall order
0:37:05 but what we’re going
0:37:05 to do is
0:37:06 we’re going to step
0:37:06 through this
0:37:08 first by focusing
0:37:08 on the protocol
0:37:09 and then now
0:37:10 that you’re familiar
0:37:11 with all the business
0:37:12 about sensory
0:37:12 and motor
0:37:13 and parasympathetic
0:37:14 now that you have
0:37:15 all that science
0:37:16 and nomenclature
0:37:16 in mind
0:37:17 it will all make
0:37:18 perfect sense
0:37:19 as I describe
0:37:19 this protocol
0:37:20 for auto-regulation
0:37:21 and improving HRV
0:37:23 and all the protocols
0:37:23 that follow.
0:37:24 Okay,
0:37:24 so embedded
0:37:25 in your brain
0:37:27 and in your vagal nerve
0:37:27 pathways
0:37:29 and in your body
0:37:30 you have
0:37:31 an incredible
0:37:31 neural circuit.
0:37:33 This neural circuit
0:37:33 is one
0:37:34 that you are born with
0:37:35 and it’s one
0:37:36 that you will have
0:37:37 your entire life.
0:37:38 This is also a pathway
0:37:38 that you want
0:37:39 to keep tuned up
0:37:40 that is that you’ll
0:37:41 want to make sure
0:37:42 is activated
0:37:43 on a pretty frequent basis
0:37:44 super easy to do
0:37:45 as you’ll soon see
0:37:47 so that the pathway
0:37:48 does not deteriorate.
0:37:50 This is a pathway
0:37:51 that originates
0:37:52 in an area
0:37:52 of your brain
0:37:53 called the dorsolateral
0:37:54 prefrontal cortex.
0:37:55 Now the dorsolateral
0:37:56 prefrontal cortex
0:37:57 and by the way
0:37:58 it’s the left
0:37:59 dorsolateral prefrontal cortex
0:38:00 in particular
0:38:01 sort of
0:38:02 on the left
0:38:04 upper part
0:38:04 of the front
0:38:05 of your skull
0:38:06 if you were
0:38:06 to go deep
0:38:07 to that area
0:38:08 you would be
0:38:09 on the left
0:38:10 dorsal top
0:38:11 lateral side
0:38:13 prefrontal cortex
0:38:13 kind of toward
0:38:14 the front
0:38:14 right behind
0:38:15 your forehead.
0:38:15 Okay,
0:38:16 dorsolateral prefrontal cortex
0:38:17 sits deep
0:38:18 to that area.
0:38:20 The dorsolateral
0:38:21 prefrontal cortex
0:38:21 has outputs
0:38:22 to a couple
0:38:23 of other brain areas
0:38:24 called the cingulate
0:38:25 called the insula.
0:38:25 You don’t have
0:38:25 to worry about
0:38:26 those names
0:38:26 unless you’re
0:38:27 really interested
0:38:27 in them.
0:38:28 Those areas
0:38:30 have communication
0:38:30 with one
0:38:33 of the brainstem nuclei
0:38:33 one of those
0:38:34 brainstem areas
0:38:35 that gets input
0:38:37 from the sensory
0:38:38 pathways from the body
0:38:39 from the head
0:38:41 of the vagus
0:38:43 and that also
0:38:44 contains neurons
0:38:45 that have motor
0:38:46 output to particular
0:38:47 areas of your body
0:38:49 and that brain area
0:38:49 and you’re going
0:38:50 to love this
0:38:50 is called
0:38:52 nucleus ambiguous.
0:38:53 I kid you not
0:38:54 it’s called
0:38:55 nucleus ambiguous.
0:38:56 Nucleus ambiguous
0:38:58 contain some neurons
0:38:59 that project
0:39:01 down to what’s
0:39:01 called the
0:39:02 sinoatrial node
0:39:03 of the heart
0:39:05 and those neurons
0:39:06 are responsible
0:39:07 for deceleration
0:39:08 of heart rate
0:39:10 and it turns out
0:39:10 that you can
0:39:11 selectively activate
0:39:12 those neurons
0:39:13 in no small part
0:39:14 because they receive
0:39:15 input albeit
0:39:16 several synapses
0:39:17 away from
0:39:18 the left dorsolateral
0:39:19 prefrontal cortex
0:39:21 because the prefrontal cortex
0:39:21 is involved
0:39:23 in deliberate action
0:39:24 in planning
0:39:25 and execution
0:39:25 of action.
0:39:26 it doesn’t do
0:39:26 it alone
0:39:27 it does it
0:39:27 through communication
0:39:28 with some other
0:39:29 brain structures
0:39:30 but if you for instance
0:39:31 decide that you’re
0:39:32 going to activate
0:39:33 this deceleration
0:39:33 pathway
0:39:34 you can do it.
0:39:36 The beautiful thing
0:39:36 is these neurons
0:39:37 that also control
0:39:38 deceleration
0:39:39 of heart rate
0:39:40 are active
0:39:40 in the background
0:39:41 they’re under
0:39:42 autonomic control
0:39:42 but you can take
0:39:43 control of them.
0:39:44 When does that happen?
0:39:46 Well for instance
0:39:46 in sleep
0:39:47 if your heart rate
0:39:48 starts to increase
0:39:50 these decelerating
0:39:50 neurons
0:39:51 which are neurons
0:39:52 of the vagus nerve
0:39:53 they’re motor output
0:39:53 neurons
0:39:54 they release acetylcholine
0:39:55 and they act
0:39:56 on the sinoatrial node
0:39:57 which is a node
0:39:58 within the heart
0:39:59 that controls heart rate
0:40:01 to slow your heart rate
0:40:01 down.
0:40:02 Okay
0:40:03 this is the way
0:40:04 in which your heart rate
0:40:05 never gets too high.
0:40:06 The seesaw
0:40:07 that is the autonomic
0:40:07 nervous system
0:40:09 it’s kind of weighted
0:40:10 to the sympathetic
0:40:11 nervous system side.
0:40:11 A simple example
0:40:12 of this is
0:40:13 if you have
0:40:14 to stay awake
0:40:16 you can probably do it.
0:40:16 At some point
0:40:17 you’ll fall asleep
0:40:18 but if you really
0:40:19 want to fall asleep
0:40:20 it’s harder
0:40:20 to make yourself
0:40:21 fall asleep.
0:40:22 The sympathetic
0:40:23 nervous system
0:40:23 is one
0:40:24 that we can
0:40:25 more easily leverage
0:40:26 in order to push
0:40:26 through things
0:40:27 deadlines
0:40:28 stay up
0:40:28 to take care
0:40:29 of a sick
0:40:29 relative
0:40:30 you know
0:40:30 push
0:40:31 push ourselves
0:40:32 to migrate out
0:40:33 from a dangerous
0:40:33 place
0:40:33 or away
0:40:34 from a famine
0:40:35 another example
0:40:35 of a dangerous
0:40:36 place I guess.
0:40:37 The idea here
0:40:38 is that the
0:40:38 sympathetic
0:40:39 nervous system
0:40:40 has kind of
0:40:40 a bias
0:40:41 towards activity
0:40:42 and in fact
0:40:42 your heart rate
0:40:44 is driven
0:40:45 by the sympathetic
0:40:45 nervous system
0:40:46 and that heart rate
0:40:47 would continue
0:40:48 to accelerate
0:40:49 unless there was
0:40:50 this deceleration
0:40:50 pathway
0:40:51 that every once
0:40:51 in a while
0:40:52 would pump
0:40:52 the brake
0:40:53 on heart rate
0:40:54 and that’s
0:40:55 what this vagal
0:40:55 pathway
0:40:57 from nucleus
0:40:57 ambiguous
0:40:58 down to the
0:40:58 sinoatrial node
0:40:59 is doing
0:41:00 and by the way
0:41:02 this deceleration
0:41:02 of heart rate
0:41:03 that goes from
0:41:04 the vagus motor
0:41:04 pathway
0:41:06 to the sinoatrial
0:41:06 node
0:41:07 is the basis
0:41:08 of what’s called
0:41:09 HRV
0:41:10 or heart rate
0:41:10 variability.
0:41:11 We hear a lot
0:41:12 nowadays
0:41:12 about heart rate
0:41:13 variability
0:41:14 for those of you
0:41:15 that have heard of it
0:41:15 and for those of you
0:41:16 that haven’t
0:41:17 having a higher
0:41:18 HRV
0:41:18 or heart rate
0:41:19 variability
0:41:20 is a good thing
0:41:21 right
0:41:22 normally if you hear
0:41:22 something like
0:41:23 heart rate variability
0:41:23 sounds like a bad
0:41:24 thing
0:41:25 turns out it’s a great
0:41:25 thing
0:41:26 heart rate variability
0:41:27 is essentially
0:41:28 the distance
0:41:29 or the time
0:41:29 rather
0:41:30 between beats
0:41:31 of the heart
0:41:32 so you might think
0:41:33 that it’s great
0:41:33 to have a really
0:41:34 consistent heart rate
0:41:34 boom
0:41:36 or actually
0:41:37 in reality
0:41:37 it’s more like
0:41:39 and I’m missing
0:41:40 some of the
0:41:41 beats within the
0:41:41 waveform
0:41:42 but you get the idea
0:41:43 but actually
0:41:44 it’s well known
0:41:45 to be correlated
0:41:46 with a number
0:41:46 of positive
0:41:47 health outcomes
0:41:48 including things
0:41:49 related to brain
0:41:50 and body
0:41:51 and longevity
0:41:52 and performance
0:41:53 to have high
0:41:54 heart rate variability
0:41:55 heart rate variability
0:41:57 is going to lead
0:41:57 to a pattern
0:41:58 of heartbeats
0:41:59 that is more like
0:42:06 now you might say
0:42:07 that’s arrhythmia
0:42:09 but there are cases
0:42:09 of arrhythmia
0:42:10 that are good
0:42:11 and there are cases
0:42:12 of arrhythmia
0:42:13 that are bad
0:42:14 higher HRV
0:42:15 in general
0:42:16 is a good thing
0:42:17 you want it
0:42:18 during sleep
0:42:19 and you want it
0:42:20 during wakeful state
0:42:20 in sleep
0:42:22 heart rate variability
0:42:22 comes about
0:42:24 because this vagal pathway
0:42:25 from nucleus ambiguous
0:42:26 so the cell bodies
0:42:28 the nuclei
0:42:29 literally the DNA
0:42:29 within those nuclei
0:42:30 of those neurons
0:42:31 reside in nucleus ambiguous
0:42:32 and they project
0:42:33 to the sinoatrial node
0:42:34 and every once
0:42:35 in a while
0:42:35 they’ll just
0:42:36 pump the break
0:42:37 on heart rate
0:42:38 and slow heart rate
0:42:38 down
0:42:38 and then they’ll
0:42:39 come off that break
0:42:40 slow down
0:42:41 come off heart rate
0:42:42 and here’s the really
0:42:43 beautiful part
0:42:44 and the way
0:42:44 that you get
0:42:45 actionable leverage
0:42:46 over the system
0:42:48 the control
0:42:49 by the vagus nerve
0:42:50 of the sinoatrial node
0:42:51 and heart rate
0:42:53 is coordinated
0:42:54 with your breathing
0:42:56 now as I tell you this
0:42:57 it’ll make perfect sense
0:42:58 but I just want you
0:42:58 to step back
0:42:59 from in a second
0:43:00 and realize that
0:43:02 these systems of the body
0:43:03 are so elegantly coordinated
0:43:05 and here’s how it works
0:43:06 with respect to heart rate
0:43:06 and breathing
0:43:08 when you inhale air
0:43:10 of course your lungs expand
0:43:11 you have a muscle
0:43:13 that sits below your lungs
0:43:14 called the diaphragm
0:43:15 as you inhale air
0:43:17 of course that diaphragm
0:43:18 moves down
0:43:19 now as your diaphragm
0:43:20 moves down
0:43:21 and your lungs expand
0:43:23 your heart literally
0:43:24 has a bit more space
0:43:25 in the thoracic cavity
0:43:27 to expand
0:43:28 okay it’s not gonna
0:43:29 swell massively
0:43:30 but it’s going to expand
0:43:32 now as a consequence
0:43:33 of that expansion
0:43:34 the blood that’s moving
0:43:35 through your heart
0:43:36 is going to move
0:43:37 a little bit more slowly
0:43:39 per unit volume
0:43:40 that is sensed
0:43:41 by a particular group
0:43:42 of neurons in your heart
0:43:44 and that sends a signal
0:43:44 to your sympathetic
0:43:45 nervous system
0:43:47 to speed your heart rate up
0:43:49 put differently
0:43:51 inhaling speeds
0:43:52 your heart rate up
0:43:53 now the converse
0:43:54 is also true
0:43:55 when you exhale
0:43:57 your lungs deflate
0:43:58 your diaphragm moves up
0:43:59 and as a consequence
0:44:01 there’s slightly less space
0:44:01 for the heart
0:44:02 so the heart
0:44:04 shrinks a little bit
0:44:05 not a ton
0:44:06 but it shrinks a little bit
0:44:07 and it’s enough
0:44:09 such that whatever blood
0:44:10 is in the heart
0:44:12 moves through more quickly
0:44:13 per unit volume
0:44:15 that faster movement
0:44:16 is sensed by neurons
0:44:16 within the heart
0:44:18 sends a signal
0:44:18 to the brain
0:44:19 and the brain
0:44:20 activates those neurons
0:44:21 within nucleus ambiguous
0:44:23 and very quickly
0:44:24 sends a signal
0:44:25 to the sinoatrial node
0:44:27 to slow your heart rate down
0:44:29 put differently
0:44:31 exhale slow your heart rate down
0:44:32 and they do so
0:44:34 by way of vagal control
0:44:35 over the sinoatrial node
0:44:37 this is the deceleration pathway
0:44:38 over heart rate
0:44:40 so as i mentioned
0:44:40 this is happening
0:44:41 all the time during sleep
0:44:42 you don’t have to be
0:44:43 consciously aware
0:44:44 for this to happen
0:44:45 it’s a fortunate
0:44:46 consequence of nature
0:44:47 that the neurons
0:44:48 within your brainstem
0:44:49 that control breathing
0:44:50 and the neurons
0:44:50 within your brainstem
0:44:51 that control heart rate
0:44:53 and the other neurons
0:44:53 within the heart
0:44:54 itself that control
0:44:54 heart rate
0:44:55 the pacemaker cells
0:44:57 all can function
0:44:57 without you having
0:44:58 to think about it
0:44:59 that’s a wonderful thing
0:45:00 for obvious reasons
0:45:01 it’s also the case
0:45:02 that because
0:45:04 we have this input
0:45:04 from the left
0:45:06 dorsolateral prefrontal cortex
0:45:07 down through a couple
0:45:07 other structures
0:45:08 like the cingulate
0:45:09 and the insula
0:45:10 and that converge
0:45:11 on nucleus ambiguous
0:45:12 if you decide
0:45:14 to slow your heart rate down
0:45:15 you can do it
0:45:16 and you do so
0:45:18 by doing a deliberate exhale
0:45:20 and or
0:45:21 by increasing
0:45:22 the intensity
0:45:23 or the duration
0:45:24 of your exhale
0:45:25 so you can do that
0:45:26 right now
0:45:27 if you want to slow
0:45:28 your heart rate down
0:45:28 that is
0:45:30 if you want to increase
0:45:31 parasympathetic nervous system
0:45:31 activity
0:45:33 and you want to calm down fast
0:45:34 you can literally just
0:45:38 exhale
0:45:39 exhales slow your heart rate down
0:45:40 and exhales
0:45:41 tilt that seesaw
0:45:43 that is the autonomic nervous system
0:45:45 more toward the parasympathetic side
0:45:47 now i’ve talked before
0:45:47 on this podcast
0:45:49 and all over social media
0:45:50 about the so-called
0:45:51 physiological sigh
0:45:52 a naturally occurring form
0:45:53 of breathing
0:45:54 that occurs in sleep
0:45:55 and that we can deliberately do
0:45:57 anytime we want to calm down fast
0:45:58 and the physiological sigh
0:45:59 consists of
0:46:00 as many of you know
0:46:02 two inhales through the nose
0:46:03 followed by a long
0:46:05 to lungs empty
0:46:06 exhale through the mouth
0:46:07 typically the first inhale
0:46:08 is longer
0:46:09 again it’s done through the nose
0:46:10 the second inhale
0:46:10 is shorter
0:46:12 kind of a sharp inhale
0:46:13 to make sure you maximally
0:46:14 inflate all the little sacks
0:46:15 within your lungs
0:46:16 and then the exhale
0:46:18 is a long slow exhale
0:46:20 that dumps all your air
0:46:22 I’ll just demonstrate
0:46:23 the physiological sigh for you
0:46:23 for those of you
0:46:24 that haven’t seen it
0:46:25 you again
0:46:27 big inhale through the nose
0:46:28 second sharp inhale
0:46:29 through the nose
0:46:30 to make sure you maximally
0:46:31 inflate the lungs
0:46:32 and then long exhale
0:46:33 to lungs empty
0:46:34 goes like this
0:46:52 okay lungs are empty
0:46:53 that is indeed
0:46:54 the fastest way
0:46:55 to activate
0:46:57 the parasympathetic nervous system
0:46:58 and to tilt that seesaw
0:47:00 from levels of
0:47:01 high sympathetic nervous system
0:47:03 activation to lower levels
0:47:04 of sympathetic nervous system
0:47:05 activation
0:47:07 in fact I immediately feel calmer
0:47:08 maybe you can even hear it
0:47:08 in my voice
0:47:10 so when you do a physiological effect
0:47:12 you’re getting both a chemical signal
0:47:13 into the brain
0:47:14 that is the adjustment
0:47:16 of that carbon dioxide oxygen ratio
0:47:17 it’s mainly due to
0:47:19 the offloading of carbon dioxide
0:47:21 that lower level of carbon dioxide
0:47:23 is registered by the brain
0:47:23 very quickly
0:47:25 and leads to an increase in calm
0:47:27 the deceleration of heart rate
0:47:28 driven by the exhale
0:47:30 is also registered by the brain
0:47:30 and very quickly
0:47:32 leads to an increase in calm
0:47:34 when you just emphasize
0:47:35 an exhale
0:47:36 meaning you extend it
0:47:37 or you make it more intense
0:47:38 and you don’t do
0:47:39 the two inhales first
0:47:40 that is you don’t do
0:47:41 the physiological sigh
0:47:44 well you get the mechanical signal
0:47:44 but you don’t get
0:47:45 the chemical signal
0:47:47 at least not to the same degree
0:47:48 you do with the physiological sigh
0:47:49 put simply
0:47:51 if you want to calm down fast
0:47:52 ideally you do
0:47:54 the physiological sigh
0:47:55 however it turns out
0:47:56 that one of the best ways
0:47:57 to improve your HRV
0:47:58 both in sleep
0:47:59 and in wakeful states
0:48:02 which takes a very minimum of effort
0:48:04 and is rarely if ever discussed
0:48:06 is simply throughout the day
0:48:07 I would say 10, 15
0:48:09 maybe even 20 times per day
0:48:10 anytime it occurs to you
0:48:13 to just deliberately extend your exhale
0:48:14 that is to pump the break
0:48:15 on your heart rate
0:48:16 through the vagus nerve pathway
0:48:17 that I’ve been describing
0:48:17 just
0:48:20 just exhale
0:48:22 slow your heart rate down
0:48:22 and then get about
0:48:23 your normal routine
0:48:24 you can do that
0:48:26 essentially anytime you remember to
0:48:28 this is literally going to
0:48:29 increase your HRV
0:48:30 you now know the mechanism
0:48:31 by which it does that
0:48:32 and get this
0:48:34 it will also increase your HRV
0:48:35 in sleep at night
0:48:36 and the reason is
0:48:37 this pathway
0:48:38 that originates
0:48:39 with the left dorsolateral
0:48:40 prefrontal cortex
0:48:42 and goes down to nucleus ambiguous
0:48:43 and then to the sinoatrial node
0:48:44 of the heart
0:48:45 because it’s under conscious control
0:48:48 and because it’s subject
0:48:50 to what we call plasticity
0:48:50 to strengthening
0:48:52 and to weakening
0:48:53 that is if you use it
0:48:54 deliberately
0:48:55 it gets strengthened
0:48:56 if you don’t use it deliberately
0:48:57 it gets weakened
0:48:59 well
0:49:00 that’s a great thing
0:49:00 because it means that
0:49:02 if you just simply remember
0:49:04 to do some extended exhales
0:49:04 throughout the day
0:49:06 you’re going to strengthen
0:49:07 this pathway
0:49:08 such that it operates
0:49:08 in the background
0:49:10 through auto-regulation
0:49:11 without you ever having
0:49:12 to think about it
0:49:13 now of course
0:49:14 that effect wears off
0:49:14 over time
0:49:15 if you don’t
0:49:16 occasionally remember
0:49:17 to just do some
0:49:18 some longer exhales
0:49:19 but this is a wonderful
0:49:20 protocol in my opinion
0:49:22 because it capitalizes
0:49:24 on a inborn circuit
0:49:25 right a circuit
0:49:26 that you were born with
0:49:28 that is already installed
0:49:29 that you can use
0:49:29 at any point
0:49:31 it doesn’t take any learning
0:49:31 but that if you just
0:49:33 ping every once in a while
0:49:34 with some extended exhales
0:49:35 throughout the day
0:49:36 it takes essentially no time
0:49:37 you get the benefit
0:49:38 of feeling a little bit calmer
0:49:39 slowing your heart rate down
0:49:40 and your HRV
0:49:40 which is correlated
0:49:42 with a host of positive
0:49:42 health outcomes
0:49:44 in the short and long term
0:49:45 will increase
0:49:47 two interesting things
0:49:48 everyone should be aware of
0:49:49 is that as we age
0:49:50 of course a number
0:49:51 of things happen
0:49:52 memory gets slightly
0:49:53 to much poorer
0:49:54 all right
0:49:54 there are ways
0:49:55 to offset that
0:49:57 heart rate variability
0:49:58 gets much worse
0:50:00 now an interesting finding
0:50:02 from Nolan Williams lab
0:50:02 at Stanford
0:50:04 is that if you activate
0:50:06 dorsolateral prefrontal cortex
0:50:07 using what’s called
0:50:09 transcranial magnetic stimulation
0:50:10 this is a procedure
0:50:11 where you take a stimulator
0:50:12 and you non-invasively
0:50:14 place it on the skull
0:50:15 outside and just above
0:50:17 dorsolateral prefrontal cortex
0:50:18 and you stimulate
0:50:19 through the skull
0:50:20 dorsolateral prefrontal cortex
0:50:22 you observe
0:50:23 as you would expect
0:50:25 a deceleration of heart rate
0:50:26 and it’s known
0:50:26 to be carried
0:50:28 through this vagal pathway
0:50:29 to the sinoatrial node
0:50:31 even after the stimulation
0:50:32 is removed
0:50:33 you find
0:50:34 that heart rate variability
0:50:35 increases
0:50:36 because this pathway
0:50:38 has been stimulated
0:50:40 into neuroplasticity
0:50:40 it’s strengthened
0:50:41 the other way
0:50:42 to strengthen this pathway
0:50:43 is to do exactly
0:50:44 what I just described
0:50:45 to deliberately engage
0:50:47 this long exhale mechanism
0:50:48 various times
0:50:48 throughout the day
0:50:50 now if you miss a day
0:50:50 is the pathway
0:50:51 going to atrophy
0:50:51 no
0:50:53 if you do it 50 times a day
0:50:54 is it going to strengthen
0:50:54 more than if you do it
0:50:55 one time per day
0:50:56 yes
0:50:57 do we know the exact
0:50:58 thresholds of how many
0:50:58 times per day
0:50:59 you should be doing
0:51:00 these deliberate exhales
0:51:01 in order to keep
0:51:01 this pathway robust
0:51:02 no
0:51:03 unfortunately
0:51:04 we do not
0:51:04 however
0:51:06 we do know
0:51:07 that in human patients
0:51:08 that suffer atrophy
0:51:09 of the dorsolateral
0:51:10 prefrontal cortex
0:51:11 that’s associated
0:51:12 with normal aging
0:51:13 or with accelerated
0:51:15 atrophy of dorsolateral
0:51:16 prefrontal cortex
0:51:17 or lesions of dorsolateral
0:51:18 prefrontal cortex
0:51:18 that tend to occur
0:51:20 in older people
0:51:20 who get strokes
0:51:22 or just associated
0:51:23 with the normal aging process
0:51:25 heart rate variability
0:51:26 declines with age
0:51:28 and it is now thought
0:51:29 that heart rate variability
0:51:30 declines with age
0:51:31 of course in part
0:51:32 through lower levels
0:51:33 of physical activity
0:51:34 because there are
0:51:34 of course
0:51:35 certain forms
0:51:36 of physical activity
0:51:37 like high intensity
0:51:38 interval training
0:51:39 to keep that
0:51:40 heart rate variability
0:51:41 elevated over time
0:51:42 using exercise
0:51:44 but it’s also true
0:51:45 that if this pathway
0:51:46 degenerates
0:51:47 you see a decrease
0:51:48 in heart rate variability
0:51:49 if you keep this pathway
0:51:51 engaged by behaviorally
0:51:51 deliberately
0:51:53 doing these long exhales
0:51:54 or if you take
0:51:55 the more robust approach
0:51:56 of transcranial magnetic
0:51:57 stimulation
0:51:58 something that most people
0:51:59 unfortunately won’t have
0:52:00 the opportunity to do
0:52:01 although maybe in the future
0:52:02 there will be commercial
0:52:03 devices that will allow
0:52:03 us to do this
0:52:05 you can keep heart rate
0:52:06 variability higher
0:52:08 as you age
0:52:09 which as I mentioned
0:52:10 before is correlated
0:52:11 with a number
0:52:12 of different positive
0:52:12 health outcomes
0:52:14 so these pathways
0:52:15 by which we can tap
0:52:16 into deliberate
0:52:17 activation of this
0:52:18 vagal control
0:52:19 over the sinoatrial node
0:52:21 are not just incidental
0:52:22 they turn out to be
0:52:23 central to the aging process
0:52:25 they turn out to be
0:52:26 central to countering
0:52:27 the aging process
0:52:28 and you now know
0:52:29 you have some agency
0:52:30 and control over them
0:52:31 so earlier I was
0:52:32 talking about how
0:52:33 despite the fact
0:52:34 the vagus nerve
0:52:35 is classified
0:52:36 as a parasympathetic nerve
0:52:38 that it also
0:52:40 can be alerting
0:52:41 it can increase
0:52:42 levels of sympathetic
0:52:43 nervous system activity
0:52:44 and that runs
0:52:46 counter to the concept
0:52:47 of parasympathetic
0:52:48 which is always
0:52:50 labeled as rest
0:52:50 and digest
0:52:52 I’m now going
0:52:53 to tell you a tool
0:52:53 that you can use
0:52:54 when you’re feeling
0:52:56 less than energized
0:52:57 less than motivated
0:52:59 and when you need
0:53:00 to exercise
0:53:01 and you don’t feel
0:53:01 like doing it
0:53:03 and when you want
0:53:04 to leverage exercise
0:53:06 as a way to improve
0:53:06 brain function
0:53:07 and plasticity
0:53:09 it all involves
0:53:10 the vagus nerve
0:53:11 and it involves
0:53:12 an aspect of the vagus nerve
0:53:14 that very few people
0:53:14 are aware of
0:53:15 but in my opinion
0:53:17 is one of the coolest
0:53:18 aspects of the vagus nerve
0:53:20 it’s at least as cool
0:53:21 as vagal control
0:53:22 over heart rate variability
0:53:23 and auto regulation
0:53:24 and it goes
0:53:25 like this
0:53:27 there’s a beautiful
0:53:28 set of findings
0:53:29 from a guy named
0:53:30 Peter Strick
0:53:30 at the University
0:53:31 of Pittsburgh
0:53:32 who used these
0:53:33 really cool methods
0:53:34 for tracing connections
0:53:34 between the brain
0:53:35 and body
0:53:36 to ask the question
0:53:38 what areas of the brain
0:53:39 are communicating
0:53:41 with our adrenal glands
0:53:42 our adrenal glands
0:53:43 are two glands
0:53:44 that sit atop
0:53:45 your two different kidneys
0:53:45 so one atop
0:53:46 each kidney
0:53:47 and release
0:53:48 as the name suggests
0:53:49 adrenaline
0:53:50 adrenaline
0:53:50 is also called
0:53:51 epinephrine
0:53:52 your adrenal glands
0:53:54 also release cortisol
0:53:56 but for sake of this discussion
0:53:56 let’s just think about
0:53:57 adrenaline released
0:53:58 from your adrenals
0:54:00 what he found
0:54:02 through a bunch of experiments
0:54:03 done in non-human primates
0:54:04 and that seem to correspond
0:54:05 very well
0:54:06 to what we observe
0:54:07 in humans as well
0:54:08 is that there are
0:54:09 three general groups
0:54:10 of brain areas
0:54:12 motor activation areas
0:54:12 so what we call
0:54:13 upper motor neurons
0:54:14 so these are the neurons
0:54:15 in the brain
0:54:15 that control
0:54:16 the lower motor neurons
0:54:17 in the spinal cord
0:54:17 that control
0:54:18 the muscles
0:54:18 of the body
0:54:20 as well as
0:54:21 neurons within our brain
0:54:21 that are involved
0:54:22 in cognition
0:54:23 and planning
0:54:24 and areas of the brain
0:54:25 that are involved
0:54:26 in emotion
0:54:27 that can communicate
0:54:28 with the adrenals
0:54:29 and cause them
0:54:30 to release adrenaline
0:54:32 now that’s great
0:54:33 but it sort of points
0:54:33 to a pathway
0:54:34 whereby
0:54:35 okay
0:54:36 you know
0:54:37 you should exercise
0:54:37 you tell yourself
0:54:38 you should exercise
0:54:39 you’re emotional
0:54:40 about it
0:54:41 and your adrenals
0:54:42 release adrenaline
0:54:43 and you exercise
0:54:45 now that’s interesting
0:54:46 but what’s perhaps
0:54:47 far more interesting
0:54:48 is that
0:54:50 the data from strict lab
0:54:51 and other labs as well
0:54:52 shows that
0:54:54 when we move
0:54:55 the large muscles
0:54:55 of our body
0:54:57 the adrenals
0:54:58 release adrenaline
0:54:59 epinephrine
0:55:01 now epinephrine
0:55:02 has an activating
0:55:04 sympathetic nervous system
0:55:05 stimulatory effect
0:55:05 right
0:55:06 it tends to make
0:55:07 the tissues of the body
0:55:07 that are associated
0:55:08 with movement
0:55:09 and with so-called
0:55:10 fight or flight
0:55:11 although again
0:55:11 fight or flight
0:55:13 is kind of an extreme example
0:55:15 it tends to activate
0:55:16 the organs of the body
0:55:18 and make them more likely
0:55:18 to be active
0:55:20 it increases the probability
0:55:21 that movement will occur
0:55:23 overall body movement
0:55:25 so when we move
0:55:25 the large muscles
0:55:26 of our body
0:55:26 our legs
0:55:27 and in particular
0:55:28 our trunk muscles
0:55:29 we release adrenaline
0:55:31 that adrenaline
0:55:32 activates the organs
0:55:32 of our body
0:55:34 and further makes it likely
0:55:35 that we’re going to move
0:55:36 our musculature more
0:55:38 but get this
0:55:39 adrenaline
0:55:39 epinephrine
0:55:40 doesn’t cross
0:55:41 the blood-brain barrier
0:55:42 so how does it
0:55:43 increase our level
0:55:44 of alertness
0:55:45 in our brain
0:55:45 right
0:55:46 you don’t want your body
0:55:47 to be super active
0:55:47 and your brain
0:55:48 to be kind of sleepy
0:55:49 that’s not good
0:55:50 that’s not adaptive
0:55:51 turns out
0:55:53 that when the adrenals
0:55:54 release adrenaline
0:55:56 it binds to receptors
0:55:58 on the vagus nerve itself
0:55:59 those sensory axons
0:56:01 that extend into the body
0:56:02 there are receptors
0:56:03 on those wires
0:56:03 right
0:56:04 not all the receptors
0:56:05 are at one end
0:56:05 or the other
0:56:06 they’re also
0:56:07 on those axons
0:56:09 the adrenaline binds
0:56:09 to the receptors
0:56:10 on those axons
0:56:11 and the vagus nerve
0:56:12 in turn
0:56:15 releases glutamate
0:56:16 an excitatory neurotransmitter
0:56:17 in a structure
0:56:18 in the brain
0:56:18 called the
0:56:20 nucleus tractus
0:56:20 solitaris
0:56:21 the neurons
0:56:22 in what I’m just going
0:56:23 to call the NTS
0:56:23 for simplicity
0:56:25 in turn
0:56:26 activate neurons
0:56:27 in a brain structure
0:56:28 called the locus
0:56:29 coeruleus
0:56:31 the locus coeruleus
0:56:31 contains neurons
0:56:32 that release
0:56:32 what’s called
0:56:33 norepinephrine
0:56:35 and the neurons
0:56:36 of locus coeruleus
0:56:37 send their axons
0:56:38 out very extensively
0:56:39 across the brain
0:56:40 in kind of a sprinkler
0:56:41 system like organization
0:56:43 such that
0:56:44 when you move
0:56:45 the large musculature
0:56:45 of your body
0:56:47 you release adrenaline
0:56:48 that adrenaline
0:56:49 activates the tissues
0:56:50 of your body
0:56:50 makes them more likely
0:56:51 to move
0:56:52 also binds
0:56:52 to receptors
0:56:53 on the vagus
0:56:54 the vagus nerve
0:56:54 in turn
0:56:55 releases glutamate
0:56:57 an excitatory neurotransmitter
0:56:58 in the NTS
0:56:59 the NTS
0:57:00 then passes off
0:57:01 that excitatory signal
0:57:02 like a bucket brigade
0:57:04 off to the locus coeruleus
0:57:05 the locus coeruleus
0:57:06 dumps a bunch
0:57:07 of norepinephrine
0:57:08 into the brain
0:57:08 and increases
0:57:09 your levels
0:57:10 of alertness
0:57:11 what this means
0:57:12 is that the vagus nerve
0:57:13 is central
0:57:14 to the process
0:57:15 of using physical activity
0:57:17 to make your brain
0:57:18 more alert
0:57:18 and we know
0:57:19 that activation
0:57:20 of locus coeruleus
0:57:22 makes the brain areas
0:57:23 that are involved
0:57:24 in motivation
0:57:25 and the propensity
0:57:26 to move more
0:57:27 higher
0:57:29 in levels of activity
0:57:29 in other words
0:57:30 if you’re not
0:57:30 feeling motivated
0:57:31 to exercise
0:57:32 or you’re not
0:57:34 feeling alert enough
0:57:35 movement of the body
0:57:36 that includes
0:57:37 especially the legs
0:57:37 the large muscles
0:57:38 of the legs
0:57:39 so quadriceps
0:57:39 hamstrings
0:57:39 etc
0:57:40 as well as
0:57:41 the trunk muscles
0:57:42 of the body
0:57:43 stimulate this pathway
0:57:44 in a kind of
0:57:45 dominoing effect
0:57:46 that makes
0:57:47 the likelihood
0:57:49 and believe it or not
0:57:50 the desire to move
0:57:52 much more likely
0:57:54 this I’ve personally
0:57:54 found to be
0:57:55 an immensely
0:57:57 useful piece
0:57:57 of information
0:57:59 because sure
0:57:59 I knew that
0:58:00 sometimes I would
0:58:01 go to the gym
0:58:02 or I’d head out
0:58:02 on a run
0:58:03 and I wasn’t
0:58:03 feeling motivated
0:58:05 or I’d sit down
0:58:05 to do some work
0:58:06 and I’d feel
0:58:06 kind of sleepy
0:58:07 despite the fact
0:58:07 that I’d slept
0:58:08 pretty well the night
0:58:09 before and eaten
0:58:10 just fine
0:58:10 and the room
0:58:11 wasn’t too warm
0:58:11 etc
0:58:12 and I feel
0:58:13 kind of lethargic
0:58:13 and I was like
0:58:14 what’s going on here
0:58:16 and yes
0:58:17 I had the experience
0:58:18 of sometimes
0:58:18 you know
0:58:19 doing a bit
0:58:19 of a warm-up
0:58:20 maybe some
0:58:21 light calisthenics
0:58:21 maybe a few
0:58:22 warm-up sets
0:58:23 or jogging
0:58:23 for a little while
0:58:24 and then finding
0:58:24 that my levels
0:58:25 of alertness
0:58:25 increased
0:58:26 but I’ve also
0:58:27 had just as often
0:58:28 the experience
0:58:30 of not feeling
0:58:31 that motivation
0:58:32 for physical activity
0:58:33 or for cognitive
0:58:34 activity come online
0:58:35 especially if I wasn’t
0:58:36 extremely interested
0:58:37 in that activity
0:58:38 or that thing
0:58:39 that I was supposed
0:58:39 to learn
0:58:40 you know
0:58:40 it’s very easy
0:58:41 to be excited
0:58:42 when we want
0:58:42 to do the activity
0:58:43 or we want
0:58:43 to learn the thing
0:58:44 that we’re supposed
0:58:45 to be learning
0:58:45 at a given moment
0:58:46 or reading
0:58:46 at a given moment
0:58:48 this pathway
0:58:49 is immensely useful
0:58:50 to understand
0:58:51 because it explains
0:58:51 why it is
0:58:52 that even when
0:58:53 you’re not feeling
0:58:53 motivated
0:58:54 if you do
0:58:54 some activity
0:58:55 that yes
0:58:56 is preceded
0:58:56 by a bit
0:58:57 of a warm-up
0:58:57 so maybe
0:58:58 I don’t know
0:58:58 you do some
0:58:59 light calisthenics
0:58:59 or you go
0:59:00 on the treadmill
0:59:00 for a few minutes
0:59:01 walking
0:59:01 maybe a little bit
0:59:02 faster
0:59:03 that it can
0:59:04 increase your
0:59:04 levels of alertness
0:59:05 and motivation
0:59:08 but it especially
0:59:08 explains how
0:59:10 if you put
0:59:10 in some effort
0:59:11 that at the moment
0:59:12 feels like a big
0:59:13 exertion
0:59:15 your entire body
0:59:16 and brain state
0:59:17 shifts in a way
0:59:17 that levels
0:59:18 of motivation
0:59:19 and energy
0:59:20 to do more
0:59:20 physical work
0:59:21 or more cognitive
0:59:22 work or both
0:59:24 increases dramatically
0:59:24 and these are
0:59:25 not small effects
0:59:26 when they’ve
0:59:26 been measured
0:59:27 in fact
0:59:28 for all the talk
0:59:29 that’s out there
0:59:30 in kind of pop
0:59:30 psychology
0:59:32 and in kind of
0:59:33 pop neuroscience
0:59:34 about the vagus
0:59:35 being a calming
0:59:36 pathway
0:59:38 all the neurophysiologists
0:59:39 out there
0:59:39 and I know
0:59:39 there aren’t
0:59:40 very many
0:59:41 but I’m friends
0:59:41 with a lot
0:59:42 of neurophysiologists
0:59:44 they’ll all tell you
0:59:45 that if they’re
0:59:45 doing a surgery
0:59:47 or they’re doing
0:59:47 some sort of
0:59:48 brain recording
0:59:49 and the animal
0:59:50 or person
0:59:50 that they’re doing
0:59:51 the brain recording
0:59:51 from
0:59:52 is starting to
0:59:53 drop into a state
0:59:54 of deep
0:59:55 parasympathetic
0:59:56 activity
0:59:56 they’re falling
0:59:57 asleep
0:59:57 where they need
0:59:57 to be more
0:59:58 alert
0:59:59 what do they do
1:00:00 they stimulate
1:00:00 the vagus
1:00:01 they stimulate
1:00:02 the vagus nerve
1:00:02 in order to
1:00:03 wake up the
1:00:03 brain
1:00:04 in fact
1:00:04 stimulating
1:00:05 the vagus
1:00:05 has been used
1:00:06 to save
1:00:06 people’s lives
1:00:07 when they are
1:00:08 drifting too
1:00:08 far down
1:00:10 into deeper
1:00:10 and deeper
1:00:11 planes of
1:00:11 anesthesia
1:00:12 so stimulating
1:00:13 the vagus
1:00:14 wakes up
1:00:14 the brain
1:00:15 and the way
1:00:16 to stimulate
1:00:16 the vagus
1:00:17 is by way
1:00:18 of these receptors
1:00:18 on the vagus
1:00:19 nerve itself
1:00:19 and the way
1:00:20 to do that
1:00:21 without an
1:00:21 electrical
1:00:21 stimulator
1:00:22 right
1:00:22 because we’re
1:00:22 not talking
1:00:23 about clinical
1:00:23 conditions
1:00:23 here
1:00:24 in order
1:00:25 to increase
1:00:25 levels
1:00:25 of
1:00:26 motivation
1:00:26 alertness
1:00:27 and focus
1:00:27 for physical
1:00:28 activity
1:00:29 or cognitive
1:00:29 activity
1:00:29 and learning
1:00:30 etc
1:00:31 or simply
1:00:31 to overcome
1:00:32 lethargy
1:00:33 and brain fog
1:00:33 work
1:00:34 is to do
1:00:34 some sort
1:00:35 of physical
1:00:35 activity
1:00:35 that includes
1:00:36 the large
1:00:36 musculature
1:00:37 of your body
1:00:38 these could
1:00:38 be things
1:00:39 like jumping
1:00:40 these could
1:00:40 be things
1:00:41 like actual
1:00:42 resistance training
1:00:42 this could
1:00:43 be running
1:00:45 this information
1:00:45 really points
1:00:46 to the idea
1:00:47 of of course
1:00:48 after a good
1:00:48 warm-up
1:00:50 doing more
1:00:50 sprinting type
1:00:51 activity
1:00:52 more strength
1:00:53 type activity
1:00:54 you know
1:00:54 six repetitions
1:00:55 or less
1:00:55 where you’re
1:00:56 getting close
1:00:56 to failure
1:00:57 this sort
1:00:57 of thing
1:00:57 to wake
1:00:58 up the brain
1:00:58 and body
1:00:59 as opposed
1:01:00 to doing
1:01:01 long
1:01:01 rhythmic
1:01:01 activity
1:01:02 that’s below
1:01:03 the threshold
1:01:03 of what would
1:01:04 activate a lot
1:01:04 of adrenaline
1:01:05 from the adrenals
1:01:06 so the idea
1:01:06 is to get
1:01:07 those adrenals
1:01:08 to release
1:01:08 adrenaline
1:01:08 into your
1:01:09 system
1:01:09 it won’t
1:01:10 cross the
1:01:10 blood-brain
1:01:10 barrier
1:01:11 but your
1:01:11 vagus nerve
1:01:12 provides this
1:01:13 beautiful link
1:01:14 between the
1:01:14 body and brain
1:01:15 to match
1:01:16 levels of
1:01:16 excitation
1:01:17 from the body
1:01:18 to the brain
1:01:18 and you can
1:01:19 leverage that
1:01:20 in addition
1:01:21 there’s also
1:01:22 the well-described
1:01:23 effects
1:01:23 and I’ve done
1:01:23 an entire
1:01:24 episode about
1:01:24 this
1:01:26 of how exercise
1:01:27 can improve
1:01:28 brain plasticity
1:01:28 and the ability
1:01:29 to learn
1:01:30 and while there
1:01:30 are a host
1:01:31 of mechanisms
1:01:32 involving long-term
1:01:33 changes in things
1:01:33 like brain-derived
1:01:34 nootrophic factor
1:01:36 and increases
1:01:36 in lactate
1:01:37 which might
1:01:37 open the door
1:01:38 to plasticity
1:01:39 and so on
1:01:39 and so forth
1:01:40 it does seem
1:01:42 that one of
1:01:43 the major ways
1:01:44 that exercise
1:01:45 improves our
1:01:45 brain function
1:01:46 and our ability
1:01:46 to learn
1:01:48 is simply
1:01:48 by increasing
1:01:49 our levels
1:01:50 of alertness
1:01:50 and I should
1:01:51 say the word
1:01:52 simply placed
1:01:52 in there
1:01:53 is probably
1:01:54 a bit unfair
1:01:54 there is
1:01:55 absolutely
1:01:56 nothing trivial
1:01:56 about using
1:01:57 exercise
1:01:57 as a way
1:01:58 to stimulate
1:01:58 a sort
1:01:59 of cascade
1:02:00 of this neural
1:02:00 circuit
1:02:01 from the adrenals
1:02:01 up the vagus
1:02:02 and into locus
1:02:03 coeruleus
1:02:04 in order to wake
1:02:05 up your brain
1:02:05 networks that are
1:02:06 involved in
1:02:06 motivation
1:02:07 focus
1:02:07 and learning
1:02:09 as we’ll talk
1:02:09 about in a few
1:02:09 minutes
1:02:10 many of us
1:02:11 most of us
1:02:11 perhaps
1:02:12 are used to
1:02:13 using pharmacology
1:02:14 like caffeine
1:02:15 or other stimulants
1:02:16 in order to try
1:02:16 and wake up levels
1:02:17 of alertness
1:02:17 in the brain
1:02:18 and I’m not
1:02:18 being disparaging
1:02:19 of that
1:02:20 I am an avid
1:02:21 consumer of caffeine
1:02:21 in the form
1:02:22 of yerba mate
1:02:23 or coffee
1:02:24 I’ll occasionally
1:02:25 take an alpha
1:02:25 GPC
1:02:27 or an L-tyrosine
1:02:27 as well
1:02:27 you know
1:02:28 I do all
1:02:28 those things
1:02:29 however in my
1:02:29 opinion
1:02:31 it’s far more
1:02:31 powerful to be
1:02:32 able to leverage
1:02:33 that is to
1:02:34 activate these
1:02:35 levels of alertness
1:02:35 in your brain
1:02:35 and body
1:02:36 in a way that
1:02:37 doesn’t require
1:02:38 any pharmacology
1:02:38 if you don’t
1:02:39 have it available
1:02:39 to you
1:02:40 or you’re trying
1:02:40 to avoid
1:02:41 pharmacology
1:02:41 or working
1:02:41 out late
1:02:42 at night
1:02:42 or you want
1:02:42 to focus
1:02:43 later at night
1:02:44 you don’t want
1:02:45 to be kept
1:02:45 awake by the
1:02:46 caffeine
1:02:47 or even if
1:02:47 you consume
1:02:47 caffeine
1:02:48 or other
1:02:48 stimulants
1:02:49 knowing the
1:02:50 organization
1:02:50 of these neural
1:02:51 circuits
1:02:51 from the body
1:02:52 to the brain
1:02:52 and how they
1:02:53 match levels
1:02:53 of alertness
1:02:54 and leveraging
1:02:55 them is so
1:02:56 straightforward
1:02:57 but most people
1:02:58 don’t actually
1:02:58 get to the point
1:02:59 where they’re
1:02:59 doing that
1:03:00 high intensity
1:03:00 work
1:03:01 or they’re
1:03:02 doing the work
1:03:02 that involves
1:03:02 the large
1:03:03 musculature of
1:03:03 their body
1:03:04 when they’re
1:03:04 feeling not
1:03:05 motivated
1:03:06 in fact they
1:03:06 usually do
1:03:07 the opposite
1:03:07 thing
1:03:07 now sometimes
1:03:08 you need
1:03:08 rest days
1:03:09 this is true
1:03:09 right
1:03:10 you need to
1:03:10 rest and
1:03:10 recover
1:03:10 to make
1:03:11 progress
1:03:11 you don’t
1:03:12 want to
1:03:12 exhaust
1:03:12 yourself
1:03:12 you need
1:03:13 to get
1:03:13 sleep
1:03:13 you need
1:03:14 to take
1:03:14 care of
1:03:14 yourself
1:03:15 however
1:03:15 the reason
1:03:15 we’re
1:03:16 talking
1:03:16 about this
1:03:17 is it’s a
1:03:17 beautiful
1:03:18 opportunity
1:03:19 to a
1:03:20 explain that
1:03:21 the vagus nerve
1:03:21 is not just
1:03:22 about calming
1:03:22 down
1:03:23 it’s actually
1:03:24 actively used
1:03:25 to wake up
1:03:25 your brain
1:03:26 when your body
1:03:27 is active
1:03:28 when the large
1:03:29 musculature of
1:03:29 your body
1:03:29 is active
1:03:30 and be
1:03:32 that like
1:03:33 with auto
1:03:33 regulation
1:03:35 this stuff
1:03:35 is under
1:03:36 conscious
1:03:36 control
1:03:38 yes if you
1:03:38 were to be
1:03:38 frightened
1:03:39 immediately
1:03:40 this is the
1:03:40 same pathway
1:03:41 that would be
1:03:42 reflexively activated
1:03:43 by an intruder
1:03:44 or by you know
1:03:44 a big explosion
1:03:45 or something
1:03:45 of that sort
1:03:46 your body
1:03:46 would wake
1:03:47 up release
1:03:47 adrenaline
1:03:47 then that
1:03:48 adrenaline
1:03:49 would set up
1:03:49 along this
1:03:50 cascade
1:03:50 and your mind
1:03:51 would be
1:03:51 immediately
1:03:52 alert as well
1:03:52 there’s some
1:03:53 parallel mechanisms
1:03:54 too to make
1:03:54 sure that your
1:03:55 brain and your
1:03:55 body are alert
1:03:56 immediately
1:03:57 but when you
1:03:58 start to understand
1:03:59 what these
1:03:59 pathways are
1:04:00 and that they
1:04:01 are very specific
1:04:02 and very powerful
1:04:03 potent inroads
1:04:04 into activating
1:04:05 these circuits
1:04:06 it does indeed
1:04:07 give you a
1:04:07 tremendous amount
1:04:08 of agency
1:04:09 especially for
1:04:10 those of you
1:04:10 that might think
1:04:11 you’re not
1:04:12 motivated to
1:04:12 exercise
1:04:12 or you’re
1:04:13 always lethargic
1:04:14 or you have
1:04:14 brain fog
1:04:15 there might
1:04:15 be other
1:04:15 reasons for
1:04:16 that
1:04:17 but for
1:04:18 many people
1:04:18 chances are
1:04:19 you’re not
1:04:20 getting past
1:04:20 that threshold
1:04:21 whereby these
1:04:22 circuits involving
1:04:22 the vagus
1:04:23 can be activated
1:04:24 and now you
1:04:24 know how
1:04:25 so activate
1:04:26 them
1:04:26 i’d like to
1:04:27 i’d like to
1:04:27 take a quick
1:04:28 break and
1:04:28 acknowledge one
1:04:29 of our
1:04:29 sponsors
1:04:30 function
1:04:31 last year i
1:04:31 became a
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1:06:02 function currently has
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1:06:09 podcast listeners again
1:06:11 that’s functionhealth.com
1:06:12 slash huberman to get
1:06:13 early access to
1:06:14 function i just got
1:06:15 done telling you how
1:06:15 you can increase your
1:06:17 levels of alertness by
1:06:18 activating this vagal
1:06:19 nerve pathway from the
1:06:20 body to the brain and
1:06:21 that increasing your
1:06:23 level of alertness allows
1:06:24 for more opportunity to
1:06:26 focus and to learn but
1:06:26 when we say focus and
1:06:27 learn what we’re really
1:06:28 talking about is
1:06:29 neuroplasticity this
1:06:31 incredible feature of
1:06:32 your nervous system to be
1:06:33 able to change in
1:06:34 response to experience in
1:06:35 deliberate ways the
1:06:36 plasticity that you have
1:06:38 when you are a child from
1:06:39 the time you’re born until
1:06:42 about age 25 typically can
1:06:44 occur even in passive
1:06:45 experience that is you’re
1:06:47 in class a teacher’s teaching
1:06:48 you something your brain
1:06:49 is changing maybe you put
1:06:50 a bit more effort into
1:06:51 something you’re focused
1:06:53 your brain will change but
1:06:54 as we get into adulthood
1:06:56 most of our neural maps in
1:06:57 the brain certainly our
1:06:58 sensory maps and our
1:07:00 cortex our motor maps that
1:07:01 allow us to move in
1:07:03 particular ways those have
1:07:04 been established you can
1:07:06 still change them but
1:07:07 they’ve mostly been
1:07:07 established throughout
1:07:08 childhood and into our
1:07:10 early 20s and if we want
1:07:11 to modify those circuits with
1:07:13 neuroplasticity there are a
1:07:14 couple of key requirements
1:07:15 one you need to be alert
1:07:16 you can’t get
1:07:18 neuroplasticity that is you
1:07:19 can’t trigger neuroplasticity
1:07:20 unless you’re alert you
1:07:21 also have to be focused
1:07:23 this is critical and
1:07:24 differentiates adult
1:07:25 plasticity in a major way
1:07:27 from plasticity when we’re
1:07:28 young where we can learn by
1:07:30 passive exposure okay when
1:07:31 we’re young we can learn by
1:07:33 passive exposure or even
1:07:35 better by focused exposure but
1:07:36 when we are adults we need
1:07:38 alertness and we need focus
1:07:39 just passively being
1:07:41 exposed to you know music
1:07:43 or to a motor pattern is
1:07:44 not going to allow us to
1:07:45 change our nervous system
1:07:46 that’s been shown over and
1:07:48 over again fortunately what
1:07:49 also has been shown over and
1:07:51 over again is that if we are
1:07:52 alert and we’re focused and
1:07:54 we are determined especially
1:07:55 if we undertake what’s
1:07:56 called incremental learning
1:07:58 where we go after small bits
1:08:00 of neuroplasticity repeatedly
1:08:02 over time we can get as much
1:08:04 neuroplasticity as one
1:08:06 observes in childhood it just
1:08:07 takes longer and you have to do
1:08:08 it so-called incrementally
1:08:11 there’s a lot to say about
1:08:12 that but for sake of today’s
1:08:13 discussion about the vagus
1:08:15 nerve I just want to tell you
1:08:17 that there’s a particular
1:08:19 pathway in the brain that
1:08:20 involves the molecule
1:08:22 acetylcholine acetylcholine
1:08:24 is used to contract the
1:08:25 muscles it’s released from
1:08:26 motor neurons in the spinal
1:08:28 cord onto muscles to contract
1:08:30 the muscles it’s also used in
1:08:30 the brain and elsewhere in
1:08:32 the nervous system and does a
1:08:33 lot of different things it’s
1:08:33 actually involved in
1:08:35 generating the rhythms of
1:08:36 the heart but acetylcholine
1:08:38 acetylcholine released from a
1:08:39 particular nucleus in the brain
1:08:42 called nucleus basalis the
1:08:43 acetylcholine released from
1:08:45 nucleus basalis is what we call
1:08:47 permissive for plasticity in other
1:08:49 words if you have acetylcholine
1:08:51 released from nucleus basalis into
1:08:53 the brain plasticity is much more
1:08:56 likely to occur and in fact acetylcholine
1:08:59 released from nucleus basalis is sort of
1:09:01 like a gate whereby if you release
1:09:03 acetylcholine the opportunity for
1:09:05 neuroplasticity and learning is available
1:09:07 for some period of time so the
1:09:09 question therefore becomes how do
1:09:10 you get acetylcholine released from
1:09:11 nucleus basalis there are these
1:09:13 incredible experiments that have been
1:09:14 done by mike merzenich and
1:09:16 colleagues showing that if you
1:09:18 stimulate nucleus basalis to release
1:09:20 acetylcholine and you expose an
1:09:21 animal or a human to a particular
1:09:24 sensory stimulus the brain remaps very
1:09:26 fast according to that experience just
1:09:28 enormous amounts of plasticity that
1:09:30 you wouldn’t observe otherwise there
1:09:32 are also fortunately experiments showing
1:09:34 that if you pharmacologically increase
1:09:37 acetylcholine that you can enhance the
1:09:39 opportunity for neuroplasticity you
1:09:40 still need to do the learning you still
1:09:42 need to attempt to learn something you
1:09:44 still have to make it incremental but
1:09:46 the amount of plasticity is significantly
1:09:48 increased when there’s acetylcholine
1:09:51 released from nucleus basalis so in the
1:09:53 absence of deep brain stimulation using an
1:09:55 electrode which most of you fortunately
1:09:57 will not experience because it requires
1:09:58 drilling down through the skull and
1:10:00 placing an electrode in basalis and
1:10:02 assuming that you’re not taking
1:10:04 anything to increase acetylcholine
1:10:06 transmission to learn although there
1:10:08 are ways to do that i’ve talked about
1:10:09 that before and i’ll talk about that
1:10:11 again in a future podcast some of those
1:10:13 ways include supplementing with things
1:10:15 like alpha gpc which is a precursor to
1:10:17 acetylcholine there are some other
1:10:19 precursors to acetylcholine or things
1:10:21 that stimulate the release of acetylcholine
1:10:23 such as huperzine and things like that that
1:10:25 will open the opportunity for enhanced
1:10:29 plasticity for a few hours and there is good
1:10:31 old nicotine i know the word nicotine
1:10:34 brings to mind things like lung cancer
1:10:36 because for many many years many many
1:10:38 people and still now smoked nicotine in
1:10:40 the form of cigarettes or vaping both of
1:10:42 which i think are absolutely terrible as
1:10:44 is dipping and snuffing because yes they
1:10:47 increase levels of nicotinic acetylcholine
1:10:49 receptor activation which is just fancy
1:10:52 nerd speak for acetylcholine transmission in
1:10:55 the brain is enhanced by nicotine but those
1:10:57 delivery mechanisms also of course can give
1:10:59 you cancer in the case of smoking dipping or
1:11:02 snuffing and vaping despite what you hear
1:11:04 out there is absolutely terrible for your
1:11:06 health i don’t care what anybody says the
1:11:09 evidence is starting to really pile up that
1:11:12 vaping is bad for you now is oral form
1:11:17 nicotine bad for you in the form of gum or in the form of a pouch etc i just want to say a couple
1:11:20 of things one it’s extremely habit forming
1:11:27 two it increases blood pressure and it’s a vasoconstrictor these drawbacks about nicotine
1:11:32 are real and are critical to consider if you’re going to use nicotine as a focusing agent or a so-called
1:11:39 nootropic i don’t really like that word but if you’re using nicotine as a way to enhance cognition and
1:11:44 enhance neuroplasticity you should know what the potential drawbacks are most notably the habit
1:11:50 forming and addicting properties which are very robust now with that said there are ways to non-pharmacologically
1:11:57 stimulate the nucleus basalis acetylcholine pathway to enhance the window for plasticity and the way to do
1:12:03 that is you guessed it through the vagus nerve studies in healthy humans and humans who have had
1:12:07 for instance stroke as well as animal studies have shown that if you stimulate the vagus nerve
1:12:13 electrically you increase the level of alertness in the brain and part of the mechanism by which you do
1:12:18 that is the one i told you about a few minutes ago the adrenals vagus locus coeruleus but also
1:12:25 there’s a separate pathway from the nts to nucleus basalis that stimulates the release of acetylcholine
1:12:32 from nucleus basalis and opens up the opportunity for neuroplasticity this i should mention is not a
1:12:39 small effect it is a rapid effect and it’s one that has allowed stroke patients for instance to improve
1:12:45 their motor capabilities very quickly as compared to when the vagus nerve is not stimulated or when
1:12:50 acetylcholine transmission is not enhanced pharmacologically and fortunately now there are
1:12:56 studies starting to accumulate in animal models and some in humans we need more but there are some
1:13:02 showing that if you enhance alertness by way of activating the vagus nerve through the mechanism
1:13:08 that i told you before which is good old-fashioned high intensity exercise that in the several hours
1:13:14 following that exercise there is an enhanced opportunity for neuroplasticity now that enhanced
1:13:19 opportunity for neuroplasticity comes by way of two different pathways you already heard about the
1:13:24 first one which is the locus coeruleus release of norepinephrine that’s going to increase alertness
1:13:30 which is a prerequisite for focus and it appears to be the case that the release of acetylcholine from
1:13:37 nucleus basalis that’s also triggered by this high intensity exercise is what allows for that alertness to be
1:13:43 converted into focus and those two things together alertness and focus are the triggers for adult
1:13:49 neuroplasticity if you think about this this is really exciting for 25 years or more we’ve known
1:13:55 that plasticity is possible in the adult human we knew you needed alertness and you needed focus we also
1:14:00 by the way know that you need to get great sleep that night and in subsequent nights in order to actually
1:14:06 allow the plasticity to occur plasticity is a process it’s not just triggered when you go about trying to
1:14:12 learn something it actually takes place in sleep as well as sleep like states like non-sleep deep rest
1:14:17 and meditation but especially in deep sleep and rapid eye movement sleep this is why you can attempt to
1:14:22 learn something cognitively or behaviorally over and over and over you can’t get those scales on the piano
1:14:28 right you can’t get the you know the information dialed in from your class a language class or from
1:14:33 engineering or you’re trying to figure out what this picture should be in your mind that you’re going to
1:14:38 paint etc you work at it you work at it you work at it you sleep you sleep and then one day you wake up
1:14:43 and suddenly you have the skill it’s because the actual rewiring of those circuits that we call
1:14:49 neuroplasticity occurs during sleep but it’s triggered in those moments of incremental learning and really
1:14:54 struggling and keep in mind the struggle to learn something that friction is part of the neuroplasticity
1:15:02 process and it’s oh so clear now that alertness and focus are the prerequisites for plasticity that
1:15:07 alertness is coming in large part by way of the release of norepinephrine from locus coeruleus that
1:15:13 the focus is being augmented and perhaps it’s even originating entirely from the release of acetylcholine
1:15:18 and nucleus basalis that acts as sort of a spotlight on a particular set of things that are happening
1:15:24 while we’re trying to learn and then that triggers the plasticity process which takes place during sleep
1:15:32 so that beautiful picture of self-directed adaptive plasticity in adulthood is allowed to happen
1:15:42 because the vagus nerve in part is triggering nts to say hey locus coeruleus nucleus basalis wake up
1:15:49 release norepinephrine release acetylcholine now is the time to learn so what this means is if you’re
1:15:54 struggling to learn if you want to continue to have robust neuroplasticity if you happen to have some
1:16:00 damage to motor pathways or you’re having trouble with focusing and brain fog keep in mind focus itself
1:16:05 is served by a circuit that is subject to plasticity you can actually get better at focusing
1:16:11 by working on focus just the same way you would on any skill and so if you’re struggling with focus
1:16:18 i highly recommend finding a threshold of exercise that stimulates brain alertness that triggers these
1:16:23 pathways that are now starting to be clear that they occur from the literature in animals and humans
1:16:29 and yes you might augment this with something like caffeine which will further increase levels of
1:16:34 norepinephrine you might even use low dose nicotine i’m not necessarily recommending that certainly not for young
1:16:40 people and you do need to be aware of the habit forming aka addictive properties of nicotine you definitely
1:16:45 don’t want to consume it in any form that’s going to cause you to increase your risk of cancer or popcorn lung from
1:16:50 vaping you could use pharmacology you could use alpha gpc you could use herpruzine in
1:16:56 a combination with exercise however i strongly strongly recommend that anyone who’s interested
1:17:01 in lifelong learning think about organizing your bouts of learning especially cognitive learning
1:17:07 to come in the two to three hours maybe even four hours but certainly in the one to two hours after you do
1:17:12 some sort of exercise that doesn’t leave you exhausted but leaves you with elevated levels
1:17:17 of energy in your body so you don’t want to take this physical exercise that i’m talking about
1:17:22 to exhaustion because that’s going to leave you depleted that’s going to cause a you know uptick
1:17:27 in parasympathetic activity any of you that have done a hard leg workout and then you know two three
1:17:33 hours later you’re just like it’s very clear brain oxygen levels are down parasympathetic activity is up
1:17:38 you are tired because you exhausted all that energy and exercise but if you can use exercise as a trigger
1:17:44 to release adrenaline and stimulate these pathways within the brain that arrive via the signaling from the
1:17:51 vegas you do indeed open up the opportunity for enhanced neuroplasticity at any age and that is a
1:17:57 non-trivial thing in fact it’s downright exciting because the search for adult neuroplasticity tools
1:18:01 is one that’s existed probably for thousands of years and that has been documented for hundreds of years
1:18:07 and the thing that makes the nervous system of humans so special is that it is capable of changing
1:18:11 itself throughout the lifespan so now you know at least one method by which you can do that
1:18:17 and it of course involves the vagus okay so one of the most incredible things about the vagus nerve
1:18:23 that i myself have really not ever heard talked about out there is the way it communicates and
1:18:30 coordinates levels of serotonin in the gut with levels of serotonin in the brain now a discussion
1:18:36 about serotonin that’s complete would take many many hours but suffice to say that serotonin is a
1:18:41 a neuromodulator much like dopamine or acetylcholine or norepinephrine in that it modulates the activity of
1:18:48 other circuits it’s critically important for mood in the gut it’s critically important for gut motility
1:18:55 for ease of digestion and for gut health in the brain we say serotonin is important for mood i don’t want
1:19:01 to give the impression that high levels of serotonin good low levels of serotonin bad serotonin needs to be at a
1:19:06 particular level so neither too high nor too low as many of you know one of the major ways that
1:19:10 depression has been treated over the last decades is through the administration of something called
1:19:16 ssri selective serotonin reuptake inhibitors which have the net effect of increasing levels of serotonin
1:19:23 at synapses ssris are somewhat controversial because in many people they do alleviate certain symptoms of
1:19:28 depression but they often carry side effects because serotonin is used in multiple circuits throughout
1:19:33 the brain i don’t want to give the impression that ssris are always bad or always good it’s highly
1:19:38 dependent on the patient and a bunch of other things that really unfortunately can only be explored
1:19:44 through experimentation that’s typically what psychiatrists will do they’ll prescribe an ssri at a
1:19:48 given dose see how a patient reacts maybe they’ll take them off an ssri entirely give them a different
1:19:52 type of antidepressant that works on a different set of neuromodulators like dopamine and norepinephrine
1:19:58 so welbutrin would be a non-ssri antidepressant and there are a whole set of issues around ssris for
1:20:04 instance they can be very beneficial for people with full clinical ocd obsessive compulsive disorder
1:20:10 and then again other people suffer terrible side effects from ssris so i don’t want to suggest that
1:20:17 ssris are a solution i also don’t want to suggest that serotonin is the only problem with depression
1:20:22 or is always a problem in cases of depression that itself is heavily debated what’s emerging
1:20:28 from the data is that elevating levels of serotonin in the brain can increase neuroplasticity which can
1:20:33 allow people who have major depression to learn new contingencies you know these are people who
1:20:38 at one point are thinking you know why would i ever try and get a new relationship or job like
1:20:43 everything always turns out terribly these are hallmarks of depression you know lack of excitement
1:20:49 about the future everything’s a negative outcome in their mind through neuroplasticity it’s clear that
1:20:54 people can form new contingencies they can start to imagine life as more positive and holding more
1:20:59 possibility and changing levels of serotonin is known to be much in the same way acetylcholine can
1:21:06 increase plasticity permissive for neuroplasticity so that might be one way by which ssris actually can
1:21:12 provide help for certain people for depression however because of the side effects associated with ssris many
1:21:18 people are leaning away from them and yet having adequate levels of serotonin is absolutely critical
1:21:23 for people depressed as well as people who are not depressed to feel a sense of well-being just overall
1:21:29 sense of well-being being okay with who they are and where life is at being able to lean into effort and
1:21:34 all these things it’s absolutely critical that we have adequate levels of serotonin in the brain now you
1:21:40 may have heard and it is absolutely true that 90 percent of the serotonin manufactured in your body
1:21:47 is in the gut now what you don’t often hear is that serotonin stays in the gut right we hear these
1:21:53 days oh you know most of your serotonin is manufactured in your gut which has given millions of people the
1:22:00 false impression that if you get your gut serotonin right somehow it’s traveling up to your brain and
1:22:04 performing all the important roles that serotonin plays in your brain that’s not how it works at all
1:22:10 fortunately however there are ways that you can modify the levels of serotonin in your gut
1:22:16 and indeed the levels of serotonin in your gut powerfully impact the levels of serotonin in your
1:22:22 brain and this occurs you guessed it by way of the vagus it’s a super cool mechanism and it’s one that you
1:22:29 can exert some positive control over in order to for instance increase your baseline levels of mood in
1:22:34 order to increase levels of serotonin if that’s something that you seek here’s the pathway in the
1:22:38 mechanism and i’m going to provide this in kind of top contour form in the future i’ll do an entire
1:22:47 episode about serotonin but here’s the idea in your gut you have cells including neurons but you also have a lot of
1:22:53 other cells mostly other cells frankly and there’s a particular category of cells called the enterochromaffin
1:22:57 cells you don’t need to know that name but if you want they’re the enterochromaffin cells and they
1:23:04 manufacture serotonin they do that through a beautiful pathway involving an enzymatic reaction that converts
1:23:09 tryptophan from the food you eat tryptophan’s an amino acid gets converted eventually into serotonin
1:23:13 there are a bunch of steps in there in the biochemistry gets converted into serotonin
1:23:20 that serotonin binds to the ends of neurons the axons of neurons in the vagus nerve that innervate
1:23:26 your gut not just your stomach but your large intestine and your small intestine remember those
1:23:34 sensory afferents those sensory axons that extend into the body have receptors on them right the serotonin
1:23:40 in the gut assuming you’re getting enough tryptophan and assuming the milieu of your gut is correct we’ll
1:23:44 talk about what that means and how you can exert control over it get the milieu right that serotonin
1:23:51 binds to the ends of those axons in the gut and stimulates a particular category of them
1:23:58 that then relays the signal up and through nodos ganglion you now are familiar with these names up into
1:24:07 the brain to the nucleus tractus solitaris okay that nts again and then the nucleus tractus solitaris
1:24:12 doesn’t just communicate with locus coeruleus and with nucleus basalis it also sends a powerful signal
1:24:17 to what’s called the dorsal raphae nucleus the dorsal raphae nucleus in your brain
1:24:23 is responsible for the release of the majority of the serotonin in your brain so when you hear that most
1:24:30 of the serotonin in your body is made in your gut that’s true and it stays in your gut but the levels
1:24:37 of serotonin are communicated to the brain by the vagus and then stimulates the release of serotonin from the
1:24:44 dorsal raphae nucleus so the question therefore becomes if we want to increase levels of serotonin
1:24:49 in the brain or simply to maintain healthy levels of serotonin in the brain for somebody who’s not
1:24:53 depressed or maybe somebody who’s having low mood just to keep elevated levels of mood and proper levels
1:24:59 of serotonin overall because it’s involved in lots of things not just mood we need to make sure that we’re
1:25:05 getting adequate production of serotonin in the gut and again adequate production of serotonin in the gut
1:25:10 has a bunch of other positive effects on the immune system on gut motility in fact having adequate
1:25:15 levels of serotonin in the gut is powerfully associated with having a healthy gut and not having irritable
1:25:21 gut irritable bowel syndrome is something that vexes many people you know it might sound kind of funny to
1:25:25 those of you that don’t have oh you have an irritable bowel people with ibs irritable bowel
1:25:30 syndrome oftentimes suffer tremendously they can’t go out to dinner they can’t eat foods that other people
1:25:35 offer them they’ll eat a bunch of foods for a while and feel fine then they feel terrible it’s not just
1:25:40 about having diarrhea often they have a bunch of other gut issues and it’s correlated with a bunch of
1:25:47 other major problems over time we’re going to do an entire episode about gut health as it relates to ibs
1:25:53 there are things that you can do to improve ibs one of them is to keep your or get your gut levels of
1:25:59 serotonin right how do you do that well one way to do that is to make sure that the microbiota of
1:26:05 your gut are healthy and that they are diverse the best way to do that not using any kind of
1:26:10 supplementation is to make sure that you’re ingesting one to four servings of low sugar fermented foods per
1:26:14 day i’ve talked about this before on the podcast this is based on beautiful data from my colleague
1:26:20 justin sonnenberg and christopher gardner at stanford showed that the ingestion of one to four servings
1:26:26 of low sugar fermented foods per day so these would be things like kimchi sauerkraut again low sugar look
1:26:31 at the labels this is the stuff that would need to be refrigerated we’re not talking about pickles kept on
1:26:36 the non-refrigerated shelf the non-refrigerated section of the grocery store but rather the brine
1:26:42 and the pickles that don’t have a ton of sugar so the sour pickles that is that are kept in the refrigerator
1:26:48 things like kimchi things like kombucha keep in mind some kombucha has alcohol so keep that in mind if
1:26:53 you’re giving this to kids who shouldn’t be ingesting alcohol any adults probably shouldn’t be ingesting
1:26:58 alcohol kombucha has very little alcohol but if you’re an alcoholic and you’re completely avoiding alcohol
1:27:06 you should know that kombucha contains some alcohol things like kefir quality yogurts low sugar yogurts
1:27:10 you can look up online what are different low sugar fermented foods these things are going to
1:27:17 improve the gut microbiota that in turn promote the production of serotonin if and only if this is
1:27:22 important if and only if there’s also sufficient levels of tryptophan in your dietary intake so you’re
1:27:26 going to want to take a look at what you’re eating and just through a simple online search you can
1:27:31 figure out whether or not you’re getting sufficient levels of tryptophan many people are familiar with
1:27:37 the idea because it’s true that turkey contains high levels of tryptophan this is thought to be
1:27:41 responsible for the post-thanksgiving dinner effect although that’s probably due to just eating a lot
1:27:47 of food and when the gut is distended the distension of the gut is communicated by mechanosensors
1:27:54 up the vagus nerve sensory neurons and set in motion the so-called rest and digest or i guess it would
1:28:01 be like uh collapse and pass out and in the case of thanksgiving collapse and pass out um effect of
1:28:04 having a lot of food in your gut doesn’t matter what the food is but you’re going to want to make sure
1:28:09 that you’re ingesting foods with sufficient levels of tryptophan so dairy products will do that white
1:28:13 turkey meat will do that there are other foods that have tryptophan in them i’m not going to bother to
1:28:17 list those off now you can simply look those up so make sure you’re getting enough tryptophan in your diet
1:28:21 make sure that you’re getting enough low sugar fermented foods or if you’re not doing that and
1:28:26 perhaps even if you are you might think about supplementing your diet with probiotic on occasion
1:28:32 right i’m not talking about constantly taking high doses of probiotics i actually don’t recommend that
1:28:36 but for many people who are suffering low mood supplementing with a quality probiotic can actually
1:28:42 improve mood and the purported mechanism by which that happens is the increase in serotonin that is
1:28:47 allowed by improving the gut microbiota and including foods with enough tryptophan which is the
1:28:54 precursor to serotonin so what i’ve done here is i’ve created the real conceptual link the anatomical
1:28:59 link and the chemical link between the production of serotonin in the gut and serotonin in the brain
1:29:03 and i wouldn’t be talking about this if there wasn’t actually data on this i’ll include links to a few
1:29:08 papers about the uh and here i’m quoting the title of a great paper the interaction of the vagus nerve and
1:29:15 serotonin in the gut brain axis there’s also been at least one clinical trial study exploring how
1:29:21 taking probiotics and in this case it was actually probiotics plus magnesium it was magnesium orotate
1:29:29 which is just one form of magnesium as well as uh i would say a low-ish dose of coin some q10 combining
1:29:35 those three things in this paper entitled probiotics and magnesium orotate it should have said probiotics
1:29:41 and magnesium orotate and coenzyme q10 but the title is probiotics and magnesium orotate for the
1:29:47 treatment of major depressive disorder a randomized double blind control trial i want to emphasize that
1:29:54 the results of this paper show that in the short term there’s an improvement in symptoms of major
1:30:00 depression that is symptoms of major depression were reduced through the administration of this
1:30:09 combination of probiotics magnesium orotate and coenzyme q10 however it was a short-lived effect
1:30:14 now it was also a short-lived treatment but it was a short-lived effect that showed up
1:30:22 in the essentially starting about the four-week mark and then carried out to 10 and 15 weeks the effect
1:30:27 disappeared now this is important because what it suggests is that in the short term if you’re
1:30:32 seeking to improve your mood or if you’re suffering from major depression please seek help for major
1:30:37 depression this of course wouldn’t be the only approach you don’t want to uh you know start being your own
1:30:41 psychiatrist you know this treatment very well could be combined with things and should be combined
1:30:45 probably with things like exercise maybe with pharmacologic treatment with antidepressant drugs it really
1:30:50 depends on the situation but if you are somebody who’s suffering from major depression or just mild
1:30:55 depression or if you’re just seeking to maintain healthy serotonin levels or improve your mood slightly
1:31:02 the consumption of things that are going to improve your gut microbiome absolutely is going to support
1:31:08 that process this has been shown over and over again because the gut microbiota create these short chain
1:31:13 fatty acids that are critically involved in this biochemical pathway that converts tryptophan into
1:31:18 serotonin i’m going to repeat that because it’s very important the microbiota of the gut if they’re
1:31:23 diverse and you have enough of them are going to produce the short chain fatty acids that are
1:31:27 critically required for the conversion of tryptophan which again is going to come from your diet
1:31:33 into the serotonin of your gut which in turn is going to be relayed and it’s not the actual serotonin
1:31:39 that’s relayed but the presence of serotonin at sufficient levels in the gut is communicated by the
1:31:44 vagus nerve up to the dorsal raffae nucleus remember there’s some stations in between but it’s communicated
1:31:50 up to the dorsal raffae and your dorsal raffae then releases serotonin in the brain again a beautiful coordination
1:31:57 of the body and the brain just as activity levels in the body and the brain are matched through the vagus or from
1:32:02 the brain to the body depending on the direction of flow right alertness in the brain body becomes alert alertness in the body brain becomes alert
1:32:11 serotonin elevated in the gut serotonin elevated in the brain all of that happens by way of vagal signaling
1:32:18 okay so the vagus is involved in lots of lots of things it’s not just for calming down it’s also
1:32:23 for slowing the heart rate which is related to calming down but it’s critically required for
1:32:28 this thing that we’re calling auto regulation for increasing hrv it’s also involved in increasing
1:32:33 levels of alertness and you can do that through exercise it’s also involved in increasing levels
1:32:38 of serotonin in the brain you just learned about that but there is as you’ve probably heard before
1:32:45 also a role for the vagus nerve in calming down now the reason i saved this portion for last is because
1:32:51 there’s just so much information out there about how vagal activation calms us down and i felt it was
1:32:58 important that i also focus on some of the ways that vagus does other things quite robustly including also
1:33:05 enhancing learning and plasticity but i would be remiss if i didn’t offer some of the science-backed tools
1:33:11 for calming yourself down by engaging the vagus and when i say engaging the vagus i mean engaging very
1:33:19 specific pathways within the vagus circuitry you now of course can appreciate that the vagus nerve is a
1:33:25 superhighway bi-directional superhighway of sensory and motor connections has a ton of specificity it’s
1:33:30 signaling mechanical and chemical information it’s controlling the body and yet there are specific
1:33:37 pathways that will indeed calm you down if you activate them these are the ones that you typically
1:33:42 hear about at the end of yoga classes that you hear about often online and i don’t want to be
1:33:48 disparaging of any of that in fact i love love love the book polyvagal theory by stephen porges
1:33:55 i think it’s a beautiful description of our understanding about the vagus nerve circa i don’t know maybe 10-15
1:34:02 years ago which is not disparaging at all i think he did an incredible job of talking about the dorsal
1:34:08 motor nucleus of the vagus which i’ll talk about in a few moments as a pathway for regulation of bodily
1:34:15 state for calming down about the role of parent-child relationships in infancy and how the vagus nerve
1:34:20 pathways are present and can be activated early in life without any learning or plasticity and how that’s
1:34:26 so critically important to the bond that’s formed between caretaker and infant and there’s just a
1:34:31 beautiful set of studies and a beautiful set of clinical data that he describes in that book
1:34:39 polyvagal theory as it relates to things like ptsd etc so hats off kudos and much respect and gratitude
1:34:45 to stephen porges for writing polyvagal theory most of what i’ve talked about up until now are things that
1:34:50 are either touched on just briefly or that are not included in his book on polyvagal theory mostly
1:34:55 because they relate to data that have been accumulated in the last 10 or 15 years and so
1:35:01 there was no way it could be in that book the ways to calm down using activation of specific vagal pathways
1:35:08 do indeed start to mimic some of the things that we hear about in or at the end of yoga classes
1:35:15 or that we think of in terms of kind of new agey uh types of things now this is coming from somebody
1:35:21 who earlier was talking about breath work right i was talking about cyclic sighing or cyclic physiological
1:35:27 sighing you know in science we tend to call it respiration physiology uh we call it cyclic sighing in
1:35:32 yogic traditions or in breath work classes they might call it something else for those of you that are familiar
1:35:39 with me you know that i appreciate all the lenses into ways to be healthier mentally physically and in
1:35:45 two ways to improve our performance i just happen to take the biological typically the neurobiological
1:35:51 and physiological perspective on these things because i like to think in fact i know that understanding
1:35:58 mechanism gives us more agency over these protocols and practices so what i’m going to describe next is
1:36:06 my view of the specific practices that yes absolutely exist in other territories related to yogic practices
1:36:13 etc that have been purported to increase levels of parasympathetic activation by engaging the vagus
1:36:20 the reason i selected the things i’m about to tell you is because i ran them by two colleagues one who is a
1:36:28 neurologist and psychiatrist practicing the other who is a neurosurgeon and is very familiar with the vagus
1:36:34 and what i did is i said listen there’s all this stuff out there you can hear all sorts of interesting
1:36:40 things on youtube and elsewhere about ways to calm down by engaging the vagus which of these and i
1:36:48 basically described five which of these typical five practices do you think actually triggers activation
1:36:54 of the specific nerve fibers that would trigger a parasympathetic response and what was interesting
1:37:00 is that both of them said actually there are three of them that absolutely trigger activation of the
1:37:06 parasympathetic response and we know because we’ve recorded from those neural pathways and so it’s
1:37:11 obvious that they work so those are the three that i’m going to describe i want to remind you that if
1:37:17 you want to calm down fast the physiological sigh is still going to be your best tool if you want to
1:37:22 improve hrv you want to get better auto regulation and you want your hrv to improve in sleep as well
1:37:27 the deliberate exhales from time to time spread throughout the day still going to be great still do
1:37:33 your high intensity interval training and other ways to increase hrv but if you want to use the vagal pathways
1:37:38 to calm down here are the three best ways that are supported by the neurophysiology in humans
1:37:44 that i’m going to tell you about the first capitalizes on the fact that a major branch of the vagus
1:37:51 that extends out of the brain stem and that includes a lot of those sensory afferents those axons
1:37:59 coursing up from the body to the brain stem runs along a portion of the neck that’s deep to the muscle
1:38:04 that’s going to stick out if you turn your head to one side now i’m specifically avoiding the muscle
1:38:09 and vasculature nomenclature right now because we’ve already had so many terms this episode
1:38:15 and it’s really not necessary to understand how to use these practices but were you to say lie down
1:38:19 or even just sit at a table surface like i am now for those of you that are listening i’m just
1:38:25 seated in front of my desk i’m putting my hands palms down my elbows at the edge of the table
1:38:33 and what i’m going to do next is i’m going to push my elbows down and away from my ears
1:38:39 then i’m going to turn my head up into the right and i’m going to talk while i’m doing it but you
1:38:48 wouldn’t want to and when one does that you feel a kind of stretch both on the outside of the neck so
1:38:53 that’s on the left hand side as well as in particular on the right hand side okay
1:38:57 and it’s important to keep your elbows pushing down and you’re looking up into the right and
1:39:02 then you do it to the other side you go up into the left yes this is looking a lot like yoga
1:39:15 but this is not yoga this is a way of mechanically activating some of the fibers that course along
1:39:21 the vasculature and the musculature at the side of the neck that is a major pathway of the vagus now
1:39:29 i had to ask my neurosurgeon and neurophysiology friends does this actually activate the vagus nerve
1:39:34 and they said yes to some degree it’s mechanically going to activate some of those
1:39:40 fibers some of those axons is it going to activate the calming pathways of your vagus nerve
1:39:46 as much as say electrical stimulation of your vagus nerve no it’s not electrical stimulation of the vagus
1:39:52 nerve is used for major depression it’s also used using different patterns of stimulation frequency to
1:39:56 calm people down it can be used for a number of different things depending on the way this stimulation is
1:40:04 what’s done and where it’s done along the vagus nerve pathways however this basically mechanical
1:40:09 activation of this vagus nerve pathway it doesn’t just feel good because you’re stretching your neck
1:40:15 out it does indeed activate some of the sensory and probably some of the motor fibers as well that
1:40:20 course through the vagus nerve and keep in mind this is interesting that the majority of the parasympathetic
1:40:26 effect of mechanically activating those vagal nerve fibers is going to be on the right hand side
1:40:30 i know this is starting to sound a little bit like yoga classes where they say hey you know breathing
1:40:35 through your left nostril your right nostril is going to reflect sympathetic or parasympathetic
1:40:41 activation guess what when we had noam sobel one of the world’s foremost experts on olfaction
1:40:48 and basically sniffing and breathing and its effects on the brain on the podcast he indeed told us that the
1:40:54 switching back and forth between right and left nostril dominance is indeed governed by changes in that
1:40:59 seesaw of the autonomic nervous system it switches over i believe once about every 90 minutes incredible
1:41:04 right obviously impacted if you have a deviated septum etc so the stuff that comes from yogic tradition
1:41:09 while it might not be mechanistically accurate and it sometimes includes other things that are unrelated
1:41:15 to the mechanism oftentimes it’s pretty spot on so if you want to calm down and you want to do that by
1:41:21 activating your vagus you already know a bunch of ways you can do that we talked about it the ear thing the exhale
1:41:28 thing etc physiological size but this simple process of looking up and to the right
1:41:33 and then up into the left and the reason for doing it both sides is you’ll feel a stretch on one side
1:41:39 then a contraction on the other doing that a few times back and forth indeed can lead to a calmer state
1:41:45 the right following how robust that is it’s going to depend on a lot of factors frankly i don’t think
1:41:51 it’s as robust as the physiological sigh or exhale emphasized breathing i don’t think it’s as fast but
1:41:56 nonetheless it is supported by the anatomy it’s supported by the function and a lot of people simply
1:42:02 like to stretch so i’d be remiss if i didn’t include that the other way that you can calm down by way of
1:42:07 incorporating vagus nerve activation and you can do that non-invasively is the following all right this
1:42:16 one again verified with people who are expert in these specific pathways in humans and i know it might not
1:42:24 sound neuroscientific but believe it or not this stuff that you hear no pun intended about humming and
1:42:29 activation of the vagus nerve and calming down by way of humming because of the way it impacts the vagus nerve
1:42:36 turns out to be true however and get this you actually have to hum correctly now you might think
1:42:44 humming is just that’s not what we’re talking about here what we’re talking about here is again
1:42:50 mechanically through vibration activating the branches of the vagus that innervate the larynx and now keep
1:42:57 in mind some of the neurons and nucleus ambiguous that carry neurons that are officially members of the vagus
1:43:02 nerve they travel with neurons that are not officially members of the vagus but they travel together from
1:43:09 nucleus ambiguous to a lot of the speech machinery in your throat and in your mouth and with your tongue
1:43:14 and your lips okay that’s a discussion for an entirely different podcast but it turns out if you view the hum
1:43:23 through the perspective of that it’s an h and an m right hmm right that if you want to activate this vagal
1:43:30 pathway to calm down the way to hum correctly i know this sounds wild but the way to hum correctly is
1:43:36 actually to extend the h part not the m i talked to somebody who’s expert in speech neurophysiology
1:43:45 and it’s because the h part the is different than the mm part the mm is slightly higher frequency and
1:43:52 actually if you notice if you do an extended h hum and then an m hum after you’ll notice that it shifts from
1:43:58 the back and deeper parts of your throat which is where the vagal activation comes from to sort of
1:44:03 further up along your speech pathway toward your mouth and your lips so just give that a try for a
1:44:07 second maybe you have to do this in private because otherwise it’d be too embarrassing but you
1:44:13 it’s incredibly calming i did this earlier and i was really positively surprised how well it worked it’s
1:44:19 it’s basically this you’re trying to get the vibration to move from the back of your throat
1:44:23 down your neck into your chest and even into your belly and diaphragm so it goes like this
1:44:35 if you want to know what it’s like from a sensation perspective think about gargling
1:44:40 well this is getting crazier and crazier toward the end of this podcast but indeed if you look online
1:44:46 gargling has been proposed as a way to activate the calming aspects so-called parasympathetic aspects
1:44:52 of the vagus nerve and indeed when you gargle you’re using the back of your throat that’s the sensation
1:44:58 it’s this vibration at the back of your throat so when you hum emphasizing the h part of the hmm and
1:44:59 leaving off the m part it’s
1:45:09 and you can actually move the vibration down into your chest i find it’s easier if i’m lying down
1:45:17 and when you do that it’s quite remarkable how fast you calm down but give this a try i know it might seem
1:45:23 a little silly but if you want to try and really deeply relax this extended humming that you’re trying
1:45:30 to move down further and further from say your lips to the back of your throat to deeper in your throat
1:45:36 near your adam’s apple to your chest region even into your uh abdomen in your diaphragm you’ll notice
1:45:41 that it really really calms you down this is also it turns out because i talked to somebody who is a
1:45:48 singer this is the way that singers often will start to relax in order to get into some of the deeper
1:45:52 frequency notes that they need to hit with their voice as you’ve probably observed high notes sort of bring
1:45:57 people up into their head and up even if they’re using their diaphragm higher and higher and higher
1:46:03 whereas lower frequency sounds deeper and deeper and it’s just mechanical activation of the particular
1:46:11 branches of the vagus that are able to drive this parasympathetic response and if you notice the hum
1:46:19 is like all speech and exhale it’s a long slow exhale so this is the third part there’s also a collateral
1:46:26 activation which is just neuroscience speak for activation of that deceleration pathway when you
1:46:31 do this humming at the back of your throat and down into your chest and into your belly you’re also
1:46:38 getting the same effect that you get with an exhale which is to slow the heart rate way way down so it
1:46:45 turns out the stuff they say it retreats in yoga classes is mechanistically supported at least some of it is
1:46:49 and some of it perhaps isn’t and that doesn’t really matter right now what we’re talking about
1:46:56 is the incredible pathway the incredible neural circuit that is the vagus nerve in fact calling it the
1:47:01 vagus nerve you now realize as i talked about the beginning of the episode is really not sufficient to
1:47:08 encapsulate the incredible variety of different pathways the sensory stuff up from the body the
1:47:14 motor stuff down from the brain the way you can calm down the way you can alert yourself the relationship
1:47:19 and pairing of serotonin levels in the gut through the microbiome and what you eat and the tryptophan with
1:47:25 serotonin levels in the brain and mood and neuroplasticity and learning and to be fair
1:47:31 we didn’t even cover everything that the vagus nerve does there’s this whole landscape of electrical
1:47:35 stimulation of the vagus nerve transcranial magnetic stimulation of the parts of the brain like the
1:47:41 dorsal lateral prefrontal cortex that allow you to engage more plasticity and control over auto
1:47:48 regulation that stuff all requires devices and a physician or a laboratory to deliver so i focused on
1:47:53 the things that you can do to activate your vagus in the various ways that’s going to serve you best in
1:47:57 terms of mental health physical health and performance and i like to think that you also
1:48:03 learned a lot about the vagus nerve biology both structurally and functionally i personally find it to be
1:48:10 one of the most incredible aspects of the nervous system it exists in all mammals it’s also in non-mammalian
1:48:17 vertebrates but it’s definitely in us humans and it’s absolutely active from the time we’re born until
1:48:24 the very last breath we take in hopefully late late age and it’s just a miraculous pathway nature
1:48:32 created this vagus nerve thing and you can control it and understanding the mechanisms by which you can
1:48:38 control it i do believe is the best way to go about it so thank you for joining me on this mechanistic
1:48:45 slash practical voyage through the vagus nerve i’m enchanted by the vagus nerve and i like to think that you
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