Essentials: How Your Brain Works & Changes

00:00:00.000 | - Welcome to Huberman Lab Essentials,

00:00:02.320 | where we revisit past episodes

00:00:04.380 | for the most potent and actionable science-based tools

00:00:07.560 | for mental health, physical health, and performance.

00:00:10.320 | I'm Andrew Huberman,

00:00:12.960 | and I'm a professor of neurobiology and ophthalmology

00:00:16.000 | at Stanford School of Medicine.

00:00:17.940 | For today's podcast,

00:00:19.200 | we're going to talk about the parts list

00:00:21.160 | of the nervous system.

00:00:22.720 | Now that might sound boring,

00:00:24.360 | but these are the bits and pieces that together

00:00:27.320 | make up everything about your experience of life,

00:00:30.640 | from what you think about, to what you feel,

00:00:32.840 | what you imagine, and what you accomplish

00:00:34.920 | from the day you're born until the day you die.

00:00:37.600 | By the end of this podcast,

00:00:39.020 | I promise you're going to understand a lot more

00:00:40.920 | about how you work and how to apply that knowledge.

00:00:43.780 | So let's talk about the nervous system.

00:00:46.240 | The reason I say your nervous system and not your brain

00:00:49.480 | is because your brain is actually just one piece

00:00:52.820 | of this larger, more important thing, frankly,

00:00:55.840 | that we call the nervous system.

00:00:57.640 | The nervous system includes your brain and your spinal cord,

00:01:01.700 | but also all the connections between your brain

00:01:04.440 | and your spinal cord and the organs of your body.

00:01:07.320 | It also includes, very importantly,

00:01:10.000 | all the connections between your organs

00:01:13.280 | back to your spinal cord and brain.

00:01:15.320 | So the way to think about how you function at every level

00:01:19.000 | from the moment you're born until the day you die,

00:01:21.860 | everything you think and remember and feel and imagine

00:01:25.680 | is that your nervous system

00:01:27.360 | is this continuous loop of communication

00:01:29.680 | between the brain, spinal cord, and body,

00:01:32.080 | and body, spinal cord, and brain.

00:01:34.000 | In fact, we really can't even separate them.

00:01:35.680 | It's one continuous loop.

00:01:37.960 | The way to think about how the nervous system works

00:01:40.280 | is that our experiences, our memories, everything

00:01:44.040 | is sort of like the keys on a piano

00:01:46.560 | being played in a particular order, right?

00:01:48.960 | If I play the keys on a piano in a particular order

00:01:51.560 | and with a particular intensity, that's a given song.

00:01:55.040 | We can make that analogous to a given experience.

00:01:57.400 | Our brain is really a map of our experience.

00:02:01.360 | We come into the world and our brain has a kind of bias

00:02:04.160 | towards learning particular kinds of things.

00:02:06.040 | It's ready to receive information

00:02:07.960 | and learn that information,

00:02:09.520 | but the brain is really a map of experience.

00:02:12.520 | So let's talk about what experience really is.

00:02:15.480 | What does it mean for your brain to work?

00:02:17.280 | Well, I think it's fair to say

00:02:19.440 | that the nervous system really does five things, maybe six.

00:02:23.160 | The first one is sensation.

00:02:25.040 | Sensation is a non-negotiable element of your nervous system.

00:02:28.880 | You have neurons in your eye

00:02:30.320 | that perceive certain colors of light

00:02:32.800 | and certain directions of movement.

00:02:34.580 | You have neurons in your skin

00:02:36.560 | that perceive particular kinds of touch,

00:02:39.080 | like light touch or firm touch or painful touch.

00:02:42.440 | You have neurons in your ears that perceive certain sounds.

00:02:46.480 | Your entire experience of life is filtered

00:02:51.240 | by these, what we call sensory receptors,

00:02:54.000 | if you want to know what the name is.

00:02:55.240 | Perception is our ability to take what we're sensing

00:02:59.400 | and focus on it and make sense of it,

00:03:02.560 | to explore it, to remember it.

00:03:04.180 | So really perceptions are just whichever sensations

00:03:06.800 | we happen to be paying attention to at any moment.

00:03:09.280 | Perception is under the control of your attention.

00:03:12.720 | And the way to think about attention

00:03:14.240 | is it's like a spotlight, except it's not one spotlight.

00:03:17.600 | You actually have two attentional spotlights.

00:03:20.920 | Anyone that tells you you can't multitask,

00:03:23.560 | tell them they're wrong.

00:03:24.960 | And if they disagree with you, tell them to contact me.

00:03:27.980 | Because in old world primates, of which humans are,

00:03:32.980 | we are able to do what's called covert attention.

00:03:36.200 | We can place a spotlight of attention on something,

00:03:38.880 | for instance, something we're reading or looking at,

00:03:41.300 | or someone that we're listening to.

00:03:42.600 | And we can place a second spotlight of attention

00:03:45.720 | on something we're eating and how it tastes,

00:03:47.880 | or our child running around in the room,

00:03:50.080 | or my dog.

00:03:51.200 | You can split your attention into two locations,

00:03:53.520 | but of course you can also bring your attention,

00:03:56.460 | that is your perception, to one particular location.

00:03:59.960 | You can dilate your attention,

00:04:01.400 | kind of like making a spotlight more diffuse,

00:04:03.600 | or you can make it more concentrated.

00:04:05.640 | This is very important to understand

00:04:08.440 | if you're going to think about tools

00:04:10.400 | to improve your nervous system.

00:04:12.480 | Attention is something that is absolutely

00:04:15.000 | under your control.

00:04:16.960 | The nervous system can be reflexive in its action,

00:04:19.740 | or it can be deliberate.

00:04:20.860 | Deliberate thoughts are top down.

00:04:23.200 | They require some effort and some focus,

00:04:25.580 | but that's the point.

00:04:26.440 | You can decide to focus your behavior in any way you want,

00:04:30.120 | but it will always feel like it requires some effort

00:04:34.200 | and some strain.

00:04:35.060 | Whereas when you're in reflexive mode,

00:04:36.400 | just walking and talking and eating and doing your thing,

00:04:39.320 | it's going to feel very easy.

00:04:40.880 | And that's because your nervous system basically wired up

00:04:43.440 | to be able to do most things easily

00:04:45.480 | without much metabolic demand,

00:04:47.120 | without consuming much energy.

00:04:48.660 | But the moment you try and do something very specific,

00:04:51.360 | you're going to feel a sort of mental friction.

00:04:54.460 | It's going to be challenging.

00:04:56.040 | So we've got sensations, perceptions,

00:04:58.560 | and then we've got things that we call feelings/emotions.

00:05:02.360 | And these get a little complicated

00:05:04.040 | because almost all of us,

00:05:06.400 | I would hope all of us,

00:05:07.440 | are familiar with things like happiness and sadness

00:05:10.620 | or boredom or frustration.

00:05:13.080 | Certainly emotions and feelings

00:05:15.100 | are the product of the nervous system.

00:05:17.380 | They involve the activity of neurons.

00:05:19.920 | But as I mentioned earlier, neurons are electrically active,

00:05:22.860 | but they also release chemicals.

00:05:25.040 | And there's a certain category of chemicals

00:05:28.240 | that has a very profound influence on our emotional states.

00:05:32.500 | They're called neuromodulators.

00:05:35.800 | And those neuromodulators have names

00:05:37.400 | that probably you've heard of before,

00:05:39.020 | things like dopamine and serotonin

00:05:41.240 | and acetylcholine, epinephrine.

00:05:44.280 | Neuromodulators are really interesting

00:05:46.720 | because they bias which neurons are likely to be active

00:05:50.120 | and which ones are likely to be inactive.

00:05:53.040 | A simple way to think about neuromodulators

00:05:55.080 | is they are sort of like playlists

00:05:57.320 | that you would have on any kind of device

00:06:00.080 | where you're going to play particular categories of music.

00:06:02.560 | So for instance, dopamine,

00:06:04.200 | which is often discussed as the molecule of reward or joy,

00:06:09.200 | is involved in reward.

00:06:11.320 | And it does tend to create a sort of upbeat mood

00:06:15.600 | when released in appropriate amounts in the brain.

00:06:17.780 | But the reason it does that

00:06:19.320 | is because it makes certain neurons and neural circuits,

00:06:23.480 | as we call them, more active and others less active, okay?

00:06:27.280 | So serotonin, for instance,

00:06:29.700 | is a molecule that when released

00:06:31.520 | tends to make us feel really good with what we have,

00:06:34.720 | our sort of internal landscape

00:06:36.320 | and the resources that we have.

00:06:38.000 | Whereas dopamine, more than being a molecule of reward,

00:06:40.680 | is really more a molecule of motivation

00:06:43.680 | toward things that are outside us

00:06:45.760 | and that we want to pursue.

00:06:47.120 | And we can look at healthy conditions or situations

00:06:51.840 | like being in pursuit of a goal

00:06:53.760 | where every time we accomplish something

00:06:55.600 | in route to that goal,

00:06:56.600 | a little bit of dopamine is released

00:06:58.040 | and we feel more motivation, that happens.

00:07:00.840 | We can also look at the extreme example

00:07:03.120 | of something like mania,

00:07:04.480 | where somebody is so, you know,

00:07:07.480 | relentlessly in pursuit of external things

00:07:09.880 | like money and relationships

00:07:11.920 | that they're sort of in this delusional state

00:07:14.300 | of thinking that they have the resources that they need

00:07:16.540 | in order to pursue all these things

00:07:17.680 | when in fact they don't.

00:07:18.920 | I want to emphasize also that emotions

00:07:22.460 | are something that we generally feel

00:07:25.200 | are not under our control.

00:07:26.440 | We feel like they kind of geyser up within us

00:07:28.320 | and they just kind of happen to us.

00:07:30.400 | And that's because they are somewhat reflexive.

00:07:33.100 | We don't really set out with a deliberate thought

00:07:35.680 | to be happy or deliberate thought to be sad.

00:07:38.000 | We tend to experience them

00:07:39.320 | in kind of a passive reflexive way.

00:07:42.080 | And that brings us to the next thing, which are thoughts.

00:07:45.040 | Thoughts are really interesting

00:07:46.240 | because in many ways they're like perceptions,

00:07:48.960 | except that they draw on not just what's happening

00:07:51.560 | in the present, but also things we remember from the past

00:07:55.520 | and things that we anticipate about the future.

00:07:58.040 | The other thing about thoughts that's really interesting

00:07:59.960 | is that thoughts can be both reflexive,

00:08:03.720 | they can just be occurring all the time,

00:08:05.600 | sort of like pop-up windows

00:08:07.340 | on a poorly filtered web browser,

00:08:09.860 | or they can be deliberate.

00:08:11.400 | We can decide to have a thought.

00:08:12.940 | And a lot of people don't understand

00:08:14.660 | or at least appreciate that the thought patterns

00:08:16.900 | and the neural circuits that underlie thoughts

00:08:19.700 | can actually be controlled in this deliberate way.

00:08:22.140 | And then finally, there are actions.

00:08:24.640 | Actions or behaviors are perhaps the most important aspect

00:08:28.460 | to our nervous system, because first of all,

00:08:31.560 | our behaviors are actually the only thing

00:08:34.900 | that are going to create any fossil record of our existence.

00:08:38.820 | You know, after we die, the nervous system deteriorates,

00:08:41.420 | our skeleton will remain, but it's, you know,

00:08:44.460 | in the moment of experiencing something very joyful

00:08:47.820 | or something very sad, it can feel so all-encompassing

00:08:52.820 | that we actually think that it has some meaning

00:08:55.220 | beyond that moment.

00:08:56.460 | But actually for humans, and I think for all species,

00:09:00.300 | the sensations, the perceptions, and the thoughts,

00:09:04.780 | and the feelings that we have in our lifespan,

00:09:08.060 | none of that is actually carried forward,

00:09:11.020 | except the ones that we take and we convert into actions

00:09:16.020 | such as writing, actions such as words,

00:09:18.740 | actions such as engineering new things.

00:09:20.980 | And so the fossil record of our species

00:09:23.860 | and of each one of us is really through action.

00:09:27.360 | And that in part is why so much of our nervous system

00:09:31.620 | is devoted to converting sensation, perceptions, feelings,

00:09:36.140 | and thoughts into actions.

00:09:38.020 | The other way to think about it is that one of the reasons

00:09:41.220 | that our central nervous system, our brain and spinal cord

00:09:43.980 | include this stuff in our skull,

00:09:45.800 | but also connect so heavily to the body

00:09:47.980 | is because most everything that we experience,

00:09:50.660 | including our thoughts and feelings,

00:09:52.460 | was really designed to either impact our behavior or not.

00:09:56.780 | And the fact that thoughts allow us to reach into the past

00:09:59.620 | and anticipate the future and not just experience

00:10:01.860 | what's happening in the moment,

00:10:03.580 | gave rise to an incredible capacity for us

00:10:06.380 | to engage in behaviors that are not just for the moment,

00:10:09.700 | they're based on things that we know from the past

00:10:11.780 | and that we would like to see in the future.

00:10:14.780 | And this aspect to our nervous system of creating movement

00:10:18.660 | occurs through some very simple pathways.

00:10:21.340 | The reflexive pathway basically includes areas

00:10:25.020 | of the brainstem we call central pattern generators.

00:10:27.860 | When you walk, provided you already know how to walk,

00:10:30.900 | you are basically walking

00:10:33.960 | because you have these central pattern generators,

00:10:35.860 | groups of neurons that generate right foot, left foot,

00:10:38.020 | right foot, left foot kind of movement.

00:10:39.900 | However, when you decide to move

00:10:41.440 | in a particular deliberate way

00:10:43.040 | that requires a little more attention,

00:10:45.100 | you start to engage areas of your brain

00:10:48.380 | for top-down processing,

00:10:49.740 | where your forebrain works from the top down

00:10:53.500 | to control those central pattern generators

00:10:55.460 | so that maybe it's right foot, right foot, left foot,

00:10:57.700 | right foot, right foot, left foot,

00:10:58.820 | if maybe you're hiking along some rocks or something

00:11:00.980 | and you have to engage in that kind of movement.

00:11:03.420 | So movement is just like thoughts,

00:11:06.860 | can be either reflexive or deliberate.

00:11:10.300 | And when we talk about deliberate,

00:11:11.860 | I want to be very specific

00:11:12.940 | about how your brain works in a deliberate way

00:11:15.620 | because it gives rise to a very important feature

00:11:19.300 | of the nervous system that we're going to talk about next,

00:11:21.100 | which is your ability to change your nervous system.

00:11:24.100 | And what I'd like to center on for a second

00:11:26.020 | is this notion of what does it mean for the nervous system

00:11:29.820 | to do something deliberately?

00:11:31.940 | Well, when you do something deliberately,

00:11:34.340 | you pay attention, you are bringing your perception

00:11:37.540 | to an analysis of three things,

00:11:40.300 | duration, how long something is going to take

00:11:43.540 | or should be done,

00:11:45.020 | path, what you should be doing,

00:11:47.100 | and outcome, if you do something

00:11:49.120 | for a given length of time, what's going to happen.

00:11:51.460 | Now, when you're walking down the street or you're eating,

00:11:53.380 | or you're just talking reflexively,

00:11:55.060 | you're not doing this, what I call DPO,

00:11:57.100 | duration, path, outcome,

00:11:58.580 | type of deliberate function in your brain and nervous system.

00:12:01.740 | Let's give an example where perhaps somebody says something

00:12:05.220 | that's triggering to you, you don't like it,

00:12:07.420 | and you know you shouldn't respond.

00:12:09.420 | You feel like, "Oh, I shouldn't respond,

00:12:11.060 | I shouldn't respond, I shouldn't respond."

00:12:12.460 | You're actively suppressing your behavior

00:12:14.920 | through top-down processing.

00:12:17.700 | Your forebrain is actually preventing you

00:12:19.660 | from saying the thing that you know you shouldn't say

00:12:22.420 | or that maybe you should wait to say

00:12:23.860 | or say in a different form.

00:12:25.620 | This feels like agitation and stress

00:12:27.840 | because you're actually suppressing a circuit.

00:12:30.180 | We actually can see examples of what happens

00:12:32.500 | when you're not doing this well.

00:12:35.160 | Some of the examples come from children.

00:12:38.040 | If you look at young children,

00:12:39.500 | they don't have the forebrain circuitry

00:12:41.980 | to engage in this top-down processing

00:12:43.980 | until they reach age 22, even 25.

00:12:47.400 | But in young children, you see this in a really robust way.

00:12:51.140 | A kid sees a piece of candy that it wants

00:12:53.340 | and will just reach out and grab it,

00:12:55.400 | whereas an adult probably would ask

00:12:57.320 | if they could have a piece

00:12:58.160 | or wait until they were offered a piece in most cases.

00:13:01.300 | People that have damage

00:13:02.380 | to the certain areas of the frontal lobes

00:13:05.300 | don't have this kind of restriction.

00:13:06.860 | They'll just blurt things out.

00:13:08.320 | They'll just say things.

00:13:09.300 | Impulsivity is a lack of top-down control,

00:13:13.260 | a lack of top-down processing.

00:13:14.940 | So a lot of the motor system

00:13:17.300 | is designed to just work in a reflexive way.

00:13:20.180 | And then when we decide we want to learn something

00:13:22.140 | or do something or not do something,

00:13:24.540 | we have to engage in this top-down restriction.

00:13:27.060 | And it feels like agitation

00:13:28.660 | because it's accompanied by the release

00:13:30.540 | of a neuromodulator called norepinephrine,

00:13:33.460 | which in the body we call adrenaline,

00:13:35.460 | and it actually makes us feel agitated.

00:13:37.700 | So for those of you that are trying to learn something new

00:13:40.340 | or to learn to suppress your responses

00:13:42.500 | or be more deliberate and careful in your responses,

00:13:45.460 | that is going to feel challenging for a particular reason.

00:13:49.840 | It's going to feel challenging

00:13:50.920 | because the chemicals in your body

00:13:52.520 | that are released in association with that effort

00:13:55.780 | are designed to make you feel kind of agitated.

00:13:59.060 | And so this is really important to understand

00:14:02.180 | because if you want to understand neuroplasticity,

00:14:05.440 | you want to understand how to shape your behavior,

00:14:07.460 | how to shape your thinking,

00:14:08.540 | how to change how you're able to perform in any context.

00:14:13.420 | The most important thing to understand

00:14:15.300 | is that it requires top-down processing.

00:14:18.460 | It requires this feeling of agitation.

00:14:21.460 | In fact, I would say that agitation and strain

00:14:23.960 | is the entry point to neuroplasticity.

00:14:26.960 | So let's take a look at what neuroplasticity is.

00:14:29.680 | Neuroplasticity is the ability for these connections

00:14:32.560 | in the brain and body to change in response to experience.

00:14:35.640 | And what's so incredible

00:14:36.880 | about the human nervous system in particular

00:14:39.080 | is that we can direct our own neural changes.

00:14:42.160 | We can decide that we want to change our brain.

00:14:45.480 | In other words, our brain can change itself

00:14:47.600 | and our nervous system can change itself.

00:14:49.840 | For a long time, it was thought that neuroplasticity

00:14:53.000 | was the unique gift of young animals and humans,

00:14:56.080 | that it could only occur when we're young.

00:14:57.840 | And in fact, the young brain is incredibly plastic.

00:15:00.840 | Children can learn three languages

00:15:02.620 | without an accent reflexively,

00:15:04.800 | whereas adults, it's very challenging.

00:15:07.460 | It takes a lot more effort and strain,

00:15:09.160 | a lot more of that duration path outcome kind of thinking

00:15:11.880 | in order to achieve those plastic changes.

00:15:15.600 | We now know, however, that the adult brain

00:15:18.400 | can change in response to experience.

00:15:20.600 | In order to understand that process,

00:15:22.160 | we really have to understand something

00:15:24.080 | that might at first seem totally divorced

00:15:26.040 | from neuroplasticity,

00:15:27.400 | but actually lies at the center of neuroplasticity.

00:15:30.440 | And for any of you that are interested

00:15:31.960 | in changing your nervous system

00:15:33.560 | so that something that you want can go from being very hard

00:15:37.320 | or seem almost impossible and out of reach

00:15:39.540 | to being very reflexive,

00:15:41.440 | this is especially important to pay attention to.

00:15:45.220 | Plasticity in the adult human nervous system is gated,

00:15:49.940 | meaning it is controlled by neuromodulators.

00:15:54.180 | These things that we talked about earlier,

00:15:56.140 | dopamine, serotonin,

00:15:58.200 | and one in particular called acetylcholine

00:16:00.780 | are what open up plasticity.

00:16:04.460 | They literally unveil plasticity

00:16:06.740 | and allow brief periods of time

00:16:08.180 | in which whatever information,

00:16:10.240 | whatever thing we're sensing or perceiving or thinking,

00:16:13.700 | or whatever emotions we feel

00:16:15.540 | can literally be mapped in the brain

00:16:17.820 | such that later it will become much easier

00:16:20.780 | for us to experience and feel that thing.

00:16:23.460 | Now, this has a dark side and a positive side.

00:16:26.460 | The dark side is it's actually very easy

00:16:28.780 | to get neuroplasticity as an adult

00:16:31.060 | through traumatic or terrible or challenging experiences.

00:16:34.940 | But the important question is to say, why is that?

00:16:38.260 | And the reason that's the case

00:16:40.200 | is because when something very bad happens,

00:16:43.800 | there's the release of two sets of neuromodulators

00:16:46.780 | in the brain, epinephrine,

00:16:49.240 | which tends to make us feel alert and agitated,

00:16:51.800 | which is associated with most bad circumstances,

00:16:54.720 | and acetylcholine,

00:16:56.280 | which tends to create a even more intense

00:16:59.680 | and focused perceptual spotlight.

00:17:01.600 | Remember earlier we were talking about perception

00:17:03.720 | and how it's kind of like a spotlight.

00:17:05.360 | Acetylcholine makes that light particularly bright

00:17:08.020 | and particularly restricted to one region of our experience.

00:17:12.640 | And it does that by making certain neurons

00:17:15.160 | in our brain and body active much more than all the rest.

00:17:20.160 | So acetylcholine is sort of like a highlighter marker

00:17:24.720 | upon which neuroplasticity then comes in later

00:17:28.320 | and says, wait, which neurons were active

00:17:30.360 | in this particularly alerting phase

00:17:33.800 | of whatever day or night

00:17:35.920 | whenever this thing happened to happen.

00:17:37.320 | So the way it works is this,

00:17:38.440 | you can think of epinephrine as creating this alertness

00:17:41.840 | and this kind of unbelievable level of increased attention

00:17:45.520 | compared to what you were experiencing before.

00:17:47.200 | And you can think of acetylcholine as being the molecule

00:17:51.400 | that highlights whatever happens

00:17:54.200 | during that period of heightened alertness.

00:17:56.960 | So just to be clear, it's epinephrine creates the alertness

00:18:01.280 | that's coming from a subset of neurons in the brainstem

00:18:03.360 | if you're interested,

00:18:04.480 | and acetylcholine coming from an area of the forebrain

00:18:07.460 | is tagging or marking the neurons

00:18:11.140 | that are particularly active

00:18:12.540 | during this heightened level of alertness.

00:18:14.940 | Now that marks the cells, the neurons, and the synapses

00:18:19.700 | for strengthening, for becoming more likely

00:18:22.940 | to be active in the future

00:18:25.100 | even without us thinking about it, okay?

00:18:28.300 | So in bad circumstances,

00:18:30.820 | this all happens without us having to do much.

00:18:34.140 | When we want something to happen, however,

00:18:36.580 | we want to learn a new language,

00:18:38.080 | we want to learn a new skill,

00:18:39.720 | we want to become more motivated,

00:18:41.880 | what do we know for certain?

00:18:43.060 | We know that that process of getting neuroplasticity

00:18:46.880 | so that we have more focus, more motivation

00:18:49.040 | absolutely requires the release of epinephrine.

00:18:53.280 | We have to have alertness in order to have focus.

00:18:56.640 | And we have to have focus

00:18:58.400 | in order to direct those plastic changes

00:19:01.320 | to particular parts of our nervous system.

00:19:04.200 | Now, this has immense implications

00:19:07.140 | in thinking about the various tools,

00:19:09.740 | whether or not those are chemical tools or machine tools

00:19:13.020 | or just self-induced regimens of how long

00:19:16.640 | or how intensely you're going to focus

00:19:18.340 | in order to get neuroplasticity.

00:19:20.400 | But there's another side to it.

00:19:23.700 | The dirty secret of neuroplasticity

00:19:26.460 | is that no neuroplasticity occurs

00:19:29.140 | during the thing you're trying to learn,

00:19:31.320 | during the terrible event, during the great event,

00:19:35.120 | during the thing that you're really trying to shape

00:19:37.680 | and learn, nothing is actually changing

00:19:40.840 | between the neurons that is going to last.

00:19:43.720 | All the neuroplasticity, the strengthening of the synapses,

00:19:48.160 | the addition in some cases of new nerve cells

00:19:51.160 | or at least connections between nerve cells,

00:19:54.000 | all of that occurs at a very different phase of life,

00:19:57.440 | which is when we are in sleep and non-sleep deep rest.

00:20:01.420 | And so neuroplasticity,

00:20:02.820 | which is the kind of holy grail of human experience,

00:20:05.460 | of, you know, this is the new year

00:20:06.980 | and everyone's thinking New Year's resolutions.

00:20:08.820 | And right now, perhaps everything's organized

00:20:11.460 | and people are highly motivated,

00:20:12.940 | but what happens in March or April or May?

00:20:15.700 | Well, that all depends on how much attention and focus

00:20:18.980 | one can continually bring to whatever it is

00:20:21.400 | they're trying to learn.

00:20:22.620 | So much so that agitation and a feeling of strain

00:20:25.860 | are actually required for this process of neuroplasticity

00:20:29.940 | to get triggered.

00:20:31.180 | But the actual rewiring occurs

00:20:32.780 | during periods of sleep and non-sleep deep rest.

00:20:37.180 | There's a study published last year

00:20:38.560 | that's particularly relevant here that I want to share.

00:20:41.820 | It was not done by my laboratory

00:20:43.820 | that showed that 20 minutes of deep rest,

00:20:47.820 | this is not deep sleep,

00:20:49.460 | but essentially doing something very hard and very intense

00:20:53.380 | and then taking 20 minutes afterward,

00:20:55.700 | immediately afterwards to deliberately turn off

00:20:58.840 | the deliberate focused thinking and engagement

00:21:02.220 | actually accelerated neuroplasticity.

00:21:04.980 | There's another study that's just incredible,

00:21:07.200 | and we're going to go into this

00:21:08.260 | in a future episode of the podcast, not too long from now,

00:21:11.700 | that showed that if people are learning a particular skill,

00:21:16.700 | it could be a language skill or a motor skill,

00:21:19.340 | and they hear a tone just playing in the background,

00:21:23.020 | the tone is playing periodically through the background,

00:21:25.060 | like just a bell.

00:21:26.980 | In deep sleep, if that bell is played,

00:21:31.100 | learning is much faster for the thing

00:21:33.240 | that they were learning while they were awake.

00:21:35.740 | It somehow cues the nervous system in sleep,

00:21:39.140 | doesn't even have to be in dreaming,

00:21:41.080 | that something that happened in the waking phase

00:21:44.540 | was especially important,

00:21:46.020 | so much so that that bell is sort of a Pavlovian cue,

00:21:50.140 | it's sort of a reminder to the sleeping brain,

00:21:52.840 | oh, you need to remember what it is that you were learning

00:21:55.140 | at that particular time of day,

00:21:56.220 | and the learning rates and the rates of retention,

00:21:59.380 | meaning how much people can remember

00:22:00.760 | from the thing they learned,

00:22:01.940 | are significantly higher under those conditions.

00:22:05.360 | So I'm going to talk about how to apply all this knowledge

00:22:08.060 | in a little bit more in this podcast episode,

00:22:10.640 | but also in future episodes,

00:22:12.460 | but it really speaks to the really key importance

00:22:16.700 | of sleep and focus,

00:22:19.140 | these two opposite ends of our attentional state.

00:22:22.300 | When we're in sleep, these DPOs,

00:22:24.300 | duration, path, and outcome analysis are impossible.

00:22:26.940 | We just can't do that.

00:22:28.320 | We are only in relation to what's happening inside of us.

00:22:31.940 | So sleep is key.

00:22:33.900 | Also key are periods of non-sleep deep rest

00:22:36.620 | where we're turning off our analysis

00:22:38.500 | of duration, path, and outcome,

00:22:40.100 | in particular for the thing

00:22:41.700 | that we were just trying to learn,

00:22:43.660 | and we're in this kind of liminal state

00:22:46.780 | where our attention is kind of drifting all over.

00:22:49.020 | It turns out that's very important for the consolidation,

00:22:51.660 | for the changes between the nerve cells

00:22:53.900 | that will allow what we were trying to learn

00:22:56.100 | to go from being deliberate and hard and stressful

00:22:59.660 | and a strain to easy and reflexive.

00:23:03.800 | This also points to how different people,

00:23:07.760 | including many modern clinicians,

00:23:09.660 | are thinking about how to prevent bad circumstances,

00:23:12.380 | traumas from routing their way

00:23:14.220 | into our nervous system permanently.

00:23:15.820 | It says that you might want to interfere

00:23:18.080 | with certain aspects of brain states

00:23:20.720 | that are away from the bad thing that happened,

00:23:23.460 | the brain states that happened the next day

00:23:26.100 | or the next month or the next year.

00:23:28.340 | And also I want to make sure

00:23:31.300 | that I pay attention to the fact that for many of you,

00:23:33.740 | you're thinking about neuroplasticity

00:23:35.140 | not just in changing your nervous system

00:23:37.420 | to add something new,

00:23:38.900 | but to also get rid of things that you don't like, right?

00:23:42.420 | That you want to forget bad experiences

00:23:44.620 | or at least remove the emotional contingency

00:23:47.020 | of a bad relationship

00:23:48.460 | or a bad relationship to something

00:23:50.520 | or some person or some event.

00:23:52.480 | Learning to fear certain things less,

00:23:55.880 | to eliminate a phobia, to erase a trauma.

00:23:59.300 | The memories themselves don't get erased.

00:24:01.520 | I'm sorry to say that the memories don't,

00:24:03.240 | themselves get erased,

00:24:04.300 | but the emotional load of memories can be reduced.

00:24:07.160 | And there are a number of different ways

00:24:08.440 | that that can happen,

00:24:09.720 | but they all require this thing

00:24:11.160 | that we're calling neuroplasticity.

00:24:14.040 | We're going to have a large number of discussions

00:24:16.440 | about neuroplasticity in depth,

00:24:18.540 | but the most important thing to understand

00:24:20.980 | is that it is indeed a two-phase process.

00:24:23.940 | What governs the transition between alert and focused

00:24:27.780 | and these depressed and deep sleep states

00:24:31.340 | is a system in our brain and body,

00:24:33.780 | a certain aspect of the nervous system

00:24:35.380 | called the autonomic nervous system.

00:24:37.980 | And it is immensely important to understand

00:24:40.340 | how this autonomic nervous system works.

00:24:42.780 | It has names like the sympathetic nervous system

00:24:44.940 | and parasympathetic nervous system,

00:24:46.260 | which frankly are complicated names

00:24:48.920 | because they're a little bit misleading.

00:24:50.280 | Sympathetic is the one that's associated

00:24:52.120 | with more alertness,

00:24:52.960 | parasympathetic is the one that's associated

00:24:54.600 | with more calmness.

00:24:56.280 | And it gets really misleading

00:24:57.640 | because the sympathetic nervous system sounds like sympathy

00:25:00.880 | and then people think it's related to calm.

00:25:02.400 | I'm going to call it the alertness system

00:25:03.960 | and the calmness system,

00:25:05.720 | because even though sympathetic and parasympathetic

00:25:09.240 | are sometimes used, people really get confused.

00:25:11.920 | So the way to think about the autonomic nervous system

00:25:15.240 | and the reason it's important for every aspect of your life,

00:25:18.480 | but in particular for neuroplasticity

00:25:20.440 | and engaging in these focused states

00:25:22.500 | and then these defocused states

00:25:24.160 | is that it works sort of like a seesaw.

00:25:26.400 | Every 24 hours, we're all familiar with the fact

00:25:29.540 | that when we wake up in the morning,

00:25:30.720 | we might be a little bit groggy,

00:25:31.840 | but then generally we're more alert.

00:25:33.520 | And then as evening comes around,

00:25:35.680 | we tend to become a little more relaxed and sleepy

00:25:37.720 | and eventually at some point at night we go to sleep.

00:25:40.180 | So we go from alert to deeply calm.

00:25:43.400 | And as we do that, we go from an ability to engage

00:25:45.920 | in these very focused duration path outcome

00:25:48.920 | types of analyses to states in sleep

00:25:51.820 | that are completely divorced from duration path and outcome

00:25:55.000 | in which everything is completely random and untethered

00:25:57.360 | in terms of our sensations, perceptions,

00:25:59.160 | and feelings and so forth.

00:26:00.580 | So every 24 hours, we have a phase of our day

00:26:04.040 | that is optimal for thinking and focusing

00:26:07.760 | and learning and neuroplasticity

00:26:09.960 | and doing all sorts of things.

00:26:11.300 | We have energy as well.

00:26:13.200 | And at another phase of our day,

00:26:14.440 | we're tired and we have no ability to focus.

00:26:17.920 | We have no ability to engage

00:26:19.720 | in duration path outcome types of analyses.

00:26:22.360 | And it's interesting that both phases are important

00:26:25.480 | for shaping our nervous system in the ways that we want.

00:26:28.140 | So if we want to engage neuroplasticity

00:26:30.120 | and we want to get the most out of our nervous system,

00:26:32.800 | we each have to master both the transition

00:26:36.240 | between wakefulness and sleep

00:26:38.360 | and the transition between sleep and wakefulness.

00:26:41.020 | Now, so much has been made of the importance of sleep

00:26:43.420 | and it is critically important for wound healing,

00:26:46.060 | for learning, as I just mentioned,

00:26:47.580 | for consolidating learning,

00:26:49.540 | for all aspects of our immune system.

00:26:52.860 | It is the one period of time

00:26:54.020 | in which we're not doing these duration path

00:26:55.660 | and outcomes types of analyses.

00:26:57.260 | And it is critically important to all aspects of our health,

00:26:59.700 | including our longevity.

00:27:01.080 | Much less has been made, however,

00:27:04.620 | of how to get better at sleeping,

00:27:07.340 | how to get better at the process

00:27:09.300 | that involves falling asleep, staying asleep,

00:27:12.160 | and accessing the states of mind and body

00:27:15.600 | that involve total paralysis.

00:27:17.260 | Most people don't know this,

00:27:18.100 | but you're actually paralyzed during much of your sleep

00:27:20.420 | so that you can't act out your dreams, presumably.

00:27:23.060 | But also where your brain is in a total idle state

00:27:27.340 | where it's not controlling anything,

00:27:29.540 | it's just left to kind of free run.

00:27:31.600 | And there are certain things that we can all do

00:27:35.420 | in order to master that transition,

00:27:37.940 | in order to get better at sleeping.

00:27:39.900 | And it involves much more than just how much we sleep.

00:27:42.220 | We're all being told, of course, that we need to sleep more,

00:27:44.920 | but there's also the issue of sleep quality,

00:27:47.300 | accessing those deep states of non-DPO thinking,

00:27:50.860 | accessing the right timing of sleep.

00:27:53.620 | Not a lot has been discussed publicly

00:27:55.340 | as far as I'm aware of when to time your sleep.

00:27:58.100 | I think we all can appreciate

00:27:59.980 | that sleeping for half an hour throughout the day

00:28:03.380 | so that you get a total of eight hours of sleep

00:28:06.500 | every 24 hour cycle is probably very different

00:28:09.560 | and not optimal compared to a solid block

00:28:11.740 | of eight hours of sleep.

00:28:12.880 | Although there are people that have tried this.

00:28:14.420 | I think it's been written about in various books.

00:28:17.340 | Not many people can stick to that schedule.

00:28:20.000 | Incidentally, I think it's called the Uberman schedule,

00:28:22.100 | not to be confused with the Huberman schedule,

00:28:24.580 | because first of all, my schedule

00:28:25.740 | doesn't look anything like that.

00:28:26.820 | And second of all,

00:28:27.640 | I would never attempt such a sleeping regime.

00:28:30.040 | The other thing that is really important to understand

00:28:34.380 | is that we have not explored as a culture,

00:28:38.380 | the rhythms that occur in our waking states.

00:28:41.380 | So much has been focused on the value of sleep

00:28:43.780 | and the importance of sleep, which is great.

00:28:45.980 | But I don't think that most people are paying attention

00:28:48.460 | to what's happening in their waking states

00:28:50.260 | and when their brain is optimized for focus,

00:28:53.060 | when their brain is optimized for these DPOs,

00:28:55.420 | these duration path outcome types of engagements

00:28:58.660 | for learning and for changing.

00:29:00.740 | And when their brain is probably better suited

00:29:02.860 | for more reflexive thinking and behaviors.

00:29:05.100 | And it turns out that there's a vast amount

00:29:08.060 | of scientific data which points to the existence

00:29:11.900 | of what are called ultradian rhythms.

00:29:13.980 | You may have heard of circadian rhythms.

00:29:16.300 | Circadian means circa about a day.

00:29:19.180 | So it's 24 hour rhythms

00:29:20.660 | 'cause the earth spins once every 24 hours.

00:29:23.620 | Ultradian rhythms occur throughout the day

00:29:26.180 | and they require less time, they're shorter.

00:29:30.180 | The most important ultradian rhythm

00:29:31.660 | for sake of this discussion is the 90 minute rhythm

00:29:34.180 | that we're going through all the time

00:29:36.540 | in our ability to attend and focus.

00:29:39.540 | And in sleep, our sleep is broken up

00:29:42.940 | into 90 minute segments.

00:29:45.040 | Early in the night, we have more phase one

00:29:47.040 | and phase two lighter sleep.

00:29:48.500 | And then we go into our deeper phase three

00:29:50.100 | and phase four sleep.

00:29:50.940 | And then we return to phase one, two, three, four.

00:29:53.060 | So all night you're going through these ultradian rhythms

00:29:55.720 | of stage one, two, three, four, one, two, three, four.

00:29:58.900 | It's repeating.

00:30:00.480 | Most people perhaps know that, maybe they don't.

00:30:03.260 | But when you wake up in the morning,

00:30:05.660 | these ultradian rhythms continue.

00:30:07.820 | And it turns out that we are optimized

00:30:10.020 | for focus and attention within these 90 minute cycles

00:30:14.020 | so that at the beginning of one of these 90 minute cycles,

00:30:16.340 | maybe you sit down to learn something new

00:30:18.020 | or to engage in some new challenging behavior.

00:30:21.240 | For the first five or 10 minutes of one of those cycles,

00:30:23.700 | it's well known that the brain and the neural circuits

00:30:26.340 | and the neuromodulators are not going to be optimally tuned

00:30:30.380 | to whatever it is you're trying to do.

00:30:31.620 | But as you drop deeper into that 90 minute cycle,

00:30:34.100 | your ability to focus and to engage in this DPO process

00:30:37.760 | and to direct neuroplasticity and to learn

00:30:40.820 | is actually much greater.

00:30:42.220 | And then you eventually pop out of that

00:30:44.700 | at the end of the 90 minute cycle.

00:30:46.580 | So these cycles are occurring in sleep

00:30:48.660 | and these cycles are occurring in wakefulness.

00:30:50.820 | And all of those are governed by this seesaw

00:30:53.500 | of alertness to calmness

00:30:54.860 | that we call the autonomic nervous system.

00:30:57.140 | So if you want to master and control your nervous system,

00:31:00.780 | regardless of what tool you reach to,

00:31:02.940 | whether or not it's a pharmacologic tool

00:31:04.580 | or whether or not it's a behavioral tool

00:31:06.180 | or whether or not it's a brain machine interface tool,

00:31:09.500 | it's vitally important to understand

00:31:12.100 | that your entire existence is occurring

00:31:15.100 | in these 90 minute cycles,

00:31:16.680 | whether or not you're asleep or awake.

00:31:18.540 | And so you really need to learn

00:31:20.060 | how to wedge into those 90 minute cycles.

00:31:23.140 | And for instance, it would be completely crazy

00:31:26.420 | and counterproductive to try and just learn information

00:31:29.560 | while in deep sleep by listening to that information

00:31:31.820 | 'cause you're not able to access it.

00:31:33.980 | It would be perfectly good, however,

00:31:36.860 | to engage in a focus bout of learning each day.

00:31:39.740 | And now we know how long

00:31:40.960 | that focus bout of learning should be.

00:31:42.660 | It should be at least one 90 minute cycle.

00:31:44.900 | And the expectation should be that the early phase

00:31:47.660 | of that cycle is going to be challenging.

00:31:49.800 | It's going to hurt.

00:31:50.640 | It's not going to feel natural.

00:31:51.820 | It's not going to feel like flow,

00:31:53.700 | but that you can learn.

00:31:55.420 | And the circuits of your brain

00:31:56.780 | that are involved in focus and motivation

00:31:58.680 | can learn to drop in to a mode of more focus,

00:32:02.300 | get more neuroplasticity in other words,

00:32:04.900 | by engaging these ultradian cycles

00:32:07.620 | at the appropriate times of day.

00:32:09.820 | For instance, some people are very good learners

00:32:12.040 | early in the day and not so good in the afternoon.

00:32:14.620 | So you can start to explore this process

00:32:17.380 | even without any information

00:32:19.180 | about the underlying neurochemicals

00:32:20.580 | by simply paying attention,

00:32:22.420 | not just to when you go to sleep

00:32:23.840 | and when you wake up each morning,

00:32:25.860 | how deep or how shallow your sleep felt to you subjectively,

00:32:29.540 | but also throughout the day

00:32:30.860 | when your brain tends to be most anxious,

00:32:33.980 | because it turns out

00:32:34.820 | that has a correlate related to perception

00:32:37.540 | that we will talk about.

00:32:40.340 | You can ask yourself, when are you most focused?

00:32:42.700 | When are you least anxious?

00:32:43.860 | When do you feel most motivated?

00:32:45.520 | When do you feel least motivated?

00:32:48.460 | By understanding how the different aspects

00:32:51.180 | of your perception, sensation, feeling, thought

00:32:53.340 | and actions tend to want to be engaged

00:32:56.560 | or not want to be engaged.

00:32:58.000 | You develop a very good window

00:33:00.440 | into what's going to be required

00:33:02.120 | to shift your ability to focus

00:33:05.100 | or shift your ability to engage in creative type thinking

00:33:08.880 | at different times of day, should you choose.

00:33:11.320 | And so that's where we're heading going forward.

00:33:13.400 | It all starts with mastering this seesaw

00:33:16.200 | that is the autonomic nervous system

00:33:17.980 | that at a course level is a transition

00:33:20.320 | between wakefulness and sleep.

00:33:22.320 | But at a finer level and just as important

00:33:25.040 | are the various cycles,

00:33:26.080 | these all trading 90 minute cycles

00:33:27.740 | that govern our life all the time,

00:33:29.720 | 24 hours a day, every day of our life.

00:33:31.960 | And so we're going to talk about

00:33:33.080 | how you can take control of the autonomic nervous system

00:33:35.600 | so that you can better access neuroplasticity,

00:33:38.600 | better access sleep,

00:33:40.280 | even take advantage of the phase

00:33:42.200 | that is the transition between sleep and waking

00:33:44.400 | to access things like creativity and so forth.

00:33:48.040 | All based on studies that have been published

00:33:50.400 | over the last hundred years,

00:33:51.560 | mainly within the last 10 years

00:33:53.200 | and some that are very, very new

00:33:54.840 | and that point to the use of specific tools

00:33:57.180 | that will allow you to get the most

00:33:58.920 | out of your nervous system.

00:34:00.660 | So today we covered a lot of information.

00:34:03.160 | It was sort of a whirlwind tour

00:34:04.960 | of everything from neurons and synapses

00:34:07.300 | to neuroplasticity in the autonomic nervous system.

00:34:09.980 | We will revisit a lot of these themes going forward.

00:34:12.760 | So if all of that didn't sink in in one pass,

00:34:16.080 | please don't worry.

00:34:16.980 | We will come back to these themes over and over again.

00:34:19.960 | I wanted to equip you with a language

00:34:22.520 | that we're all developing a kind of common base set

00:34:25.820 | of information going forward.

00:34:27.720 | And I hope the information is valuable to you

00:34:29.720 | and you're thinking about what is working well for you

00:34:32.840 | and what's working less well

00:34:34.920 | and what's been exceedingly challenging,

00:34:36.560 | what's been easy for you in terms of your pursuit

00:34:39.160 | of particular behaviors or emotional states,

00:34:41.840 | where your challenges or the challenges of people

00:34:43.800 | that you know might reside.

00:34:46.000 | So thank you so much for your time and attention.

00:34:47.940 | And above all, thank you for your interest in science.

00:34:50.540 | [upbeat music]

00:34:53.120 | (upbeat music)

Essentials: How Your Brain Works & Changes

Chapters