Tools to Enhance Working Memory & Attention

00:00:00.000 | - Welcome to the Huberman Lab Podcast,

00:00:02.280 | where we discuss science and science-based tools

00:00:04.880 | for everyday life.

00:00:05.920 | I'm Andrew Huberman,

00:00:10.240 | and I'm a professor of neurobiology and ophthalmology

00:00:13.340 | at Stanford School of Medicine.

00:00:15.400 | Today, we are discussing working memory.

00:00:17.900 | Working memory is a special category of memory

00:00:20.620 | in which we are able to hold small amounts of information

00:00:23.560 | in our mind for short periods of time.

00:00:26.120 | Working memory is also very closely related to attention.

00:00:29.280 | So for any of you that are interested

00:00:30.860 | in how to develop better focus and attention,

00:00:34.000 | understanding what working memory is

00:00:35.840 | and some of the things that you can do

00:00:37.360 | to improve your working memory can be very beneficial.

00:00:40.540 | Today, I'm going to talk about what working memory is,

00:00:43.240 | including some of the underlying biology,

00:00:45.280 | although I promise,

00:00:46.720 | irrespective of whether or not you know any biology

00:00:49.120 | or you are an expert in biology,

00:00:51.300 | I'll make the conversation accessible to you.

00:00:53.860 | In addition, I will talk about tools

00:00:55.680 | to improve working memory,

00:00:57.280 | and I'll also compare working memory to other forms of memory

00:01:00.160 | like long-term memory and short-term memory.

00:01:02.180 | And through that understanding,

00:01:03.320 | I'm confident that you'll be able to develop better focus

00:01:06.600 | as well as be able to commit certain forms of information

00:01:10.060 | to your short and long-term memory stores.

00:01:12.640 | Before we begin, I'd like to emphasize that this podcast

00:01:15.480 | is separate from my teaching and research roles at Stanford.

00:01:18.220 | It is, however, part of my desire and effort

00:01:20.360 | to bring zero cost to consumer information

00:01:22.240 | about science and science-related tools

00:01:24.280 | to the general public.

00:01:25.740 | In keeping with that theme,

00:01:26.840 | I'd like to thank the sponsors of today's podcast.

00:01:29.760 | Our first sponsor is Matina.

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00:01:34.980 | I often discuss Yerba Mate's benefits,

00:01:37.040 | such as regulating blood sugar,

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00:01:43.300 | and possible neuroprotective effects.

00:01:45.500 | I also drink Yerba Mate because I love the taste.

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00:02:46.960 | Today's episode is also brought to us by BetterHelp.

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00:02:54.760 | - I've been going to therapy for well over 30 years.

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00:05:00.740 | Okay, let's talk about working memory.

00:05:02.960 | And let's start off this discussion

00:05:04.620 | by comparing working memory to other forms of memory

00:05:07.640 | that most people are more familiar with.

00:05:09.340 | Or at least when most people hear the word memory,

00:05:12.120 | they typically are thinking about long-term memory,

00:05:14.720 | like one's ability to remember the capitals of states

00:05:17.820 | or countries, the different continents,

00:05:20.040 | directions from one location to another, even one's name.

00:05:23.800 | All of those things are examples of long-term memory.

00:05:26.920 | Now I want to emphasize that long-term memory

00:05:28.880 | really has two components.

00:05:30.720 | There are what we call declarative long-term memories.

00:05:33.640 | So these are the things that we can declare,

00:05:35.520 | things like facts about ourselves or the world or others.

00:05:38.840 | And then there are procedural long-term memories.

00:05:41.800 | Procedural long-term memories, as the name suggests,

00:05:44.620 | are aspects of our memory that allow us

00:05:46.560 | to perform certain procedures.

00:05:48.360 | They are literally action steps that we take

00:05:50.960 | to, for instance, ride a bicycle or drive a car,

00:05:53.700 | which, by the way, we might not be conscious

00:05:56.220 | of ourselves doing after we learn,

00:05:59.160 | that is, after we pass information

00:06:01.520 | into our procedural long-term memory.

00:06:04.260 | But even once those things become reflexive,

00:06:06.580 | they are stored in our long-term memory.

00:06:08.740 | Now, a discussion of long-term memory

00:06:10.200 | is not the focus today, but me being a neuroscientist,

00:06:13.920 | and I like to think you all generally being interested

00:06:17.280 | in the underlying biology,

00:06:18.520 | I'll just mention that there is a key structure

00:06:20.980 | within the brain that is part of a larger neural network

00:06:24.160 | that is a collection of structures,

00:06:25.420 | which is absolutely essential for the formation

00:06:27.940 | and storage of long-term memories.

00:06:29.500 | And that's the hippocampus, which in Latin means seahorse.

00:06:32.940 | And it does look a little bit like a seahorse,

00:06:35.060 | but we actually have one on each side of your brain,

00:06:37.440 | so we say hippocampi, plural.

00:06:39.460 | And so what we know is that if people have damage

00:06:42.100 | to their hippocampus of any kind,

00:06:44.080 | that people have trouble accessing

00:06:46.340 | or forming long-term memory, sometimes both.

00:06:49.220 | And there's a lot more that we could say

00:06:50.960 | about long-term memory.

00:06:51.880 | Indeed, I did an entire episode of the Huberman Lab Podcast

00:06:55.020 | about the formation and storage of long-term memories,

00:06:57.460 | including some tools to improve long-term memory.

00:06:59.760 | We'll touch on a few of those tools later today,

00:07:01.980 | but you can access that episode

00:07:03.760 | if you go to HubermanLab.com and just put memory

00:07:06.080 | into the search function and you'll find it there.

00:07:08.480 | In the meantime, if we want to understand working memory,

00:07:11.400 | we not only have to understand

00:07:12.700 | how it's different from long-term memory,

00:07:14.740 | but also how it's different from short-term memories.

00:07:17.460 | Short-term memory is a capacity that we all have

00:07:20.620 | that, as the name suggests,

00:07:21.940 | represents a short-term memory bank for information

00:07:25.080 | that may or may not get passed into long-term memory.

00:07:28.840 | So for instance, if you've learned anything,

00:07:30.640 | and of course you have,

00:07:31.620 | if you can understand what I'm saying,

00:07:33.120 | you've learned English language.

00:07:35.220 | If you can write, you've learned how to write, et cetera.

00:07:37.760 | Well, in order to learn those things

00:07:40.020 | and to commit them to long-term memory,

00:07:42.420 | the information required to do those things

00:07:44.700 | and to have that knowledge

00:07:46.300 | needed to be held in short-term memory.

00:07:48.620 | And short-term memories are the sorts of memories

00:07:50.460 | that we maintain for somewhere between a few minutes

00:07:54.200 | and potentially a few hours, maybe a little bit longer,

00:07:57.440 | but only a certain percentage of that

00:07:59.200 | is passed into our long-term memory.

00:08:01.040 | So for instance, if you listen to this podcast

00:08:03.320 | or you go to a course lecture,

00:08:05.720 | whether or not that lecture is about cognitive material

00:08:08.400 | or whether or not it's about learning a new physical skill,

00:08:11.340 | regardless of what you learn,

00:08:12.560 | you're only going to learn

00:08:13.600 | a certain amount of that information.

00:08:15.840 | But were we to examine

00:08:17.820 | how much of the information you just heard

00:08:19.640 | or that you're hearing now,

00:08:20.900 | you remember immediately after this podcast episode,

00:08:24.680 | as compared to say a week later,

00:08:26.800 | we know based on, gosh,

00:08:29.200 | probably millions of scientific papers and studies,

00:08:31.720 | that you are going to have more information

00:08:33.980 | in your short-term memory stores

00:08:35.640 | shortly after being exposed to new information

00:08:37.860 | than you will later.

00:08:39.220 | In other words, only a small percentage of what we perceive,

00:08:41.880 | what we see, what we hear, et cetera,

00:08:44.120 | gets passed into short-term memory.

00:08:45.880 | And then only a fraction of that

00:08:47.600 | gets passed into long-term memory.

00:08:49.520 | Now, the neural circuits for short-term memory

00:08:51.940 | and the passage of short-term memories into long-term memory

00:08:55.040 | involve a lot of different brain structures.

00:08:56.700 | But here again, we can implicate the hippocampus

00:08:59.820 | because the actual passage of short-term memories

00:09:02.720 | into long-term memories

00:09:04.480 | occurs in part within the hippocampus.

00:09:06.520 | And then, a lot of people don't know this,

00:09:08.840 | some of the memories that we think of as long-term memories

00:09:11.740 | are actually distributed into the neocortex,

00:09:13.900 | which is the outer portion of the brain.

00:09:16.120 | Now, the point here is less to fill your mind

00:09:18.340 | with different names of things and nomenclature,

00:09:20.700 | but rather to get you thinking about

00:09:22.940 | what's involved in creating short and long-term memories.

00:09:26.000 | And equally important,

00:09:27.480 | that even though the hippocampus is critically involved

00:09:30.200 | in the formation of short and long-term memories,

00:09:32.440 | that the formation of short and long-term memories

00:09:34.760 | is really a network phenomenon.

00:09:36.540 | In fact, among the more important themes

00:09:38.240 | that comes up again and again on this podcast,

00:09:40.520 | anytime that we're talking about neuroscience,

00:09:42.640 | or actually biology in any case,

00:09:44.980 | is that rarely, if ever,

00:09:47.120 | is there one location in the brain where something happens.

00:09:49.560 | Typically, it's a network phenomenon,

00:09:51.260 | meaning it's the collaboration

00:09:52.600 | of a bunch of different brain areas,

00:09:54.200 | passing information from one location to the next

00:09:56.760 | and storing it in a kind of distributed way.

00:09:59.660 | Now, another key thing to understand about working memory

00:10:01.980 | and how it is different from short and long-term memory

00:10:05.100 | is that the formation of short and long-term memories

00:10:08.340 | almost always involves neuroplasticity.

00:10:11.640 | Neuroplasticity is the nervous system's ability to change

00:10:14.980 | in response to experience.

00:10:16.820 | Now, there are different types of neuroplasticity.

00:10:19.420 | So often when we hear about neuroplasticity

00:10:21.760 | in the popular sphere,

00:10:23.320 | people don't emphasize that there are different types

00:10:25.780 | of neuroplasticity,

00:10:26.700 | and it's worth paying a little bit of attention

00:10:28.380 | to what those different types are.

00:10:30.460 | There is, for instance, what we call long-term potentiation.

00:10:34.200 | Long-term potentiation, or LTP, as the acronym goes,

00:10:38.140 | is the strengthening of connections between neurons

00:10:41.380 | as a consequence of their repeated firing

00:10:43.740 | very closely together in time.

00:10:46.220 | Okay, there's a lot more to it,

00:10:47.860 | but if you've ever heard the phrase

00:10:49.460 | fire together, wire together,

00:10:51.500 | sometimes that is misattributed to Donald Hebb,

00:10:54.580 | who did talk about neuroplasticity.

00:10:56.340 | By the way, Donald Hebb was a psychologist up in Canada

00:10:58.820 | who talked about neuroplasticity in the context

00:11:00.820 | of lots of different forms of learning,

00:11:02.700 | but that fire together, wire together phrase

00:11:05.620 | was not actually stated by Donald Hebb.

00:11:07.580 | It was stated by Carla Schatz, my colleague at Stanford,

00:11:10.660 | and she was referring to LTP,

00:11:12.560 | but other forms of neuroplasticity

00:11:14.420 | that occur mainly in development

00:11:16.340 | when neurons fire very closely in time

00:11:18.980 | and thereby strengthen those connections,

00:11:21.040 | which can include LTP, okay?

00:11:23.380 | So for now, think of LTP as any time

00:11:25.980 | that some small group of neurons, could be two neurons,

00:11:29.540 | could be 2,000 neurons,

00:11:31.780 | are very active closely together in time,

00:11:35.260 | and they have access to one another physically,

00:11:38.380 | and the consequence is often, not always, but is often LTP.

00:11:42.640 | That is the strengthening of those connections

00:11:45.100 | such that after that barrage of activity subsides,

00:11:48.340 | those neurons can speak to each other.

00:11:50.280 | They can communicate through electrical activity

00:11:52.280 | and chemical activity much more easily.

00:11:54.980 | Their communication is more robust.

00:11:56.740 | It's like removing a wall between a conversation

00:11:59.740 | such that the conversation can take place more fluidly.

00:12:03.500 | Now, there are other forms of neuroplasticity,

00:12:05.340 | including LTD, long-term depression,

00:12:08.260 | which unfortunately the name often calls to mind

00:12:11.100 | ideas about depression as a psychiatric

00:12:13.620 | or a psychological symptom,

00:12:14.860 | but it has nothing to do with that.

00:12:16.200 | Long-term depression is simply the inverse of LTP.

00:12:19.120 | It's actually the weakening or the removal of connections

00:12:21.880 | that we call synapses between neurons.

00:12:24.220 | I want to emphasize that both LTP and LTD

00:12:27.420 | are both critically involved

00:12:29.320 | in lots of different kinds of learning,

00:12:31.300 | and both of them tend to be involved in the formation

00:12:33.720 | of both short-term memories and long-term memories.

00:12:36.220 | And this is very important in the removal

00:12:39.540 | of short-term memories and long-term memories,

00:12:41.980 | literally forgetting of certain things,

00:12:43.960 | because as we all know,

00:12:46.180 | there are many things that we will never forget,

00:12:48.420 | and there are also things that we almost always forget.

00:12:52.240 | Now, there's a third form of neuroplasticity

00:12:54.060 | that's involved in the formation

00:12:55.220 | of short and long-term memories

00:12:56.460 | that's important for us to discuss just briefly.

00:12:58.840 | But I do want to emphasize

00:12:59.780 | that there are not just three forms of neuroplasticity.

00:13:02.780 | There are many other forms, dozens, if not more,

00:13:05.300 | things like spike timing-dependent plasticity,

00:13:07.620 | paired pulse facilitation, and on and on.

00:13:10.080 | But the third type of neuroplasticity

00:13:11.680 | that I'd like to mention now is neurogenesis.

00:13:14.560 | Neurogenesis is the formation of new neurons.

00:13:18.040 | Now, neurogenesis is robust

00:13:20.140 | in the developing nervous system.

00:13:21.420 | We know this.

00:13:22.260 | Neurogenesis is robust in the developing nervous system

00:13:24.120 | of animals and humans.

00:13:26.520 | However, neurogenesis,

00:13:28.500 | the literal formation of new neurons in the brain,

00:13:32.140 | is a very exciting idea, and it does occur.

00:13:36.040 | And it's very exciting in a way

00:13:37.400 | that has motivated lots of popular press outlets

00:13:40.660 | to talk about or to discuss papers

00:13:44.100 | that have discovered neurogenesis in the adult brain.

00:13:47.180 | Because let's be honest,

00:13:48.820 | what's more exciting than the idea

00:13:50.140 | that your brain can add new brain cells later in life?

00:13:53.100 | And indeed, that has been shown,

00:13:54.740 | even in people well into their 80s and 90s.

00:13:57.280 | However, it's very important to know

00:13:58.700 | that the total amount of neurogenesis that occurs

00:14:01.280 | in the adult human brain is infinitesimally small

00:14:06.280 | as a mechanism for neuroplasticity and learning

00:14:09.240 | as compared to the other forms of neuroplasticity

00:14:12.200 | that we discussed,

00:14:13.040 | such as long-term potentiation and long-term depression.

00:14:16.220 | So I don't want to throw cold water

00:14:18.720 | on the topic of neurogenesis.

00:14:20.220 | It's an incredibly interesting and important topic,

00:14:22.700 | but all too often they tend to eclipse

00:14:24.320 | the much more common mechanism

00:14:25.840 | for the formation of short and long-term memories,

00:14:28.220 | which are those other forms we just talked about,

00:14:29.920 | LTP, LTD, et cetera.

00:14:31.580 | So the point here is that, yes, indeed,

00:14:35.460 | there are new neurons that can be added in the adult brain,

00:14:37.800 | maybe even in the adult human brain.

00:14:39.640 | And there is some evidence that some of those new neurons

00:14:42.300 | are added to the hippocampus.

00:14:44.660 | In fact, a particular region of the hippocampus

00:14:46.980 | called the dentate gyrus of the hippocampus.

00:14:49.240 | And there's been a lot of controversy

00:14:50.680 | about how much neurogenesis occurs or doesn't occur

00:14:53.500 | and whether or not it occurs after puberty or not.

00:14:55.500 | There's a whole field of people battling over this,

00:14:57.800 | now for several decades.

00:14:59.260 | But one thing is very clear.

00:15:01.180 | Neurogenesis, while it's very exciting and intriguing,

00:15:03.800 | is not the main mechanism by which the formation

00:15:06.360 | of short and long-term memories occurs.

00:15:08.360 | When you learn new information, as you are right now,

00:15:11.820 | the storage of that information

00:15:13.240 | in your short-term memory networks,

00:15:15.280 | which is then passed on to your long-term memory networks,

00:15:18.200 | and that can be recalled,

00:15:20.120 | that allows you to state certain facts about,

00:15:22.760 | for instance, the existence of this thing

00:15:24.120 | called a hippocampus.

00:15:24.960 | Hopefully you will remember that going forward.

00:15:26.920 | Or your ability to perform any kind of motor movement

00:15:29.520 | that you learned now or way back in childhood.

00:15:33.720 | Most of that is the consequence of the strengthening

00:15:36.320 | of particular connections

00:15:37.320 | and the weakening of other types of connections.

00:15:39.740 | Those are the two major forms of neuroplasticity.

00:15:42.520 | Okay, so I don't want you to get the impression

00:15:44.920 | that there's something wrong with my memory

00:15:46.620 | and that I forgot that this episode

00:15:48.120 | is not about short or long-term memory,

00:15:49.880 | but it's about working memory.

00:15:51.440 | And indeed, I have not forgotten.

00:15:53.380 | So now is where I tell you why I've been talking

00:15:55.800 | about short and long-term memory and the mechanisms of those

00:15:58.800 | because I want them to provide a stark contrast

00:16:01.960 | for what we call working memory.

00:16:04.480 | Working memory, as far as we know,

00:16:06.980 | does not involve neuroplasticity, or at least if it does,

00:16:11.480 | it's not a particularly robust aspect of working memory.

00:16:15.120 | Rather, working memory is the reflection

00:16:17.080 | of a particular neural circuit

00:16:18.680 | running an algorithm over and over and over

00:16:22.060 | for different types of information,

00:16:23.900 | but the information isn't stored,

00:16:25.880 | it is actually intentionally discarded.

00:16:28.900 | Now, what sorts of daily activities and life activities

00:16:31.600 | would require working memory?

00:16:33.320 | The answer to that is basically everything

00:16:37.080 | that you need to do, but that you don't want to remember.

00:16:41.440 | Now, what types of things would those be?

00:16:42.960 | Well, let's think about it.

00:16:44.280 | Most all of us learned at some point in our life

00:16:46.480 | to tie our own shoes.

00:16:47.800 | Presumably, you know how to tie your own shoes.

00:16:49.680 | If you don't, perhaps you should learn

00:16:51.920 | or wear Velcro or slippers, I don't know,

00:16:53.820 | but assuming you can tie your own shoes,

00:16:55.760 | that's something that you know how to do

00:16:57.340 | and you can do it as a procedural long-term memory.

00:17:00.080 | You can do that action.

00:17:01.320 | You don't have to think about it too much.

00:17:03.320 | Working memory would come into play

00:17:04.800 | when say you wake up in the morning

00:17:06.880 | and you know that you need to head out for a jog,

00:17:09.880 | but you also need to make a cup of coffee first

00:17:12.200 | and you need to remember where the coffee is,

00:17:13.840 | where your shoes are,

00:17:14.920 | and perhaps you're making a phone call

00:17:16.800 | or you're having a conversation

00:17:17.900 | while you need to tie your shoes and so on and so forth.

00:17:21.040 | Working memory is basically the taking in of information

00:17:24.440 | that's critical for you to sequence your actions

00:17:27.400 | over a short period of time and then forget that sequence.

00:17:31.440 | For instance, I'm willing to bet

00:17:33.420 | that you put your shoes on to go running

00:17:35.400 | before you go running.

00:17:36.720 | That's sort of a duh.

00:17:38.000 | And if you're like me, you drink your water, your coffee,

00:17:40.480 | your Yerba Mate before you go running.

00:17:42.600 | The point here is that if you wake up in the morning

00:17:44.400 | and you like caffeine before you go for a run,

00:17:46.800 | there are certain series of action steps

00:17:49.560 | that you need to carry out to hydrate,

00:17:51.360 | make that cup of coffee or tea,

00:17:53.480 | drink it, put on your shoes, head out the door.

00:17:55.680 | You need to sequence things properly,

00:17:57.680 | but you don't want to commit your long-term

00:18:00.440 | or even your short-term memory stores

00:18:02.600 | to carrying out that sequence.

00:18:04.520 | You simply want to be able to carry out that sequence

00:18:06.720 | and then discard that information about the sequence

00:18:10.120 | and focus your attention on, for instance,

00:18:12.320 | what trajectory you're going to run through the park

00:18:14.460 | or around your neighborhood.

00:18:16.240 | Then you want to discard that information

00:18:17.880 | and you want to lean into the next portion of your day

00:18:19.880 | and so on and so on.

00:18:21.800 | In fact, working memory is involved

00:18:23.480 | in essentially every activity, both cognitive and motor

00:18:27.560 | from the point you wake up in the morning

00:18:29.240 | until the time you go to sleep at night

00:18:31.520 | for every single day of your life.

00:18:33.280 | And we know this because there are indeed people

00:18:35.200 | who have diminished working memory

00:18:37.200 | or even lack working memory entirely,

00:18:39.140 | although the latter is somewhat rare, it has happened.

00:18:42.320 | And as you can imagine, they have a complete failure

00:18:45.240 | of ability to sequence activities

00:18:47.400 | and their lives are extremely difficult.

00:18:49.200 | They need a ton of assistance from other people,

00:18:52.000 | even more assistance than do people

00:18:54.000 | who have minimal or no long-term memory, okay?

00:18:57.360 | So this is really highlighting

00:18:58.960 | just how important working memory is.

00:19:01.100 | Working memory is basically the way

00:19:02.920 | that you navigate any immediate environment.

00:19:05.320 | And as I mentioned earlier,

00:19:06.480 | it's very closely tied to attention

00:19:08.520 | because in order to know what to do now

00:19:10.640 | and then what to do subsequently

00:19:12.200 | and then subsequent to that,

00:19:14.200 | you need to be able to hold your attention

00:19:16.320 | to the things you need to do.

00:19:17.480 | So working memory and attention collaborate

00:19:20.400 | literally at a neural circuit level

00:19:22.040 | and at a neurochemical level

00:19:23.760 | in order to allow you to move through your day

00:19:26.120 | in an adaptive, functional way.

00:19:28.360 | And people who have challenges with attention or focus

00:19:32.520 | or working memory, and sometimes it can be hard

00:19:34.360 | to dissociate which one they're having challenges with,

00:19:36.940 | really have a hard time moving through life

00:19:40.020 | as compared to people whose attention

00:19:41.860 | and working memory is more robust.

00:19:43.720 | Now, the good news is today,

00:19:44.720 | we're going to talk about working memory,

00:19:46.000 | some of the neural circuits involved

00:19:47.640 | and some of the neurochemicals involved

00:19:49.920 | that can augment or improve working memory.

00:19:52.440 | And we're also going to talk about what one can do

00:19:55.280 | to directly increase the amount of neurotransmission

00:19:58.320 | of those particular chemicals within the circuits

00:20:00.520 | that control working memory.

00:20:01.760 | In other words, to improve your working memory.

00:20:04.060 | Now, I can talk about working memory

00:20:05.640 | and the mechanisms, et cetera, all day long.

00:20:08.720 | But as is often the case, sometimes it's better

00:20:12.000 | to not just learn about concepts,

00:20:14.040 | but actually to experience them in real time.

00:20:17.040 | So what we're going to do now

00:20:18.240 | is I'm actually going to give you a working memory test.

00:20:21.640 | This is the sort of working memory test that you would take

00:20:23.860 | if you were to go into a psychology laboratory

00:20:26.780 | or a neuroscience laboratory

00:20:28.240 | and they were studying working memory in humans.

00:20:31.040 | Now, there's another advantage to us doing this in real time

00:20:33.600 | right here as you're listening

00:20:35.460 | or as you're listening and watching.

00:20:37.240 | And that's because you're going to get data.

00:20:39.160 | You're going to get information

00:20:40.540 | about what your baseline working memory capacity is.

00:20:44.680 | And you're going to want to keep those data

00:20:46.120 | in your short-term memory stores,

00:20:47.960 | maybe even your long-term memory stores,

00:20:49.600 | but certainly your short-term memory stores

00:20:51.280 | because shortly later in this episode,

00:20:53.760 | I'm going to talk about different ways

00:20:55.960 | to improve your working memory

00:20:57.320 | depending on where your baseline working memory starts,

00:21:01.720 | which by the way, turns out to be a pretty good proxy

00:21:05.320 | for the levels of a neuromodulator called dopamine

00:21:08.280 | within the neural circuits that control working memory.

00:21:11.640 | So right now, let's take a working memory task.

00:21:14.620 | We're going to do this purely through audio form

00:21:16.880 | because I realize some people are watching

00:21:18.360 | and listening to this on YouTube

00:21:19.680 | and others are just listening to this episode.

00:21:22.060 | So there are not going to be any visual cues

00:21:23.960 | or slides that I present.

00:21:25.640 | And that's perhaps what distinguishes what we're about to do

00:21:28.800 | most from what would happen in a laboratory.

00:21:30.640 | Typically in a laboratory,

00:21:31.760 | there would be some visual presentation

00:21:33.760 | of what I'm about to say.

00:21:35.120 | But here, because of the format

00:21:36.680 | that most of you are consuming this information by,

00:21:38.740 | we're going to do this purely by audio.

00:21:41.300 | So the first test of your working memory is very simple.

00:21:45.260 | I'm going to read off a series of letters.

00:21:48.800 | And your task is to remember

00:21:51.160 | as many of those letters as you can.

00:21:54.360 | The first string of letters is J, K, Z, P, I.

00:21:59.360 | Okay, just to make this really easy,

00:22:04.600 | I'm going to say it twice.

00:22:06.080 | Although typically in a working memory task,

00:22:08.320 | it would just be said once,

00:22:09.380 | but I'm going to make this extra easy.

00:22:12.000 | J, K, Z, P, I.

00:22:15.840 | Okay, now you in your own head

00:22:19.400 | can try and recite back those letters if you like.

00:22:22.640 | Okay, second string of letters, R, O, M, K, L, E.

00:22:27.640 | I'm going to make this extra simple and do it again.

00:22:37.320 | Not typical for a working memory task,

00:22:38.920 | but there are some working memory tasks where that happens.

00:22:42.500 | R, O, M, K, L, E.

00:22:46.740 | Okay, now a third string of letters.

00:22:50.120 | This one's going to be a little bit longer.

00:22:52.020 | So cue up that working memory and attention.

00:22:54.640 | W, A, C, Q, V, D, N.

00:23:00.560 | I'll repeat that again.

00:23:03.020 | W, A, C, Q, V, D, N.

00:23:07.920 | How many of the letters I just read can you remember?

00:23:11.720 | Okay, so depending on how many letters you can remember,

00:23:14.960 | perhaps you have a low, moderate,

00:23:17.140 | or high degree of working memory.

00:23:20.480 | Keep in mind that some of you are perhaps

00:23:22.420 | doing other things, you're attending to driving

00:23:24.760 | or other tasks within your home or your office.

00:23:28.120 | And so perhaps you weren't able to pay full attention.

00:23:30.520 | So there'll be some variation there.

00:23:32.480 | But nonetheless,

00:23:33.320 | after reading each of those strings of letters,

00:23:34.960 | you were asked to recall those letters in your mind.

00:23:37.720 | And if you wrote them down and you're rereading them,

00:23:39.800 | yes, that's cheating.

00:23:41.640 | But how about this?

00:23:42.480 | What if I were to ask you now

00:23:44.420 | about the simplest first string of letters,

00:23:47.060 | the one that consisted of only five letters?

00:23:50.580 | How many of you can remember any of those five letters now?

00:23:54.140 | Okay, I can't hear you if you're shouting them out.

00:23:58.460 | I can't see you if you're raising your hand.

00:24:00.340 | But chances are most of you have forgotten

00:24:02.380 | the first series of letters,

00:24:03.700 | even though it was quite short

00:24:04.920 | and you could remember it early on.

00:24:07.140 | That ability to remember that string of letters

00:24:09.380 | when you first heard them, and indeed I read them twice.

00:24:12.660 | So I'd be very surprised if any of you

00:24:14.220 | couldn't remember that string of letters

00:24:15.540 | after hearing them twice.

00:24:17.020 | But I also read you some other letters in the interim, okay?

00:24:21.140 | So that now, just a couple minutes later,

00:24:23.380 | I'm asking you to remember

00:24:24.420 | that first string of five letters.

00:24:26.260 | And assuming that you didn't write it down

00:24:27.900 | and you're not cheating,

00:24:29.120 | chances are you remember anywhere from two to zero

00:24:32.320 | of those letters in that first word,

00:24:34.740 | which is a perfect example of your working memory.

00:24:37.860 | Nothing got committed to short-term,

00:24:39.940 | much less long-term memory.

00:24:41.960 | Rather, your working memory

00:24:43.340 | was able to work with that information

00:24:45.420 | and hold it in mind for just as long

00:24:47.460 | as you thought you needed to know that information,

00:24:49.580 | but then, thank goodness, that information was discarded.

00:24:54.220 | You didn't know that I was gonna ask you

00:24:55.680 | for that first string of letters,

00:24:56.740 | again, after reading you the longer string of letters,

00:24:59.160 | but I did that deliberately

00:25:00.520 | to show you how your working memory works.

00:25:03.060 | So in some sense, the working memory task is a bit unusual

00:25:06.140 | in that it's a test of, yes, memory

00:25:08.460 | in the very, very short term,

00:25:10.500 | but also a test of your ability to forget,

00:25:13.020 | to discard information that's not critical.

00:25:15.500 | And that gets us back

00:25:16.540 | to the original definition of working memory,

00:25:18.460 | which is our ability to attend

00:25:20.180 | to specific small batches of information,

00:25:22.900 | remember it for just as long as we think we need to,

00:25:26.180 | and then to discard that information.

00:25:28.180 | And by the way, if you want to know

00:25:29.380 | what those first five letters were, they were J-K-Z-P-I.

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00:25:58.940 | Now, gut health is something that over the last 10 years,

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00:26:07.200 | and for the production of neurotransmitters

00:26:09.380 | and neuromodulators, things like dopamine and serotonin,

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00:27:02.120 | So now's where we talk a little bit about

00:27:04.540 | the neural circuitry and the neurochemistry

00:27:07.200 | of working memory.

00:27:08.580 | Now, it's important that we do this,

00:27:10.100 | because in a few minutes, you're also going to learn

00:27:12.500 | that people generally fall into two broad bins

00:27:16.500 | of having a high or low baseline

00:27:19.660 | of a certain neurochemical in the brain

00:27:21.600 | that affords them either high or low

00:27:24.340 | working memory capacity.

00:27:25.820 | Now, in reality, it's a distribution.

00:27:27.860 | In fact, it's what we call a normal distribution.

00:27:30.180 | So it really isn't two bins.

00:27:32.320 | But during today's discussion,

00:27:33.500 | and in fact, in a lot of laboratory studies,

00:27:35.460 | we can actually bin people into these two groups.

00:27:38.540 | The neural circuitry underlying working memory

00:27:40.700 | involves a lot of different brain locations,

00:27:42.900 | that is, a lot of different neural networks

00:27:45.260 | collaborating to create this thing we call working memory.

00:27:47.740 | However, there are a couple of key hubs,

00:27:50.740 | that is, locations within the brain,

00:27:53.180 | that are especially important for working memory.

00:27:56.620 | The ones that I'd like to focus on today

00:27:58.820 | involve the prefrontal cortex.

00:28:00.800 | So this is neural real estate

00:28:02.420 | that resides just behind the forehead.

00:28:04.540 | And the neurons in the brainstem,

00:28:07.500 | so further back in the brain,

00:28:10.100 | that manufacture dopamine and that send their little wires

00:28:13.720 | that we call axons up to the prefrontal cortex

00:28:16.260 | to release dopamine.

00:28:17.860 | Dopamine is a neuromodulator.

00:28:19.340 | Many people are familiar with dopamine

00:28:21.380 | and familiar with it in the context of motivation and drive.

00:28:25.340 | Sometimes people mistakenly think

00:28:27.020 | it's only involved in pleasure,

00:28:28.620 | but dopamine is involved in motivation and drive.

00:28:31.940 | When dopamine systems go awry,

00:28:34.180 | that is, if their levels get too high,

00:28:36.220 | that can create manic states,

00:28:37.760 | it can create addictive states.

00:28:39.900 | When dopamine levels are too low,

00:28:41.540 | you can get movement challenges such as in Parkinson's,

00:28:44.700 | which is a deficit or a literal destruction of the neurons

00:28:47.840 | that manufacture dopamine.

00:28:49.340 | There are a bunch of different areas of the brain

00:28:51.280 | that those dopamine neurons in the brainstem project to.

00:28:53.840 | But for right now, we're going to focus almost entirely

00:28:56.600 | on the dopamine projections from the brainstem

00:28:59.060 | to the prefrontal cortex,

00:29:00.700 | which is called the mesocortical circuitry.

00:29:04.100 | I'm not going to get into the origins

00:29:05.560 | or the meaning of the mesocortical

00:29:07.360 | versus other dopamine projection systems.

00:29:09.360 | I did that in a couple of episodes

00:29:11.880 | about ADHD and attention and dopamine in particular.

00:29:15.260 | And you can find those at hubermanlab.com.

00:29:17.340 | Just put dopamine and circuits into the search function

00:29:20.580 | and it will take you to those particular timestamps

00:29:22.380 | where I described that.

00:29:23.420 | But since we want to keep things fairly top contour

00:29:26.340 | at the level of neural circuitry here,

00:29:28.340 | just know that there are a bunch of neurons

00:29:29.680 | that manufacture dopamine back in the brainstem

00:29:31.540 | that send their axons, those little wires,

00:29:33.460 | up to the prefrontal cortex,

00:29:34.780 | and that the amount of dopamine released per unit time,

00:29:39.780 | so in a certain amount of time,

00:29:42.520 | strongly dictates the extent to which

00:29:45.680 | working memory capacity is going to be high, medium, or low.

00:29:49.480 | Now, I want to be very clear

00:29:50.500 | because I'm going to come back to this

00:29:52.200 | a little bit later again and again.

00:29:54.380 | It is the case that when dopamine levels are lower,

00:30:00.020 | that is either there are fewer neurons

00:30:01.820 | that have the potential to release dopamine

00:30:03.600 | in the frontal cortex, or for whatever reason,

00:30:05.760 | less is being released in the frontal cortex,

00:30:08.020 | that working memory performance tends to be lower

00:30:10.700 | as compared to conditions where dopamine release

00:30:13.220 | or the availability of dopamine is higher.

00:30:15.640 | However, it is not the case that more dopamine

00:30:18.440 | is always going to equate to improved working memory.

00:30:21.720 | This is so important that I'm going to say it again.

00:30:24.040 | It is not always the case that increasing

00:30:26.420 | the amount of dopamine transmission in the frontal cortex

00:30:29.220 | leads to improvements in working memory.

00:30:31.100 | There is a specific criteria that allows us to predict

00:30:34.500 | whether or not it will improve or maintain

00:30:38.200 | or actually degrade working memory performance.

00:30:41.020 | So before you head to the end of the podcast

00:30:42.880 | to try and figure out ways to increase dopamine

00:30:44.800 | to improve working memory, please keep that fact in mind.

00:30:48.400 | Don't just commit it to your working memory,

00:30:49.700 | commit it to your short and long-term memory

00:30:51.580 | because that's very important

00:30:52.840 | if your goal is to improve your working memory.

00:30:55.100 | With that said, I do want to describe

00:30:56.940 | just a little bit of research showing the relationship

00:30:59.880 | between having a low working memory span, as it's called,

00:31:04.340 | the ability to only remember a few letters or numbers

00:31:06.980 | or short batches of information

00:31:08.900 | as compared to a high working memory span,

00:31:11.380 | meaning longer strings of letters,

00:31:13.220 | longer strings of numbers,

00:31:14.580 | which of course in the real world translates

00:31:16.340 | to being able to carry out shorter

00:31:17.980 | versus longer action sequences as described earlier

00:31:21.460 | in the scenario where you're getting up in the morning

00:31:23.820 | and you're making coffee and you're heading out for a run,

00:31:25.700 | et cetera, et cetera.

00:31:26.540 | People do differ in terms of their working memory capacity

00:31:29.500 | and there's a classic study done by Kules

00:31:32.640 | and Desposito and colleagues, this was published in 2008,

00:31:36.040 | where they had a way to label the amount of dopamine

00:31:39.600 | that is available for release in the frontal cortex

00:31:41.900 | in human subjects.

00:31:43.880 | They did this by the injection of a specific dye.

00:31:46.580 | That dye gets taken up specifically by the neurons

00:31:49.020 | in the brain that manufactured dopamine.

00:31:50.720 | Then they were able to image the brains of those people

00:31:53.680 | while those people were wide awake

00:31:55.360 | using something called positron emission tomography.

00:31:57.940 | Again, the specific tool isn't necessarily important,

00:32:00.400 | but since some of you like to know,

00:32:02.200 | and what they found is that for people

00:32:04.540 | that had a high working memory span,

00:32:06.580 | that is could remember long strings of numbers or letters

00:32:10.000 | or other information,

00:32:11.560 | they tended to be the people that had more dopamine

00:32:13.880 | available for release in the frontal cortex,

00:32:17.120 | either because they had more of the dopamine neurons

00:32:19.440 | themselves or similar number of neurons,

00:32:21.740 | but those neurons had more dopamine to release, okay?

00:32:26.480 | And they also found the converse.

00:32:27.860 | Individuals that had a low working memory span and ability

00:32:31.400 | had less dopamine available for release.

00:32:33.940 | So that establishes a correlation, but it's not causal.

00:32:37.580 | A different study, which is also a classic,

00:32:39.940 | was carried out by Brzozki, Brown, Rosvold, and Goldman.

00:32:45.420 | And this is a really important study

00:32:47.340 | because in this study,

00:32:48.180 | they were able to introduce small amounts of dopamine

00:32:51.380 | directly into the cortex

00:32:53.560 | and evaluate working memory capacity.

00:32:56.320 | Now, anytime a working memory test is done,

00:32:58.640 | the same pattern always emerges.

00:33:00.500 | This is regardless of any dopamine

00:33:02.280 | being infused into the brain,

00:33:03.360 | which is people and animals for that matter

00:33:06.760 | are very good at remembering short spans of numbers,

00:33:09.040 | letters, or other types of information.

00:33:10.720 | So if you tell them one thing, like the letter A,

00:33:12.840 | and then you ask them, do you remember the letter?

00:33:15.260 | Almost everybody remembers that,

00:33:16.440 | but if you give them a string of 10 letters,

00:33:18.500 | they remember fewer of those 10 letters.

00:33:20.320 | That's sort of obvious,

00:33:21.740 | but it's an important point to emphasize nonetheless.

00:33:24.320 | And so there's a kind of a dropping off curve of performance

00:33:29.280 | as one progresses from fewer to greater number of items

00:33:32.540 | to be remembered.

00:33:33.840 | In this study, when dopamine was introduced

00:33:35.600 | to the frontal cortex,

00:33:37.460 | the number of things that individuals could remember

00:33:41.280 | simply increased.

00:33:42.960 | It was a very straightforward result.

00:33:44.960 | More dopamine introduced, allowed longer letter, number,

00:33:48.640 | and information strings to be remembered.

00:33:50.840 | And of course, forgotten,

00:33:51.720 | because that's what working memory involves,

00:33:53.280 | remembering and then discarding of information

00:33:55.780 | shortly thereafter.

00:33:57.240 | Now, the findings that I just described

00:33:59.800 | compliment what I said before,

00:34:01.200 | which is the naturally occurring experiment.

00:34:02.900 | Bring people into the lab,

00:34:03.740 | measure their working memory span,

00:34:05.180 | look at how much dopamine they make,

00:34:06.640 | higher dopamine, better working memory,

00:34:08.120 | lower dopamine, lower working memory.

00:34:10.000 | The experiment I just described

00:34:12.820 | was one in which dopamine is introduced,

00:34:14.920 | showing that dopamine is very likely the rate limiting

00:34:18.300 | or the capacity limiting,

00:34:19.920 | that's probably the better way to put it,

00:34:20.880 | the capacity limiting neuromodulator

00:34:23.800 | for improving working memory.

00:34:25.760 | That's a fancy nerd speak way of saying

00:34:27.920 | more dopamine allows for better working memory.

00:34:30.360 | But a critical feature of this experiment

00:34:32.280 | is that they did a number of experiments

00:34:34.860 | where they didn't introduce dopamine,

00:34:36.480 | but instead they introduced other neuromodulators

00:34:39.680 | to the prefrontal cortex,

00:34:40.920 | such as norepinephrine or serotonin.

00:34:44.820 | And the interesting finding is that

00:34:47.300 | the addition of norepinephrine or serotonin,

00:34:50.380 | which of course are other neuromodulators

00:34:52.420 | that can change the firing patterns of neurons

00:34:55.360 | in the prefrontal cortex, but elsewhere as well.

00:34:58.500 | It's just that in this case,

00:34:59.380 | they were added to the prefrontal cortex,

00:35:01.220 | had no effect on working memory.

00:35:03.840 | It neither improved nor degraded working memory

00:35:07.080 | when those neuromodulators were introduced.

00:35:09.320 | In other words, dopamine, and perhaps only dopamine,

00:35:12.100 | seems to be the dominant neuromodulator

00:35:14.860 | for regulating the degree,

00:35:18.140 | that is whether or not you have small, medium,

00:35:21.560 | or large amounts of working memory capacity

00:35:24.300 | in the prefrontal cortex.

00:35:25.820 | And of course, there have been a bunch of other experiments

00:35:28.020 | that are worth mentioning briefly in this context,

00:35:30.140 | such as taking people

00:35:31.480 | that have a high working memory capacity

00:35:33.380 | and then indeed have their brains imaged,

00:35:34.900 | and one sees that they have

00:35:36.220 | high levels of baseline dopamine,

00:35:38.240 | especially the dopamine projecting

00:35:39.580 | to the prefrontal cortex.

00:35:41.280 | And then they're given a drug that depletes dopamine

00:35:43.700 | within the prefrontal cortex and their performance drops.

00:35:46.440 | And so what's so nice about the literature

00:35:47.900 | around working memory is that

00:35:49.500 | while I'm not covering all of that literature exhaustively,

00:35:53.100 | it all tends to jive.

00:35:54.220 | It all points in a direction

00:35:55.420 | whereby the levels of dopamine being released

00:35:58.140 | in the prefrontal cortex during working memory tasks

00:36:02.040 | correlates very strongly

00:36:03.620 | with capacity to perform working memory tasks.

00:36:07.100 | Lower dopamine, lower working memory span, as it's called.

00:36:10.660 | Higher dopamine, higher working memory span.

00:36:13.860 | Okay, so next we're going to do another working memory task

00:36:16.700 | different than the one we did earlier.

00:36:18.900 | And we're going to do that with a specific purpose in mind,

00:36:21.260 | which is for you to be able to determine

00:36:23.660 | what your working memory capacity is,

00:36:26.760 | and by extension, your baseline levels of dopamine,

00:36:30.140 | or at least the levels of dopamine

00:36:31.540 | that are likely being released into your prefrontal cortex

00:36:34.180 | while you do these working memory tasks.

00:36:36.180 | In other words, we're going to try and figure out

00:36:38.020 | whether or not you are of the low, medium,

00:36:40.280 | or high working memory capacity.

00:36:42.100 | And of course, we're doing that in part

00:36:44.400 | to try and establish whether or not

00:36:46.160 | you likely have low, medium, or high amounts of dopamine

00:36:49.960 | available for release in the prefrontal cortex.

00:36:52.760 | Now, of course, we're not putting you

00:36:53.960 | into a positron emission tomography scanning device.

00:36:57.120 | We aren't able to do that for obvious reasons,

00:36:59.760 | but keep in mind that what we were about to do

00:37:01.540 | is very similar, and in some cases,

00:37:03.400 | identical to laboratory studies

00:37:05.500 | where the researchers were trying to determine

00:37:07.920 | what people's levels of dopamine

00:37:10.120 | within these particular neural networks

00:37:11.660 | we've been discussing, the mesocortical pathway,

00:37:13.860 | are likely to be.

00:37:15.240 | In other words, performance on the working memory task

00:37:17.160 | that we are about to do is a decent indication

00:37:20.240 | of what the dopamine levels that are available

00:37:22.920 | for release in your prefrontal cortex perhaps might be.

00:37:26.740 | Now, I say perhaps might be

00:37:28.100 | because I don't want to cause any unnecessary alarm

00:37:30.760 | if, for instance, you fall into

00:37:32.040 | the low working memory span group.

00:37:33.620 | In fact, if you fall into the low working memory span group,

00:37:36.580 | there are actually some terrific tools that you can use

00:37:38.820 | to improve dopamine transmission in those pathways

00:37:41.860 | and improve your working memory.

00:37:43.400 | I also don't want people to get the impression

00:37:45.060 | that somehow performance on this working memory task

00:37:47.660 | is reflective of some larger dopamine issue in the brain,

00:37:51.880 | and certainly it is not, I repeat,

00:37:53.720 | it is not diagnostic of Parkinson's

00:37:55.800 | or any kind of neurodegenerative condition.

00:37:57.720 | Although I will say that deficits in working memory

00:38:00.320 | are common in patients with Parkinson's for obvious reasons.

00:38:03.360 | Those patients have deficits in dopamine neurons,

00:38:07.080 | not only production, but the number of dopamine neurons,

00:38:10.120 | it's one of the hallmark features of Parkinson's,

00:38:12.320 | but also in things like traumatic brain injury, et cetera.

00:38:14.840 | But the working memory tasks that you're about to take

00:38:16.960 | when given to a general population

00:38:18.680 | or a group of undergraduates or so-called normals

00:38:22.000 | or typical control subjects, which all of you are, okay?

00:38:25.200 | So unless you're dealing with a traumatic brain injury

00:38:27.660 | or you know you have Parkinson's,

00:38:30.020 | we know that the data that you're going to get back right now

00:38:32.520 | is very similar to the data that people get back

00:38:34.880 | when they do these sorts of studies in a laboratory.

00:38:37.740 | That is, it's typical for some people

00:38:39.780 | to have a short working memory span,

00:38:41.320 | some people to have a medium working memory span,

00:38:43.040 | and some people to have a high working memory span.

00:38:45.200 | And today we're actually just going to divide into two bins,

00:38:47.940 | short working memory span and high working memory span.

00:38:50.600 | And we can have some degree of confidence

00:38:52.700 | that correlates with the amount of dopamine available

00:38:55.520 | for release in the frontal cortex.

00:38:57.800 | But, and this is a very important point,

00:39:00.320 | as we progress along this discussion of working memory,

00:39:02.640 | the neural circuits, dopamine, et cetera,

00:39:04.620 | I want to make clear something that I said earlier,

00:39:06.380 | which is that it is not the case

00:39:08.600 | that increasing the amount of dopamine that's available

00:39:11.640 | always increases working memory span.

00:39:14.240 | In fact, there's a common circumstance whereby people

00:39:17.080 | with a relatively high degree of working memory capacity

00:39:20.240 | increase their dopamine levels even further

00:39:23.040 | using pharmacology or other methods that we'll discuss,

00:39:25.480 | and their performance actually can degrade, okay?

00:39:29.000 | So if any of that is confusing now,

00:39:30.720 | we'll make it all very simple going forward

00:39:32.960 | so that if you decide to implement any of the protocols

00:39:35.320 | discussed in this episode,

00:39:36.740 | that you are aware of what you can expect

00:39:39.440 | and whether or not you were in the category of people

00:39:41.200 | that should or perhaps should not

00:39:43.700 | incorporate those protocols.

00:39:45.240 | Okay, let's test your working memory again.

00:39:47.560 | This time, the working memory task is going to be

00:39:49.540 | a little bit different than the one you did previously.

00:39:52.240 | This working memory task involves me reading

00:39:54.540 | six different sentences to you,

00:39:56.560 | and your job is to pay attention to these six sentences

00:39:59.720 | because you're going to be asked some information

00:40:01.680 | about these sentences in a few moments.

00:40:04.280 | The first sentence is real estate costs are going up.

00:40:10.240 | The second sentence is the Atlantic Ocean is warm in summer.

00:40:15.240 | The third sentence is there's a lot of interest now

00:40:20.280 | in electric cars.

00:40:21.580 | The fourth sentence is some reptiles eat only once a year.

00:40:27.300 | The fifth sentence is kids nowadays look at screens

00:40:32.400 | more than 60% of their waking life.

00:40:36.600 | And the sixth and final sentence is football can mean

00:40:40.640 | different sports depending on the country.

00:40:43.120 | Okay, so I read you six sentences.

00:40:47.060 | They were moderately long, I confess.

00:40:49.980 | Your job for the working memory task is now to recall

00:40:53.160 | as many of the final words of each of those sentences

00:40:56.760 | as you can.

00:40:58.080 | I'll give you a few moments to do that.

00:41:00.440 | Now, before I tell you what the final word

00:41:02.160 | of each of those sentences actually is,

00:41:04.840 | I want to remind everybody that working memory capacity

00:41:08.640 | follows a normal distribution.

00:41:10.460 | So some of you will be able to remember the final word

00:41:13.280 | of perhaps five or even six of those sentences.

00:41:16.200 | Although I must say that is exceedingly rare.

00:41:20.040 | Some of you are going to be able to remember three to four

00:41:23.520 | of the final words of those sentences.

00:41:25.560 | And that's more typical.

00:41:26.740 | That actually represents the average or the mean

00:41:29.440 | as we call it.

00:41:30.840 | And then fewer people, although still many of you

00:41:33.160 | will only be able to remember one or two

00:41:35.640 | of the final words of those sentences.

00:41:37.840 | Okay, so now I'm assuming that most of you

00:41:41.300 | have tried to call to memory the final word

00:41:44.120 | of as many of those six sentences as you can.

00:41:46.960 | And maybe you've written them down

00:41:48.180 | or you've typed them into your phone

00:41:49.780 | or you have some record of what you recall

00:41:52.160 | those six final words of those sentences are.

00:41:55.200 | Now I'm going to tell you the actual final word

00:41:58.220 | of each of those sentences.

00:41:59.560 | The final word of the first sentence was up

00:42:02.300 | because as you may recall the sentence was

00:42:04.540 | real estate costs are going up.

00:42:07.440 | The final word of the second sentence was summer

00:42:10.880 | because the sentence was the Atlantic ocean

00:42:13.360 | is warm in summer.

00:42:15.580 | The final word of the third sentence was cars

00:42:18.720 | because the sentence was there is a lot of interest

00:42:21.560 | in electric cars.

00:42:23.540 | The final word of the fourth sentence was year

00:42:26.160 | because the sentence was some reptiles eat only once a year.

00:42:30.380 | The final word of the fifth sentence was life

00:42:34.040 | because the sentence was kids nowadays look at screens

00:42:37.040 | more than 60% of their waking life.

00:42:40.040 | And the final word of the sixth sentence was country

00:42:43.200 | because the sentence was football can mean different sports

00:42:46.720 | depending on the country.

00:42:48.420 | Okay, so be honest with yourself and tell yourself

00:42:51.400 | and you don't have to tell anyone else if you don't want to

00:42:54.000 | how many of the final words of those six sentences

00:42:56.680 | you could remember correctly.

00:42:58.360 | It's important that you remember them correctly.

00:43:00.460 | Again, the number of words that you can recall

00:43:02.420 | that is your working memory span is going to vary

00:43:04.920 | from person to person.

00:43:06.200 | But we can take the normal distribution of those scores

00:43:08.820 | and sort of draw a line down the middle

00:43:10.460 | and say that if you could remember three to six

00:43:13.300 | of the final words of those sentences correctly

00:43:16.160 | you're going to fall into the high working memory

00:43:18.900 | span group.

00:43:20.240 | Whereas if you could only remember one or two

00:43:23.160 | or maybe zero of the final words of those six sentences

00:43:26.660 | then you're going to be in the low working memory

00:43:29.000 | span group.

00:43:29.840 | Again, I don't want to alarm anybody.

00:43:31.420 | This doesn't mean that you have any global memory deficits

00:43:34.300 | or dopamine deficits, but it is important

00:43:36.520 | especially if you plan to apply any of the protocols

00:43:39.460 | to improve working memory that you faithfully

00:43:42.300 | that is you accurately report your working memory

00:43:45.100 | performance at least to yourself.

00:43:46.840 | Now, as you recall, whether or not you have low or high

00:43:49.480 | and here we are just binning into low and high

00:43:51.320 | there's no medium.

00:43:52.160 | We've divided right at that line.

00:43:53.760 | We're saying, if you can remember three to six

00:43:55.400 | we're calling that high working memory span

00:43:56.920 | at least for this discussion.

00:43:58.120 | And if you can remember fewer than three, even down to zero

00:44:01.600 | of the final words of those sentences

00:44:03.200 | that's low working memory span.

00:44:04.720 | We're dividing it in two.

00:44:06.280 | We divided you into two groups.

00:44:07.680 | And we do know when this has been done

00:44:10.280 | in large numbers of human subjects

00:44:13.200 | and some, in some cases, all of those subjects

00:44:16.400 | have their brains imaged for the amount of dopamine

00:44:19.360 | available for release in their prefrontal cortex

00:44:22.280 | that short working memory span correlates

00:44:25.720 | with lower amounts of dopamine.

00:44:28.080 | Whereas higher working memory span

00:44:30.280 | or longer working memory span

00:44:31.460 | whatever you want to call it correlates

00:44:32.920 | with more dopamine available for release

00:44:36.060 | in the prefrontal cortex.

00:44:37.920 | Now, this is where things get really interesting

00:44:39.880 | and frankly, really exciting for everybody

00:44:43.120 | especially the folks in the low working memory span group

00:44:48.000 | work from Martes Bizito and colleagues at UC Berkeley

00:44:52.000 | as well as other laboratories

00:44:53.520 | have explored the consequences of increasing dopamine levels

00:44:57.560 | in the brain of typical populations of individuals.

00:45:01.200 | So these are not people with Parkinson's or TBI

00:45:03.840 | but undergraduate students

00:45:05.400 | which we do realize is not completely representative

00:45:07.960 | of the quote unquote normal population

00:45:10.360 | outside the university, but also people from the community.

00:45:13.400 | So people who are not university students and so on.

00:45:16.320 | And the ways that they've increased dopamine

00:45:18.480 | in those individuals had tended to rely on pharmacology.

00:45:21.920 | So these are prescription drugs

00:45:23.920 | that most often have been developed

00:45:25.680 | for the treatment of Parkinson's

00:45:26.820 | in order to increase dopamine levels

00:45:28.480 | but for some other purposes as well.

00:45:30.320 | Drugs like bromocriptine

00:45:32.000 | which we know are so-called dopamine agonists.

00:45:35.320 | And agonists is a drug that has the consequence

00:45:37.800 | of increasing the amount of a given neurochemical

00:45:40.560 | in this case, dopamine.

00:45:41.720 | Whereas an antagonist is a drug that either blocks

00:45:45.000 | or prevents or somehow lowers the total available amount

00:45:48.660 | of a certain chemical

00:45:49.800 | such as dopamine or serotonin, et cetera.

00:45:52.040 | So bromocriptine is a drug that increases dopamine.

00:45:56.040 | So when human subjects came into a laboratory

00:45:58.700 | didn't take any drug, no bromocriptine yet.

00:46:01.200 | And of course they were being evaluated

00:46:03.240 | for whether or not they were taking any meds for ADHD

00:46:05.520 | their caffeine consumption, et cetera.

00:46:07.180 | There were certain rule ins and rule outs for that study

00:46:09.960 | but certainly people that were taking any kind

00:46:12.280 | of prescription medication for ADHD

00:46:14.080 | were not included in the study

00:46:16.440 | or were eliminated from the study

00:46:17.760 | because those drugs can indeed increase dopamine

00:46:21.400 | as well as some other neuromodulators

00:46:23.080 | such as norepinephrine and epinephrine.

00:46:25.160 | I covered all that in the two ADHD episodes that I did

00:46:27.780 | which again, you can find it human lab.com

00:46:29.520 | just go to the search function, put in ADHD.

00:46:31.720 | In any event, in these studies,

00:46:33.360 | they took people that had not taken any drugs

00:46:35.480 | to increase dopamine, had their working memory measured

00:46:39.960 | very similarly to the way

00:46:41.360 | that you measured your working memory a few minutes ago

00:46:43.520 | with the six sentence business that we did.

00:46:47.840 | And then they took bromocriptine

00:46:50.160 | and they either took a low, a moderate

00:46:52.280 | or high dose of bromocriptine.

00:46:54.960 | And 90 minutes later, they took a working memory task.

00:46:59.500 | And what was observed was very interesting.

00:47:02.240 | You can probably predict what it is

00:47:03.480 | based on everything I've said up until now.

00:47:05.560 | Individuals that initially had low baseline levels

00:47:08.320 | of dopamine and therefore shorter working memory span.

00:47:11.880 | So they only remembered zero to about three

00:47:15.000 | of the final words of that six sentence series.

00:47:18.320 | Their performance significantly improved.

00:47:22.280 | They were able to remember four and in some cases

00:47:24.720 | up to six of the final words of those sentences.

00:47:27.920 | Now that is in complete agreement

00:47:30.600 | with everything we set up until now.

00:47:32.920 | Simply says that dopamine is important for working memory.

00:47:35.140 | If you start off with lower dopamine stores

00:47:37.840 | or dopamine availability for release in the prefrontal cortex

00:47:40.380 | lower working memory performance,

00:47:42.040 | increased dopamine through ingestion of bromocriptine,

00:47:46.080 | which is this dopamine agonist.

00:47:48.620 | All of the circuit changes that we want

00:47:50.740 | and would expect to improve working memory occur

00:47:53.100 | and indeed working memory improves.

00:47:54.920 | Very straightforward.

00:47:56.360 | That's interesting.

00:47:57.200 | But the even more interesting part of the study

00:47:59.020 | is that individuals that already had

00:48:01.720 | high working memory span, when they took bromocriptine

00:48:05.160 | at a low or a moderate dose,

00:48:07.800 | their working memory did not increase further.

00:48:10.180 | Now, if somebody was already getting six of the final words

00:48:13.460 | of those six sentences, well then of course

00:48:14.980 | they couldn't improve their performance anymore.

00:48:16.780 | But many of the people in the high working memory span group

00:48:20.060 | of course only remembered four, in some cases three,

00:48:22.560 | typically it would be four, five or six

00:48:24.160 | of the final words of those sentences.

00:48:25.860 | When they took bromocriptine at low or moderate doses

00:48:29.860 | their working memory did not improve significantly.

00:48:33.080 | There was either no change or a very modest change.

00:48:36.280 | And here's where things get really interesting.

00:48:38.180 | When individuals who already had a high working memory span

00:48:41.060 | took the highest dose of bromocriptine.

00:48:43.140 | And by the way, studies verified that the amount

00:48:45.540 | of dopamine available indeed increased.

00:48:47.700 | So that was important to do and they did that.

00:48:50.260 | Well, their working memory performance actually decreased

00:48:54.480 | such that now they had a short or a low working memory span.

00:48:58.400 | So what this tells us is that the relationship

00:49:00.980 | between dopamine and working memory follows

00:49:03.260 | an inverted U-shape function.

00:49:04.820 | So imagine a U and then just flip it over,

00:49:07.020 | meaning if you have low dopamine availability

00:49:09.740 | in the prefrontal cortex, working memory span is short.

00:49:13.140 | As you increase that amount, working memory becomes greater.

00:49:16.940 | But if you increase the amount of dopamine

00:49:18.700 | in the prefrontal cortex too much,

00:49:20.800 | working memory span actually drops significantly

00:49:24.000 | below the baseline that you started with.

00:49:26.740 | Now, this is important for a number of reasons,

00:49:29.320 | not the least of which is the known relationship

00:49:31.900 | between working memory and attention.

00:49:34.940 | Now, this is very important to understand

00:49:36.380 | in the context of ADHD,

00:49:38.060 | but also for people who don't have ADHD

00:49:40.100 | and are struggling to maintain focus and attention

00:49:43.280 | and carry out working memory tasks

00:49:45.060 | throughout their normal everyday life,

00:49:46.480 | not in the laboratory, but just moving through life.

00:49:49.260 | Because these days we hear a lot, a lot, a lot

00:49:51.860 | about people struggling with focus and attention.

00:49:54.320 | Perhaps, we don't know, perhaps in part

00:49:56.700 | due to overuse of smartphone, social media, et cetera,

00:49:59.900 | although there's not yet a direct causal relationship

00:50:02.420 | that's been established, the data that are emerging

00:50:05.100 | suggests that indeed overuse of those things

00:50:07.780 | can cause problems.

00:50:08.740 | But regardless of the source,

00:50:11.260 | there does seem to be more ADHD,

00:50:12.980 | both in kids and in adults and subclinical challenges

00:50:17.580 | in focus and attention.

00:50:18.860 | And here's where things get really interesting

00:50:20.940 | as it relates to the neural circuitry.

00:50:22.660 | Work from Desposito and colleagues

00:50:24.620 | and other laboratories as well

00:50:26.220 | have shown using the similar paradigm

00:50:28.440 | that I described before,

00:50:29.500 | giving people drugs to increase their baseline levels

00:50:31.600 | of dopamine above their initial starting point

00:50:34.520 | of short or long-term memory span capacity.

00:50:37.620 | And then had people can perform different types

00:50:40.660 | of working memory tasks that tap into two different aspects

00:50:43.460 | of attention and working memory.

00:50:44.960 | Up until now, we've been talking about working memory,

00:50:46.880 | it's kind of just one thing.

00:50:48.280 | But working memory actually involves two things

00:50:50.860 | or at least two things.

00:50:52.100 | The first is that in order to carry out a working memory task

00:50:55.340 | and to attend to something, to really focus,

00:50:57.780 | we need the ability to rule out distractors.

00:51:00.680 | We need to be able to not pay attention

00:51:02.660 | to things that would otherwise distract us.

00:51:05.460 | In addition to that, we need to be able to switch

00:51:08.320 | from one context to the next, right?

00:51:10.440 | Making the cup of coffee to putting on one shoes

00:51:12.440 | and heading out the door.

00:51:13.280 | And in some cases, layering different contexts together,

00:51:15.820 | talking on the phone while tying one shoes

00:51:17.720 | and so on and so forth.

00:51:19.620 | What this work shows us is that the ability to task switch

00:51:24.040 | and context switch that is to shift around

00:51:26.900 | what it is that we're paying attention to

00:51:28.300 | and interleave different things

00:51:29.440 | that we're paying attention to,

00:51:30.560 | something that's so critical

00:51:31.880 | for moving through our daily lives,

00:51:33.500 | is largely dependent on the dopamine projections

00:51:36.460 | to a structure in the brain called the basal ganglia,

00:51:39.160 | which is a structure I've talked about before

00:51:41.120 | on this podcast, but if you didn't hear about it,

00:51:42.920 | we can just broadly define this structure

00:51:44.940 | as being involved in movement generation

00:51:47.140 | and stopping movement generation.

00:51:49.180 | In fact, it's often discussed as the neural circuitry

00:51:52.020 | that generates go, as in do commands,

00:51:55.160 | and no go, don't do commands.

00:51:57.380 | So the basal ganglia are involved in task switching

00:52:00.180 | and they're involved in task switching

00:52:02.120 | in part by sending certain commands to go,

00:52:05.020 | do certain things and no go, to not do other things.

00:52:07.740 | Okay, task switching, stop doing this, start doing that,

00:52:10.920 | start doing that, stop doing this.

00:52:12.780 | And sometimes to varying extents, right?

00:52:14.680 | I mean, we could take any real world scenario

00:52:16.680 | of tying one shoes while talking on the phone

00:52:18.480 | and we could micro analyze it in the context of this,

00:52:20.620 | but I think if you think about it just a little bit,

00:52:23.480 | you understand that in order to perform daily tasks,

00:52:26.000 | we need to be able to task switch

00:52:27.280 | and that's not always a start one task end,

00:52:29.700 | start a new task end.

00:52:30.920 | Oftentimes we're interleaving different tasks

00:52:32.680 | to varying degrees.

00:52:33.840 | Now, the other aspect of working memory and attention

00:52:36.360 | is to eliminate distractions, to not pay attention

00:52:39.360 | to the irrelevant stuff in one's environment

00:52:41.800 | or even the irrelevant stuff on your own body.

00:52:44.000 | Like you can't get distracted by, you know,

00:52:45.960 | a button that, you know, might be only partially buttoned

00:52:48.400 | or maybe some little something on your sleeve

00:52:51.040 | if you're trying to do something else at that moment.

00:52:53.040 | Okay, and people with ADHD

00:52:54.360 | and people who have subclinical challenges and focus

00:52:56.940 | really have a hard time with this, right?

00:52:59.040 | You know, the sort of stereotype is, you know, the,

00:53:01.660 | oh look, a squirrel, that whole thing.

00:53:03.320 | But really this typically exists as a more subtle

00:53:06.080 | and challenging phenomenon for people

00:53:07.900 | where they either can't remember what they were doing

00:53:10.720 | or they're simply drawn down different trajectories,

00:53:13.680 | different thought trajectories or action trajectories

00:53:16.180 | and then they have a hard time making it back

00:53:18.560 | to the original thing that they were trying to focus on.

00:53:22.160 | And we know based on these studies of dopamine

00:53:24.060 | and neuroimaging that eliminating distractors

00:53:27.200 | is largely the consequence of dopamine neurons

00:53:29.440 | projecting to the prefrontal cortex.

00:53:32.000 | Okay, now, why am I telling you

00:53:33.360 | all this neural circuitry stuff?

00:53:34.740 | Well, yes, there are a bunch of studies

00:53:37.040 | showing that if you selectively activate the neurons

00:53:40.160 | that send dopamine into the basal ganglia,

00:53:42.520 | you improve task switching ability

00:53:43.880 | without an improved ability to rule out distractors.

00:53:47.040 | Or if you selectively increase the amount of dopamine

00:53:49.520 | from neurons projecting the prefrontal cortex,

00:53:51.440 | that you're able to selectively improve

00:53:53.760 | the elimination of distractors without improving

00:53:58.280 | task switching ability.

00:53:59.840 | For practical purposes, in this discussion,

00:54:02.200 | we want to pay careful attention

00:54:03.880 | to whether or not the data tell us

00:54:05.640 | that those particular protocols, those particular approaches

00:54:09.400 | are globally increasing dopamine,

00:54:11.560 | that is increasing the activity of dopamine neurons

00:54:14.280 | projecting to the basal ganglia and the prefrontal cortex

00:54:17.040 | or selectively to the basal ganglia

00:54:20.180 | or selectively to the prefrontal cortex.

00:54:22.080 | And what I can tell you now is that fortunately,

00:54:24.320 | there are several protocols, some of which are behavioral,

00:54:26.480 | some of which involve specific over-the-counter supplements

00:54:29.800 | and some of which involve prescription pharmacology

00:54:33.360 | that can tap into each of these systems independently

00:54:36.240 | as well as globally increased dopamine

00:54:38.880 | to improve focus and working memory at large.

00:54:42.060 | I'd like to take a quick break

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00:54:55.400 | And that correct ratio of electrolytes

00:54:57.160 | is extremely important because every cell in your body,

00:55:00.320 | but especially your nerve cells, your neurons,

00:55:02.600 | relies on electrolytes in order to function properly.

00:55:05.680 | So when you're well hydrated

00:55:07.180 | and you have the appropriate amount of electrolytes

00:55:09.060 | in your system, your mental functioning

00:55:10.900 | and your physical functioning is improved.

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00:55:14.840 | in about 16 to 32 ounces of water

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00:55:20.760 | And if I've sweat a lot during that exercise,

00:55:22.840 | I often will drink a third Element packet dissolved

00:55:25.320 | in about 32 ounces of water after I exercise.

00:55:28.280 | Element comes in a variety of different flavors,

00:55:30.460 | all of which I find really tasty.

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00:55:43.340 | I tend to do that in the winter months

00:55:44.780 | because of course you don't just need hydration on hot days

00:55:48.380 | and in the summer and spring months,

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00:56:01.580 | Again, that's drinkelement.com/huberman.

00:56:05.180 | Okay, so let's talk about protocols

00:56:06.900 | to improve working memory,

00:56:08.500 | specifically by way of changing levels

00:56:11.500 | of dopamine in the brain.

00:56:13.100 | Now I've discussed dopamine many times before

00:56:15.220 | in this podcast.

00:56:16.060 | In fact, we have entire episodes devoted

00:56:18.100 | to optimizing and regulating dopamine.

00:56:20.460 | And of course, dopamine comes up within the context

00:56:22.740 | of the ADHD episodes and other episodes as well.

00:56:26.060 | And again, if you have specific questions about dopamine

00:56:28.800 | or any other topic for that matter,

00:56:31.140 | if you go to hubermanlab.com,

00:56:32.740 | that website has been engineered

00:56:33.940 | so that you can put one word such as dopamine,

00:56:36.260 | but also multiple keywords.

00:56:37.780 | So perhaps dopamine exercise or dopamine cold plunge,

00:56:41.500 | et cetera, into the search function.

00:56:43.000 | And it will take you to the specific timestamps

00:56:45.600 | of multiple episodes where those topics were discussed,

00:56:49.300 | as well as newsletters where some of that information

00:56:51.560 | has been condensed into short PDF form, et cetera.

00:56:54.160 | So we certainly are going to cover some material

00:56:55.920 | about improving dopamine

00:56:57.040 | for sake of improving working memory now.

00:56:59.140 | But if you're generally interested in the science

00:57:00.880 | and pharmacology of dopamine

00:57:02.280 | and protocols to modulate dopamine levels,

00:57:04.600 | all of that can be found at hubermanlab.com.

00:57:07.220 | Okay, so let's say you have a short working memory span

00:57:09.560 | or a moderate working memory span,

00:57:11.000 | and you want to experiment with increasing levels

00:57:13.740 | of dopamine for sake of improving working memory.

00:57:16.380 | Now, there are a lot of different ways

00:57:17.980 | that one could imagine doing that.

00:57:19.180 | Let's start with the behavioral tools

00:57:20.980 | known to increase dopamine stores.

00:57:23.120 | That is shown in peer reviewed studies

00:57:24.920 | to increase dopamine stores within certain circuits

00:57:27.980 | of the brain that are relevant

00:57:29.100 | for working memory performance.

00:57:30.660 | And the protocol that immediately leaps to mind

00:57:33.780 | is the use of certain non-sleep deep rest protocols.

00:57:38.140 | Now, non-sleep deep rest or NSDR

00:57:40.800 | is actually a term that I coined

00:57:42.300 | because there is a practice that's been established

00:57:45.340 | for many hundreds of years called yoga nidra,

00:57:47.460 | which actually means yoga sleep,

00:57:49.220 | whereby individuals, potentially you,

00:57:51.900 | if you decide to do them, lie down, listen to a script,

00:57:55.440 | that is listen to an audio script,

00:57:56.820 | which generally instructs you to do long exhale breathing,

00:57:59.620 | to deliberately relax your musculature of your face

00:58:03.100 | and of your body.

00:58:04.260 | And yoga nidra typically also involves

00:58:06.260 | doing certain intentions.

00:58:07.860 | And the instruction always given

00:58:09.080 | at the beginning of yoga nidra

00:58:10.340 | is that you should try to not fall asleep.

00:58:12.900 | Now, some people sometimes fall asleep,

00:58:14.780 | some people don't fall asleep,

00:58:16.020 | but the idea, and there are data support,

00:58:18.460 | that yoga nidra puts people

00:58:20.220 | into kind of a shallow pattern of sleep,

00:58:23.780 | certainly not deep sleep and not rapid eye movement sleep,

00:58:26.460 | but it's a very interesting and unusual brain state

00:58:29.080 | for which we're starting to understand more

00:58:30.900 | and actually have some plans in the not too distant future

00:58:34.820 | to collaborate with Matthew Walker,

00:58:36.860 | the author of the book, "Why We Sleep,"

00:58:38.180 | and some other colleagues

00:58:39.140 | to try and figure out what exact patterns of neural activity

00:58:42.280 | are taking place in the brain and rest of nervous system

00:58:44.700 | during yoga nidra and this similar protocol,

00:58:47.960 | which I call non-sleep deep rest.

00:58:49.580 | The difference between yoga nidra and non-sleep deep rest

00:58:52.120 | is that non-sleep deep rest

00:58:54.400 | doesn't include any of the intentions

00:58:56.380 | and removes a lot of the kind of opaque

00:58:58.380 | or sometimes called mystical language from the protocol.

00:59:01.100 | Now, a great thing is that yoga nidra scripts or protocols,

00:59:04.560 | as well as NSDR scripts or protocols are available,

00:59:08.040 | totally zero cost.

00:59:09.100 | You can find them certainly on apps like Waking Up,

00:59:11.560 | but also on YouTube.

00:59:12.640 | For instance, if you put NSDR and my last name,

00:59:16.000 | there's a 10 minute NSDR script there.

00:59:17.760 | There are a lot of yoga nidra scripts.

00:59:19.680 | If you prefer a female voice,

00:59:21.700 | there are a lot of different,

00:59:22.540 | excellent female voices out there.

00:59:24.160 | One in particular that I like very much is Kelly Boyce,

00:59:27.200 | first name Kelly, last name B-O-Y-S.

00:59:29.700 | She has both yoga nidra and NSDR scripts

00:59:32.120 | of various durations of anywhere from eight minutes

00:59:34.380 | all the way out to, I believe, 45 minutes.

00:59:37.260 | Why am I telling you all this?

00:59:38.380 | Well, there've been several studies, but in particular one,

00:59:41.380 | and I do realize we're talking about only one study,

00:59:43.220 | but the results are really intriguing

00:59:45.780 | as it relates to what we're talking about today.

00:59:48.280 | In this study,

00:59:49.120 | they had individuals do effectively an NSDR protocol.

00:59:52.500 | They call it yoga nidra.

00:59:53.620 | And the protocol they used

00:59:55.640 | was essentially a yoga nidra script.

00:59:57.120 | They had people lie down and listen to a yoga nidra script

01:00:00.020 | and to perform yoga nidra.

01:00:01.220 | And they evaluated the amount of dopamine available

01:00:05.740 | within the brain both prior to

01:00:07.540 | and after performing this yoga nidra script.

01:00:10.240 | And what they discovered was that

01:00:12.140 | after performing a yoga nidra protocol,

01:00:16.360 | the baseline levels of dopamine,

01:00:18.420 | that is the amount of dopamine available

01:00:21.100 | in the basal ganglia and a few other structures

01:00:23.820 | of the human brain, of course, these are humans,

01:00:26.400 | was increased by as much as 60%

01:00:30.840 | as compared to individuals that did a different protocol,

01:00:34.560 | not yoga nidra, not NSDR.

01:00:36.800 | Now, did that study evaluate lots of different durations

01:00:39.900 | of yoga nidra, AKA NSDR?

01:00:42.540 | No.

01:00:43.380 | They looked at fairly long hour plus yoga nidra sessions.

01:00:46.940 | However, there's some other data

01:00:48.700 | that have explored yoga nidra, AKA NSDR,

01:00:52.900 | in the context of cognitive performance

01:00:55.560 | and a few other circumstances,

01:00:57.440 | all of which point to the fact that cognitive performance

01:00:59.680 | and in particular cognitive performance tasks

01:01:01.940 | that have a working memory element to them.

01:01:04.740 | So they weren't the exact working memory tasks

01:01:06.500 | that you did earlier,

01:01:07.500 | but they have a working memory element to them.

01:01:09.580 | That is, subjects had to keep certain small batches

01:01:11.640 | of information in mind and then discard that information

01:01:14.400 | in order to be able to perform the task well.

01:01:17.120 | All of those show significant improvements

01:01:19.440 | in task performance.

01:01:20.800 | So while something like NSDR or yoga nidra

01:01:23.900 | might sound kind of mystical or kind of wishy-washy,

01:01:27.100 | or I guess as the kids say, weak sauce to some of you,

01:01:30.700 | it is anything but weak sauce.

01:01:32.880 | It is really powerful stuff.

01:01:35.520 | And it's powerful stuff as it relates

01:01:37.260 | to the very neurochemicals and neural circuits

01:01:39.720 | that are involved in working memory.

01:01:41.420 | So if I were to take a step back and just say,

01:01:43.460 | okay, what are some zero cost, very low,

01:01:46.580 | if any risk protocols that one could perform

01:01:50.260 | in order to improve dopamine levels

01:01:52.160 | without having to ingest anything, take anything,

01:01:54.760 | really do much of anything at all, except lie there,

01:01:57.180 | do this progressive muscle relaxation.

01:01:59.260 | There are a few other things involved in NSDR as well,

01:02:01.600 | which you'll learn if you decide to try them,

01:02:03.180 | and improve or increase the levels of dopamine availability

01:02:07.420 | in the brain significantly, well, then NSDR and yoga nidra

01:02:11.380 | really are the first line tools if one wants to do that.

01:02:14.620 | I think it's reasonable to say that.

01:02:15.980 | And as I mentioned before, there's no reason to think

01:02:18.100 | that there's any risk of doing NSDR yoga nidra,

01:02:20.940 | provide that you're lying down in a safe place

01:02:22.500 | as opposed to like in the middle of the road or something.

01:02:24.660 | But assuming you do it in a safe location,

01:02:26.980 | I would encourage you to try it for,

01:02:29.340 | really for 20 to 30 minutes when you first explore it,

01:02:33.240 | perhaps you do longer.

01:02:34.340 | Although I personally have a hard time

01:02:36.880 | doing long yoga nidra scripts regularly,

01:02:39.180 | a full hour is a big commitment.

01:02:40.940 | I don't generally have that much time.

01:02:42.780 | I often will do a 10 minute NSDR.

01:02:45.080 | Have there been brain imaging experiments done

01:02:47.200 | for each and all of these yoga nidra scripts

01:02:49.100 | to determine the amount,

01:02:50.780 | or if there's any dopamine increase within the brain?

01:02:53.540 | No, but I think that we can safely extrapolate

01:02:56.260 | from that wonderful study out of Scandinavia

01:02:58.520 | that showed that when human subjects

01:03:00.180 | do this yoga nidra protocol,

01:03:02.260 | that there's a significant increase

01:03:03.940 | in baseline dopamine levels within key neural structures

01:03:06.700 | that relate to working memory.

01:03:08.420 | Now, many of you perhaps heard that getting in a cold plunge

01:03:11.820 | or taking a cold shower, or provided you can do it safely,

01:03:14.660 | getting into a cold ocean or a cold lake can significantly,

01:03:18.380 | maybe even double or even triple

01:03:20.700 | your circulating dopamine levels.

01:03:22.680 | And indeed that is true.

01:03:24.480 | It has been shown that when people get into cold water,

01:03:28.080 | typically up to their neck,

01:03:29.800 | and that cold water, by the way,

01:03:31.780 | can range in temperature anywhere from low 40s to low 60s,

01:03:36.580 | depending on how long you stay in,

01:03:38.220 | that there is a significant increase

01:03:40.040 | in the so-called circulating catecholamines.

01:03:42.480 | What are the catecholamines?

01:03:43.520 | The catecholamines are dopamine,

01:03:44.980 | norepinephrine and epinephrine.

01:03:46.680 | Now, the evidence for the catecholamine increase

01:03:48.640 | in response to cold water mainly stems from two studies,

01:03:51.660 | and in particular one.

01:03:52.720 | And in that particular study,

01:03:53.940 | they had people get into, I wouldn't say super cold water.

01:03:57.260 | It was in the low 60 degrees.

01:03:59.080 | And by the way, I'm speaking in Fahrenheit here.

01:04:01.780 | And they had those human subjects submerged in water

01:04:05.340 | up to their neck.

01:04:06.180 | I think they actually had them sitting in lawn chairs

01:04:07.860 | on the bottom of a pool.

01:04:09.280 | But again, their heads were above water

01:04:10.780 | so they could breathe.

01:04:11.900 | And they stayed in for quite a long while,

01:04:14.060 | 45 minutes or longer.

01:04:15.400 | And it was observed that there was a big,

01:04:18.580 | big statistically significant increase

01:04:20.540 | in epinephrine, norepinephrine and dopamine

01:04:22.740 | that lasted several hours or more.

01:04:25.060 | This is one of the reasons why,

01:04:26.300 | if you've ever done deliberate cold exposure as it's called,

01:04:29.880 | it often is uncomfortable when you get in,

01:04:31.800 | but then when you get out, you feel different.

01:04:34.020 | You feel really good in most cases,

01:04:36.300 | provided if you're me, you take a warm shower afterwards.

01:04:38.660 | Yes, I like to do that.

01:04:39.620 | I realize if you want to increase your metabolism,

01:04:41.340 | perhaps it's better to not warm up afterwards.

01:04:43.540 | I like a nice warm shower or to get in the sauna afterwards.

01:04:46.220 | That's just me.

01:04:47.300 | But nonetheless, deliberate cold exposure

01:04:49.660 | clearly induces a state shift of mind and body

01:04:52.900 | that most people, provided they do it correctly

01:04:55.020 | and they don't go into water that's far too cold for them

01:04:58.140 | for too long, they report as pleasant.

01:05:00.700 | And I think it's reasonable to assume

01:05:02.500 | that some of that is the consequence

01:05:03.940 | of these increases in catecholamines,

01:05:05.800 | which is why many people opt for a cold shower,

01:05:09.120 | which if you're me,

01:05:09.960 | cold shower followed by a warm or hot shower

01:05:12.080 | or a cold plunge in the morning,

01:05:13.420 | or maybe even just once or twice a week.

01:05:15.680 | Many people like them.

01:05:16.740 | Typically people like getting out of them

01:05:18.780 | and the feeling that they have after they do them.

01:05:21.180 | Although some of you sickos really like the feeling

01:05:23.160 | of getting in and being in it, but not me.

01:05:26.060 | The point here is that if we were to take a look

01:05:28.160 | at the landscape of zero cost behavioral tools,

01:05:30.860 | in fact, behavioral tools that could potentially

01:05:32.660 | save you money, meaning reduce your heating bill,

01:05:35.380 | that are known to increase the very neurochemicals,

01:05:38.660 | AKA dopamine, that are involved in improving working memory,

01:05:41.700 | I think it's reasonable to assume that a cold shower

01:05:45.020 | about 30 to 60 minutes prior

01:05:47.300 | to doing any kind of working memory tasks

01:05:49.060 | or any kind of activity

01:05:50.060 | that would require increased focus could be, okay,

01:05:53.540 | we don't know, the specific studies have not been done,

01:05:55.560 | but could be in theory.

01:05:57.540 | It makes sense mechanistically, it's logically sound,

01:06:00.140 | could be done after deliberate cold exposure.

01:06:03.860 | And indeed many people report not just feeling

01:06:06.180 | a bit of mild euphoria or feeling good

01:06:09.000 | after deliberate cold exposure,

01:06:10.180 | but also an increased capacity to focus.

01:06:12.620 | In fact, so much so that a lot of people

01:06:14.540 | who do deliberate cold exposure say that they don't require

01:06:16.580 | as much caffeine in order to maintain

01:06:18.300 | their alertness and energy,

01:06:19.340 | which shouldn't be surprising to us at all, right?

01:06:21.980 | I mean, it's increasing catecholamines, we know this.

01:06:24.700 | So that's another protocol that you could explore as well.

01:06:27.580 | Is there an important difference or not

01:06:29.420 | between deliberate cold exposure done by cold shower

01:06:32.420 | or deliberate cold exposure in a cold plunge or the ocean?

01:06:35.700 | Frankly, there haven't been a lot of studies

01:06:37.400 | comparing those, but I think it stands to reason

01:06:39.960 | that if you have access to a cold plunge

01:06:42.240 | or a cold body of water that you can safely get into

01:06:44.260 | up to your neck for 30 seconds to a minute,

01:06:46.460 | if it's 50 degrees or less, right?

01:06:48.660 | If you get in colder water, we know, for instance,

01:06:50.980 | if you get into say 45 degree water

01:06:53.300 | and you only get in for 30 seconds,

01:06:55.820 | you're going to get a big increase in the catecholamines,

01:06:58.220 | perhaps as big as the catecholamine increase

01:07:00.260 | that you would get from being in 60 degree water

01:07:01.920 | for 45 minutes.

01:07:02.880 | Most people don't have 45 minutes to sit around in water

01:07:05.500 | up to their neck.

01:07:06.340 | So most people opt for 30 seconds

01:07:09.300 | to as much as three minutes deliberate cold exposure

01:07:12.540 | in a shower or cold plunge or other body of water.

01:07:15.740 | Again, only do this if you can do it safely.

01:07:17.200 | Never, ever, please, for the love of God,

01:07:20.640 | please never, ever do any kind of hyperventilation breathing

01:07:24.360 | or breath holding while doing deliberate cold exposure

01:07:26.980 | because you can pass out, you can die.

01:07:28.640 | Don't combine breath work and deliberate cold exposure.

01:07:30.740 | Just don't. Separate those two things completely, okay?

01:07:33.700 | But deliberate cold exposure, we know,

01:07:35.540 | is a very reliable way to increase the catecholamines,

01:07:37.960 | which includes dopamine.

01:07:39.820 | So if you want to explore deliberate cold exposure protocols

01:07:42.900 | and get into the nuance of temperature and duration, et cetera,

01:07:46.060 | you can find that, completely zero cost.

01:07:47.780 | Go to Hubermanlab.com, go to the menu tab,

01:07:49.980 | scroll down to newsletter

01:07:51.140 | and go to the cold exposure newsletter

01:07:54.240 | where it details all of that in short PDF form.

01:07:57.040 | Now, some of you are probably asking,

01:07:58.460 | hey, what if I was in the high

01:08:00.180 | or long working memory span group?

01:08:01.860 | I ought to have high baseline levels of dopamine.

01:08:04.420 | Should I not do yoga nidra or NSDR?

01:08:08.180 | Should I not do deliberate cold exposure?

01:08:11.460 | Well, there, you're just going to have to experiment.

01:08:13.260 | Again, there's essentially zero risk

01:08:15.580 | to doing yoga nidra, NSDR, as I mentioned before.

01:08:18.980 | Deliberate cold exposure,

01:08:19.940 | there's always some risk getting into water, cold water.

01:08:22.340 | People always want to know how cold.

01:08:24.180 | Well, the newsletter gets to this,

01:08:25.620 | but I'll just tell you right now as well.

01:08:27.840 | The ideal temperature is the temperature

01:08:29.580 | that you can safely get into and stay in

01:08:32.260 | for a duration of 30 seconds to three minutes

01:08:34.660 | before getting out.

01:08:35.920 | Some people opt to go longer,

01:08:37.180 | but I think 30 seconds to three minutes

01:08:38.660 | is a good duration to work with for most people,

01:08:41.580 | especially if you're going to do it frequently.

01:08:43.480 | So the temperature should be safe

01:08:45.160 | for you to stay in for that duration,

01:08:46.580 | but uncomfortable enough that there's some impulse

01:08:49.840 | to want to get out,

01:08:50.700 | that you have to work to stay in there,

01:08:53.140 | that you have to kind of overcome that adrenaline release

01:08:55.860 | and the impulse to get out.

01:08:57.300 | So for some people that's going to be 45 degrees,

01:09:00.100 | for some people it'll be 40 degrees,

01:09:01.580 | depends on how cold adapted you are,

01:09:03.040 | depends on how rested you are.

01:09:04.180 | There is no specific temperature.

01:09:05.980 | You have to really gauge for yourself.

01:09:07.660 | And so err on the side of caution

01:09:09.380 | and you can experiment provided you experiment

01:09:11.220 | within the margins of safety.

01:09:12.700 | So if you found during the working memory tasks

01:09:14.460 | that you took today,

01:09:15.300 | that you have a very good working memory,

01:09:17.340 | I don't think there's any reason to avoid

01:09:19.280 | yoga nidra, NSDR, and deliberate cold exposure.

01:09:21.680 | In fact, there may be reasons to increase your dopamine

01:09:24.340 | and other catecholamines by way of NSDR, yoga nidra,

01:09:27.180 | deliberate cold exposure.

01:09:29.000 | Perhaps for working memory performance,

01:09:30.560 | maybe it could increase further.

01:09:32.160 | Perhaps it would decrease performance,

01:09:34.840 | in which case there, you got your answer.

01:09:36.380 | You don't have to do those protocols again,

01:09:37.860 | and you certainly wouldn't want to do them before anything

01:09:39.780 | that involves a lot of working memory and attention.

01:09:41.900 | But of course, those protocols have other benefits as well.

01:09:44.420 | So there's no reason to avoid them entirely,

01:09:46.100 | just perhaps avoid them within the context

01:09:48.220 | of trying to improve working memory.

01:09:49.780 | However, if you're somebody that has challenges

01:09:51.680 | with working memory, challenges with attention,

01:09:53.900 | challenges with focus,

01:09:55.380 | well then I think that the protocols I've been talking about

01:09:57.380 | up until now would be an excellent first foray

01:10:00.880 | into the sorts of things that you could do

01:10:03.220 | to increase dopamine.

01:10:04.680 | And of course those other catecholamines

01:10:06.620 | as a way to see whether or not it augments

01:10:08.960 | your focus and attention and working memory capacity.

01:10:12.040 | Now, some of you are probably shouting, shouting, shouting.

01:10:14.880 | What about exercise?

01:10:15.760 | Doesn't exercise increase dopamine?

01:10:17.240 | It does, yes.

01:10:18.180 | There are other things that increase dopamine.

01:10:20.060 | It's not just exercise.

01:10:21.520 | There are activities that increase dopamine.

01:10:23.160 | Some people are probably saying,

01:10:24.000 | wait, doesn't playing video games increase dopamine?

01:10:26.200 | Sex increases dopamine.

01:10:27.740 | Chocolate increases dopamine.

01:10:29.080 | Yes, yes indeed, those things can increase dopamine.

01:10:32.280 | What's interesting and important about the protocols

01:10:35.000 | I've been talking about however,

01:10:36.680 | NSDR, yoga nidra, deliberate cold exposure,

01:10:39.120 | is not just that they increase dopamine,

01:10:41.200 | but the duration over which they increase dopamine.

01:10:44.820 | Okay, this is very important.

01:10:45.960 | If you want to understand more about the relationship

01:10:47.800 | between dopamine spikes as they're called

01:10:50.640 | and dopamine baseline,

01:10:51.720 | and why I'm emphasizing these tools that cause large,

01:10:55.240 | long lasting increases in baseline dopamine,

01:10:58.040 | check out the episodes I did on optimizing dopamine.

01:11:00.440 | We've got a link to them in the show note captions.

01:11:02.580 | Now, before I talk about other ways to increase dopamine

01:11:05.080 | for sake of improving working memory,

01:11:07.680 | things like over-the-counter supplements like L-tyrosine,

01:11:10.600 | Macuna purine, things like that.

01:11:12.640 | I do briefly want to mention, and I promise briefly,

01:11:15.180 | I know sometimes I say briefly,

01:11:16.340 | and then I spend 20 minutes telling you about something,

01:11:18.560 | but very briefly, I just want to spend two minutes

01:11:21.860 | telling you about protocols that we do not yet know

01:11:24.740 | whether or not they increase dopamine levels,

01:11:27.160 | but we do know that they improve working memory,

01:11:29.200 | because after all this episode is about working memory,

01:11:32.040 | not just about dopamine and working memory.

01:11:34.640 | It has been shown that the use of binaural beats, okay,

01:11:38.560 | binaural beats being the presentation or the listening

01:11:40.880 | to sounds of different frequencies in the two ears,

01:11:43.440 | typically by headphones,

01:11:44.840 | I think that's been shown to work best.

01:11:47.800 | And there's a subtraction between the two frequencies

01:11:50.760 | such that the brain tends to entrain or start to follow

01:11:54.000 | a particular frequency within not the entire brain,

01:11:56.400 | but certain neural circuits.

01:11:57.720 | So if you've heard of say 15 Hertz binaural beats

01:12:00.400 | or 40 Hertz binaural beats,

01:12:02.360 | that doesn't mean that you listen to a 15 Hertz sound

01:12:05.060 | or a 40 Hertz sound.

01:12:05.920 | You listen to two different frequencies of sound,

01:12:08.160 | like Hertz is just a measurement of sound frequency

01:12:11.360 | in each of the two ears.

01:12:12.740 | And then the difference between them is 40 Hertz or 15 Hertz.

01:12:16.640 | And there are several studies that show not enormous, okay,

01:12:19.860 | I want to be clear,

01:12:20.840 | small to moderate improvements in working memory performance,

01:12:24.440 | but in some cases, significant improvement.

01:12:26.760 | And I'll provide a link to these two papers

01:12:28.600 | in the show note captions,

01:12:29.480 | but I'll just briefly describe them by way of their title

01:12:32.380 | and their major conclusions.

01:12:33.640 | The first is a study entitled,

01:12:35.320 | the effects of binaural and monaural beat stimulation

01:12:38.000 | on cognitive functioning in subjects

01:12:39.560 | with different levels of emotionality.

01:12:41.060 | A really interesting study published in 2019,

01:12:43.860 | it was a relatively small number of subjects,

01:12:45.680 | only 24 participants, 16 males, eight males,

01:12:48.420 | between 19 and 31 years old,

01:12:50.380 | listen to these 40 Hertz binaural beats.

01:12:52.600 | And by the way, it's very easy to find apps

01:12:54.800 | and other sources of 40 Hertz binaural beats at zero cost

01:12:58.240 | or nominal cost out there.

01:12:59.780 | You simply look for 40 Hertz binaural beats

01:13:03.120 | and looked at performance on working memory tasks,

01:13:06.880 | as well as some other cognitive tasks

01:13:08.280 | and found in some cases, a small to moderate,

01:13:10.960 | but significant improvement in cognitive performance

01:13:14.320 | on working memory tasks.

01:13:16.440 | The aspect of the study looking at emotionality

01:13:18.540 | did not find a significant effect.

01:13:20.240 | So it doesn't seem that emotionality impacts things there,

01:13:23.620 | but nonetheless, that study plus the other one entitled,

01:13:26.540 | the effect of binaural beats on visual spatial

01:13:28.820 | working memory and cortical connectivity.

01:13:31.440 | This was a study published in 2016,

01:13:33.920 | found generally something similar.

01:13:37.000 | In this case, they were using 15 Hertz binaural beats,

01:13:39.300 | and here I'm paraphrasing,

01:13:41.440 | produced network activity characteristic

01:13:44.280 | of high information transfer

01:13:45.600 | with consistent connection strengths.

01:13:46.920 | What they're really talking about

01:13:48.100 | is changes in neural activity patterns within the brain

01:13:51.400 | that led to, or at least were correlated with,

01:13:53.880 | improvements on visual spatial working memory.

01:13:56.040 | Visual spatial working memory tasks

01:13:57.680 | are different than the working memory tasks

01:13:59.220 | that you performed earlier.

01:14:00.500 | Visual spatial working memory tasks

01:14:02.480 | involve the cognitive generation that is within your head

01:14:06.300 | of the so-called visual spatial sketch pad.

01:14:08.780 | So it's this idea that you see something

01:14:10.800 | and then you got to sketch it out in your mind.

01:14:12.620 | You have to know the relationships between things in space,

01:14:15.320 | pay attention to what they are, keep those in mind again,

01:14:17.640 | 'cause it's working memory

01:14:18.500 | just as long as it's necessary to perform a task.

01:14:21.220 | That's what visual spatial working memory is.

01:14:23.360 | As you can imagine,

01:14:24.300 | it translates to an enormous number of everyday activities

01:14:27.380 | required for focus and attention

01:14:29.040 | and learning and performance.

01:14:30.760 | And indeed, 15 Hertz binaural beats

01:14:33.820 | was able to produce a small but significant improvement

01:14:37.700 | in that sort of working memory tasks.

01:14:39.300 | So I want to emphasize again,

01:14:41.640 | we don't know the relationship

01:14:42.880 | between binaural beats and dopamine,

01:14:44.420 | at least not from these studies,

01:14:46.020 | but I felt I'd be remiss if I didn't mention

01:14:48.600 | these two studies that show that 40 Hertz binaural beats,

01:14:52.080 | 15 Hertz binaural beats

01:14:53.740 | can indeed improve working memory performance.

01:14:56.160 | And in these sorts of scenarios,

01:14:57.620 | individuals are listening to the binaural beats

01:15:00.200 | while they are doing the working memory task

01:15:02.440 | and in some cases,

01:15:03.280 | before they are doing the working memory task.

01:15:05.820 | Either seems to work, it depends on the study.

01:15:07.660 | There are a bunch of other studies,

01:15:08.620 | but I thought I'd mention binaural beats

01:15:10.520 | because I know a number of people are interested in them.

01:15:12.960 | Again, non-pharmacologic, zero cost

01:15:15.960 | because you can find tools for binaural beat generation,

01:15:19.480 | zero cost out there,

01:15:21.020 | approaches to improving working memory.

01:15:23.380 | Okay, what about over-the-counter compounds

01:15:25.340 | that are known to increase circulating dopamine

01:15:28.320 | that can potentially improve working memory

01:15:30.500 | and that indeed have been shown in peer-reviewed studies

01:15:33.060 | to improve working memory by way of increasing circulating,

01:15:37.100 | presumably brain levels of dopamine?

01:15:40.060 | Well, I can think of two specific categories of supplements

01:15:43.260 | that is over-the-counter compounds

01:15:45.020 | that at least at this point in time

01:15:46.600 | are legal in the United States

01:15:48.240 | that can increase dopamine levels.

01:15:50.680 | Those two are L-tyrosine,

01:15:52.500 | which is an amino acid precursor to dopamine

01:15:55.240 | and mucuna prurines, which is a,

01:15:58.140 | believe it or not, it's a velvety bean

01:16:01.060 | or the outer component of this velvety bean

01:16:03.860 | that contains or is equivalent to 99% L-dopa.

01:16:08.860 | L-dopa is a key component in the biochemical cascade

01:16:12.860 | leading to the production of dopamine.

01:16:14.660 | In fact, L-dopa is often prescribed

01:16:16.780 | for Parkinson's patients

01:16:18.340 | as a means to increase their dopamine levels.

01:16:20.660 | There are at least three studies that I am aware of

01:16:23.020 | of the use of mucuna prurines to increase dopamine

01:16:26.220 | for the treatment of Parkinson's.

01:16:27.860 | In other words, mucuna prurines increases dopamine levels

01:16:30.740 | and yes, it has been shown to improve

01:16:32.500 | some of those symptoms of Parkinson's patients.

01:16:34.680 | We're not talking about treatment of Parkinson's today.

01:16:36.540 | I want to caution people against any sort of

01:16:39.740 | use of supplements to treat Parkinson's or other conditions

01:16:42.420 | without consulting your doctor, all right?

01:16:44.100 | That's very, very critical to point out.

01:16:46.340 | If we're talking about ways to increase dopamine

01:16:48.420 | for sake of improving working memory

01:16:49.840 | by way of supplementation,

01:16:51.340 | I think we should start with L-tyrosine

01:16:53.280 | because L-tyrosine, unlike mucuna prurines,

01:16:56.080 | is a bit further up, actually it's way further up

01:16:58.580 | the biochemical cascade leading to dopamine production.

01:17:01.540 | However, it has been shown in several studies

01:17:04.260 | that L-tyrosine supplementation

01:17:05.980 | can indeed increase dopamine.

01:17:07.940 | And moreover, and here I'm quoting the title of a study

01:17:11.460 | published in 1999, which I realized is a few years back,

01:17:14.140 | but of course there's some excellent studies

01:17:15.700 | from a few years back or more,

01:17:17.700 | tyrosine improves working memory

01:17:19.160 | in a multitasking environment.

01:17:20.940 | Now, this particular study from Thomas et al

01:17:24.380 | has some interesting aspects and some aspects

01:17:26.500 | that made me go a little bit wide-eyed,

01:17:28.660 | but not necessarily wide-eyed

01:17:29.840 | because the results are so dramatic.

01:17:31.900 | In fact, when one looks at all of the data in this paper,

01:17:34.820 | what you find is that supplementing with L-tyrosine

01:17:37.020 | as they did in this study,

01:17:38.680 | did indeed lead to improvements in working memory

01:17:41.440 | under multitask conditions as the title suggests.

01:17:44.440 | Those improvements were significant,

01:17:46.300 | but they weren't enormous, okay?

01:17:47.880 | They were statistically significant,

01:17:49.300 | but they were not enormous increases.

01:17:51.840 | Now, what was enormous and the reason I got wide-eyed

01:17:54.560 | and still get wide-eyed is that the dosages

01:17:56.960 | of L-tyrosine used in the study are really big.

01:18:01.460 | They had subjects take 150 milligrams per kilogram

01:18:05.240 | of L-crystalline tyrosine.

01:18:07.620 | I had them take it in applesauce for whatever reason

01:18:09.780 | or placebo and they did a number of different

01:18:12.720 | control conditions to make sure that whatever effects

01:18:14.900 | of L-tyrosine they observed were in fact due

01:18:17.120 | to L-tyrosine supplementation.

01:18:19.320 | Why am I going wide-eyed when I see this 150 milligrams

01:18:22.660 | per kilogram of tyrosine?

01:18:25.100 | Well, I weigh 220 pounds, so that's about 100 kilograms.

01:18:30.100 | So if I weigh 100 kilograms and it's 150 milligrams

01:18:36.260 | for every kilogram, that means that if I were a subject

01:18:39.560 | in the study that they would give me 15,000 milligrams,

01:18:43.180 | that is 15 grams of L-tyrosine prior to doing

01:18:47.580 | these cognitive tasks.

01:18:48.660 | Now, 15 grams of tyrosine to me seems like a very,

01:18:53.440 | very high dose and I frankly can't in good conscience

01:18:56.300 | recommend that.

01:18:57.260 | Why?

01:18:58.100 | Well, maybe I'm just hypersensitive to L-tyrosine,

01:19:01.300 | but I've taken 1000 or 1500 milligrams of L-tyrosine

01:19:05.820 | and I've definitely experienced an increase in alertness

01:19:08.980 | from taking 1.5 grams, not 15, 1.5 grams of L-tyrosine.

01:19:13.980 | And in fact, at a subjective level,

01:19:15.980 | I can feel a meaningful increase in alertness and focus

01:19:18.700 | from 500 milligrams of L-tyrosine.

01:19:21.340 | So I can't in good conscience suggest that people replicate

01:19:24.020 | the exact dose protocols within the study.

01:19:26.540 | Nonetheless, the study as the title suggests shows

01:19:29.620 | that supplementing with L-tyrosine can indeed increase

01:19:33.300 | working memory capacity,

01:19:34.420 | especially in a multitasking environment,

01:19:36.140 | which in many ways carries over to the sorts of requirements

01:19:38.740 | for working memory and attention capacity to get through

01:19:41.460 | life in a very focused for lack of a better word way,

01:19:45.280 | in a very regimented, do this, do that, task switch,

01:19:47.940 | multiple things, interleave.

01:19:49.180 | That's what moving through one's day or at least workday

01:19:52.580 | or anything that requires cognition and focus entails.

01:19:55.700 | So first of all, I'll just say what I always say

01:19:57.560 | when discussing any kind of compound or prescription drug,

01:19:59.960 | never add or remove any supplement

01:20:02.420 | from your supplement regimen, if you have one,

01:20:04.960 | without consulting with your health provider first

01:20:07.000 | to make sure that you are safe

01:20:08.840 | to take that particular supplement.

01:20:10.260 | Now, many physicians, MDs,

01:20:12.240 | are not familiar with most supplements.

01:20:13.700 | So you'll probably need to bring some literature

01:20:16.020 | to the phone call or to the visit.

01:20:17.860 | But of course there are many healthcare providers,

01:20:19.620 | including some MDs that are open to supplementation,

01:20:22.940 | especially these days as supplements have become,

01:20:26.460 | I would say generally more accepted.

01:20:28.380 | I mean, there are certain ones like vitamin D3

01:20:30.860 | and fish oils and things like that

01:20:32.380 | that are more common than L-tyrosine,

01:20:33.820 | but there are many physicians who are open to discussions

01:20:35.980 | about supplements such as L-tyrosine.

01:20:37.800 | If you know that you can supplement with L-tyrosine safely

01:20:41.140 | and you opt to do so, what dosages

01:20:43.500 | would you potentially take?

01:20:45.140 | Well, here we have to look at the dosages

01:20:48.940 | used in these studies.

01:20:50.160 | I think it's only fair, it's only safe,

01:20:52.060 | that we acknowledge that these dosages

01:20:53.400 | are really, really high.

01:20:54.740 | And I think the logical, the safe thing to do

01:20:57.340 | would be to start with the minimal effective dose.

01:21:00.080 | So if you weigh 50 kilograms rather than start right off

01:21:04.980 | with the equivalent dosage to this study,

01:21:07.700 | maybe you start with 250 milligrams of L-tyrosine.

01:21:11.560 | If you weigh a bit more like me or 100 kilograms

01:21:13.700 | or 75 kilograms, maybe you take 500 milligrams of L-tyrosine

01:21:17.240 | and see whether or not you experience a significant effect

01:21:19.940 | on working memory, attention, and performance.

01:21:22.180 | So the idea here is to establish the minimal effective dose.

01:21:25.140 | I should also point out that some people, not all,

01:21:27.520 | but some people experience a bit of a crash

01:21:29.660 | after L-tyrosine supplementation,

01:21:31.340 | such that they feel more alert, more focused,

01:21:33.720 | better ability to perform working memory tasks,

01:21:35.620 | move about their day, but then three or four hours later,

01:21:37.720 | experience kind of a drop.

01:21:38.940 | So you need to be mindful of that.

01:21:40.480 | In fact, you need to be mindful of any kind of pharmacology

01:21:43.160 | where you're increasing dopamine.

01:21:44.460 | This is one of the reasons why I like

01:21:45.680 | the behavioral protocols that we talked about earlier,

01:21:47.580 | because they're known to create big but long lasting

01:21:50.540 | and slowly tapering off increases in dopamine

01:21:53.820 | and other catecholamines.

01:21:55.100 | Now, for those who are curious about,

01:21:56.660 | and perhaps even want to try mucuna purines,

01:21:58.540 | please absolutely talk to your doctor first.

01:22:01.340 | Mucuna purines is essentially the equivalent of L-dopa.

01:22:04.340 | L-dopa is a prescription drug, as I mentioned before,

01:22:07.300 | and mucuna purines potently increases dopamine.

01:22:11.460 | What dosages of mucuna purines can increase dopamine?

01:22:14.500 | Well, typically in studies of Parkinson's patients,

01:22:17.700 | but also studies exploring typical people

01:22:20.580 | who don't have Parkinson's in cognitive tasks

01:22:23.260 | or in sports performance have explored

01:22:25.220 | anywhere from one to five grams of mucuna purines.

01:22:28.060 | Mucuna purines, again,

01:22:29.180 | is a very potent way to increase dopamine.

01:22:31.140 | And here, if your healthcare provider approves it

01:22:34.180 | and you decide to try it,

01:22:35.400 | I would suggest starting with a very, very low dose,

01:22:38.340 | again, to find the minimal effective dose.

01:22:40.140 | So maybe even just 500 milligrams,

01:22:42.540 | not even going to the one gram dose,

01:22:44.100 | maybe even 250 milligrams,

01:22:45.540 | and really evaluating how much mucuna purines

01:22:48.820 | can produce a meaningful impact

01:22:51.180 | on working memory and attention for you.

01:22:53.580 | So mucuna purines is kind of a bridge

01:22:55.600 | between over-the-counter supplements and prescription drugs.

01:22:58.700 | I say it's a bridge because it is oh so similar

01:23:01.140 | to that prescription drug, L-DOPA.

01:23:02.960 | And of course, there is a long list of prescription drugs

01:23:06.300 | that are known to be dopamine agonists,

01:23:08.860 | several of which, many of which, in fact,

01:23:10.460 | have been shown to improve working memory.

01:23:12.220 | You already learned about one of those before,

01:23:14.060 | which is bromocriptine.

01:23:15.240 | Now, you need a prescription from a physician

01:23:18.100 | to get bromocriptine,

01:23:19.280 | but bromocriptine, we know,

01:23:21.160 | based on that work from Desposito and colleagues

01:23:23.060 | that I talked about earlier,

01:23:25.000 | increases dopamine.

01:23:26.340 | It does so in about 90 minutes.

01:23:28.260 | It achieves peak levels of dopamine about 90 minutes

01:23:30.480 | and improves working memory in individuals

01:23:32.560 | that start off with a low working memory span.

01:23:34.640 | And we know from neuroimaging,

01:23:36.480 | those are the individuals

01:23:37.380 | with lower baseline levels of dopamine.

01:23:39.520 | So should you run out and ask your doctor for bromocriptine?

01:23:42.020 | Maybe, most doctors won't prescribe bromocriptine

01:23:44.260 | for that reason.

01:23:45.680 | I should mention that work from Desposito lab

01:23:48.500 | and other laboratories has shown that

01:23:50.980 | one of the hallmark features of traumatic brain injury,

01:23:54.340 | especially frontal lobe injury,

01:23:56.560 | as well as certain neurodegenerative conditions

01:23:58.620 | like Parkinson's, but other forms of dementia,

01:24:00.920 | as well as ADHD involve deficits in working memory

01:24:04.640 | and attention, which makes sense,

01:24:06.500 | given what we know about the symptoms of those conditions.

01:24:10.320 | And that bromocriptine has been prescribed off-label

01:24:13.760 | for the treatment of those conditions

01:24:15.440 | to some degree of success.

01:24:16.680 | However, those are off-label circumstances.

01:24:18.520 | Right now, as far as I know,

01:24:20.540 | bromocriptine is not prescribed specifically

01:24:23.160 | for those conditions at a kind of whole population level.

01:24:27.040 | It's not one of the drugs on the lookup table

01:24:29.200 | for ADHD or TBI, but certain well-informed neurologists

01:24:32.560 | and physicians do prescribe it for that reason.

01:24:35.180 | There are other dopamine agonists

01:24:36.500 | that are relevant in this context.

01:24:37.840 | The ones that I think most of you will be familiar with

01:24:39.840 | are the drugs that increase dopamine and norepinephrine

01:24:43.600 | for the treatment of ADHD.

01:24:45.720 | And I did an entire episode of the Huberman Lab podcast

01:24:48.160 | about those compounds, things like Adderall,

01:24:50.680 | things like Ritalin, which by the way is quite different

01:24:53.760 | than Adderall in terms of how much dopamine

01:24:56.120 | relative to norepinephrine it causes the increase of.

01:24:59.040 | I cover all that in those episodes.

01:25:01.560 | And you can simply go to HubermanLab.com,

01:25:03.240 | put ADHD, Adderall, or ADHD, Ritalin,

01:25:06.120 | and I talk about other things as well.

01:25:07.480 | I also talk a little bit about Modafinil,

01:25:10.040 | which is a entirely different category of drug

01:25:12.720 | known to improve cognitive performance,

01:25:14.400 | in some cases in ADHD, but in everybody.

01:25:16.780 | So there are a lot of different drugs

01:25:18.720 | that can improve working memory.

01:25:20.840 | Most of those do so by increasing transmission of dopamine

01:25:24.660 | or availability of dopamine,

01:25:26.060 | somehow changing dopamine levels in the brain

01:25:28.940 | by increasing them.

01:25:30.220 | So if you're somebody that has challenges

01:25:32.080 | with working memory, focus, and attention,

01:25:34.240 | please see those episodes and please talk to your doctor

01:25:37.000 | about potentially using pharmacology to increase dopamine.

01:25:41.040 | However, and this is very important,

01:25:43.400 | many people who have challenges with focus,

01:25:46.120 | attention, and working memory, and fall under the category

01:25:49.560 | of subclinical levels of ADHD,

01:25:51.440 | and even some individuals with ADHD, young and old,

01:25:54.740 | manage their symptoms and in some cases improve their focus

01:25:57.920 | through the use of behavioral tools, nutritional tools,

01:26:00.520 | supplement-based tools in ways that either allow them

01:26:03.640 | to reduce their total prescription drug dosages,

01:26:07.000 | and in some cases come off them entirely.

01:26:09.100 | Now, I am definitely not saying

01:26:11.260 | that people should come off those drugs entirely.

01:26:13.220 | And in fact, I want to take a really firm stand here

01:26:15.680 | 'cause I know this is a bit controversial,

01:26:16.960 | but I'm just going to tell you,

01:26:18.120 | having evaluated the whole literature several times over now,

01:26:22.520 | I do think, I personally believe that there is a strong case

01:26:25.720 | for certain children and adults to take these compounds

01:26:29.000 | that increase dopamine and epinephrine.

01:26:32.680 | Yes, those compounds are different forms of amphetamine,

01:26:36.400 | but those compounds we know can increase neuroplasticity,

01:26:39.920 | the rewiring, LTP, LTD, et cetera,

01:26:43.220 | within the neural circuits that control focus, attention,

01:26:46.260 | and working memory.

01:26:47.260 | And so they do have their place for certain individuals.

01:26:50.020 | We don't want to rule those out.

01:26:51.500 | Are they over-prescribed?

01:26:53.400 | My feeling is that yes, they are probably over-prescribed.

01:26:56.700 | However, there are a number of individuals

01:26:58.260 | that strongly benefit from them as well.

01:27:00.280 | So if you are going to explore the use of those compounds

01:27:03.480 | for sake of improving working memory,

01:27:05.160 | certainly if you're going to explore them

01:27:06.980 | for sake of improving working memory and focusing young kids,

01:27:09.940 | please, please, please talk to your physician

01:27:12.780 | because they're prescription drugs,

01:27:13.820 | you would need to talk to a physician anyway,

01:27:15.620 | but regardless of whether or not you're trying to improve

01:27:17.460 | focus and working memory in a child, in an adult,

01:27:19.940 | someone with TBI, someone with Parkinson's,

01:27:22.780 | I think it stands to reason that you would arrive

01:27:25.200 | to that conversation with some knowledge

01:27:27.660 | of not just the prescription drugs

01:27:29.620 | that are potentially available,

01:27:30.820 | but also some of the supplement-based tools,

01:27:33.180 | some of the behavioral tools,

01:27:34.980 | because as we know, and as a good friend of mine,

01:27:37.900 | who's an excellent physician,

01:27:38.980 | says better living through chemistry

01:27:40.780 | still requires better living,

01:27:42.260 | meaning yes, prescription drugs can have a positive impact

01:27:45.180 | on these aspects of brain function

01:27:46.880 | in a way that can really improve lives,

01:27:49.080 | but that behavioral tools also work.

01:27:51.380 | In fact, they can collaborate in a very synergistic way

01:27:54.380 | to increase the amount of neuroplasticity

01:27:56.300 | in the relevant circuit.

01:27:57.420 | So I'm of the mind,

01:27:58.700 | and I think more and more people out there,

01:28:00.940 | I like to think are of the mind that behaviors, nutrition,

01:28:05.500 | supplement-based tools, and prescription drugs

01:28:08.320 | all can have their place to varying degrees,

01:28:10.900 | depending on the circumstances and the individual.

01:28:13.540 | Okay, so today we talked about working memory,

01:28:15.500 | this incredible capacity of our brain.

01:28:17.600 | In fact, a specific set of brain circuits

01:28:20.020 | designed for us to absorb information

01:28:22.900 | that is perceive it in our environment,

01:28:24.840 | use the relevant parts, and then chuck it,

01:28:27.580 | just get rid of it, forget it.

01:28:29.460 | So very different than short and long-term memory,

01:28:32.180 | which we also discussed,

01:28:33.260 | and we talked about a few of the mechanisms as well.

01:28:35.740 | I think you'll agree that working memory

01:28:37.300 | is one of the more incredible aspects to brain function.

01:28:40.380 | I mean, if you think about it,

01:28:41.220 | this is a set of neural circuits

01:28:43.140 | that engage the same algorithm over and over

01:28:45.780 | in different contexts

01:28:46.860 | in order for us to be able to navigate new environments,

01:28:49.340 | familiar environments, to interleave different activities,

01:28:52.220 | different strategies, to task switch,

01:28:54.180 | to rule out distractors.

01:28:56.100 | It's oh so critical to every aspect of our waking life.

01:28:59.380 | And fortunately, there are also zero cost

01:29:02.180 | and low cost behavioral supplement-based

01:29:04.780 | and prescription drug approaches

01:29:06.580 | to improving this incredible thing we call working memory.

01:29:09.700 | So it was a pleasure to share some of those

01:29:11.340 | with you today as well.

01:29:13.060 | If you're learning from and/or enjoying this podcast,

01:29:15.460 | please subscribe to our YouTube channel.

01:29:17.240 | That's a terrific zero cost way to support us.

01:29:19.780 | In addition, please subscribe to the podcast

01:29:21.900 | on both Spotify and Apple.

01:29:24.000 | Please also check out the sponsors mentioned

01:29:25.780 | at the beginning and throughout today's episode.

01:29:27.700 | That's the best way to support this podcast.

01:29:29.940 | If you have questions for me or comments about the podcast,

01:29:32.580 | or guests or topics that you'd like me to host

01:29:34.380 | on the Huberman Lab Podcast,

01:29:35.700 | please put those in the comment section on YouTube.

01:29:37.880 | I do read all the comments.

01:29:39.760 | During today's episode and on many previous episodes

01:29:42.140 | of the Huberman Lab Podcast, we discuss supplements.

01:29:44.900 | While supplements aren't necessary for everybody,

01:29:47.040 | many people derive tremendous benefit from them

01:29:49.080 | for things like improving sleep,

01:29:50.420 | for hormone support, and for focus.

01:29:52.340 | To learn more about the supplements discussed

01:29:53.980 | on the Huberman Lab Podcast,

01:29:55.400 | you can go to Live Momentus, spelled O-U-S.

01:29:57.880 | So that's livemomentus.com/huberman.

01:30:00.980 | If you're not already following me on social media,

01:30:03.020 | I am @hubermanlab on all social media platforms.

01:30:05.620 | So that's Instagram, Twitter, now called X,

01:30:08.420 | Threads, Facebook, and LinkedIn.

01:30:09.920 | And on all of those platforms,

01:30:11.500 | I discuss science and science-related tools,

01:30:13.840 | some of which overlaps with the content

01:30:15.400 | on the Huberman Lab Podcast,

01:30:16.560 | but much of which is distinct from the content

01:30:18.400 | on the Huberman Lab Podcast.

01:30:19.820 | Again, that's Huberman Lab on all social media platforms.

01:30:22.940 | If you haven't already subscribed

01:30:24.140 | to our monthly Neural Network Newsletter,

01:30:26.180 | the Neural Network Newsletter

01:30:27.300 | is a completely zero-cost newsletter

01:30:29.260 | that provides podcast summaries and protocols

01:30:31.600 | in the form of brief PDFs of one to three pages,

01:30:34.500 | in which I detail things like

01:30:36.060 | how to do deliberate cold exposure

01:30:37.720 | and some of the science behind it,

01:30:39.300 | how to regulate your dopamine levels,

01:30:41.060 | how to improve your sleep, and on and on.

01:30:43.460 | Everything from focus, neuroplasticity,

01:30:45.340 | and all of which is available, again,

01:30:46.780 | completely zero cost by going to HubermanLab.com,

01:30:49.820 | go to the Menu tab, scroll down to Newsletter,

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01:30:54.320 | And I want to emphasize

01:30:55.160 | that we do not share your email with anybody.

01:30:57.580 | Thank you once again for joining me for today's discussion

01:30:59.860 | about working memory and ways to improve

01:31:02.100 | your working memory.

01:31:03.260 | And last, but certainly not least,

01:31:05.300 | thank you for your interest in science.

01:31:07.300 | (upbeat music)

01:31:09.880 | (upbeat music)

Tools to Enhance Working Memory & Attention

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