Intro to Neuroscience, Overview and goals

Let's talk about brains! Hi my name is Bing Brunton and I'm a neuroscientist at the University of Washington in Seattle. In this video I'm going to introduce to you the next series of videos that comprise a university level course: "Introduction to Neuroscience". This is a course that I've taught several times at the University of Washington, and I'm going to talk to you about the topics we're going to cover as well as my expectations and hopes for you in terms of what you'll get out of taking this course. Now I love teaching this course this is

one of my favorite things to do and introducing Neuroscience to people who are not yet neuroscientists maybe some of you will be inspired to become neuroscientists and the reason I love talking about it so much is because Neuroscience is such an interdisciplinary field that I get to talk not only about biology but about how Neuroscience connects with almost everything else that you can think of and this includes a lot of different Sciences we have connections to physics to chemistry to psychology and as well as connections to engineering applications to health as well as to your

sense of self and philosophy and legal ramifications of what we know about fundamentals of neurobiology before we get we get all of that I wanted to talk first about my brain and you can use where we all start right we're using our brains to understand each other right now so the mammalian brain the human brain looks something like this there's a picture of it on the bottom here and you can look at it and you can kind of compare it to some of the other mammalian brains that are in the animals that are in the

world around us and welcome to tell you is that the mammalian brain is a lot in common with other type of Malian brains but there's also some key differences as well in particular the human brain weighs about one and a half kilograms and it has 86 billion neurons-ish now what does this actually mean right this is so these are just numbers here what does this actually mean so what I want you to do is take your two Fists make two fists and put them together go ahead and do it yourself if you look then at

your hands put together as two fists this is going to be approximately the size of your brain stuffed inside your skull now I don't know about you the first time I did it very first time I did this I was surprised at how small it is maybe I have a big head I don't really know who knows what that means I also know that some of you are going to have larger hands than others don't take it too seriously this is only approximately how big your brain is now we know the brain is really important

for a lot of different reasons and one of the reasons is because even though for an adult human the brain weighs approximately two percent of your body mass at rest it occupies approximately 20 percent of your metabolic costs so about 20 of the calories you're burning at any particular moment when you're not doing anything this is not true if you're running a marathon it's devoted to just keeping the brain alive and functioning and ready to do the next thing that is getting ready to do so that's one indication of how important it is now a

few more things about the brain that I think are really interesting just I like thinking about size skills and time skills the brain has this wrinkly bits on the outside we'll have a later video talking about exactly what those are and why they're there the short version of the story is that that's what you're looking at is a very outer layer of the brain called the cortex it's kind of like a helmetus on the outside and it's wrinkly because it's actually a two-dimensional sheet approximately that's quite a bit larger than what you can stuff inside

your skull if you took it out if you took the cortex out shook it out and ironed it you get a sheet that is uh well you know it's actually approximately the size of a towel a small hand towel like this one right so if you can kind of Imagine wrinkling it up and then stuffing inside your head I don't remember actually doing this that's approximately how large your cortex is I told you the cortex is also a two-dimensional sheet so what does that mean well it's actually remarkably thin um I have a something like

a credit card okay so if you take any credit card and look at it you can see how thin it is that's approximately two millimeters so the entire cortex is about that thin and in fact the size of a regular credit card is about the size of your primary visual cortex if you imagine taking one of these credit cards folding in half and then stuffing the back of your brain that is the size of your primary visual cortex so those are kind of cool things that I like to telling people the first time I introduced

them to brains but Anatomy is only a very small part of our understanding of Neuroscience and neurobiology so as a neuroscientist I happen to be a type of neuroscientist called computational neuroscientists and what that means is that I really like thinking about mathematical models and different ways that we can analyze data from both brain and behavior and so rather than giving you a syllabus first what I'm going to tell you first is my perspective why I'm a neuroscientist how it is that I feel like this is a really interesting thing that's going to occupy not

only the rest of my career but hopefully the careers of lots of other people in the world as well so from my perspective one of the coolest things about Neuroscience is that the brain has multi-scale structures in space now I'm going to break that down and tell you what I mean by that phrase what we're looking at here on the vertical axis is what's called a logarithmic accessing size and so every tick mark is 10 times larger as we go up okay so right here is a millimeter we have a thousands of a millimeter and

then we have a meter up here so the reason that the brain is cool one of the reasons brain is cool is because it has really cool interesting structures that are worth studying at every single scale of description the smallest thing that we sometimes think about in Neuroscience is the size of a synapse so the cells of your brain are called neurons and neurons talk to each other at these Junctions called synapses the male in the human brain has 86 billion neurons on average every neuron in your brain makes a thousand to ten thousand synapses

with other neurons and so there's a ton of these things inside your brain right now we're only looking at one of them now despite having lots and lots of them and you see these really tiny structures they're in fact extraordinarily complicated and very very cool there's going to be a video all about the synapse later on it is so cool that you think about the infrastructure that goes into running and keeping alive and functioning one of these synapses it has the complexity of a small City we have things like roads we have garbage collection we

have power plants we have recycling plants even this is very green here and that is only one synapse among all of the synapses that go into running your brain and your nervous system but of course that's not all because every neuron and you might even see pictures of neurons like a couple of drawings of the ones over there neurons are also cool because they actually have non-trivial geometry they're not blobs like generic eukaryotic cells and you might have learned about when you first learned about cells in grade school they're very much not spherical and in

fact they're so not spherical that they have these beautiful dendritic and arsonic arborizations that very much look like the way that trees reach into the sky and their root systems reach into the ground those are just individual neurons neurons talk to each other and form networks of neurons that get larger and larger and larger and and so a lot of things that we talk about in systems Neuroscience are how all of those networks are coordinated how do they work together and give rise to what we think of as thoughts and memory and our sense of

identity and of course your nervous system at some point has to run the rest of your body so you're not just the brain in the jar Thinking by yourself you also have to run a body and so your central nervous system your brain and your spine innervates the rest of your body which is on the order of a meter and so that includes summarizing Sensations from all over your body as well as controlling the muscles and other inter and terrorists your internal organs and running all of those different structures by the nervous impulses of your

nervous system so I'm going to tell you one of my favorite cocktail party Neuroscience facts the next time you find yourself as a fancy cocktail party you can share this with your friends the brain is really cool and these neurons have really interesting shapes and they're really long and thin sometimes what takes the cake is that you have a neuron that is super thin and very very long and it's so long that it's practically as tall as you are in particular it is a sensory neuron called the dorsal root ganglion cell and there's one that's

in the very last segment of your spinal column kind of where your tailbone is in the very back of your spine one end of this neuron innervates the tip of your toe so it carries sensory information from your Tippy Toe big toe the other end of the cell goes all the way up to your brain stem to the very back of where your head meets your neck in other words if you think about this neuron it goes all the way from your toe to your head and it's practically as tall as you are I think

that's super cool what makes it cooler is that this cell is not something that's very much unique to humans in fact presumably all vertebrates have it so if you're a giraffe there is a same cell the door through a ganglion cell that goes from its toe all the way up to the base of its neck try to imagine this for a whale try to imagine this for extinct dinosaurs now the field of paleoneuroscience is fascinating um and you can and you can kind of imagine that how difficult it would be to study but if the

nervous system of these extinct dinosaurs are the same that it is for all EX for um all vertebrates that exist in in the in our life right now then presumably that this dinosaur had one of these neurons as well and so that probably takes the record for the longest cell that has likely existed in the history of life so I'm now told you about how the brain has multi-straw structures in space and how that's super cool and interesting you can you can spend a lifetime working at any single one of the size scales right but

there's cool stuff at every one of them but there's more because not only does the brain have multi-scale structures in space it also has multi-scale Dynamics in time now as a computational neuroscientist I love dynamical systems I love writing models that changing time and this is one of the things that I was actually drew me to Neuroscience into the study of neurobiology in the first place the fact that we can write down these really beautiful equations that not only describe Dynamics at any single time scale but actually allow us the ability to tie them together

to describe multi-scale Dynamics in time once again just like on the previous plot we have a logarithmic plot this time it's in time so every tick mark is actually 10 times longer on the very far end we have a millisecond which is usually the time scale on which the smallest times going which three systems Neuroscience talk about because it is about the length of an action potential the action potential is going to be the top think of a whole series of videos for the first section of these uh this this video course and you'll learn

all about it the basic point is that the action potential is the fundamental unit of communication for the electrically active neuron and the actual potential is characteristic shape occupies approximately one millisecond now of course as we go longer and longer and longer there's cool things happening at every scale of description in time we have things like neuromodulation and synaptic plasticity the fact that the synapses how neurons talk to each other are able to change rapidly as well as slowly throughout your day throughout your week okay and in order to produce speech in order to move

my arms and produce Sensational movement requires coordination of dynamics of neurons on the order of tens of milliseconds to seconds we then have things that occupy a little bit longer in time like short-term memory and long-term memory your brain and your nervous system just like many other parts of your body are prone to having cyclic variations that are Acadian Rhythm seasonal rhythms hormonal rhythms in thinking about neurogenesis the fact that in over your lifetime you actually do produce some numbers of neurons that get incorporated into your nervous systems you're not stuck with just the ones

that you were born with and of course we can talk about long-term learning and memory both procedural memory as well as memory of things that you know such as the fundamentals of neurobiology that you're going to be learning about a human lives or on the order of decades right and so I feel like I'm kind of the same person I was when I was when I was 10 years old there's some continuity there but in reality I don't share a lot of cells and proteins in common with that person and so how it is that

we have these long-term memories and learn things over time that is something that we can think about in the context of Neuroscience and neurobiology as well so those are some of uh the reasons that I really like neuroscience and if you wanted to come on this adventure with me I'm going to tell you about the topics that we're going to talk about all right I'm going to start slow and talk about the fundamentals of neurophysiology of a single Neuron a single cell of the brain and nervous system brains occupy a really cool space because it

fundamentally communicates with each other by using electricity so we're going to be talking about in a series of First videos electrical properties of a neuron how it is we generate an action potential how the action potential propagates and how they act a potential translates to communication among different neurons through different types of synopsis and so this part is going to be approximately 10 videos the second part we're going to go a little bit longer in time and also larger in size scales kind of moving up and to the right in those axes that we had

before thinking about the organization of the nervous system both the central as well as peripheral neurosystem we're going to talk about all of the different sensory systems vision olfaction for example it's as well as some unusual ones like your sense of time and of course nothing really happens without movement so we're going to talk about the Neuroscience of movement as well as motor control how does your motor neurons activate and um and excite and animate your body in the third part of our itinerary is going to be a bunch of additional topics and to be

frank these are just topics that I really like and I can't help myself so I'm going to tell you about them there are topics that usually reach a little bit farther beyond the scope of a traditional introduction to Neuroscience Course and there are things like Neuroscience of behavior not only human behavior but behavior of diverse animal including vertebrate and invertebrate insect species we're going to be talking about topics like mental health and addiction and how these impact our sense of self and how that ties together with society and community and um and other and and

the legal system and then we're also going to be going towards connections between neuroscience and Technology by looking at things like neuroscience and artificial intelligence the history of how these fields have evolved together into doing things like um the different different artificial neural networks that are like that are able to generate speech and generate images that all of you have seen all over the Internet and we're also going to be talking about topics for example like bring computer interfacing how it is that we can build machines that interact with our brains both for rehabilitation augmentation

as well as other applications and each of these parts is going to be approximately 10-ish videos and the whole thing is supposed to be a quarter long course at the University of Washington and so it's going to be approximately 30 hours worth of videos broken up into small sections so my goals for you in this course are the following first it is University level course on introduction neuroscience and so I hope that you will learn the fundamental biological principles of Neuroscience I hope to give you enough intellectual scaffolding so that you can hang knowledge that

you learn later on onto the fundamentals of how neurons work how neural systems work and so all of the additional topics will be added on top of that fundamental layer of principles of Neuroscience next I want you to appreciate Neuroscience as a living breathing field rather than having telling you how things are and this is just the way things work you know I'm memorizing a bunch of terms and different Pathways Frankly Speaking I can't memorize them either so I don't really want you to what I would rather you come away from the course with is

an appreciation of when we discovered something in Neuroscience what was the state of the field at the time what were the leading ideas on hypotheses of how that particular thing worked what were the Technologies and so what was the process of discovery of finding that thing out as well as who were the very human scientists with our very human floss who discovered those things a corollary of that is that one of my favorite things to do as a neuroscientist is thinking about future Technologies this is actually what I do in my research life I think

about not only what can we do right now but what is inevitably going to be possible in the next 5 10 30 years and to appreciate that Neuroscience is going to grow by Leaps and Bounds over that time framing waste that perhaps none of us can really appreciate and anticipate but we can kind of think about it and think about okay so if we can record not only from one single neuron at a time but hundreds of thousands of them what will we do with all of that data right what can we do if we

don't only are able to monitor animal behavior in a single animal in a single lab in a small box but we can actually see what it does out in the wild world and so appreciating neuroscience and the process of discovery as well as the people who are players is one of the things that is my goal for you and hopefully that's something you'll see throughout the course in all of the topics we'll cover third thing that I have a goal for you is to be able to connect Neuroscience with health and Society is an organ

just like every other organ in your body and so just like every other organ in your body if this is a course on the liver or the kidney we would most certainly talk about pathologies and diseases of the liver and the kidneys so just like that we're also going to be talking about neurological disease but those other diseases the brain is in a way that is not true of deliver tied to my sense of self and identity and so when there are things that change with my brain that very much changes my connection not only

with myself but with the way that I interact with people around me with my community and my relationship with my community and with my with my local environment and so thinking about the implications of that is one of my goals in throughout the course and I hope to especially highlight this in the context of mental illness and drug addiction because throughout the last couple of decades our growing appreciation for the fundamental biological basis of mental of mental illness as well as drug addiction has very much changed the discourse of how people relate to themselves as

well as relate to their loved ones and other people around them it is social as well as legal sense at the same time I recognize that hopefully I will inspire some of you to become career research scientists in Neuroscience but I recognize that that's probably not the case for the majority of you who might find yourself watching these videos and so if this is the last course on Neuroscience that you take in your life well you're about to be bombarded with for the rest of your life is a bunch of news coming out claiming to

be the latest and the greatest advances in Neuroscience especially neuroscience and health you're going to see articles claiming things now some of these are going to be genuine advances really exciting things that are inevitably going to come out in the next several decades but some of them are going to be BS so I want you to learn enough about the fundamental biological principles of Neuroscience so that you can call BS when you see it for the rest of your life Okay so our first lesson starts right now um you all know that you can see

with your eyes right okay so but your eyes you kind of sometimes people think of it as a camera so you can kind of you know take a picture with your camera you can take a picture of your eyes it kind of is the same thing right well you might know that it is in fact not so what you see with your eyes is not at all what it is in reality in other words what you think you see is oftentimes not at all what is in the physical reality because you don't actually see with

your eyes you see with your brain it is nowhere easier to demonstrate this than with visual Illusions and so I when I'm not teaching this course I'm actually constantly on the lookout for really cool visual Illusions I save them it's like I gotta show my students about this later so I'm going to show you a couple of my favorite ones right now demonstrating this this observation that we don't see with our eyes our eyes are not cameras and we see with our brains instead okay so the first one is a really simple one there's two

yellow dots on the screen I'm going to ask you the question which one appears larger hopefully what you can tell for yourself is that the one on the right that's surrounded by the relatively smaller purple circles appears larger it will not surprise you because I've already told you this is a visual illusion that those two circles are in fact exactly the same size because they're surrounded by larger circles they're surrounded by smaller circles there's a relative perception that one of them is larger than the other one even though it is not at all what is

happening in reality your brain is lying to you but it's lying to you for a good reason the second one this one is a kind of a recent one that I saw in social media and it kind of totally broke my brain at the time I sent it to all my friends and broke their brains and they're kind of mad at me one of them was actually mad at me because it made them kind of nauseous okay so in this grid of dots what you're seeing is that there's two different sides of this picture you'll

see a bunch of intersecting gray lines and there's black dots on the left side as well as the right side of this image what you'll see is that there's a bunch of black dots that you can see on the right side of the image and they stay there right I'm telling you I'm just going to tell you have to believe me now the left side has exactly the same number of black dots as the right side but when you look at them and you look away they disappear it is almost impossible for me hopefully this

works on your screen even if it's a small phone screen you can see that the black dots disappear when I look at it so I'm looking right now I'm looking at up here I can see a couple of black dots the ones down here have gone away once I look down I can kind of see the ones down here I can't see the ones up there anymore these dots disappear on you but they don't disappear on the right hand side if you don't believe me I'm going to zoom in on the right hand side here's

the gray grid with the black dots and over here is the same gray grid with the black dots as you'll see the only difference here is that the black dots on the left side of the screen are at the intersections of those great grids under the right-handed side of the screen they are not and so that's kind of a clue of why it is that one side of the dots disappear you can't even see them if you look away a little bit on the right hand side they stay put and you can kind of see

how many there are in this grid now visual Illusions are cool for two reasons one is that humans are extraordinarily visual creatures and so demonstrating that you see with your brain and not with your eyes is really easy to do and kind of fun and Charming to do when you do it with visual Illusions but of course these Illusions are not um uh it's nothing intrinsically visual about the fact that you can hack your brain by tricking it to think that something is there that it's not and so if we were in a haptic Universe

I can show you the following illusion but right now you just have to take my word for it there's these illusions that exist in other sensory modalities besides visual ones so here's uh one example of what's called a somatosensory or tactile illusion so it works the following way if you um take your arm okay you take your forearm region and what you can do is take something like a real little robot arm or something and then tap in Rapid succession one spot tap tap tap tap tap and then I'm going to do the same thing

by tapping at a second spot tap tap tap tap tap tap okay that's it I'm going to tap one place location a and a different place location B now the purse intercept the perception of what's Happening Here is not a series of tops at a and a series tops at B the percept is going to be a series of taps that walk from location a to location B in Rapid succession as if there were a small rabbit that is running on your arm that is why this is called a cutaneous rabbit illusion now the salute

salute pretty robust but it does vary depending on exactly what locations you tap for example this works on a patch of skin like euphora but it does not work on your fingertips because you actually have a ton of touch receptors on your on your fingertips you can actually resolve that there's two locations that are being tapped okay probably works on your calf on your leg too and you have to be able to tap at the right frequency and with the right latency between location a and location B otherwise to cutaneous rapid illusion breaks for them

I can talk about this forever and I'd be tempted to but we're not going to right now because this is just lesson a and I hope I convince you with a couple of examples that we don't in fact see with our eyes we see with our brains and our brains are built in such a way to represent information from the external world not to just represent them I am not a camera I'm not interested in the reality what I'm actually seeing right now I'm interested in looking at the aspects of the visual scene and the

sensory tactile physically seeing the auditory scene all of these different scenes in such a way that's relevant for me as as a person and as a living thing to survive in the world okay that's why we see with our brains and not with our eyes so to go on this adventure with me like I said this is a university level course and so I will assume some basic familiarity with a couple of topics now if these are things that you are totally familiar with that's awesome if you're not familiar with every single one these topics

it's actually totally okay you can come with me anyway and if it inspires you to go back and review some of these topics that's something that you can very much do in the middle of the series of videos and so because you Neuroscience is such an interdisciplinary field we're going to be drawing a little bit of Concepts from a lot of different fields and so here's a list of the things that I will assume that you have heard of and have some familiarity with okay in the realm of biology I will assume that you know

about the parts of an animal cell that you eukaryotic cell that it has a nucleus where the genome the DNA lives that is surrounded by a lipid membrane that is hydrophobic and separates the internal environment of the cell from the external environment of the cell I will assume that you have heard about the fact that there are proteins in in these cells that are expressed from The genome and that these proteins are molecular machines that do all the work the really cool work that we do in all of these animal cells because after all in

order to understand the neuron we have to understand neurons as a cell as a cell of your body just like every other cell because I already talked about how neurons are electrical cells we're going to be drawing on a little bit of basic terminology and Concepts from electricity and magnetism from physics so relatively basic things like what is a current what is a conductance what is Ohm's Law things of that nature the mathematical prereqs are not too rigorous I don't expect you to actually know calculus or differential equations but I am going to use some

notations from calculus and differential equations so for example if you see something like the following DX DT equals f of x you should probably have heard of this concept at some point where dxt means the derivative of x with respect to T and oftentimes I'm going to be using t as a proxy for time so this is a Time derivative of x okay I don't expect you to be able to solve these equations but I will be using this as a representation of ideas to connect them with electricity and magnetism as well as to proteins

as molecular machines and of course the basic communication of neurons involves not only electricity but also organic molecules and so I'll be assuming some basic knowledge of chemistry and organic molecules so for example there's ions like sodium and potassium are ions they are electrically charged and aqueously soluble and a lot of organic molecules that are that are going to be important players and many of the things that neurons are going to do Okay so here's the itinerary if you choose to go on this adventure with me I hope to see you for the next series

of videos I'm really excited to get started I hope to see you and uh because I'm a professor and I'm a pedantic neuroscientist I will have to say that I hope to see you is something that people say on YouTube but I fully recognize that you might see me but I'm not actually going to see you but I am excited to make the next series of videos and I hope that you find them as interesting as I have found the exercise of teaching them thanks