Comprehensive Overview of Biological Psychology and Neuroscience

All right. Hey folks uh today we are talking  about uh biological psychology. um and So   when we think about biological  psychology one of the   the key pieces that we're talking about broadly  is this idea of how do biological systems the  

activity of cells proteins hormones um you  know amino acids right increasingly these days   we won't talk about this today but um or  during the course this class but things like   gut health right um the bacteria that live  inside of our stomach and intestines how you know  

all of the functions of our body influence our  mind and our behavior right and then beyond that   or not beyond that but part of that also being  what is the relationship between activity in the   brain and our conscious experience of the world  right so one of the ways we investigate this is  

through something called neuroscience which is the  study of the body's electrochemical communication   circuitry right so um your body is in the  same way that you have blood vessels running   through your whole body you also have uh neurons  running through your whole body many of you have  

probably heard of the concept of the nerve a nerve  before right or your hopefully your nervous system so the nervous system much like what we call  your circulatory system is your is all your blood   vessels that help carry oxygen to the different  parts of your body um right and nutrients and all  

kinds of materials and and also some communication  stuff it's your circulatory system your nervous   system runs from your uh runs throughout your  entire body and it is complex it has multiple   parts to it um at the same time as it has multiple  parts it is also integrated it is interconnected  

um one of the things you need to be prepared for  as you move from introductory psychology into the   higher levels is we are going to teach you lots of  parts and categories and columns uh when we talk   about things in psychology um do not be fooled  those things still all touch each other and affect  

each other there are very few genuinely isolated  aspects of anything in psychology right um the the   song you are going to hear over and over again as  you learn psychology and i'll try to i'm going to   be super brief here the thing that you're going to  hear over and over again is this group thinks that  

uh that co that a concept is explained by  explanation x this group believes that the   same concept is better explained by explanation  why and then at the end of the song you hear this   today we think it's really something in  the middle and that is the story you're  

going to hear over and over and over and  over and over again in psychology and so   you're going to get taught lots of different  categories lots of different structures lots   of different things that are taught to you  as sort of separate sections always assume  

always assume that by some means or another those  things have the ability to talk to each other   somehow they are somewhat connected have the  capacity to influence one another so they're   into so your nervous system is integrated  even though we're about to talk about two  

different parts of the nervous system further  down the line um you know just know that   they they still talk to each other right for  our purposes in this class it's okay to think   of them as separate um but just know that the  truth of the matter is they touch each other  

finally the nervous system is adaptable it has  what is called plasticity what this means is that it changes in response to experience right [Music]  you know you've heard me say already every feeling   and thought you have is directly  caused by activity in your brain right

so when you remember something when you learn  something new it should follow that that learning   or that experience that change in behavior that  results from something that has happened to you   right or something you've done right uh is likely  reflected in some kind of structural change  

in the brain now it is far more complicated than  that but the thing to keep in mind is your nervous   system is not something that is static it changes  in um it changes in response to things that happen   to it right and so that's everything from damage  which we'll talk about much later in this lecture  

to things like learning and memory which we'll  talk about later in the class and the process   through which the nervous system communicates is  an electrochemical process electrochemical process   it's got a lot of syllables in there but it's  got electro and it's got chemical which means  

there's some electricity zap zap zap and  there's some chemical uh elements too um and   yeah that is how communication happens within  the nervous system we'll talk exactly talk about   exactly what this electrochemical process is but  just keep in mind that there's both a mixture of  

electric charge and um the uh the  production and like projection of chemicals   all right so we have two sections in the nervous  system and each and those sections have some of   their own subsections so just you know be ready  here so we have the central nervous system this  

is comprised of the brain and the spinal cord  that is your central nervous system your brain   and your spinal cord um sometimes people are  surprised to hear the spinal cord is part of a   central nervous system and to you i have some some  very like scary uh uh you know um and and perhaps  

perhaps just interesting and i i think it's a  little weird to think about uh your spine does   some thinking for you actually um uh in the very  loosest sense of the term uh uh loose sense of the   word um in some instances some of your reflexive  responses don't really implicate much of the brain  

actually um it's just your um your your spine  receives some incoming information of having for   instance stubbed your toe um and your retraction  of your foot you barely need your brain for that   your spine handles most of that now as you then  start to feel the pain as you start to grab  

hold your foot and go oh wow that hurts that's  your your brain has now joined the party so to   speak um but the brain sits right on top of  the spinal cord um your spinal cord plugs   right into your brain through your brain stem  and that is that is the central nervous system

then we have the peripheral nervous system  and the peripheral nervous system is made   up of the somatic nervous system which governs  your sensory nerves and your motor nerves right   which are going to be kind of in charge of your  muscular activity right so your sensory nerves are  

things like um hey when you see right you  see because light is entering your eyes   right and that's going to stimulate  cells on your retina right which is   the the film on the back of your eyeball and  though the cells that make up your retina  

are going to get excited and they're going to  send a signal along right and that signal is going   to make its way to your brain so that you can  figure out what the heck you're looking at right   that's the sensory nerves and then you're gonna  realize oh hey uh that's a spider that you see  

there and then you're gonna get a you're gonna  get a piece of paper you're gonna roll it up and   you're gonna smack the spider right and that's  your motor nerves getting the piece of paper   rolling it up smacking the motion of your body  as you do that is the motor nerves right so the  

somatic then we have the autonomic nervous system  which governs things like your internal organs   uh all of you are immediately gonna stop  doing this when i say it but you know how   you don't think about breathing uh it just kind of  happens on its own most of the time your heartbeat  

beats on its own most of the time if it's not  beating on its own uh-oh you're in trouble   your autonomic nervous system is governing a  lot of that stuff including things like how   your stomach is operating um it's just it is  controlling all the stuff that runs on its own

within the autonomic nervous system right so  you can see here that these slides are these   slides are laid out correctly to help you  sort of understand like the somatic nervous   system has these two subparts the autonomic  nervous system has two of its own subparts  

and one is the sympathetic nervous  system which is in charge of arousal   to clarify and this is gonna i'll have to say  this multiple times throughout the class but   for this to be the first time  i get to say it this semester  

arousal is not just sexual arousal colloquially  which is to say as we talk in our normal everyday   lives arousal generally refers to sexual  arousal in psychology and social sciences um   in biology arousal it refers to a process called  physiological arousal wherein um when the when  

the going gets tough uh the sympathetic nervous  system gets going physiological arousal happens   when you know a lion walks into your room right  absurd situation but a lion walks into your room   you are either going to fight uh you're gonna  fight uh run away or fight flight fight or  

flight or freeze right those are the three for now  freeze is a relatively new one but um it is a uh   it's always been there since we've newly  identified it as another response to danger   and what's gonna happen is your body is gonna  spin up to either again like fight for your life  

run for your life or in like freeze and endure  or wait for the passing of whatever is happening   right and either way what's going to happen  is your heart rate's going to increase you're   going to start sweating a little bit more  your palms are going to get sweaty right

your digestion is gonna slow down right  your pupils are gonna dilate to take in more   light you're um you're gonna be breathing more  right because your body is being like we need   every available resource right now to live and  that's the sympathetic nervous system right  

and it's in charge of physiological arousal  when the danger passes we move on to what is   called the parasympathetic nervous system now  uh this goes back all the way to when i was   in psych 100. the way that i remember this is the  sympathetic nervous system is in charge of arousal  

and the parasympathetic nervous system is  the parachute that brings you back down right   the parasympathetic sympathetic nervous  system calms right it calms your heart   rate is going to slow back down right your  breathing is going to go back to normal  

right maybe even get slower right all that sweat  is finally going to be allowed to dry up right   you're gonna go back to baseline right and those  are the the parasympathetic and parasympathetic   nervous system are the the structures that  uh make up the autonomic nervous system right

so your nervous system what is  it made out of it's made of cells   the first type of cell that are nerve that  makes up a nervous system are called glial cells   they provide support and nutrition  right so if you imagine um

your nervous system is a big highway right and there's a lot of information  moving along that highway um   your glial cells are like a service road that runs  along that highway right and so um if there's a  

accident that somehow destroys the highway right  or there's a big old traffic jam or something um   city workers and stuff can use that service road  to get to where they need to go to do repairs and   and um uh and do maintenance on the road  without having to interfere with traffic  

and so that's again it's a glial cell  it's um it it is a hanger on to the uh   to um what you will in a moment know are  called neurons right and these glial cells   are there to make sure that everybody's fed  to provide like literal structural support  

for the uh for for our nervous system right um  [Music] and then help uh help build and foster   connections between our neurons right in our brain  alone we have about 100 billion of them which is   a which is you know if for those of you following  along at homes a lot with neurons um and so those  

are in charge of information processing the way  that that works in the simplest terms possible   is a neuron receives information it receives  stimulation from the area around it right and that stimulation either stimulates the  neuron enough that it passes the message along  

or it doesn't right and it's imagine a  game of telephone where somebody whispers   too quietly to the next person game of  telephone's over the information stops   in the game of telephone you say it loud enough  the other person can hear they receive enough  

stimulation and they are capable of passing that  message along that is the most fundamental basic   way in which neurons process information is there  enough stimulation for me to send this along   that's the most basic form it takes now  there are many different kinds of neurons  

that have specializations right or uh multiple  neurons like i cut like three or four neurons   networked together in a special way that  allow them to process information in a more   complicated way right they can mess with the  timing of the information they can mess with  

whether the information that gets passed along is  hey settle down or hey speed up right and so the   information processing that a neuron can do gets  much more complicated it's outside of the scope of   this class but the most basic thing that a neuron  does is it again not consciously but through its  

structure and its machinery it quote-unquote  big air quotes around this it decides whether   or not the information will get passed along  or not and when you're making those decisions   on on the scale of hundreds of you know 100  billion of those decisions at a time you can do  

really complicated work remember fundamentally a  computer operates in binary zeros and ones is what   what your everything your computer does comes down  to binary right and so hopefully you can imagine   if your computer can do all these amazing cool  things 100 billion neurons that aren't restricted  

to binary um could probably create something  amazing like consciousness for instance right   so computing and communicating right that is the  that is kind of what what it what it comes down to   um uh a particular type of neuron that is of  a lot of research interest lately are these  

are called mirror neurons this is an example of  what i talked about of those specialized neurons   mirror neurons are these cool things that they  turn on when you are doing something and then   watching somebody doing that same kind of activity  so for instance if you have a lot of experience  

playing soccer and you watch professional soccer  you have mirror neurons that are firing up um that   are mimicking uh the experience of playing soccer  right it's not just oh i'm watching somebody play   soccer it's that neurologically somewhere deep  down you're also having the experience of playing  

soccer which makes you more able to have some  scientists put forward this idea have empathy   toward those players of like oh um you know  oh i bet he feels really bad about that play   an example of this for me my wife is an athlete  she [Music] still plays volleyball but was a d1  

volleyball player in her day and one of the  things she'll say a lot when she's watching   professional volleyball players and they make  a mistake or she watches you know her uh other   teams play and they make mistakes she'll say  things like oh i would be doing sprints back  

and forth for that right my coach would be having  me doing sprints if we made this mistake um and   that to me speaks to this idea that um we have  this again the subsection of this type of neuron   that helps us imagine what the people  we are observing are going through  

right um and and so again athletes are an easy one  to go to because you know when i watch somebody   play soccer somebody who's just god awful at  soccer i just i've i have i have three left feet   um uh i all i do is i just i see somebody  running around with the ball but somebody who has  

experience playing soccer can really keenly and  easily imagine what it would be like to be in that   player's position right and that's thanks  to things like mirror neurons right so   you know i talk about this idea of like a neuron  is either sending a signal or not sending a signal  

but the things they're capable of that  individual mirror neurons are capable of and what   what individual neurons as a group are capable of  are pretty extraordinary right so mirror neurons   help us for things like imitation and social  perception right if i watch you do it i can  

easily replicate it if it's something um that  i have a little bit of experience doing right so let's talk about what what is and what is  a neuron made of so the first thing i want you   to do when you look at this image is this image  looks kind of scary it looks like some kind of  

you know alien monster um but  what i want you to focus on   is the circle part here see this the circle  and there's a circle in the middle of it   this is you all know this this is a cell this  is an animal cell right a somatic cell is what  

they're is what you probably were taught in  high school biology right and neurons are   very specialized somatic cells right so you know  like oh well here's the nucleus right there's   probably some like an endoplasmic reticulum or  whatever i don't you don't need to worry about it  

right all the different you know the mitochondria  there's a mitochondria in here somewhere i promise has all the same structures as the cells  that you were exposed to in high school but   uh what's what generally we don't always  learn in in high school bio is um there's a  

cells get really specialized and neurons are an  example of a very specialized cell so there's the   cell body you know this one already right because  you learned all about cell bodies in high school   then there's the dendrites these are arms  that reach out and as you can see over here  

they network with other cells right cells  connect to the dendrites and these dendrites   are there to receive signal they're there  to receive signal from other neurons   then neurons have this cool  tail that tail is called an axon  

when a cell receives information  it sends a signal down this tail   right and when that happens it passes the signal  onto a neighbor cell right now axons this axon   you can see compared to the body is is pretty  is pretty long but some axons um i think  

uh axons can get as long as like three feet in  our bodies right um so when we think about the   nervous system we can think about like a single  cell might have an axon that runs the length   of our arm for instance right um most neurons  don't have axons that long but when it comes to  

communication between brain and fingertip usually  it's a chain of neurons um but in some cases in   in particular areas of our of our body we do have  some axons that are just super long right the axon   is coated in something called myelin and we call  this the myelin sheath what myelin is is it's fat  

it's insulating fat because the signal moving  through the tail is electrical in nature   the myelin sheath uh helps uh prevent interference  right and so if you all i can say i have a pair of   wired headphones sitting next to me right now  or if you look at the like the charging cable  

of your um of your laptop or any device  it's coated in like a plastic right and   this plastic is useful because it insulates the  wiring right if you were to cut open your power   cord don't do that but if you cut open the power  cord you see a bunch of like metal looking stuff  

and uh that metal is a good conductor of  electricity it allows power to pass through your   cord really easily and what the plastic around  your power cord does is it stops the outside world   from interfering or trying to like take  some of the power running through it away  

if any of you have any experience being  electrical engineers you would know that that is   just i utterly probably butchered the science  of that but i can tell you for neurons right the   myelin sheath is there to prevent interference  with the passage of this electrical signal  

right um fun thing i'll add to this is you may  notice hey the myelin sheath is made of fat that's   interesting um yes this is one of the reasons why  um uh just very briefly we'll talk about this more   later on but a thing that i want to add while  we're on the topic that i think is interesting  

is from the clinical perspective is people who  get eating disorders while they're young in late   elementary school middle school early high  school they will have long lasting deficits   in their um in their cognitive functioning and  their in their mental functioning in part in part  

there's a lot of things going on when you deprive  your body of the food it needs when you're growing   but in part because um malnutrition interferes  with the development of myelin because it's made   of fat you deny your your body the opportunity  to make fat um and what you get is a bunch of  

a bunch of neurons that are not adequately  coated in myelin and so their signals are   easily interfered with right and so um all more  reason not to completely cut fat out of your diet   um especially especially when we're talking  with kids right we will we will talk about um

the other negative psychological influences  of diet culture and disordered eating   that are rampant in our country  so as this animation shows you   um when a neuron receives enough stimulation it  sends what is called a nerve impulse down the axon

and so let's talk about where a neural impulse  comes from so where where are neurons neurons   are surrounded by fluid that's why it's important  to drink lots of water because it's it ultimately   is a pretty moist environment where all of  our neurons are right your brain is pretty wet  

um at the end of the day and so your neurons  are usually surrounded by sort of a you know   a solution we would say um outside of the neuron  is a great many positively charged ions right   and inside of the neuron are a bunch of  negatively charged ions when your neuron is just  

chilling at its baseline its internal um polarity  is negative right this is this is polarization   right this is called resting potential  your neuron is chilling right now this neuron is is it's quote unquote skin is  what we call a semipermeable membrane basically  

it's got some windows and doors that open and  close right your house is a semi-permeable   membrane right i can open some windows and  all of a sudden i can get in i can open a   door and walk on it right so so we've got this at  resting potential inside of the neuron kind of a  

negative charge right when the neuron receives  enough stimulation to send a neural impulse   it starts opening doors and windows and  what happens those positively charged   ions on the outside are able to rush in right and  we call these windows and doors ion channels right  

um but yeah they're windows and doors in the in  the uh the edge and this is called depolarization   right the ion channels open and uh those uh  positively charged ions are going to rush in   right and the negatively charged ions are going  to come out for a little bit right now this only  

this only happens when a neuron releases  a particular reaches a particular um uh   level of positive charge usually as you can  see right here about 40 millivolts we start at   negative 70 um the positive star uh positive ions  rush into those open doors the open ion channels  

and the part of depolarization as we get to  about 40 millivolts right and this is called   the threshold once we get to that 40 millivolts  it's happening and this is the what happens is the   action potential sweeps through the axon right so  each one of these pluses and minuses you see here  

think of there being an ion channel here that is  opening and closing and so as the impulse moves   this one opens and the plus and minus switch then  they close this one opens this one opens and then   you can see in this image here right this is the  current position of the impulse right where the  

plus has come in and the minus is here and then  it's going to move it's going to move on down   and continue through this axon right um the  particular ions that are interacting here are   going to be your sodium and potassium there are  other ions in play here in in particular um but uh

uh but for now we're not gonna we don't we  don't need to worry about those for now um   most mostly because um the the other ions that are  involved in this process um have play a bunch of   other really interesting roles um that you'll  learn about more if you take a particular a  

biocide focus class but the idea here right  is our uh our sodium ions outside are going   to rush in our potassium ions are going  to get um uh are going to get joined here   and we're going to get a total of a total um  positive charge right at the end of the day

now it is more complicated than this but  for our purposes here today um it's like   100 um neurons follow the all or none principle  either an action potential happens or it does not   right either they fire or they don't there's  not like a half firing right um where there's  

a lot of variability where there's room for  variability is neurons fire or they don't   but also they can fire quickly or they can  fire slowly right and there's a gradient   there and that rate of firing is also information  right a neuron firing fast fast fast fast fast  

is maybe sending different information compared  to a neuron that's firing just you know just kind   of fast right or a neuron that's getting really  slow right that speed of firing is information   uh but there are no there's no half firing  either happens or it doesn't so we have our  

neural impulse right the neuron has fired  right that neural impulse is moving through   the axon and it gets all the way to the end here  right and so what happens here with this the the   the the tail end right what you can see here is  labeled the terminal button well let's just let's  

zoom in right so in this we see this terminal  button is connected to but you can see down here   not touching it's connected to right and so what's  in between these again more of that solution right   more of that uh uh um yeah more of that more of  that solution and so inside the terminal button  

the action potential right the impulse reaches  the terminal button and inside the terminal button   are vet what are called vesicles which  are bubbles and inside those bubbles   are something called neurotransmitters this  is the chemical part the nerve the neural  

impulse is the electrical part right that  change in charge right that's electricity   when the electricity reaches the terminal button  the vesicles which contain neurotransmitters   release those neurotransmitters into the synaptic  gap the synapse is where the terminal button  

meets a receiving dendrite the synapse gap is  that open space between them this white space here   right and so the vesicle moves to the edge  and that bubble pops right in the same way   if you've ever watched a bubble fall onto the  surface of water right if it doesn't pop right  

away it just turns into a semi-circle right a  semi-sphere right where it just makes a dome   on top of the water the vesicle does the same  thing and empties its contents into the gap where the neurotransmitters will bind with

an ion channel right and on this and so what  you're looking at here is this is one of those   i talked about the ion channels  as being like doors or windows   right and so what happens is a neurotransmitter  will like a lock and key bind with  

the keyhole or a receptor site on an  ion channel and when that ion channel   has a neurotransmitter fit into its lock  bind with its receptor site it opens   right and you'll remember what causes the  sort of hyperpolarization what ha what causes  

an action potential ion channels opening right  so ion channels open hyperpolarization happens   we get a neural impulse that neural impulse  results in the sending of neurotransmitters   which in turn open the ion channels of the  receiving cell boom we're going to get another  

neural impulse and that cell is going to fire  assuming enough of its ion channels open and   that's the that's the that's the the bread and  butter of it that's the that's how it works um yeah and as you are hearing me saying this as  you are comprehending it as the your ears are  

receiving sound as you are listening to the sound  of my voice and comprehending it this is happening   over and over and over again inside of your  inside of your brain and throughout your body so we have our our synapse which is where the  terminal button meets a receiving dendrite  

inside the terminal button are vesicles right  these uh these vesicles reach the edge of the   terminal button and release into the synaptic  gap neurotransmitters which are just chemicals   these chemicals have particular shapes and  they fit with particular receptor sites  

in a lock and key fashion so some receptor sites  are not interested in certain neurotransmitters   right and so this is how the electrical  impulse is converted into a chemical signal   right the impulse comes through and  the neurotransmitters are released

the neurotransmitter is received   ion channel opens right so let's talk about a  couple of different neurotransmitters um you   all uh you all know you probably know serotonin  and dopamine and i think we'll get to those um  

but just know the neurotransmitter is a chemical  of a particular shape that binds with particular   receptor sites right and so acetylcholine  is related to muscle actions learning and   memory um black widow venom is a chemical that  increases our acetylcholine levels and this is  

going to interfere that's why part of getting bit  by black widow is the experience of like paralysis   in certain parts of your body [Music] botox is is  associated with decreasing acetylcholine levels   alzheimer's disease is also associated with  lower acetylcholine levels which is part of why  

we assume it's related to learning and  memory now note that i said the word assume   because when it comes to neurotransmitters most  of the time we are developing correlational   relationships right we look and we go oh there  are lower levels of acetylcholine in a person  

with alzheimer's there is a relationship  there right is it causal unclear right uh gaba is a like a your basic inhibitory  neurotransmitter when gaba is firing right um   generally speaking you are uh  

experiencing in like uh inhibition or less  movement right gaba is is helpful like uh um   data levels are sort of helpful for um slowing  your movement down as part of sleeping right so those are two examples of an excitatory  neurotransmitter like acetylcholine and an  

inhibitory neurotransmitter like gaba which is uh  down here um so um this is a this is a huge chart   and i'm not necessarily gonna gonna read through  um the ones you're gonna recognize are dopamine   right which is involved with mood sleep and  learning um we get increased pleasure and  

suppressed appetite our potential like changes  in levels of dopamine influence these things a   lot of times people talk about dopamine being  associated with anticipation of a reward right   uh serotonin gets associated with mood a lot right  it also impacts our sleep which again makes sense  

because people with depression have lower levels  of serotonin and also experience sleep problems um   and so i uh again uh the thing to keep in mind  is when we think about neurotransmitters being   related to certain things remember we're talking  about potential effect because most uh research  

on neurotransmitters is correlational at best for  instance some of you may have heard especially   those of you who are maybe who have like fallen  into like mental health tick tock um uh have   likely heard that the connection between serotonin  levels and depression is being questioned um  

and uh i think that's a super useful like thing  for us to think about here um because here's   the thing uh ssris are antidepressants that um  [Music] it's believed the thing that helps uh   that causes them to help with depression is they  um i don't want to necessarily get into the the  

specifics of the mechanism because it's it ends  up being a long explanation but the gist of it is   um serotonin gets more time in the synaptic  gap to be picked up right and so if you have   less serotonin what it does is it basically  means like hey you're gonna you may have less  

but we're gonna help you use what you have  more effectively that's what ssris do and   um the misinterpretation of this  finding that like hey i don't know that   levels are really necessarily that like predictive  of depression um the incorrect inclusion people  

are drawing is like i should stop taking my ssris  which no don't do that um take your medication   as your psychiatrist prescribes it please um uh  and as your doctor prescribes it right doctor   psychiatrist you know whoever's prescribing your  meds follow their directions i'm begging you  

um that's the incorrect conclusion what  the conclusion we should actually draw is   huh ssris are pretty effective treatments of  depression for most people who have depression   um but if serotonin isn't the thing that is  like predominantly causing depressive symptoms  

um we should be thinking more about how ssris are  helping people with depression right um and so uh   i i i say that because it's ob it's obvious that  you know based on clinical trials ssris work not   for everybody i'm sure there's somebody listening  to this right now who's like you know they didn't  

help me that much that's fine you're the exception  um uh generally speaking based on the the data   and and that's fine that happens [Music]  depression is not really a monolith in that way   but um on the idea that saying like oh  depression is caused by lower serotonin  

levels is an oversimplification right and  these findings about the kind of like now   questionable relationship between depression  and serotonin uh should highlights this idea   that like you know it's not it's the connection  between neurotransmitter levels and any disease  

or you know or psychological disorder um is not  going to be perfect right and are under uh there's   lots of room to get a better understanding of  how these things influence our behavior but there is again research correlational  mostly research that sort of shows  

that in people that have certain challenges  we see lower or higher levels of various   neurotransmitters right so there's a relationship  between neurotransmitter levels and various   aspects of our behavior what causes those  relationships to exist remains unclear  

right if you remember from last week right  that correlation does not equal causation so we talked about neurons we talked about  how one neuron talks to another and the thing   the the fact the matter is neurons talk to  lots and lots and lots of other neurons it's  

not just a one to one it's a one to a you know  anywhere between you know two and a hundred   and so our nervous system is made up of an  interconnect uh many interconnected pathways   and so the reason they need  to be integrated is because  

um our world gives us lots of information and  we need to be able to put those things together   right and so neural networks are  really good for doing things like   um uh integrating sensory input like you know  being able to very quickly hear a sound behind us  

turn around and then visually identify  what made that sound right that doesn't   work unless there's some level of integration  between our auditory systems and our visual   systems even though we study them separately  they do talk to each other at some level right  

and also motor output this is my favorite one of  these um uh my my not my actual challenge don't do   this unless you want to take a robotics class  but design a robot that can hold an egg right   and the process of doing that is  you're gonna make a robot that breaks  

a lot of eggs for one of two reasons  either that robot is going to crush the egg   or that robot is going to drop the egg you  have to hold an egg in a really particular way   to hold it firmly without breaking it the  only way that works is an integration between

all the sensory input that comes from  your hand and right your motor system   there is a constant intricate dance between  your sensory system and your motor system uh and   they are they're they are it's uh they're tanga i  shouldn't say about i if i said ballet that was a  

mistake i mean tango they are close right because  as you squeeze that egg and start to feel that   little bit of give that happens right before you  break you know to let up a little bit right and   you're in this constant state of i'm holding this  egg perfectly i could you know run down the street  

and i'd still be able to hold on to that egg  and the reason that you're able to do that is   again because there is an integration between uh  your the different systems these neural networks   develop over a long period of time um anyone who  again if you have done anything and developed a  

sort of muscle memory around it congratulations  you have developed a neural network that's gonna   help you help you do whatever that is right  whether it's um the one that i can never do is   i'm terrible at dribbling a soccer ball right  um but any of you who played soccer it's the  

easiest thing in the world right you have perfect  muscle memory for how to move your move your feet   to both run and then move a ball at pace with you  right and this took years of practice i bet you   were terrible at it when you were a kid right  and uh now as uh you know a fully grown person  

you're probably pretty reliably good at night but  even if you took a year off of soccer you could   do it pretty reliably because that neural network  will probably stick around for a while right so um   these neural networks get built because as  neurons fire they release neurotransmitters and as  

a neighboring neuron gets excited by a particular  neuron that connect the strength of that   connection is going to grow remember the glial  cells we talked about glial cells are going to   work with those two neurons and uh and and help  build more connections and stronger connections  

right so that every time one neuron's firing  it's basically a guarantee the other is going   to start firing too right and so that's how we  get these networks over time is the more that   the thing we say is that neurons that fire  together wire together right so again for  

instance the neurons that were once you had an  independent set of neurons for kicking a ball and   another independent set of neurons for running  and then over time as you practice dribbling   those two networks are going to get really  familiar with each other and you're going to  

get this whole new system that's going to be  there to fire for dribbling that soccer ball   of running and kicking and you know the rhythm of  that the process of that i can barely talk about   it coherently because it eludes me so much but you  but hopefully you get this idea of like oh yeah  

my running neurons are firing my kicking neurons  are firing and over time if that they're firing   at the same time together eventually they're  going to be like hey we're in the same place   all the time we should totally you know we should  exchange phone numbers and become friends right  

where we should network together and so one thing  to keep in mind is that no single neuron contains   any piece of information right um in  memory research this is called an engram   and an n grim is the idea that like oh there's  a spot in the brain that contains a particular  

memory and if i could extract it or remove  it or damage it i could kill that memory   it's not how memory works and how any  storage of information works storage is   diffused throughout the network the existence  of the network and the activity of the network  

is likely uh how quote-unquote storage happens  and you'll notice i talk about the activity   of the network which means storage is never  really static right your computer has a hard   drive where if i take that hard drive and  destroy it the memories are gone right um  

and uh your brain if i destroyed your brain  your memories are obviously gone but there's   no particular region of your brain that i  could destroy to get rid of a particular memory   right um because again uh storage of these  things is what we would say it's diffused  

throughout these networks right spread  over multiple connections and neurons   so how do we learn this how do we know  how the brain works and so one of the   ways that we do it is uh through lesions  not legions lesions a lesion is damage

now most of the time when we're working with  humans we are not deliberately damaging the brain   um but sometimes we are and that's called ablation  um so sometimes we are deliberately damaging the   brain most of the time though we are looking at  people who have been in accidents identifying  

which regions of the brain are damaged and then  identifying what functions have they lost right   this person got damage to their occipital lobe  which we'll talk about in a little bit um uh but   they got damaged the occipital lobe the occipital  lobe tends to govern vision and they went blind  

in one eye so we know this region of the brain is  responsible for sight out of the left eye right   or at least we can know that  there's a relationship there   right so we can also electrically uh record  activity in the brain um we use something called  

an electroencephalograph or the an eeg what that  does is that records uh what's cool about the eeg   is it records electrical activity on the surface  of the brain in particular regions see there's   these many electrodes here each of those is  recording information which means we can look at  

the the sort of like the spindly uh it makes you  know much of a series of draws a series of spikes   basically in a graph and we know for instance that  oh there's a lot of activity on this electrode   versus a lot of activity on this electrode so the  electrocephalograph is cool because it gives us

good data over time and good data for particular  places of the brain right and so yeah each unit   each electrode is recording we also use x-ray  this tells us more about structural changes   more than anything um which is uh uh not going  to be necessarily as uh as useful um a ct can  

as a similar scan is going to be a similar process  it's going to give us structural information it's   going to give us better fidelity of structural  information than an x-ray a pet scan gives us even   more internal information the way that a pet scan  works is i inject you with a a radioactive isotope

the idea is that that's not harmful the idea  is that that isotope is designed in such a   way the shape of the molecule is designed  in such a way that it's going to end up in   a particular part of the body and then i use  the the pet scan then scans for that isotope  

and that gives us structural  information um as well so the mri is uh uh is is going to give us more  detailed internal um uh structural information uh   particularly about uh information about um how how  oxygen is being distributed throughout the brain  

which is going to give us some information  about activity but really the thing that we   we like for that is the functional mri which  is going to give us um information over time   about how energy is being used in the brain which  we use to make guesses about levels of activity we  

assume that if an area of the brain is being given  more uh more oxygen and more glucose uh that it is   being more active and so uh we can give people  certain activities to do we can [Music] image   people that are having particular experiences  and sort of see what areas are active right and  

then again this ends up being correlational right  where we go hey when a person's doing this these   regions are on right and then over time with  many observations right we kind of do this in   sort of an inductive way as opposed to a deductive  way hey every time we make a person look at a face  

there's this particular region right and that's  called the fusiform face area right um and that's   a region of the brain that across people tends to  be active when we're looking at faces and so now   we've seen this enough that we get to call  it the fusiform face area right um and that's  

the kind of thing that f uh that functional  magnetic resonance imaging can uh can give us all right so let's talk about some brain  anatomy what i want you to remember   is this is gonna be a lot of memorization  this is gonna be some flash card stuff

before you allow yourself to  feel overwhelmed by the amount   of information here i want to encourage you to take a bunch of index cards out and  write down all the different parts  

and and what they and what they do and what i  think you will find is that it's actually not   that many at the end of the day so um but this is  going to be a lot but also if we really sit down   and think carefully about how much it really is  it's a manageable amount of vocabulary so first  

we have the brain stem this is evolutionarily  speaking the oldest part of the brain you can look at any mammal of any kind and  chances are their brain probably just looks like   a brain stem with some stuff on top of it right  especially like a you know smaller mammals or  

things like lizards um reptiles fish it's the  most kind of basic most primitive uh thing um   part of the brainstem is the medulla which deals  with controlling breathing and regulating reflexes   right now this image is a little misleading  because this is a woman doing yoga likely taking  

a deep breath as she sort of stretches high to the  sky the majula is really doing the sort of like   when you're not thinking about it kind of  breathing right and again reflexes right   so thinking about your most basic units of  motion and response to the world around you  

the pawns discovering sleep and arousal again the  very basic processes of sleep uh just making sure   like all right we're going to bed time to turn  on the lights right interior internally right   the cerebellum just a little this  little mini brain looking thing  

is going to be in charge of  things like motor coordination   right and so in part this is going to be things  like uh there's other structures that help with   this quite a bit but things like being aware  of where your body is in space um and again if  

we're thinking about these regions of the brain as  being more primitive because they're they're lower   down it's kind of a general rule of thumb is the  lower it is and the more internal it is the more   like essential and the more um of those structures  we'll share with other animals this is gonna  

be sort of your basic like i am out hunting  right i need to move my head in a particular   way do you grab this bug right the cerebellum is  helping with that all right so the limbic system   is going to go is governing memory and emotion  so that's this is this is more these we would  

call these subcortical structures which the cortex  is the outside of the brain so subcortical means   inside or lower at the end of the day  right below the wrinkly part and the   limbic system is an internal area that's going  to govern again memory and emotion the amygdala  

is some people call it like the fear center of  the brain um you can think of the amygdala as   the part of the brain sort of responsible for um  imparting an emotional valence onto a situation   which is a really fancy way of saying the amygdala  helps introduce um what we experience as emotion  

to a moment is this a moment that requires fear  anxiety worry um right and the amygdala is uh is   helping just like paint a scenario  with that uh that feeling right um   even more more specifically we're looking at the  we talked about this idea of discrimination of  

objects needed for survival the amygdala is uh  at the most like in the most like primitive way   um i talk about it as as painting a situation  with uh with emotion um particularly fear   um the amygdala's also also the way that that's  adaptive is if something is really important  

right we're going to experience a level of  anxiety around it right it's going to be   labeled as important i must have this right i  need this i don't need that i care about this   i don't care about that right and those  judgments um when we were first evolving  

we're going to be about i need this food  right oh no that squirrel is running off of   my apple i need to act quickly right to get  my apple back or i'm going to starve right so again also governs emotion awareness and  expression so the hippocampus i love the old  

hippocampus uh the hippocampus is is in charge  of the formation and recall of memories um   so um the easiest way to explain what the  hippocampus does is it is not a place where   memories are stored at all the hippocampus is like  a um it's both conductor and tran and and uh and  

kind of transcriber so what they the  hippocampus kind of does is when you're   having an experience and it's significant enough  to work being remembered is the hippocampus is um   uh there to when you then go to remember an  experience the campus is there to be like okay  

when we were having that experience regions a b  and d were turned on so if we're going to remember   this experience i need to turn on regions a b and  d right um and so the hippocampus is sort of a   again like a conductor when it comes time  to remember things it's going to be there  

to help you turn on the right area so that you  can reconstruct the experience accurately right   so we have the thalamus the thalamus is the  relay station for sensory information right every sensory experience runs through the thalamus  where is then routed into the relevant part of the  

cortex the outside of the brain for processing  so when you see something the information   goes to the thalamus in particular it goes to  a nucleus in the thalamus right don't worry   about that goes to a particular region of the  thalamus for now you can just say goes to the  

thalamus where the thalamus says this is visual  information it goes here right to the occipital   lobe back of the brain where the occipital lobe  then is going to be like okay i think we're seeing   a square thing oh that's a sheet of paper oh i  can write on this right and that that judgment  

happens as the information is passed further  forward in the brain but the thalamus is the   starting place thalamus is going to receive  information and go oh that goes over there right the forebrain ah the basal ganglia is gonna govern  the coordination of voluntary movements right and  

so this is gonna support the cerebellum for uh  for movement in people with adhd who struggle   with coordination we see um some differences  in the size of the basal ganglia here and so   i bring that up because i have a good amount of  experience working with kids with adhd in like a  

therapeutic summer camp environment and so you  you see a lot of like issues with coordination   um and this is we relate those issues there's a  relationship between those issues and coordination   and in uh and the differences in like size and  shape of the basal ganglia and people with adhd  

and so um uh that's going to have a lot to do with  again understanding where your body is in space   and coordinating the different parts of your  body moving together to maintain balance right yeah so that's the that's the basic now  the hypothalamus is going to govern um a  

wide variety of things eating drinking and sexual  behaviors sort of governs a lot of the regulation   of the desire to pursue survival activities  right so am i hungry should i eat i've eaten   am i full right um the hypothalamus is managing  those uh those and it's also governing again our  

body's internal state like internal temperature  and stuff like that hypothalamus real heavy lifter finally again if the hypothalamus is regulated  helping us regulate our pursuit of survival   activities it's also then regulating our feelings  because feelings are generally speaking a sort of  

our conscious experience of our bodies  really motivating us to take action   right um and so it's governing our experiences  of stress emotion and reward right again   um do we feel satisfied right and the  hypothalamus is regulating that experience so  

then we get to our cortex so the cortex is  kind of like a is a word that i think that in   our society like the use of the word cortex is  like a signifier of like intelligence and bear   with me here um i feel like if you're watching  a cartoon and they want to like communicate that  

a character is smart they're going to be using  work they're going to use a bunch of like brain   anatomy terms and they're going to talk about  cortices and stuff and so i i want you i want   to demystify this a little bit because y'all the  cortex is just the wrinkly part on the outside  

it's just the wrinkly part of the outside that's  all it means it's what that term means if i talk   about your cortices i'm talking about plural  because there's different regions of the cortex   right it's just the wrinkly outside layer if  you hear cortex just think wrinkly outside layer  

right the neocortex which means new cortex is the  outermost layer right because it seems like as   we evolved we get our brain stem then we  get our subcortical structures like the   hypothalamus the amygdala right and then around  wrapped around that is the cortex right so  

when we look at animals we generally  consider to be very intelligent like   primates and dolphins they also have very  complex large neo cortices like we do   all is the wrinkly part it's just the wrinkly part  when you hear cortex wrinkly part never be afraid  

of this word again um it just it's the wrinkly  part so the neocortex is divided into four lobes   these are the occipital which governs vision it's  in the back here there it is there it is and we   have the temporal lobe which governs hearing  language processing and memory and right the  

you'll remember the temporal lobe because it's by  your temple right that part of the side of your   head then the frontal lobe governs intelligence  personality voluntary muscle movements judgment   all this stuff frontal lobe is super important  to like who we are as people um if you damage  

the frontal lobe we get all kinds of fun stuff  like decreased impulse control more aggression   who you are changes considerably finally  we have the parietal lobe which governs a   lot like spatial location attention and motor  control now how you remember these the frontal  

lobe is in the front the temporal lobe is by  your temple which is kind of like toward the   bottom of where the brain is the parietal lobe  sounds like parental and it's always on top   right the parent is always like a helicopter i'm  on top of you ah i take out the trash right that's  

the parietal lobe sounds like parental so there it  is on top and then the occipital lobe i don't know   sounds like optical so that's how i remember that  it's vision um and then it's the one that's left   over it's in the back right um so again these  can be pretty straightforward to keep track of

so beyond that uh and sort of like beneath  the uh those those the the neocortex   we have a variety of other regions here um  the first being the somatosensory cortex   which is dealing with body sensations touch  the motor cortex which is right next to it  

right so we've got somatosensory and motor um  these are governing voluntary movements um you   know you see a deep division here if you see  a good accurate drawing of the brain there's   like a deep division here these guys they talk to  each other um we talk about point-to-point mapping  

uh again we are talking about  we're talking about movement   the rest of it is the association cortex these are  the regions that help the different parts of the   brain communicate to each other right so most of  your cortex is really about carrying information  

and making sure that the different regions of the  brain are talking to each other efficiently and   effectively again your brain is really your whole  nervous system right this is how we started it's   a really integrated system it has to be talking  to every other part because if it starts acting  

in isolation we get all kinds of weird like  stuff is going to go wrong right again if your   site isn't communicating with your auditory you're  not going to turn around and be like oh that's the   bird that's singing right um a really fun one  of these is uh when it comes to your senses  

taste touch sight and smell are all super  connected to each other this is why food   that looks good tastes better right it's why  professional chefs care about how they plate food   because vision does influence our perception of  flavor right many of you probably already know and  

we'll talk about this more toward the um pretty  soon i'm going to get to sensation perception   uh many of you know that like smell is a  super important important part of tasting   so when your nose is stuffy you lose your sense  of taste in a way that's really kind of like  

annoying and if you have you know covet and it  goes for a long time it's really distressing   um but like texture and so like the feel of  food and the visual appearance of food are also   like physiologically tied to each other right and  the association cortex uh is is managing all of  

those connections right to uh to make sure that  your experience of the world is an integrated one   right because our senses aren't really  separate because we don't really experience   them as separate at the end of the day  right we use all of our senses to make  

judgments about things going on around us and you  know i'm speaking mostly about sensation because   it's the easiest thing it's the easiest example  to use here but you know it also helps us make   judgments for like i am seeing something and then  i recognize it as a tree right that's because the  

association cortex is managing connections between  my frontal lobe and my somatosensory cortex right right so the the brain is divided into two hemispheres  right there's a big crease down the middle  

um there is specialization of  function for the different hemispheres   that is true what is not true what is made up  and not grounded in science is that people do   not have a dominant hemisphere right people talk  about oh you're more right brain so you're you  

know you're uh more uh logical or creative or  whatever right now that's that's totally made   up utterly fictional however different sides of  the brain do tend to focus on different things   so for instance the left hemisphere is in charge  of verbal processing speech grammar uh there you  

will find broca's and wernicke's area which are  in charge of which govern um receiving information   and then speaking or verbally communicating so  like uh one area governs understanding and another   area governs like expression right damage to those  areas means that you'll you know respectively lose  

the ability to kind of like really speak or you  know form sentences and the other makes it really   hard for you to understand what others are saying  the right hemisphere is going to be in charge of   spatial perception visual recognition emotion kind  of get the idea of like oh somebody's more right  

brain is going to be more creative somebody who's  more left brain is going to be like so much more   um you know analytical and it's just like  that's not that's not how it works um there   is specialization in these areas but people  don't have a dominant hemisphere in that way

so you know beyond our nervous system we also  have something called the endocrine system which   is a set of a set of glands as you can see here  the the hypothalamus the pituitary the thyroid   uh parathyroid pancreas adrenal gland the ovary um  in females and testes in uh in in males um these  

glands all uh secrete hormones which are chemical  messages that move through the bloodstream   which is slow right so our nervous system uses  electricity right so it's moving let's not fool   ourselves absolutely not at the speed of light  right because remember there's that chemical  

part two that's gonna slow down the process right  um but the nervous system is much faster whereas   the endocrine system is a lot slower a perfect  example of this is uh everyone listening to this   as overeating at one point or another because  you 88 and you ate fast and then eventually your  

endocrine system catches up to be like hey we're  full we have everything we need right but that   went really really slow right that message takes a  long time to reach you right you uh will feel your   surging adrenaline for instance right which  secretive which is created from the adrenal  

gland right that adrenaline caused you to say some  things you regret caused you to get you know in   that physical altercation as you were defending  yourself right and you'll be shaking right from   the adrenaline for a while after the situation  is over because the endocrine system works slowly

but also just to clarify has influences on your  behavior right um the you know the secretions   of for instance our ovaries or our testes  right uh influence our mood right so when   uh teenagers are going through puberty and the the  action of those of those glands is gonna be like  

it's going to be intensified as part of the that  process um you're going to see um in but again in   in both boys and girls you're going to see big  swings in mood emotional outbursts um all of   those things are going to be influenced by those  those rising levels of various hormones right

so a lot of people talk about the idea that like we  don't grow new brain cells and stuff like that   like that's all that's all fake that's made  up we absolutely do produce more brain cells  

um when we are young our neurons are much more  interconnected when we're very young as babies and   young toddlers and then as we age around like  18 months on uh we begin pruning right so we   have fewer of those connections so that might be  where that idea came from but we are continuously  

producing new brain cells right uh and in fact  the brain cells we do have are adjusting the way   they're connected to each other all the time as  well so let me get that myth out of the way but um   uh there are some things that can influence how  well we recover from things like brain damage  

so age right being younger you're going to have  better recovery right the extent of the damage   unsurprising right minor damage to the brain  can be repaired major damage you're probably   going to be looking at lifelong deficits right so  one piece uh so let's uh um put these up so with  

um uh when we talk about the idea of repairing  the uh repairing the damaged brain like how does   the uh how does the brain fix itself right as it  um you know once it perceives damage right um so   the uh one of the ways that we do this is  through something called collateral sprouting  

right one of the processes we use for repair  um and so uh one of the things that can happen   with [Music] is is when we lose part of  our um our body right or part of our brain intact axons right will grow new new terminal  buttons and we'll grow those into the damaged area  

in order to kind of like try to substitute for  um the area that's missing or damaged right   substitution of function is is kind of it  is a little bit similar but this is where   um for instance a person who is uh is is blind  the area of their brain responsible for seeing  

will get taken over by other areas right  where it's like okay well you're not using   this right you're not using your eyes so  over time those neurons are going to be   receiving no stimulation because you're  blind and instead uh air like areas of  

the brain responsible for hearing or other  functions are going to kind of take that over   right no none of you are going to become daredevil  if you go blind right it doesn't work that way uh   none of you are going to be able to like get  super human hearing but the other senses do  

get a little sharper to substitute right  and that's part of substitution of function   finally neurogenesis really straightforward  you just grow new cells scroll back right neurons reproduce through mitosis just like  

other somatic cells do and often times if  the damage is small enough that's enough finally you can do brain tissue  graphs where you move less less vital brain tissue into areas  to hopefully be sort of replaced um  

uh to hopefully replace vital areas that are  damaged right it's moving brain tissue around   so uh the last thing that we're going to  talk about is genetics and behavior so um the nature versus nurture debate is  ongoing um no one thinks it's only  

one or the other that's that part's done  um we we solved that one it's always both   the question is the extent to which it is both  right is it 90 nature 10 nurture 90 nurture   10 nature right um is it closer to 50 50 it's  probably not um and so we know that right um and  

especially those of you who are who are younger  adults in this class those of you who are older   adults in this class you've felt this already  uh horribly i know you're all going to you all   have already or are going to grow up into your  parents i'm so sorry to give you this terrible  

news um you probably especially those of you or  young adults have probably already caught yourself   having your parents words fly out of your mouth  right um of like you know when you're paying the   bills you can run the ac whenever you want right  oh no i've turned into my dad right um and so  

obviously a lot of that's going to be  upbringing but also a large part of it   of the you becoming your parents thing is because  you are half your mom and half your dad sorry   um and the and there are genetic influences on  behavior humans behave the way they do because  

they are human right um this is kind of hard for  people to wrap their heads around so just think   about it as nature documentary anytime you watch a  nature documentary what's the narrator doing he's   telling you how you know he's telling you how  toucans are or telling you how this is how the  

elephant seal behaves right and the reason that  they behave that way the explanation is always   well they behave that way because they're elephant  seals and that's what they do so for every other   animal but humans we pretty widely accept that  the species you are and your genetics govern a  

lot of your behavior for humans we love free will  and so we like to say like oh well no you see the   way you were raised and the choices you make  about who to be right really govern who you are   when um what is likely is that a lot of our  behavior is a function one of the species we are  

right and two uh where there are variations  from person to person a lot of that is probably   accounted for by um genetic inheritance and then  of course then going to be reinforced by being   raised by a person with those genes so absolutely  there's a nurture component to behavior of course  

lots of learning involved lots of peer influences  and stuff like that but it's important to accept   that there's a large genetic influence on behavior  so um within our chromosomes our genes uh these   these genes are um are either expressed or not  whether they are expressed depends on stuff during  

our like development like post-conception but also  genes are expressed or not expressed that changes   throughout the course of our lives right so um  our genetics are not a thing that is decided like   at conception and then you know carried on into  the rest of our lives gene expression shifts over  

time um so uh the goal of the human genome project  was to map the human genome and put together the   exact sort of like dna um uh instructions right  dna sort of contains the instructions for building   a person um and the the hope was that this  would you know immediately yield a lot of really  

important information um but it turns out  that it's taking us a really long time to   parse through a lot of that um and so uh we are  still still trying to understand the relationship   between genetics and behavior it's not uh that  causal relationship of hey if genes one two and  

three are on or off in this way you're going to  get this behavior we don't have that yet right   um we have lots of relationships between those  things right in the same way that they say for   instance there's a particular gene responsible  for the aversion to cilantro that some people  

experience right most behavior is not as simple  as hey there's just one gene right uh some genes   are dominant versus recessive where some are  expressed and some are not right so for instance   um uh you if um you had a brown-haired parent  and a red-haired parent chances are you were born  

with uh chances are you're bored with brown  hair because brown hair tends to be dominant   right and when genes get combined as by part of  reproduction um certain genes just tend to win   out right so for instance the genes responsible  for red hair tend to be recessive right and so if  

both parents have red hair um then the probability  of that child having red hair changes and gets a   little bit higher but um what's interesting is  that you may a red-headed person still may carry   the genes for having brown hair and so two  red-headed people might get together and  

make a kid with brown hair is a possibility  the reason we talk about this is because   uh what we're doing is distinguishing between  genotype and phenotype genotype is the blueprints   and phenotype is what it looks like or how  it expresses how we see it or experience it  

in our genotype is a lot of unused information  that may or may not be expressed or not right so   for instance a red a brown-haired person  might have a recessive red-headed gene   that uh is like unlikely to be expressed unless  that brown hair person gets together with another  

brown-haired person with a recessive redheaded  gene and these two brown-haired people might get   together and make a red-headed kid right there's  like a one in four chance of that happening   um assuming that that recessive  gene is present and so  

uh the reason that we need to be aware of this  concept right that um that a person's phenotype   how they appear is not super uh does not always  tell us information about their genotype is that   we have a long history in um in in anthropology  and biology of looking at how a person expresses  

and making assumptions about what kind of  stuff they're likely to pass on to their kids   right um and so we look at people who are like  oh you have this particular like disability or   challenge cool we should stop you from breeding so  you don't pass it on when in fact we can't really  

be certain what the underlying genotype is behind  a particular expression right so um for instance   there are there are some people who maybe watch  the movie idiocracy and go yeah we should totally   institute breeding programs to make sure smart  people have more kids and i'm here to tell you uh  

two smart people get to other uh get together  all the time and have real dump kids right   like it's just not let's just know how it works  right and so we can't really use phenotype to um   get a good understanding of what the genotype  is right so we have to be cautious about that  

we can't look at a particular behavior and say  we should really try to breed this out of people   right so molecular genetics it  brings us to um uh a uh more uh more sort of an even an even deeper um  

a subfield of biology right that is uh  interested in how differences in like dna   structure itself those are going to predict  different pieces of behavior right um beyond that when we talk about the idea of  selective breeding um it's interesting because  

molecular genetics is a really like i don't want  to necessarily call it deep as though selective   breeding is not a deep process but molecular  genetics is such like a particular micro   level examination and selective breeding  is the exact opposite it's like the biggest  

like most macro most uh uh one like commonly and  widely used way we use um genetics to mess with   behavior now i know i just got done saying like  hey you can't really look at particular behaviors   and um and assume genotype uh that is true for  people it's also true for animals but um uh  

when done over a long enough period of time you can use selective breeding to encourage  particular behaviors to be more common   it would be unethical to do that  with people because it would involve

heavy state control of who can reproduce which  hopefully you hear that and immediately go oh   that could get ugly really quickly because  every time any country's done it it just   ends with a lot of people being dead it's called  eugenics when we do it with animals however um we  

have a lot of really positive results for people  um note that i didn't say for animals the positive   results were for people for instance um our  ancestors long long ago uh had some leftover food   and a wolf wanders into camp doesn't eat anybody  doesn't maul a child or anything it just walks  

up to the leftovers and chows down huh that's  interesting this wolf doesn't want to hunt us   it just wants to chill and camp and just eat our  leftover bones huh hey that wolf also is that way   we should get these two wolves together and  make sure they have puppies right and over  

time what you do is you kill all the aggressive  wolves right again not very good for wolves but   great for people kill all the aggressive wolves  encourage the wolves that are chill to breed   and then 150 000 years later we have dogs  right that's a product of selective breeding  

the cows we get our milk from are the product  of selective breeding i'm taking really like   you know an otherwise like pretty scary animal  um and over time breeding them for being more   docile breeding them for having more milk which  is kind of a different thing than behavior but um  

we selectively breed animals in order  to encourage certain behaviors now   do we still occasionally get an aggressive  dog absolutely again further evidence that   phenotype right does not always predict  genotype super reliably but um if you do  

this long enough eventually you do get to a  point where it's dramatically more likely for   you know a german shepherd for instance to  be docile and um and probably pretty good at   hurting people around right hurting people and  then sheep if you train them right um but then  

occasionally you're probably gonna have one that  that that is super sensitive and bites and and   um uh that is likely where our the societal norm  of putting down aggressive dogs comes from is that   for a long long time we that's we had we did  that right if a dog was aggressive we're like  

oh that's the wrong that's the wrong phenotype  there's an aggressive one get rid of it and make   sure it doesn't have puppies right and it's it's  you know uh you can you can make your own moral   judgments about that if you want um but again i'm  here to say doing that with people is very bad um

but we as a species of a very long history of   manipulating animal behavior with selective  breeding over long periods of time so the uh the way that we look at how genetics  influence behavior with people one of the key  

ways we do this as close to experimentally as we  can and we can't really do experiments with this   because it would involve deliberately separating  children from their parents which isn't great but   what we do is we look at twins who are separated  um uh um yeah we look at twins who are separated  

and adopted by different families and we see how  their development goes over time for instance   right and so um sorry i'm going to stay here for  a second and so we find overwhelmingly is that   there's a lot of weird similarities surprising  similarities between twins even when they're  

raised apart right they tend to have the same  interests there's always there's fun anecdotes   all the time about like hey yeah these twins  they didn't meet each other until they were   both married and they ended up marrying people  that looked really similar to each other right  

like and and you know they ended up having  the same taste and partner the same you know   taste and music and those kinds of things and  so in many cases we see that uh twins who share   more genetic information than typical siblings  particularly identical twins when we separate them  

there's still many similarities in  their behavior and their preferences later in life right regardless of how they  were raised which suggests a strong influence   of nature on behavior not total but some we  talked about genotype and phenotype already  

right um and so generally speaking um the way that  uh that we think about um uh genotype that's our   genetic heritage the stuff that we got from our  parents right when we add in experience um uh   we add in the effects of our lived experience we  also then have this element of um the environment  

alters how genetic traits develop right so the  environment determines which genes are expressed   this all combines right so we have our genetic  heritage experience the environment that all   combines to affect our phenotype which is  our observable characteristics both physical  

and psychological right so this is the behave the  psychological part here's the behaviors we observe   right so the genotype we have the genetic heritage  two loud parents parents who just they are just   loud they love to talk right plus they're raised  right by parents who are who really reward a  

gregarious kid they're like oh you love to talk  you're just like mommy and daddy which when you're   three is like the best thing in the world to  hear right so we have this experience right   and then the environment also just you know not  just your experience right of being rewarded for  

um being outgoing you also have this idea that  then you get to school and like the teachers love   it when you raise your hand like oh great yeah  tommy raised his hand again okay yeah what do   you want to what do you want to add right and over  time we get a phenotype where this is a boisterous  

kid who's going to stand out he's going to like  take theater as an as an elective or something and   is going to be very outgoing very confident right  um and uh and that is all like a product not just   it's not just about having loud parents it's about  having loud parents that also are going to listen  

to you right and having an environment where the  teacher likes you enough to be glad you're raising   your hand over and over again and that gives  us our phenotype right so you can see here how   if we just worry about like oh well this  kid's loud boisterous you know um you know  

i bet he'll have loud and boisterous children of  his own one day we then need to remember that it's   genetic heritage plus the effects of experience  right maybe this kid as a parent is like i want my   kids to be quiet and so we're going to see fewer  rewards for that right this kid then is going to  

let's say he goes to uh a school in a different  country right where the ex because schools out of   the united states generally um uh there are many  schools who are like we really only want you to   express yourself in writing like you're meant  to take notes and only really ask questions if  

you really firmly don't understand something so  he's incur he's really discouraged from talking   right really not being rewarded at home by his  parents he's not having good experiences with   speaking out and then this is a kid who has  this genetic heritage of being really loud  

but the phenotype what we observe ends  up being a kid who's pretty reserved   right and so the relationship between these  things isn't like 100 perfectly causal   right it's the key thing genotype doesn't  perfectly predict phenotype but it gives us  

some good guesses to go on but again we  need experience and environment as well   to determine behavior and so that's the that's the  end here and and so we've covered a lot of ground   and the the the thing that we really started with  um is is going to be this essential nervous system  

right and talking about like neural communication  right and that being sort of the the that's   the infrastructure that's the the the like  basic foundation of how our brain is able to   govern the movement of our body right um is it  sense that it sends information through those uh  

through the the nervous system which is made  up of neurons right when we talked about those   communication pieces um within the brain itself  are some are some key structures that govern   really like important parts of like being a  human being or being an animal in general right  

um and then we kind of moved on talking about how  some of the structures can fail by talking about   brain damage and then um in talking about this  idea of genetics right we're talking about how   our heritage how our upbringing but in  particular like just how our parents  

right by like just by the virtue  of mixing their dna to make us   right how that can also have an influence on our  behavior right and so um your major takeaway from   this what what your major takeaway really needs  to be in truth is um i i hope that you struggle  

to think of a psychological process an aspect  of being human that what we talked about today   like doesn't touch right what we've talked  about today is some part of it is implicated in   literally every aspect of being a person biology  touches all aspects of psychology period it's  

why it's the third thing we talk about we talk  about what is psychology how do we do psychology   and then the next thing we talk about is how does  biology intersect with human behavior and there is   no part of psychology that is complete without a  biological explanation and so i know that this has  

been a long lecture i know this has been a dense  lecture make sure that you're doing your reading   make sure you're thinking carefully about the  different parts of what we've talked about because   um if you ignore the bio biological aspect of a  psychological phenomenon of a thing in psychology  

you might get good enough you might  get a good enough understanding of it   maybe but it's always going to be incomplete  right so in the same way that research methods   last week's lecture is foundational you need to  think of this lecture as also foundational as well  

right or else you are not going to be in  a position to know psychology well right   so with that being said last thing i promise um  if there's parts of this that you don't understand   come to me with specific questions i'm begging  you because this part is super important and it's  

and and and all everything we've talked about  you can you can you can grasp 110 i said at the   beginning of this class and i mean it now this  is really the lecture where it really comes up   the most right um all of this is something that  you can grasp uh and grasp sturdily right so  

um listen to this lecture re-listen to parts of  it take good notes read your book think about the   overlap between the lecture the book how they are  and how they are in conversation with each other   talk to your friends about it make  your talk to your friends significant  

others parents about what you learned today um  make flash cards and then explain the crap on your   flash cards to your friends significant others  your parents and really try to internalize what   we've talked about today because again a lot of  this is going to come up in your future classes  

and again this lecture is as foundational as the  other three as from here we're going to splinter   off into really different subcategories of psych  that again still are connected to each other but   this is the one that the strongest strands of  psychology stand on so um yeah thank you for  

your time and energy and uh in listening  to this and um we will talk again soon