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honor professor Lobo and and she knows I'm never going to pronounce that correctly with my terrible Portuguese accent but his life and his work and I will come back to him right at the end of my talk now I was going to end with brainstorm but as you just mentioned it I think I might begin with it so um I work on the adolescent brain I run a lab in London that and we all work on the adolescent brain but one of the things as Maria in her very kind introduction said is that I do
a lot of work with education groups with teenagers education policymakers that kind of thing and one of the opportunities I had I was very very fortunate to have in the last few years is working with a theatre company in London they used to be called the Islington community theatre they have changed their name to company three I don't know why but anyway they have and for the last few a few years ago they contacted me because they had watched a talk that I gave a TED talk online about the teenage brain and they wanted to
work with me on that and the reason is because this theatre company is a theatre group for young people for teenagers actually from the age of 10 to 18 from very disadvantaged backgrounds in London a lot of them have been referred to this theatre company from social services or finesse school because they come they come from such chaotic families deprived backgrounds many of them have siblings in prison many of them have never met their fathers they're from a very yeah poverty but most of them are from very poverty-stricken areas in London not all of them
but many of them and they wanted to make a play about the teenage brain because they'd been reading some of the science about the teenage brain so what I was I helped them with this production but really it was theirs they wrote it they edited it with the help of Ned Glaser and Emily NIM who are the directors of this theatre company and they performed it and they ended up performing it at the National Theatre in London and it was so good and it got such good reviews in the National Press that the National Theatre
which is a major theatre another invited them back for a second run six months later it was such a outstandingly impressive performance and I can show you a video just two minute video so Marcus can you show the video now you say to me your brain is broken [Music] it's like an adult's brain but it doesn't work properly it's like you're in a city you've never been to and you don't have a map and you don't know what you're doing and you keep taking the wrong turns you say listen to me don't worry one day
you'll be okay probably your brain will start working properly one day your brain will be just like mine and then you'll be okay but until then you've got to try and be more like me [Laughter] I say to you my brain isn't broken it's beautiful I'm in a city I've never been to and I see bright lights and new ideas and fail and opportunity and a thousand million roads all lit up and flashing I say my brain isn't broken it's like this full reason I'm like this full reason I'm becoming Who I am and I'm
scared and you're scared because Who I am might not be who you want me to be all you want and I don't know why but I don't say it's all going to be okay there are so many things I don't say to you I don't know why I want to say them but I can't I pick up my plate put in the kitchen and go upstairs [Music] yes so this was their interpretation of the science of their brains which is what I work on so um as Maria said I did my PhD and also a
postdoc on on schizophrenia which as you may know is a very debilitating psychiatric illness that's characterized by symptoms like hearing voices inside the head and being deluded particularly um having delusions about some paranoid delusions that other people are out to get you that you're being followed by social by the security services and that kind of thing so this is a very debilitating illness and when I was testing patients in hospitals both in the UK and in France where I did my postdoc I became interested in the fact that all the many hundreds of patients that
I tested I asked the question when did you first start experiencing these symptoms and without a single exception every single patient said at some age between 18 and 25 years and I became interested in why this is what is it about the brain development of teenagers that is different in teenagers who develop schizophrenia why does schizophrenia develop in in late adolescence early adulthood now that was in about the 2001 that I became interested in that question and to my surprise when I looked in the scientific literature I found very little information about even how their
typically developing adolescent brain changes in humans let alone the brains of teenagers who go on to develop schizophrenia so it was around that point in the early 2000s that I decided to change the focus of my own research and to start to study the adolescent brain and that is what I've been doing ever since sorry this is very good microphone is very efficient um okay so it's not just gets afrien eeeh that starts in adolescence in fact adolescence is associated with lots of different mental illnesses it's been estimated that 75% of mental illnesses start in
adolescence before the age of 24 years and you can see that in this graph here so what this graph shows is various different psychiatric and psychological disorders here on this vertical axis and their age of onset the range of onset age plotted against years here so you can see that many different psychological and psychiatric illnesses they start around the period of adolescence so it's really important to understand why this is what is it about adolescent brain development that makes this period of life vulnerable to the development of mental illness we normally define adolescence as the
period of life that starts at puberty so the beginning of adolescence is defined biologically by the hormonal and physical changes of puberty but the end of adolescence has a much more social definition and vague definition and that is the age at which you attain a stable independent role in society so it can go on a long time and in fact in this culture in in the West we it's perfectly normal for young people to be not independent so to be living at home may be in full-time education of course right throughout their teenage years and
also beyond that into their 20s and some in some cases even in their 30s and that's not the case at all for for young people in other some other cultures where they're expected to there's the societal expectations on them are very very different and their ex to be financially independent earn money for themselves in childhood and they're expected to have babies as soon as they as soon as they reach sexual maturity so there are really big cultural differences in societal expectations of this of this age group now some people have argued that these vast cultural
differences between this age group suggest that the whole concept of adolescence is something that's recently been been invented about a hundred years ago in the US and I would argue against that position so I would argue that there are there's lots of evidence to suggest that in fact adolescence is a unique period of biological psychological and social development and there are three pieces of evidence that I will just briefly mention are based around the fact that you can see certain adolescent typical behaviors like risk-taking behaviors that we stereotypically associated with this age group so risk-taking
impulsivity peer influence self-consciousness you can see some of those behaviors across species you can see some of them across cultures even very different cultures and you can see certainly see evidence of these behaviors right throughout history so let me just show you a couple of examples adolescent animals so non-human animals go all go through a period of adolescence between puberty and becoming fully sexually mature adults and in those in those days or weeks or months depending on the animal you can measure behavior so for example many scientists around the world measure behavior of adolescent rats
and mice who go through adolescence just for about 20 or 30 days in those 30 days of adolescence you can see increased risk taking on risk-taking tasks you can see increased exploration of the environment and you can see increased socialization during that period there was a paper published a few years ago by Larry Steinberg and his colleagues showing that adolescent mice drink more alcohol when they're with other mice and that's not the case for adult mice so this is um you can see this here so this is the time spent drinking alcohol when they're on
their own and when they're with their cage mates the blue bar here are the adolescents so they drink more when they're with their when they're with other mice whereas the adults here in red drink about the same whether they're alone or with their cage mates across cultures as well you can see examples of adolescent typical behaviors so even where cultures differ in their societal expectations this age group you can never see similarities if you measure the if you measure behaviour properly again another study by Larry Steinberg published this year looking at adolescent typical behaviors across
11 very different cultures around the world the first behavior they looked up was sensation-seeking sensation-seeking is defined as the desire to seek an experience novelty exciting stimuli and to take risks and they measured that in that with various different tasks and questionnaires in eleven different cultures and what this shows is the average developmental trajectory of sensation-seeking across those 11 cultures and this is you probably can't see these numbers they're too small but they're plotted against age from ten to thirty years so what you can see is that across cultures sensation-seeking and risk-taking increases during the
teenagers its highest in the late teen ages and then it decreases during the 20s a different finding was found for self-regulation so that's a bit that's the ability to regulate your behavior to inhibit risk-taking and to plan there you can see that some self-regulation improves gradually throughout the teen ages and levels off in the twenties across history you can find many different examples of adolescents being described in the same kinds of ways that we stereotypically describe them today there are many you there are some really really interesting quotes from the Greeks from Aristotle and Plato
but I will show you one from Shakespeare so this is over 400 years ago just they before many years ago in The Winter's Tale Shakespeare says I would there were no age between ten and three and twenty or that youth would sleep out the rest so there is nothing in the between but getting wenches with child wrong in the ancient tree stealing fighting so here's a pretty negative view of this age group and we can see this negative stereotype you put portrayed today particularly in the media about adolescence this is a more recent example this
is a letter written to The Guardian newspaper a few years ago so this is a reader and she says in her letter there's nothing like teenage Diaries for putting momentous historical events in perspective this is my entry for the 20th of July 1969 I went to Art Center by myself in yellow cords and blouse Ian was there but he didn't speak to me got Ryan put in my handbag from someone who's apparently got a crush on me it's Nicholas I think a man landed on moon [Music] so that's a really nice example of what's important
to this teenage girl at that moment in her life less important at the fact that man happened to land on the moon for the very first time that day and more important to things like what she's wearing who she likes who she doesn't like who she's hanging out with adolescence is the period of life where we develop our sense of self-identity our sense of who we are and particularly how other people see us undergoes a really profound transformation during adolescence during our teenage years and into our early adulthood so if you think back about your
own teenage years or maybe you have teenage children or work with teenagers what changes in particular is the sense of your social self so things like how you come across to others what music you're into what fashion you're into which peer group you want to hang out with who you're who you like and you don't like even things like your moral beliefs and your political beliefs come online in a much more profound way than they did prominently during childhood this is the period of life where we very slowly become who we are now one of
the one of the adolescent typical behaviors that is studied a lot in labs who study adolescence is risk-taking and there is a stereotype that adolescents take lots of risks and you can find evidence for that for example if you look at things like accidents or if you look at mortality rates across the lifespan you find that the leading cause of death in adolescents is from accidents that are often caused by risk-taking like driving accidents and that's not true at any other stage of life it's actually a bit more complicated than that and I'm sure that
you're all thinking well you know not all teenagers take such big risks and of course some risks are really useful and important to take and there are lots of different contexts of risk taking and one of those texts for risk-taking is when adolescents are their friends so if you think about the kinds of risks that we worry about adolescents taking so things like smoking binge drinking experimenting with drugs even dangerous driving those kinds of risks are not risks that they normally take when they're on their own when they're alone it's they are risks that adolescents
will tend to take when they're with their friends and there's a lot of evidence for that there's a lot of evidence that peer influence is a critical factor in risk-taking in adolescents so this is an example again binary Steinbach of a an experiment where groups of well groups of different age participants came into the lab and they carried out a driving video game where they have to get round a circuit in the minimum amount of time possible and they can take risks they can try to go through a light which is changing from green to
M amber to red and if they make it great they get around quicker and they earn more points if they don't make it and the light goes red before they've gone through the eyes then they crash and in this virtual game and that loses them points so you can look at you can measure the number of crashes people have you can measure the number of risks they take this is the this shows you the number of crashes that people have when they're on their own this is the red bar here are adolescents aged 13 to
16 the green bar in the middle are young adults and they can see just about this bar here young adults aged 17 to 24 and adults in white 25 and over but in an in a second condition in this experiment the experiment has asked the participants to bring a couple of friends with them and the friends stood behind them as they carried out this driving task and just having friends standing behind them tripled the number of risks that the adolescents aged 13 to 16 took and almost doubled the number of risks that the young adults
took and I had effect on the number of risks that adults age 25 and over - so what this suggests is that firstly when they're on their own adolescents don't really take any more risks than adults so this stereotype that adolescents always take take risks isn't actually as simple as that however the second thing that this experiment suggests is that peers are the critical factor in risk-taking at least in a driving video game this is data from the lab but if you look at real-life data from car accidents you see exactly the same phenomenon so
car insurance companies record data about car accidents and analyze it because they need that information to make decisions about car insurance premiums and what they find is that firstly young people 25 and under have more accidents than older people that's why their car insurance car insurance premiums are higher but in addition they find that the precise circumstances in which young people are likely to have an accident or most likely to have an accident or when they have similar aged passengers in the car with them and that's not the case for adults in fact having a
passenger in the car is protective for adults if you're less likely to crash so peers really seem to matter - add up to adolescents in a way that they matter less as you get older into adulthood why is this well this is what we study in my group one of our hypotheses is that adolescents might be particularly sensitive to being rejected by their peers they need to become independent from their parents that's what adolescence is all about and that and therefore they need to affiliate with their peer group and find out where they are in
their social hierarchy and to do that they need to be accepted by their peer group so they our hypothesis was that maybe they're particularly worried about being excluded by their peer group and we looked at that using this task which is called the cyber bull it's an online game of catch which was designed by Kip Williams and his colleagues so you are that person down there represented by this hand here and you're told right this is a game of catch a bull throwing game over the internet with these two other players they're going to throw
you a ball and you just throw the ball back to them you can choose which one to throw it to and that's what you're told but actually it's a cover story because in reality there are no other players and we have programmed the task and we program the task either to include the participant in the game of catch or to exclude them and I'll show you what that looks like so here you're being thrown the ball you choose you to throw it back to and then they could throw it back to you but because this
is an exclusion condition they don't they just throw it to each other this goes on for about 90 seconds and it's really sad and people adults feel sad after that their mood decreases and they feel more anxious just in that very simple game of catch so cat Sebastien who is my PhD student many years ago wanted to look at what happens when adolescents play this cyber ball game so I'm now going to show you some data so this is the mood rating so we measure mood on using a standardized questionnaire for adults at baseline this
yellow bar here is baseline so before the experiment has started this green bar is their mood when they've been included in that game of catch and that's not a significant increase by the way there's not statistically significant suggesting that we expect to be included in this game it doesn't have any effect on our mood but when they're excluded the adults who took part in our experiment their mood is significantly decreased and that's what other people had found so that one was replicating the already established effect of social exclusion on mood in adults we also tested
two groups of adolescents young adolescents aged 11 to 14 and mid adolescents aged 14 to 16 their mood showed exactly the same pattern of change except that it was the drop in mood after being excluded was significantly greater in both adolescent groups compared with adult groups and what that suggests is that adolescents are hypersensitive to social exclusion even in this very simple short online social exclusion condition they are more affected by it in terms of negative mood than adults are okay so we became interested in social influence social influence on decision-making social influence on risk-taking
that kind of thing and to get you to experience social influence I want you to do something which is I'm going this is the question I'm going to ask you how long is the 25th of April bridge okay but this half of the room you're going to do it in groups of about four so the pit the four people next to doesn't matter if it's four or five or three or whatever but the group's people I want you to discuss you're going to have 45 seconds only to discuss how long the the bridge is okay
and you and you try and come up with answer you don't discuss anything so you're just gonna think yourself about how long it is okay sorry we have no time we have no more time the this group over here you didn't really discuss it I mean it's not a controlled experiment I didn't check whether you were discussing anything but anyone want anyone to get guess phalanx five kilometers three kilometers four and a half okay anyway over here shout it out two two three this is this experiment has worked perfectly because it's actually 2.25 kilometers so
they were more correct than you were this is this is perfect science I can write it up in a scientific paper so discussing with other people well there's actually a lot of literature on that a lot of unscientific experiments have shown that discussing things with people I mean not surprisingly you you are more likely to reach a correct solution and quicker because there might be someone in your group who knows or you might be able to work it out logically more quickly that kind of thing the other thing though so you weren't you weren't to
experience this but the other thing is that dinner I think what's interesting when you do that exercise is that you notice being socially influenced so if you're in a group of four people and one of you actually says you know what I was just talking about this last week with someone and they were telling me that it's 2.25 kilometres you're going to be much more influenced by that person then someone says who says I've never even heard of the 25th of April bridge or something like that this is social influence we're all influenced by other
people and eat and what's interesting is that you may hit you may start with a really strong opinion about how long this bridges and through the course of a one-minute discussion with other people you might change your mind that is social influence you are being influenced by other people we are influenced by other people all the time it's a fundamental component of human nature that we are social beings and we're influenced by each other there's a huge literature on on social influence in social psychology things like group behavior we humans behave differently when we're in
groups compared with when we're on our own so this whole area of social psychology came out of the football hooligan phenomenon where men mostly men back in the 60s that people wanted to understand why very decent and well behaved men at home or at work suddenly became simple hooligans when they were with other men at the football match and it's not just football hooligans that this phenomenon explains we're all influenced by other people and we all behave slightly differently while more in groups okay so we Kate Mills was my PhD student until a couple of
years ago she's now a postdoc in Oregon um we wanted to make a kind of model of social influence on decision-making in adolescents so this is a good model of decision-making imagine a decision that has some kind of health risk associated with it like shall I Drive really fast tonight like you might be driving over the 25th of April bridge you speed over I don't even you know if you can speed over X maybe the traffic's too bad but let's see you can can you drive at a hundred and thirty kilometers an hour is it
worth doing that these are kinds of decisions we actually do we make all the time in life and what we do is we weigh up the pros and cons the advantages and the disadvantages so driving home speeding it might be really useful you might get home in time for dinner you might be someone who loves driving past first and gets a kick out of it on the other hand you might decide not to because you're worried about crashing or you're worried about getting caught by the police and in addition to those factors there's also the
social factor so how other people maybe in the car or at home or at work how they would influence that decision so you might be you might think yeah but I really want to see my family so I'm gonna go home or you might think oh god wouldn't it be so embarrassing if I got caught by the police mate licensed way I would never be able to face my work colleagues again you know these are kinds of social influences on our decisions and what we're suggesting is that this social influence is greater in adolescence than
any other period of life now if you think about an adolescent making a risky decision this kind of sheds a more rational light over that risky decision so see imagine you have a 13 year old girl who hasn't never smoked before she understands that smoking is dangerous she gets it but she's out at the weekend with her 13 year old friends and they're all smoking cigarettes and they offer her one now for her what is the more risky decision saying yes to a cigarette even though she knows that cigarettes are dangerous and she might get
caught and get into trouble or saying no and potentially ostracizing herself from her peer group well we would argue that for a teenager the social risk of being ostracized carries more weight weighs in more heavily than health risks and we would argue as a consequence of that that when you're designing public health advert are advertisements to young people you should really focus on the social risks and the social norms and the peers rather than the health risks advert advertisement very rarely does that still advertising aimed at young people tends to focus on the long-term health
risks okay so we did an experiment recently where we looked at social influence on risk perception this was with Lisa Knoll who was my postdoc until recently lucia magus who is a PhD student and Martin speaking brink is a statistician who I work with closely so we were we this this experiment involved five hundred and sixty three participants aged between 8 to 59 years and this is what the experiment looks like ok so you're presented on a laptop computer with a a scenario that carries a moderate health risk so for example crossing a street on
a red light or other examples were cycling without helmet walking down a dark alley swimming in a lake by yourself that kind of thing so these are only moderately risky scenarios but the critical factor about them is that that each individual would associate these scenarios with a different amount of risk some people would say this is not risky at all other people would say it was very risky that was important because we asked participants to rate how risky they thought this situation was and then we told them all the teenagers who've taken part in this
experiment so far this is how risky they think this situation is and in a completely different condition we tell them that this is how risky the adults who've taken part so far think this situation is in fact these are fictitious that's a cover story these are fictitious ratings just randomly generated by the computer and then all that information goes off the screen and participants are asked to rate the situation again and what we're really interested in is how much participants ratings change from the first time they rate to the second time they rate in the
direction of the provided rating so in other words do we move our ratings of risk when we see how risky other people rate these situations and more critically are we more influenced by adults perception of risk than by teenagers exception of risk that was our hypothesis that we probably would be more swayed by adults than by teenagers okay so the first data set shows that all groups show a social influence effect in all of the so our our participants were aged between 8 & 59 we split them into these 5 age groups here and all
of them showed a significant shift in their ratings in the direction of the provided rating meaning that they're all socially influenced the amount of social influence goes with age which perhaps what you'd expect children and most children aged eight to eleven years are most influenced and it gradually decreases but even adults are significantly influenced by other people but more interestingly what have what's the difference between when the provided rating comes from teenagers apparently or from adults are we more influenced by adults than by teenagers and here in this graph groups whose ratings were more influenced
or whose change in rating were more influenced by adults the bar will be below the zero line if you're more influenced by teenagers the bar will be above the zero line so three groups the children and both adult groups were more influenced by adults than by teenagers the mid-adolescence showed no difference between the two so they were equally influenced by both adults and teenagers but the young adolescents aged 12 to 14 years were more influenced by teenagers than by adults and what this suggests is that young young adolescents age 12 to 14 risk perception is
influenced more by people their own age by other teenagers than by adults they care more about what other teenagers think than what adults think and we replicated this effect and a completely new independent cohort of five hundred and ninety participants earlier this year has just been published we replicated this this effect here and again what this suggests is that when you're thinking about health risks and public health you should really focus on peer influence and social norms rather than always focusing on the health the potential negative health effect of a risky behavior when your phone
or when you're targeting adverts to young to young people particularly young adolescents okay to summarize so far peer influence is an important determinant of adolescent typical behavior now in the next just a few minutes left of my talk I'm going to talk about the brain when I was an undergraduate five years ago I was almost I was taught that brain development mostly happens in childhood and the brain doesn't really stop changing after childhood but this is an example from one of my textbooks that I read as an undergraduate so it's talking about myelination which is
a developmental process in the brain it says it begins usually late in embryonic life blah blah blah and it continues for considerable periods of time into childhood in the case of humans well we now know that there actually that's completely wrong and that this particular process myelination continues throughout childhood throughout adolescence into the 20s 30s and even 40s so in the last 20 years our whole understanding of brain development has completely changed and this is because we are now able to scan the living human brain using MRI magnetic resonance imaging many of you I expect
might have had an MRI scan it's very common these days to have MRI scans to look inside the brain and the body of living humans we use MRI to measure the structure of the human brain and we're particularly interested in measuring the amount of gray matter which is not mostly found in the surface of the brain and contains cell bodies and neuronal cell bodies and the synapse is connections between cells and lots of other things and white matter which contains the long fibers called axons that communicate between neurons we also use MRI right we also
use MRI to measure brain activity we we measure brain activity as participants are carrying out tasks inside the scanner we look at where their brain is active and we can look at how structure and function of the brain changes across the lifespan using MRI and that has now been done many times in large cohort and I'm going to show you an example of that and the data from these particularly structural MRI studies have completely revolutionized the way we think about the development of the human brain because they have shown that brain development does not stop
in childhood in fact it continues in most of the brain throughout childhood and adolescence and even into the early adulthood so this is a very recent example that I was involved with really run by Kate Mills who I already mentioned and Christiane termina's amongst many other people from four different institutions the National Institute of Health and Pittsburgh in America Leiden in the Netherlands and also in Norway so each of these institutions or each of the scientists has been scanning children and adolescents as they get older so it's a longitudinal study and we analyzed all the
data together a total of 391 participants each of which each of whom was scanned at least twice as they get older so a total number of 852 MRI scans so we measure lots of different things I'm just going to show you a couple of examples cortical gray matter how much gray matter your cortex the surface of your brain contains and what this shows firstly is that the the trajectory is the shape of the graph is almost identical for all four cohorts so even though these children and adolescents are growing up in completely different parts of
the world I mean not completely different it's all West middle high-income countries but still they are independent cohorts that their brains are all showing the same kinds of development and what you can see is that this is gray matter plotted against age from 5 to 30 years gray matter increases during childhood it Peaks innate childhood and then it decreases really substantially during adolescence and that levels off into the 20s and then it stays level for many decades there's a 1.5 percent decrease in gray matter volume every year in adolescence in contrast white matter increases during
adolescence so again in four cohorts white matter shows a significant increase of about one percent per year across the period of adolescence okay so and why does white matter increase and gray matter decrease in adolescence the answer is we don't really know because MRI although it gives us beautiful images of the living human brain in terms of gray matter and white matter it doesn't yet have the resolution to tell us about what's going on in the brain at a cellular level or at a synaptic level so we can just make guesses about what's happening to
the cells and the connections between cells based on animal research and also research involving post-mortem human brain tissue so just very briefly why does gray matter decrease and white matter increase during adolescence there are lots of different series is probably for a number of reasons but here are three firstly myelination that is the fibers that connect up neurons together and it the way neurons talk to each other get coated in myelin throughout development and this speeds up the transmission of signals along them and we know that this process of myelination is happening throughout childhood and
adolescence and even into the early adulthood myelin appears white and it's what white matter is so that's increasing during adolescence which might account for the increase in white matter another factor accounting for the increase in white matter is axonal growth axons these fibers they grow and that will increase white letter at the same time sign up sis that's the connections between cells that you find in grey matter are being pruned away so sign APS's are over produced in childhood the brain produces many more signups as many more connections than it will ever need and the
excess finances have to be eliminated and this is a really important process because synaptic pruning the process by which axes are eliminated is partly dependent on the environment that the child or adolescent is in in that Sciences that are being used in a particular environment are the ones that remain and grow stronger and sciences that are not being used in that particular environment are the sign APS's that get pruned away and eliminated so that is the way or that is one way firstly that would account for a decrease in gray matter volume during adolescence and
it's a really important neurodevelopmental process and it's one way that the environment can shape and mold the developing adolescent brain it leads to neuroplasticity during adolescence okay so to summarize I've told you that peer influence is an important determinant of adolescent typical behavior gray matter decreases and white matter increasing isn't and in adolescence for the last couple of slides I'm going to change to the social brain back to peer influence I'm really interested in how the social brain develops and to illustrate the social brain I like showing this picture of Michael am missing a goal
here for Liverpool so the first aspect of the social brain that this picture really nicely illustrates is how automatic social emotional responses are so within a split-second of Michael Owen missing this goal everyone is doing the same things with their arms and has this similar facial expression even Michael Owen as he slides along and the only guys who don't are these guys up here in yellow I don't even see them but I think they're on the wrong end of the stadium and they're doing a different social emotional gesture that we instantly recognize and that's the
second aspect of the social brain that this picture really nicely illustrates how good we are at reading other people's behavior in terms of their underlying mental states and emotions so that is that's right that is sometimes called mentalizing or theory of mind I think I will show this video so it's been mentalizing the ability to read other people's behavior in terms of mental states has been studied for many years in young chill infants are just so one nice example demonstrating that even very young toddlers have an understanding of other people's mind so this is an
experiment by Tomasello and colleagues where they invite parents with the toddler into the lab they don't give them any instructions and look at the eye contact right at the end like I'm doing so that what that shows is that that toddler even at this very young age 18 months is able to read the intentions of the adult the intentions to put the books in the cupboard but he couldn't cuz hands with all so that's a very early example of mentalizing the ability to read other people's behavior in terms of its underlying mental states we're interested
in that we've done lots of work on it I'm just going to show you one example we're interested in how the social brain network develops so the social brain network is the network of brain regions that you use when you do these kinds of things when you mentalize when you think about other people these four regions it doesn't really matter what they are but in the prefrontal cortex and then three in the temporal cortex on both sides of the brain are activated whenever you think about other people's minds so we're interested in how this network
develops in adolescence and one way we look at that is to look at its structure and again this is a study by Kate where we we worked with data from the NIH pediatric new imaging project looking at how the brains of 288 participants change in those four regions of the social brain network between the ages of seven and thirty total of 857 nice guns so we're interested in these four areas and just to show that all of them gray matter development changes really very substantially during the period of adolescence just like it does across the
cortex in these four individual parts of the the social brain there's a significant drop decline in gray matter volume in the this this percentage here I don't know if you can see it but that corresponds to the percentage decline of gray matter so it's 17% in the in the dorsal medial prefrontal cortex and slightly less in other areas but still substantial and perhaps because of those three really important neurodevelopmental processes that I already mentioned that's also been replicated recently in a different cohort of children okay I've pretty much finished so to summarize I told you
about peer influence the brain develops both in terms of its structure and function in adolescents adolescents may be a sensitive period of brain development what I mean by that is that we know this brain development is influenced by the environment so that means that Patt that's why adolescents going right back to the beginning of this talk confers vulnerability to mental illness because it's a period where the environment for example stressful by environmental events have a negative effect on brain development but it also means that it's a period of opportunity plasticity might be particularly high so
things like learning and rehabilitation and intervention might be particularly efficient during the period of adolescence so I want to thank my funding and also my group all these people have been involved in this research for the last fourteen years and I wanted to mention that I have for the last three years been writing a book and it's not out yet but it will be out very soon in a few months time and I mention this because I know that Professor Lobo and chile's I said that long ago but anyway not only did it was he
a neurosurgeon and published hundreds of papers but he also wrote four books and I can tell you from having just written one book well I also co-authored a book about about ten years ago with my colleague Goethe frist but this one I wrote by myself and it's such it's so hard writing the book that I don't think I'm ever gonna write one again it took three years and it was a labor of love so I have total respect for his productivity in this area thank you very much for listening [Applause]
