Welcome to my brain. In here, I've got over 300 trillion files ` everything that makes me me. This section is all the instructions on how I move. And this is a really important section. This is where all of my memories are. There are some... (DRAWER SCRAPES) ...some old ones ` that's my childhood ` some nice ones ` that's my boys when they were little. Down here, I've got some basic but pretty important stuff. There's breathing, and also... there's fear. This whole place comes together to form both my operating system and my hard drive. A supercomputer tried to replicate the human brain, and it took it 43 minutes to recreate just one second of the action in this place. While our journey to fully understand the human brain is in its infancy, we've made major breakthroughs in discovering what the brain is capable of. Over the course of this series, we're going to show you the astounding things neuroscientists now know about our brain. And we'll explore how these discoveries could improve the way we live our lives in this modern, busy, stressful world. (SOLEMN, MAJESTIC THEME MUSIC) Captions by James Brown www.able.co.nz Captions were made with the support of NZ On Air. Copyright Able 2018 (REFLECTIVE MUSIC) This is Maria. Maria's brain has six main jobs to do, and it's pretty much doing them all the time. A really important job is keeping her alive with some basics ` pumping blood around her body, making her heart beat, and sending instructions on breathing to her lungs. Her brain, floating in the dark inside her skull, needs data from the outside world. So it collects all the information from her senses ` what she can see, the smells, tastes and sounds. Her brain is also responsible for moving her body around. Maria's brain is in charge of talking and understanding language. The brain also makes all of Maria's decisions. Even though it's only 2% of her mass, it uses 20% of her energy. And when she's doing intense thinking, it's using half of her energy. The brain decides on Maria's emotions. Right now, she feels peaceful. (FLIES BUZZ) Emotions, arguably, are what make us human. And they play a hugely important role in our lives. I don't like spiders at all, so what I'm about to do, to me, is completely horri... horrifying. OK, go on. Oh Jesus. Oh, for (BLEEP)'s sake. Oh my God! HIGH VOICE: This is a... OK. Right now,... my... my brain... i-is... is doing some really complex things. My brain is experiencing an enormous amount of stress. Inside my brain, there are three main parts ` there's the oldest bit, known as the reptilian brain, which is concerned with survival; the mammalian brain, which deals with emotions; and finally, my clever bit, the cortex. The clever bit is trying to say that it's OK. Oh, its little legs. Its little legs. Isn't it... lovely? Yeah, so my prefrontal cortex is trying to keep me calm so I can actually talk to you about... a-about this. And I feel an actual spider ` like, its warm little, creepy little body, just there on my hand. But the almost overpowering message from the conversation between the survival instincts of my reptilian brain and the emotions of my mammalian brain is to run. I think it's planning something. I-I don't trust it. I don't think it's got... Its motives are not... It's... Why is it doing this? Why is it doing this? The emotions from my mammalian brain, in this case, are disgust and fear mixed together. I... Why am I doing this? WHISPERS: Oh man. Oh my God. There is some evidence that we... have this genetic fear of spiders. Uh, and then my brain is accessing all of the memories that I have of spiders. So why am I so scared of spiders? Fear is one of my emotions, and emotions are incredibly complex things. How could we ever hope to understand them? (BABY GURGLES, LAUGHS) This is BabyX, and she's helping scientists unravel the mysteries of how our brains work. She's one of the most advanced brain simulations in the world, and she's enjoying playing a peekaboo game with me. Over the course of this series, BabyX is going to help us see how our brains shape and influence every aspect of our lives. Now, at first glance, she may look like just a very clever animation, like you would see in a movie or a video game. But BabyX is so much more than that. In a movie or a video game, we watch the animation. BabyX watches us. Over here. Hey, Baby. That's it. (GURGLES) Peekaboo! (LAUGHS) What's happening here is that BabyX is responding very much like a real baby would. Boo! (LAUGHS) She gets a fun surprise, and that manifests as joy. But where did she come from, and how is she going to help us figure out the mysteries of the brain? BabyX is literally the brainchild of computer scientist and two-time Oscar winner Mark Sagar. Together with his team of neuroscientists, psychologists, engineers and programmers, they've built BabyX. Mark, how did you come to build something as complicated as BabyX? Well, I was always interested in... in the brain and the mind. And I was also interested in, you know, human simulation, and interested in human behaviour in general. So I was thinking, 'How can I put together all these things that I've been interested in?' But the reason to make it a baby, I just happened to have a real baby lying around. My daughter, at that time, that it was modelled on, was about 3 months. And so then I thought, OK, I'll try to scan the baby. So I built a scanner at home when she was asleep and then started creating the first geometry to then start putting the first brain models in. And so the strange thing is that we're sitting here talking now, and BabyX is over there, and she's listening and watching us as well. That's right. Yeah. You can call her. Hey, over here. (GIGGLES) (LAUGHS) So, what is BabyX? It's a virtual infant simulation. What we're trying to do is build a Lego-like system which can encapsulate models of` neuroscience models, models of human behaviour, models of social interaction and learning. It's trying to create the elements which put together aspects of what make something lifelike. The only way to do that is to give it a brain and sensory systems, and so forth. And so that was the sort of next step in what to do in simulating` doing human simulation. To understand the absolutely awesome power of the brain and its remarkable ability to adapt to any situation, we can look to an Australian teenager. Karley Miller was having seizures daily, and they were bad. How bad did it get, when you were growing up? It got pretty bad, to the point where I had a nine-and-a-half-hour seizure. I was put in a coma three times, to sustain my life. When she was 15, a neurosurgeon came up with an incredible idea ` to remove half of her brain. In that moment, it was just Mum and I, and we looked at each other. We were pretty shocked, and we were just like, 'What?' The surgeon's words were, 'Karley, with simple surgery, I can cure you.' And Mum and I were speechless. We just looked at each other. We were like, 'Simple surgery?' It sounded like complicated surgery. But I wasn't gonna live my life... knowing that one of my seizures was going to kill me. So I decided to take a leap of faith and trust my life in the hands of a neurosurgeon. Nobody could be certain what would happen if they took out half of Karley's brain. It was possible she could die. When I got back down to ICU, you were all wired up and lying there, still quite lifeless. But you hadn't spoken, so we were thinking, can you understand? You know, do you know what's going on?' And I was telling you about the driers at Ronald McDonald House. Yeah. And when I started telling you about the driers, and that it wouldn't work, and this, that and the other, all of a sudden, you opened your eyes and you just said, 'Did you push the start button, Mum?' (LAUGHS) I remember that clearly. Do you remember that? I remember that clearly. Yeah. I'll never forget it. Because then I stood there and I think, if you remember rightly, I was crying` You were howling. Howling. Like, that really ugly crying. Karley survived because of the brain's plasticity ` its ability to change. In Karley's case, she has literally had half of her brain removed, so most people would think that she would lose some memory, that she would lose some movement, but she hasn't. Why is that? Well, if they came to me and took out half of my` one of my hemispheres, cortical hemispheres, that's exactly what would happen ` there'd be immense impairments. But the fact that this disorder has been going on for quite a long time, through childhood, when the brain is particularly plastic and particularly able to learn new information, then actually the memories haven't been stored in that damaged hemisphere. And that's evident, because they're still there when that hemisphere has been removed. In a way, it sounds incredible. It actually is incredible. But whatever the normal brain tissue is, and wherever it is, it can take over functions, particularly if it's happening early in life. Half of Karley's brain was damaged from birth, and, because of the plastic nature of the brain, it wired all the functions it needed into the good side. When the surgeon removed the misfiring side, all that was lost was the constant seizures. I'm living proof that you can live with half a brain. Karley illustrates the power and the ability of the brain to change and adapt. But if the brain's trapped inside our skull, floating in fluid, what do our senses do to lend a helping hand? Garnier Fructis Hair Food, to nourish hungry hair. 98% natural, no parabens, with superfruits, instantly absorbed with three ways to enjoy - as a conditioner, mask or leave-in. For healthy hair: Choose yours. Garnier. * (WHIMSICAL MUSIC) This is Kevin. He's a tuatara, and they've been around since the dinosaurs. So clearly their small brains have served them quite well. What's interesting is that the oldest part of the human brain is also known as the reptilian brain, and that's because it does pretty much the same stuff as Kevin's brain. It's responsible for hunger, breathing and fear ` the stuff that keeps us alive. But we've got a lot more inside our skulls than Kevin here. We've got the mammalian parts of our brain, which are responsible for feelings and emotions, and the cortex, which does our thinking. So Kevin here is never going to feel sadness or embarrassment. But experts reckon that humans have something like 34,000 different emotions. So what's the point of them? (PLAYFUL MUSIC) Emotions are clearly expressed on our faces, and they're universal. There are seven major emotions. (BALLOON POPS) (BALLOON POPS) We need emotions to survive. Emotions act as signposts, to tell us what's important. If we think about the world, there are a million things I could be paying to at any time. Emotions tell me which are the ones that are most useful or most valuable to pay attention to. Emotions help me store the memories that are going to be most important for my future decision-making or survival. BabyX isn't an animation. She's a virtual human, and all of the behaviours are generated by neural networks. And she can actually help us see emotions. She watches and listens to what I do and makes her own decisions in real time about how to respond. And because I've been talking to you and not to her, she's starting to get upset. And so, just like a real baby, I have to calm her down. (CRIES) That's it. It's all fine. That's it. Little smile. There you go. (GIGGLES) Good girl. BabyX is driven by a virtual nervous system. It controls her breathing rate, her heartbeat, her facial expressions, and we can even see her facial nerves. Deeper still is the virtual brain which drives it all. Her brain triggers the production of cortisol, because she's upset and stressed. BabyX is the result of combining neuroscience research from all around the world and shows how sophisticated our knowledge of the human brain has become. (INTRIGUING MUSIC) We used to think our brains worked a bit like this ` imagine this building represents my brain. If I see a spider, then the spider parts of my brain light up. And if I see Jennifer Aniston, then the Jennifer Aniston parts of my brain light up. And it is a little bit like that, because certain areas of our brain do seem to be responsible for particular functions. So this bit does smell... and this bit does taste. But it's way more complicated than that. Your brain has 86 billion neurons, and each neuron has 10,000 connections to other neurons, which means you have something like 100 trillion connections. And that means that the best analogy for the brain is actually the universe. There are more connections in your brain than there are galaxies in the known universe and stars in the Milky Way. I'm going to meet distinguished professor Sir Richard Faull. He's been studying the brain for over four decades and is considered an international expert in the field. We know a lot, and yet we know very little. There is so much new to find out... about how... the brain enables us to read, to write, to see a picture,... to store a memory, to create an idea, to have love and all the rest of it. We are so primitive in our understanding, I say, if you are a neuroscientist, you're going to have a job for life. But one thing that has profoundly advanced our understanding of the brain is the MRI machine. Morning, Nigel. Anna. Hi, Anna. Let's just do a final check before we bring you in the room. Definitely no pacemaker? No. No injury to your eye with metal fragments? Nope. The MRI machine uses powerful magnets and radio waves to produce a detailed scan of the brain. Neuroscientists use this to look inside the human brain. I'm going to see where my memories are kept. (MOTOR WHIRRS) The MRI was invented 40 years ago and is now one of the most important tools in neuroscience. Previously, we could only look at the brains of people who'd died or people that experienced traumatic brain injuries or illnesses. Hi, Nigel, can you hear me OK? Yep. We're about to do the motor task, OK? So when you see a fixation cross, do nothing, but when you see a zero or a circle, if you can tap your right hand. Now we can look inside healthy, functioning brains and watch what happens in real time as it performs different tasks. When you see a picture of yourself, generate a very specific memory from your past. The MRI machine shows my brain responding to photos from my past. You can actually see my hippocampus lighting up ` a structure deep in the brain associated with memory. Memories are one of the important sources of data your brain uses to help you react to things happening around you. We use things that happened to us in the past to try and predict what's about to happen. But those memories can only do half the job. The only way that our brains can learn about the outside world are through our senses ` sound, sight, smell, touch and taste. And then it has to filter all of that information through our memories, to try to figure out what's going on and what it should do next. Right now, my brain is getting a lot of tiger-related sensory information. (TIGER GROWLS) But it's also getting a whole bunch of fence-related sensory information, and it's combining all of that to tell me that, really, I've got nothing to worry about. So how does our brain utilise all of that information that's coming in from our senses? Our senses literally tell the brain what's out there. But what happens when they find things in the world that our brain has never encountered? We know from our memory that milk is white. Given we use our senses to verify things in the real world, what happens if we offer people grey milk? So this is our little drink. What are your initial... thoughts about that? It looks a bit funny. Would you like to taste that? It doesn't look very appetising. Why is it grey? It's a little grey. Oh, well, a grey green is not an appealing colour. Our senses send information to the brain which figures out something's not right here. Perhaps this grey liquid is poisonous. Will you have some first? (CHUCKLES) After we see the grey milk, our brain asks for more data ` for the nose for the smell it or, for the braver ones, to use taste. This new information is then returned to the brain for evaluation. It's milk. It... What? Our sense of taste sends massive amounts of data to the brain ` stuff we're not even aware of. This miso is salty, and that gives my brain important information about the level of electrolytes, minerals and water. The rice tastes slightly sweet, and that's all about carbohydrates. The tofu tastes of umami, and that tells my brain that there's some protein on the way. The green tea is bitter and the soy sauce is sour. And back in the day, that would have been a warning, because lots of poisonous plants are either bitter or sometimes sour, and that's why you throw up if you have stuff that's too bitter. Like all of our senses, taste sends information to the brain so it can work on its most important job ` keeping us safe from harm. All right, Marie, so, I'm going to do a very simple thing. I'm just going to use these two brushes... So, I'm just going to brush your finger like so. And all I want you to do is just pay attention to the feeling of the brush against your finger. And just keep watching the brush. And this strange experiment shows how our brain relies on our senses. It's a pretty strange sensation, isn't it? It's getting weird now, yeah. We've created a scenario that our participants' brains have never come across. The brain works hard to figure out what's going on. One of the senses its using is proprioception. This is the same sense that allows you to touch your nose with your eyes closed. (LAUGHS) The brain is being sent mixed messages. It can see a hand being stroked, and it feels the hand being stroked, but it mixes the two messages and comes up with a faulty result. Feeling a bit of affinity with this hand, actually. Our brain is convinced that the fake hand in front of us is our actual hand. (BOTH LAUGH) Floating in the dark, inside your skull, your brain is worried for a second. (LAUGHS) Is that weird? Yeah. Is there a moment of alarm when I do that? But then new data arrives from the senses ` there was no pain. And the brain uses memory to explain the lack of pain, recalling the circumstances of the fake hand. Your brain has instantly built a new and accurate picture of the world ` one that will hopefully keep you safe. But our newborn brain starts off without any of these skills. How does it actually develop? * How does our brain develop? Well, we know we're born with our full set of neurons ` 86 billion. But our brain gets four times bigger over our life. And why is that? Well, it's because of the increasing connections between the neurons, called synapses, which make the brain bigger. Children under the age of 3 make 7000 new synapses a second. So, what happens to them all? How come it doesn't all end up a great tangled mess? Strangely, our brains work much the same way as this field of tangled weed. So, if this was a baby's brain and it wanted to move its hand, it would have to get that thought from this part of its brain all the way over to the motor part of its brain, way over there. And it does that through a combination of wearing in a new path and pruning the synapses that it doesn't need. Now, at first, it's slow and hard going, because there isn't a clear path, and there's a lot of tangled stuff to fight through. When we learn to do a new thing, our brain has to make a new path and clear old synapses. But as the messages go backwards and forwards, something interesting starts to happen. It gets easier and easier for the message to travel between these two parts of the brain because they effectively create a path. The connections between each cell in the pathway are strengthened, and the message can travel faster and easier. The baby is learning a new skill. Essentially, cells that fire together wire together. And the connections we don't need are simple pruned and disappear, which is why it's so important for babies to interact with their caregivers and with the world. That process of wiring in useful paths and pruning the synapses they don't need is crucial to their development. But what happens to a developing brain if, instead of being nurtured, it's neglected? There's a very famous psychological experiment called the still face experiment. And it shows in a simple but quite striking way what happens if you stop interacting with a baby even for a few seconds. There we are. Happy baby. That's it ` nice and smiley. Smiley, smiley. It's all good. There we are. And now I let my face go completely still. (SUSPENSEFUL MUSIC) BabyX shows us how a lack of interaction can make us feel. There you are. It's fine. Happy, happy. Smiling again. It's all good. Happy baby. There we are. Little smiley face. (GIGGLES) There we are. Now, obviously isn't not gonna harm a baby if you stop interacting for a few seconds. But what happens if you neglect a baby for years? So, if children have an attentive and interactive caregiver, then those social circuits are constantly reinforced. But if they're neglected for long periods of time, then they effectively become desensitised to social interaction. It's like they're a flat battery. I'm going to simulate the effect of years of neglect on BabyX's brain ` something we wouldn't want to do in the real world. That's it. There we go. BabyX no longer reacts to me. The impact of neglect is complex and can affect areas responsible for memory, self-control and emotions. Our brains change the most in the first three years of our lives. But the next major change happens around puberty, and insurance companies recognised this before neuroscience got there. They saw that the evidence showed teens took more risks. Do you ever make risky decisions? Do you ever take risks? It really just depends on the situation. Like, usually I like to play it safe. I'd like to make sure that, like, it's not gonna result in a bad consequence. When you do take a risk, does it make you feel good or bad? I mean, in the moment, it does make me feel good, and I do get that rush of adrenaline. But if it's something that I wasn't, like, 100% wanting to do, then I will overthink it and I won't feel that good afterwards. The brain is fully developed, but there's an intense period of pruning and strengthening ` in evolutionary terms, getting the adolescent ready to set out on her own. What we previously thought was that the teen's decision-making part of their brain wasn't properly formed, so they weren't able to properly evaluate risk. But it turns out that's wrong. The latest evidence tells a different story. Teens understand risk as well as adults. But they do take more risks. So why? Well, one theory is their nucleus accumbens, their pleasure centre, is the biggest it's ever going to be. They do know what they're doing. It's just that everything feels so good. They get waves of dopamine after an ice cream, sex, drinking with friends. The pleasure centre is excited when they take risks with friends. They're rewarding each other for trying new, grown-up things, practising for leaving the nest. But when they're driving with their parents, their pleasure centre lights up when they follow the rules, because their parents are pleased for them when they slow down for the orange light. The brain has finished most of its development by age 25, and everything is working at full speed. But how exactly does it work? How do we do something as simple as recognising someone? Oh, it's my daughter. * It's pretty tiring being your brain. Your brain is only 2% of your body weight, but it consumes 20% of your energy, which is a lot, so it's always looking for shortcuts. Now, most of the time, we don't even notice these. But occasionally we get to peek behind the curtains to see what's really going on. This square has some black dots. But, at a glance, you can probably only see a few of them. Your brain doesn't bother to draw them, and saves energy by assuming a pattern. But you can see all 12 when I point them out. One, two, three, four, five, six, seven, eight, nine, 10, 11, 12. Our brains are always looking for patterns to save energy. And a recent discovery suggest that energy-saving drive applies to recognising faces too. Our phones can recognise faces ` even gorilla faces ` using some facial-recognition code called an algorithm. But could our brains work in exactly the same way as our phones? Recently, scientists showed monkeys this picture of a face. And then they measured the activity in neurons in the facial-recognition part of the monkeys' brains. The neuroscientists created photos using just the signals from those neurons and, incredibly, they were almost identical to the face the monkey was looking at. The scientists were literally mind reading. And when you really think about that, it is astounding. What this seems to show is that, just like our phones, our brains use a facial-recognition algorithm. And it also seems to show that we use just 200 of our 100 billion neurons to recognise and recreate any face in the world. A key feature of the human visual system is that it's not a single general-purpose machine that handles all kinds of visual information. But, rather, it's a collection of many, many little systems ` subsystems, you call it. And each of these subsystems is specialised for handling a particular part of the visual world. So for a long time we knew that there is a subsystem for processing motion. Another one is for processing colour. More recently, we've learned that there are subsystems for recognising special kinds of objects. Professor Doris Tsao, an American scientist, made this breakthrough. There's about 200 neurons that she studies. These neurons, they're like a concert. So they sing a song together. And by singing a particular song, they can basically create an image of any face you can imagine by combining, mixing and matching the right facial features. And so that study is a big deal, because it's the first one that gives us a pretty precise description of how faces are actually encoded in the brain. Taylor? But what happens if that algorithm doesn't work? In Social Studies, she sits there. Tena koe, Gabby. Behind you. Oh, phew. Teacher Joe Tapper suffers from prosopagnosia. Joe, what's your understanding of prosopagno`? Pro`? I can't even say it. We just call it face blindness. Face blindness? Prosopagnosia. Yeah, face blindness. Basically, the part of the brain that's responsible for face recognition doesn't work. In class, when you've got lots of kids and they're all wearing the same clothes, how do you recognise students in your class? (CHUCKLES) I don't. I really don't. I fake it. I notice who's got earrings. I look at people's ears ` their earlobes. I get you mixed up with Georgia, but you're Elizabeth. And I know it's you, Jade, cos you're wearing jade. And I looked at your bag before. Literally is just that central human face ` that's the bit that doesn't stick. Yeah, making sense of the human face. There's something in the processing that just doesn't happen as it should do. And it's such a tiny, fine, delicate thing. So if we were to pass in the supermarket tomorrow, does that mean that you wouldn't recognise me? Well, Nigel, I have to be honest. You have some distinctive ears. They're beautifully formed. The camera crew are just having quiet hysterics there. (LAUGHTER) When you see your own reflection, do you recognise your own face? I don't always recognise myself. And I remember, back in the '80s, I got a perm, a spiral perm. And I kept looking, ever shop window. I just had to keep looking. I mean, I wonder too, sometimes, if this is why I've got long hair. Because it's really distinctive ` that's me. That's the hair. That's something that's really strong for me ` your hair, your ears, your jewellery, the things around the face, I recognise. So, do you have a problem recognising objects or pets? No. No. So there's something about the human face. There must be something really special in our brains that is the way that we identify human faces. If the facial-recognition study done with monkeys is correct, then perhaps Joe's facial-recognition algorithm has some errors somewhere in those 200 highly specialised neurons. One description that is used by some people with prosopagnosia is that it's like looking at a face upside-down. So you know that it's a face. You have access to all the same information as when the face is right-side-up. But it's really hard to recognise who owns the face. All right, Chris, I'm gonna show you some photographs of people, and you have to tell me if you know who they are. No. Hmm,... nope. Oh, Hillary Barry. No. Um, Toni Street. Nope. Oh! (CHUCKLES) You. (BOTH LAUGH) Oh, that's Jenna. (LAUGHS) My niece. No. Sure? Yep. Oh, it's my daughter! (LAUGHS) Your brain has a map of faces,... Mm. ...but it bases that on the very reasonable assumption that the face is right-way-up. Yeah. And so when it encounters the upside-down face, it applies the same map, and it just goes, 'Flick, flick, flick. I don't recognise any of these people.' Yeah, correct. But as soon as you do that, it goes, 'Oh, yeah. Clunk. I know exactly who that is.' So we know how our brain develops, the purpose of emotions, what our senses do. But is there a bit in the brain that makes you you? * The first question in figuring out what makes you you is a big one ` are the brains of males and females different? A very popular book from the '90s reckoned that men are from Mars and women are from Venus. The theory is that men and women's brains are very different. And if you walk into a toy store, you can find evidence which seems to support that theory. This is the boys' aisle of toys, which is mainly cars and trucks and Nerf guns and war toys. And this is the aisle for girls. It's all pink and fluffy stuff and dolls ` not a single gun or truck in sight. (TINKLY MUSIC) Does neuroscience back this up? Are boys' and girls' brains different? It actually turns out that when you look at younger children ` so, up to age of about 3 ` and you put them in a lab setting, and have a range of boy toys and girl toys and gender-neutral toys all around, you actually find that there's a huge amount of overlap at that age, in what kind of toys kids will play with. You often get boys playing with girl toys, girls playing with boy toys. Dr Cordelia Fine is one of the world's foremost experts on gender in the brain. There would be some people who would say boys are born with a tendency to be dominant, risk-taking, competitive; girls are born with a tendency to be more nurturing and to care more about their appearance, and all that we're doing in gendered toy marketing is really just sort of enhancing or developing those sort of initial predispositions. There would be other people ` and I include myself in this ` who say, look, the scientific data is really quite unclear on that point. There are lots of reasons to think that that isn't the case. There is one definite difference between male and female brains. The male brain, on average, is larger. So, what does that mean? We know we have 20g of brain per kilogram of body mass, generally speaking. And so differences in body weight ` of muscle mass and bone mass ` are reflected in differences of whole-brain size. So brain size does not equal intellectual capacity. So, if you look at a brain, you can't tell whether it's a male brain or female from the outside. You can't tell whether it was an intelligent person who was an atomic physicist or whether the person was a carpenter or a netball player or whatever. You cannot tell that. We're still very early on in our journey of understanding how properties of the brain translate into behaviour or how we think, how we feel. So we have to be extremely careful not to just project gender stereotypes on to those ambiguous findings. It's generally agreed that trying to separate whether nature or nurture makes boys boys and girls girls is as pointless as arguing whether a cake is made out of flour or sugar. So what is it that makes you you? If I could only answer this question, I would be getting the Nobel Prize, I'm sure. It's so complicated, but so incredibly fantastic that each person is a different personality. Every single person on earth ` there's some people more similar to others ` but there is a total diversity, and that is one of the most unique things, I think, about human life. Personality is an incredibly complicated thing. We know that it's made inside our brains, but how and where? In reality, there is no personality section of your brain. It's probably more accurate to think of it as different parts of your brain which all contribute to the final product we think of as personality. One way to think about this incredibly complex sequence of interactions inside our brain is in terms of sensitivities. So, for example, if you are an introvert, then you're more sensitive to the negative effects of being around people. And if you're an extrovert, then you're more sensitive to the positive effects. So what'll happen if I take BabyX and make her overly sensitive to surprises? What if I make her really afraid of sudden and unexpected events? Woof! Woof, woof, woof! Ruff-ruff-ruff-ruff-ruff! 'If BabyX's personality was like this,...' There you are. It's fine. Happy, happy. '...highly sensitive to sudden and unexpected events, 'she might look for more certainty and less risk throughout her life.' But what happens if I make her less sensitive to this? Ruff-ruff-ruff-ruff! Ruff-ruff-ruff-ruff-ruff! Ruff-ruff-ruff! Ruff-ruff-ruff! 'How much of our personality is shaped by our genes, 'and how much of it is about the things which happen to us along the way?' Ashleigh, Olivia and Kimberly are identical triplets. And so if personality came just from our genes, we'd expect these three to be all the same. Hello. What's your name? My name's Ashleigh Parkinson. Hello. Could you tell me what your name is? (INDIAN MUSIC) Sure. Olivia Parkinson. What's your name? My name is Kimberly 'Princess' Parkinson! (PEOPLE CHATTER) Whoa! That is a way-cool name, eh? # Do-do-do-do-do! # When they were young, their parents saw minor differences in their personalities. But, as they grew, they became more and more different from each other. We had the same friend groups growing up, and then when we got to intermediate was when we really took our own sort of pathways. So we found out our interests and, yeah. (ALL CHEER) You know, my sister got in with the nerd herd and then the other sister got in with the sport-o crew, and then I got in with my little... other crew. Kim would do` her friends were sporty too, but they'd do a bit more partying and stuff as well as that. A lot of the stuff that I got into was because of my friends. I wasn't just like randomly one day, 'I really need to start partying.' Some of the girls would be like, 'Let's drink when my parents are away.' And I was like, 'Oh, that's badarse. Let's do that.' How are you different to your sisters now? How we spend our time and what we value in life ` what actually fulfils us. Olivia gets up at 5, and sometimes I'll come home at 5. (LAUGHS) That's kind of like the difference, I suppose. Olivia is a dedicated Hare Krishna. Ashleigh's the more sporty one. (CHUCKLES) More gentle, caring. Kimberly's more ` I don't want to say 'materialistic' cos it sounds like I'm bagging, but you know what I mean ` like, pursuing success through job and career and social circles. Yeah, I don't take life as seriously, I don't think. Kind of like two different ends of the spectrum, eh, Kim and Liv, and then I'm kind just in the middle. At its most simplistic level, personality is simply patterns of behaviour we repeat. For example, Olivia regularly goes to Hare Krishna meetings, and so her personality would include the description 'spiritual'. And we now know our personality is the result of the interaction between nature and nurture. Does everything that happens make us who we are? To some degree, yes. So some things are going to be more important than others. Some things are entirely trivial and do not matter and all in determining who you are. But other things are very important in determining who you are, to the extent that I would not be the same person that I am if, for example, we didn't emigrate to New Zealand. That's a big factor in determining the kind of person than I've become. Those kinds of big events or important factors in one's life have a strong impact on the kind of person that you become. The triplets may have begun their lives with the same genes, but over the course of their lives, they've created their own identities. Their brains, like all of ours, may look the same, but they've each forged their own individual pathways through all those trillions of synapses as a result of the lives that they've lived. And you've also created your own unique brain. Those trillions of pathways you carve through your plastic brain every single day of your life, well, that's what makes you you. Captions by James Brown www.able.co.nz Captions were made with the support of NZ On Air.