[Script Info]
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[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.69,0:00:03.58,Default,,0000,0000,0000,,Fifteen years ago, it was widely assumed
Dialogue: 0,0:00:03.58,0:00:05.63,Default,,0000,0000,0000,,that the vast majority of brain development
Dialogue: 0,0:00:05.63,0:00:08.61,Default,,0000,0000,0000,,takes place in the first few years of life.
Dialogue: 0,0:00:08.61,0:00:11.32,Default,,0000,0000,0000,,Back then, 15 years ago, we didn't have the ability
Dialogue: 0,0:00:11.32,0:00:13.94,Default,,0000,0000,0000,,to look inside the living human brain
Dialogue: 0,0:00:13.94,0:00:16.98,Default,,0000,0000,0000,,and track development across the lifespan.
Dialogue: 0,0:00:16.98,0:00:20.14,Default,,0000,0000,0000,,In the past decade or so, mainly due to advances
Dialogue: 0,0:00:20.14,0:00:21.94,Default,,0000,0000,0000,,in brain imaging technology
Dialogue: 0,0:00:21.94,0:00:24.89,Default,,0000,0000,0000,,such as magnetic resonance imaging, or MRI,
Dialogue: 0,0:00:24.89,0:00:28.01,Default,,0000,0000,0000,,neuroscientists have started to look inside the living
Dialogue: 0,0:00:28.01,0:00:30.43,Default,,0000,0000,0000,,human brain of all ages, and to track changes
Dialogue: 0,0:00:30.43,0:00:33.30,Default,,0000,0000,0000,,in brain structure and brain function,
Dialogue: 0,0:00:33.30,0:00:36.98,Default,,0000,0000,0000,,so we use structural MRI if you'd like to take a snapshot,
Dialogue: 0,0:00:36.98,0:00:40.04,Default,,0000,0000,0000,,a photograph, at really high resolution of the inside
Dialogue: 0,0:00:40.04,0:00:43.26,Default,,0000,0000,0000,,of the living human brain, and we can ask questions like,
Dialogue: 0,0:00:43.26,0:00:45.70,Default,,0000,0000,0000,,how much gray matter does the brain contain,
Dialogue: 0,0:00:45.70,0:00:47.50,Default,,0000,0000,0000,,and how does that change with age?
Dialogue: 0,0:00:47.50,0:00:51.22,Default,,0000,0000,0000,,And we also use functional MRI, called fMRI,
Dialogue: 0,0:00:51.22,0:00:54.61,Default,,0000,0000,0000,,to take a video, a movie, of brain activity
Dialogue: 0,0:00:54.61,0:00:57.48,Default,,0000,0000,0000,,when participants are taking part in some kind of task
Dialogue: 0,0:00:57.48,0:01:00.37,Default,,0000,0000,0000,,like thinking or feeling or perceiving something.
Dialogue: 0,0:01:00.37,0:01:03.14,Default,,0000,0000,0000,,So many labs around the world are involved in this kind
Dialogue: 0,0:01:03.14,0:01:05.37,Default,,0000,0000,0000,,of research, and we now have a really rich
Dialogue: 0,0:01:05.37,0:01:08.89,Default,,0000,0000,0000,,and detailed picture of how the living human brain develops,
Dialogue: 0,0:01:08.89,0:01:11.96,Default,,0000,0000,0000,,and this picture has radically changed the way
Dialogue: 0,0:01:11.96,0:01:14.59,Default,,0000,0000,0000,,we think about human brain development
Dialogue: 0,0:01:14.59,0:01:17.36,Default,,0000,0000,0000,,by revealing that it's not all over in early childhood,
Dialogue: 0,0:01:17.36,0:01:20.07,Default,,0000,0000,0000,,and instead, the brain continues to develop
Dialogue: 0,0:01:20.07,0:01:24.12,Default,,0000,0000,0000,,right throughout adolescence and into the '20s and '30s.
Dialogue: 0,0:01:24.12,0:01:28.10,Default,,0000,0000,0000,,So adolescence is defined as the period of life that starts
Dialogue: 0,0:01:28.10,0:01:32.49,Default,,0000,0000,0000,,with the biological, hormonal, physical changes of puberty
Dialogue: 0,0:01:32.49,0:01:35.78,Default,,0000,0000,0000,,and ends at the age at which an individual attains
Dialogue: 0,0:01:35.78,0:01:39.23,Default,,0000,0000,0000,,a stable, independent role in society.
Dialogue: 0,0:01:39.23,0:01:41.02,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:01:41.02,0:01:43.78,Default,,0000,0000,0000,,It can go on a long time. (Laughter)
Dialogue: 0,0:01:43.78,0:01:46.80,Default,,0000,0000,0000,,One of the brain regions that changes most dramatically
Dialogue: 0,0:01:46.80,0:01:50.07,Default,,0000,0000,0000,,during adolescence is called prefrontal cortex.
Dialogue: 0,0:01:50.07,0:01:53.04,Default,,0000,0000,0000,,So this is a model of the human brain,
Dialogue: 0,0:01:53.04,0:01:55.92,Default,,0000,0000,0000,,and this is prefrontal cortex, right at the front.
Dialogue: 0,0:01:55.92,0:01:58.43,Default,,0000,0000,0000,,Prefrontal cortex is an interesting brain area.
Dialogue: 0,0:01:58.43,0:02:01.55,Default,,0000,0000,0000,,It's proportionally much bigger in humans than
Dialogue: 0,0:02:01.55,0:02:05.17,Default,,0000,0000,0000,,in any other species, and it's involved in a whole range of
Dialogue: 0,0:02:05.19,0:02:08.46,Default,,0000,0000,0000,,high level cognitive functions, things like decision-making,
Dialogue: 0,0:02:08.46,0:02:10.55,Default,,0000,0000,0000,,planning, planning what you're going to do tomorrow
Dialogue: 0,0:02:10.55,0:02:13.29,Default,,0000,0000,0000,,or next week or next year, inhibiting
Dialogue: 0,0:02:13.29,0:02:15.96,Default,,0000,0000,0000,,inappropriate behavior, so stopping yourself saying
Dialogue: 0,0:02:15.96,0:02:18.88,Default,,0000,0000,0000,,something really rude or doing something really stupid.
Dialogue: 0,0:02:18.88,0:02:20.66,Default,,0000,0000,0000,,It's also involved in social interaction,
Dialogue: 0,0:02:20.66,0:02:23.78,Default,,0000,0000,0000,,understanding other people, and self-awareness.
Dialogue: 0,0:02:23.78,0:02:26.84,Default,,0000,0000,0000,,So MRI studies looking at the development of this region
Dialogue: 0,0:02:26.84,0:02:29.30,Default,,0000,0000,0000,,have shown that it really undergoes dramatic development
Dialogue: 0,0:02:29.30,0:02:32.24,Default,,0000,0000,0000,,during the period of adolescence.
Dialogue: 0,0:02:32.24,0:02:35.20,Default,,0000,0000,0000,,So if you look at gray matter volume, for example,
Dialogue: 0,0:02:35.20,0:02:40.04,Default,,0000,0000,0000,,gray matter volume across age from age four to 22 years
Dialogue: 0,0:02:40.04,0:02:42.37,Default,,0000,0000,0000,,increases during childhood, which is what you can see
Dialogue: 0,0:02:42.37,0:02:46.12,Default,,0000,0000,0000,,on this graph. It peaks in early adolescence.
Dialogue: 0,0:02:46.12,0:02:48.68,Default,,0000,0000,0000,,The arrows indicate peak gray matter volume
Dialogue: 0,0:02:48.68,0:02:52.15,Default,,0000,0000,0000,,in prefrontal cortex. You can see that that peak happens
Dialogue: 0,0:02:52.15,0:02:55.66,Default,,0000,0000,0000,,a couple of years later in boys relative to girls,
Dialogue: 0,0:02:55.66,0:02:57.50,Default,,0000,0000,0000,,and that's probably because boys go through puberty
Dialogue: 0,0:02:57.50,0:02:59.75,Default,,0000,0000,0000,,a couple of years later than girls on average,
Dialogue: 0,0:02:59.75,0:03:03.19,Default,,0000,0000,0000,,and then during adolescence, there's a significant decline
Dialogue: 0,0:03:03.19,0:03:05.87,Default,,0000,0000,0000,,in gray matter volume in prefrontal cortex.
Dialogue: 0,0:03:05.87,0:03:07.90,Default,,0000,0000,0000,,Now that might sound bad, but actually this is
Dialogue: 0,0:03:07.90,0:03:11.05,Default,,0000,0000,0000,,a really important developmental process, because
Dialogue: 0,0:03:11.05,0:03:15.15,Default,,0000,0000,0000,,gray matter contains cell bodies and connections
Dialogue: 0,0:03:15.15,0:03:18.61,Default,,0000,0000,0000,,between cells, the synapses, and this decline
Dialogue: 0,0:03:18.61,0:03:21.35,Default,,0000,0000,0000,,in gray matter volume during prefrontal cortex
Dialogue: 0,0:03:21.35,0:03:24.24,Default,,0000,0000,0000,,is thought to correspond to synaptic pruning,
Dialogue: 0,0:03:24.24,0:03:26.57,Default,,0000,0000,0000,,the elimination of unwanted synapses.
Dialogue: 0,0:03:26.57,0:03:29.70,Default,,0000,0000,0000,,This is a really important process. It's partly dependent
Dialogue: 0,0:03:29.70,0:03:32.83,Default,,0000,0000,0000,,on the environment that the animal or the human is in,
Dialogue: 0,0:03:32.83,0:03:36.28,Default,,0000,0000,0000,,and the synapses that are being used are strengthened,
Dialogue: 0,0:03:36.28,0:03:38.21,Default,,0000,0000,0000,,and synapses that aren't being used
Dialogue: 0,0:03:38.21,0:03:40.54,Default,,0000,0000,0000,,in that particular environment are pruned away.
Dialogue: 0,0:03:40.54,0:03:43.05,Default,,0000,0000,0000,,You can think of it a bit like pruning a rosebush.
Dialogue: 0,0:03:43.05,0:03:45.89,Default,,0000,0000,0000,,You prune away the weaker branches so that
Dialogue: 0,0:03:45.89,0:03:48.93,Default,,0000,0000,0000,,the remaining, important branches, can grow stronger,
Dialogue: 0,0:03:48.93,0:03:52.85,Default,,0000,0000,0000,,and this process, which effectively fine-tunes brain tissue
Dialogue: 0,0:03:52.85,0:03:55.52,Default,,0000,0000,0000,,according to the species-specific environment,
Dialogue: 0,0:03:55.52,0:03:58.44,Default,,0000,0000,0000,,is happening in prefrontal cortex and in other brain regions
Dialogue: 0,0:03:58.44,0:04:01.99,Default,,0000,0000,0000,,during the period of human adolescence.
Dialogue: 0,0:04:01.99,0:04:05.69,Default,,0000,0000,0000,,So a second line of inquiry that we use to track changes
Dialogue: 0,0:04:05.69,0:04:08.94,Default,,0000,0000,0000,,in the adolescent brain is using functional MRI
Dialogue: 0,0:04:08.94,0:04:12.22,Default,,0000,0000,0000,,to look at changes in brain activity across age.
Dialogue: 0,0:04:12.22,0:04:13.86,Default,,0000,0000,0000,,So I'll just give you an example from my lab.
Dialogue: 0,0:04:13.86,0:04:17.42,Default,,0000,0000,0000,,So in my lab, we're interested in the social brain, that is
Dialogue: 0,0:04:17.42,0:04:21.00,Default,,0000,0000,0000,,the network of brain regions that we use to understand
Dialogue: 0,0:04:21.00,0:04:23.44,Default,,0000,0000,0000,,other people and to interact with other people.
Dialogue: 0,0:04:23.44,0:04:27.20,Default,,0000,0000,0000,,So I like to show a photograph of a soccer game
Dialogue: 0,0:04:27.20,0:04:31.61,Default,,0000,0000,0000,,to illustrate two aspects of how your social brains work.
Dialogue: 0,0:04:31.61,0:04:33.04,Default,,0000,0000,0000,,So this is a soccer game. (Laughter)
Dialogue: 0,0:04:33.04,0:04:35.68,Default,,0000,0000,0000,,Michael Owen has just missed a goal, and he's lying
Dialogue: 0,0:04:35.68,0:04:38.48,Default,,0000,0000,0000,,on the ground, and the first aspect of the social brain
Dialogue: 0,0:04:38.48,0:04:41.44,Default,,0000,0000,0000,,that this picture really nicely illustrates is how automatic
Dialogue: 0,0:04:41.44,0:04:44.49,Default,,0000,0000,0000,,and instinctive social emotional responses are,
Dialogue: 0,0:04:44.49,0:04:47.46,Default,,0000,0000,0000,,so within a split second of Michael Owen missing this goal,
Dialogue: 0,0:04:47.46,0:04:49.27,Default,,0000,0000,0000,,everyone is doing the same thing with their arms
Dialogue: 0,0:04:49.27,0:04:51.07,Default,,0000,0000,0000,,and the same thing with their face, even Michael Owen
Dialogue: 0,0:04:51.07,0:04:52.90,Default,,0000,0000,0000,,as he slides along the grass, is doing the same thing
Dialogue: 0,0:04:52.90,0:04:55.16,Default,,0000,0000,0000,,with his arms, and presumably has a similar
Dialogue: 0,0:04:55.16,0:04:57.14,Default,,0000,0000,0000,,facial expression, and the only people who don't
Dialogue: 0,0:04:57.14,0:05:00.60,Default,,0000,0000,0000,,are the guys in yellow at the back — (Laughs) —
Dialogue: 0,0:05:00.60,0:05:03.14,Default,,0000,0000,0000,,and I think they're on the wrong end of the stadium,
Dialogue: 0,0:05:03.14,0:05:05.44,Default,,0000,0000,0000,,and they're doing another social emotional response
Dialogue: 0,0:05:05.44,0:05:08.07,Default,,0000,0000,0000,,that we all instantly recognize, and that's the second aspect
Dialogue: 0,0:05:08.07,0:05:11.71,Default,,0000,0000,0000,,of the social brain that this picture really nicely illustrates,
Dialogue: 0,0:05:11.71,0:05:15.09,Default,,0000,0000,0000,,how good we are at reading other people's behavior,
Dialogue: 0,0:05:15.09,0:05:17.77,Default,,0000,0000,0000,,their actions, their gestures, their facial expressions,
Dialogue: 0,0:05:17.77,0:05:21.58,Default,,0000,0000,0000,,in terms of their underlying emotions and mental states.
Dialogue: 0,0:05:21.58,0:05:23.36,Default,,0000,0000,0000,,So you don't have to ask any of these guys.
Dialogue: 0,0:05:23.36,0:05:25.90,Default,,0000,0000,0000,,You have a pretty good idea of what they're feeling
Dialogue: 0,0:05:25.90,0:05:28.49,Default,,0000,0000,0000,,and thinking at this precise moment in time.
Dialogue: 0,0:05:28.49,0:05:30.24,Default,,0000,0000,0000,,So that's what we're interested in looking at in my lab.
Dialogue: 0,0:05:30.24,0:05:33.82,Default,,0000,0000,0000,,So in my lab, we bring adolescents and adults into the lab
Dialogue: 0,0:05:33.83,0:05:36.22,Default,,0000,0000,0000,,to have a brain scan, we give them some kind of task
Dialogue: 0,0:05:36.22,0:05:39.51,Default,,0000,0000,0000,,that involves thinking about other people, their minds,
Dialogue: 0,0:05:39.51,0:05:42.41,Default,,0000,0000,0000,,their mental states, their emotions, and one of the findings
Dialogue: 0,0:05:42.41,0:05:45.25,Default,,0000,0000,0000,,that we've found several times now, as have other labs
Dialogue: 0,0:05:45.25,0:05:48.47,Default,,0000,0000,0000,,around the world, is part of the prefrontal cortex called
Dialogue: 0,0:05:48.47,0:05:51.69,Default,,0000,0000,0000,,medial prefrontal cortex, which is shown in blue on the slide,
Dialogue: 0,0:05:51.69,0:05:54.44,Default,,0000,0000,0000,,and it's right in the middle of prefrontal cortex
Dialogue: 0,0:05:54.44,0:05:56.84,Default,,0000,0000,0000,,in the midline of your head.
Dialogue: 0,0:05:56.84,0:06:00.12,Default,,0000,0000,0000,,This region is more active in adolescents when they make
Dialogue: 0,0:06:00.12,0:06:02.25,Default,,0000,0000,0000,,these social decisions and think about other people
Dialogue: 0,0:06:02.25,0:06:05.05,Default,,0000,0000,0000,,than it is in adults, and this is actually a meta-analysis
Dialogue: 0,0:06:05.05,0:06:08.29,Default,,0000,0000,0000,,of nine different studies in this area from labs around
Dialogue: 0,0:06:08.29,0:06:10.99,Default,,0000,0000,0000,,the world, and they all show the same thing, that activity
Dialogue: 0,0:06:10.99,0:06:14.36,Default,,0000,0000,0000,,in this medial prefrontal cortex area decreases
Dialogue: 0,0:06:14.36,0:06:16.81,Default,,0000,0000,0000,,during the period of adolescence.
Dialogue: 0,0:06:16.81,0:06:19.45,Default,,0000,0000,0000,,And we think that might be because adolescents and adults
Dialogue: 0,0:06:19.45,0:06:21.82,Default,,0000,0000,0000,,use a different mental approach, a different
Dialogue: 0,0:06:21.82,0:06:25.24,Default,,0000,0000,0000,,cognitive strategy, to make social decisions,
Dialogue: 0,0:06:25.24,0:06:28.75,Default,,0000,0000,0000,,and one way of looking at that is to do behavioral studies
Dialogue: 0,0:06:28.75,0:06:30.73,Default,,0000,0000,0000,,whereby we bring people into the lab and we give them
Dialogue: 0,0:06:30.73,0:06:33.28,Default,,0000,0000,0000,,some kind of behavioral task, and I'll just give you
Dialogue: 0,0:06:33.28,0:06:36.48,Default,,0000,0000,0000,,another example of the kind of task that we use in my lab.
Dialogue: 0,0:06:36.48,0:06:39.13,Default,,0000,0000,0000,,So imagine that you're the participant in one of our
Dialogue: 0,0:06:39.13,0:06:40.86,Default,,0000,0000,0000,,experiments. You come into the lab,
Dialogue: 0,0:06:40.86,0:06:43.53,Default,,0000,0000,0000,,you see this computerized task.
Dialogue: 0,0:06:43.53,0:06:46.32,Default,,0000,0000,0000,,In this task, you see a set of shelves.
Dialogue: 0,0:06:46.32,0:06:49.14,Default,,0000,0000,0000,,Now, there are objects on these shelves, on some of them,
Dialogue: 0,0:06:49.14,0:06:52.11,Default,,0000,0000,0000,,and you'll notice there's a guy standing behind the set
Dialogue: 0,0:06:52.11,0:06:55.70,Default,,0000,0000,0000,,of shelves, and there are some objects that he can't see.
Dialogue: 0,0:06:55.70,0:06:57.97,Default,,0000,0000,0000,,They're occluded, from his point of view, with a kind of
Dialogue: 0,0:06:57.97,0:07:00.62,Default,,0000,0000,0000,,gray piece of wood.
Dialogue: 0,0:07:00.62,0:07:04.10,Default,,0000,0000,0000,,This is the same set of shelves from his point of view.
Dialogue: 0,0:07:04.10,0:07:07.60,Default,,0000,0000,0000,,Notice that there are only some objects that he can see,
Dialogue: 0,0:07:07.60,0:07:10.05,Default,,0000,0000,0000,,whereas there are many more objects that you can see.
Dialogue: 0,0:07:10.05,0:07:12.24,Default,,0000,0000,0000,,Now your task is to move objects around.
Dialogue: 0,0:07:12.24,0:07:14.60,Default,,0000,0000,0000,,The director, standing behind the set of shelves,
Dialogue: 0,0:07:14.60,0:07:17.35,Default,,0000,0000,0000,,is going to direct you to move objects around,
Dialogue: 0,0:07:17.35,0:07:19.24,Default,,0000,0000,0000,,but remember, he's not going to ask you to move objects
Dialogue: 0,0:07:19.24,0:07:22.96,Default,,0000,0000,0000,,that he can't see. This introduces a really interesting
Dialogue: 0,0:07:22.96,0:07:25.16,Default,,0000,0000,0000,,condition whereby there's a kind of conflict
Dialogue: 0,0:07:25.16,0:07:28.32,Default,,0000,0000,0000,,between your perspective and the director's perspective.
Dialogue: 0,0:07:28.32,0:07:31.56,Default,,0000,0000,0000,,So imagine he tells you to move the top truck left.
Dialogue: 0,0:07:31.56,0:07:33.60,Default,,0000,0000,0000,,There are three trucks there. You're going to instinctively
Dialogue: 0,0:07:33.61,0:07:35.76,Default,,0000,0000,0000,,go for the white truck, because that's the top truck
Dialogue: 0,0:07:35.76,0:07:38.58,Default,,0000,0000,0000,,from your perspective, but then you have to remember,
Dialogue: 0,0:07:38.58,0:07:40.64,Default,,0000,0000,0000,,"Oh, he can't see that truck, so he must mean
Dialogue: 0,0:07:40.64,0:07:43.40,Default,,0000,0000,0000,,me to move the blue truck," which is the top truck
Dialogue: 0,0:07:43.40,0:07:46.04,Default,,0000,0000,0000,,from his perspective. Now believe it or not,
Dialogue: 0,0:07:46.04,0:07:48.99,Default,,0000,0000,0000,,normal, healthy, intelligent adults like you make errors
Dialogue: 0,0:07:48.99,0:07:52.13,Default,,0000,0000,0000,,about 50 percent of the time on that kind of trial.
Dialogue: 0,0:07:52.13,0:07:54.97,Default,,0000,0000,0000,,They move the white truck instead of the blue truck.
Dialogue: 0,0:07:54.97,0:07:58.29,Default,,0000,0000,0000,,So we give this kind of task to adolescents and adults,
Dialogue: 0,0:07:58.29,0:07:59.84,Default,,0000,0000,0000,,and we also have a control condition
Dialogue: 0,0:07:59.84,0:08:03.90,Default,,0000,0000,0000,,where there's no director and instead we give people a rule.
Dialogue: 0,0:08:03.90,0:08:05.82,Default,,0000,0000,0000,,We tell them, okay, we're going to do exactly the same thing
Dialogue: 0,0:08:05.82,0:08:08.66,Default,,0000,0000,0000,,but this time there's no director. Instead you've got to
Dialogue: 0,0:08:08.66,0:08:11.86,Default,,0000,0000,0000,,ignore objects with the dark gray background.
Dialogue: 0,0:08:11.86,0:08:14.56,Default,,0000,0000,0000,,You'll see that this is exactly the same condition, only
Dialogue: 0,0:08:14.56,0:08:17.41,Default,,0000,0000,0000,,in the no-director condition they just have to remember
Dialogue: 0,0:08:17.41,0:08:20.48,Default,,0000,0000,0000,,to apply this somewhat arbitrary rule, whereas
Dialogue: 0,0:08:20.48,0:08:22.16,Default,,0000,0000,0000,,in the director condition, they have to remember
Dialogue: 0,0:08:22.16,0:08:25.70,Default,,0000,0000,0000,,to take into account the director's perspective
Dialogue: 0,0:08:25.70,0:08:29.100,Default,,0000,0000,0000,,in order to guide their ongoing behavior.
Dialogue: 0,0:08:29.100,0:08:32.61,Default,,0000,0000,0000,,Okay, so if I just show you the percentage errors
Dialogue: 0,0:08:32.61,0:08:35.17,Default,,0000,0000,0000,,in a large developmental study we did,
Dialogue: 0,0:08:35.17,0:08:38.73,Default,,0000,0000,0000,,this is in a study ranging from age seven to adulthood,
Dialogue: 0,0:08:38.73,0:08:39.94,Default,,0000,0000,0000,,and what you're going to see is the percentage errors
Dialogue: 0,0:08:39.94,0:08:41.91,Default,,0000,0000,0000,,in the adult group in both conditions,
Dialogue: 0,0:08:41.93,0:08:45.20,Default,,0000,0000,0000,,so the gray is the director condition, and you see
Dialogue: 0,0:08:45.20,0:08:47.77,Default,,0000,0000,0000,,that our intelligent adults are making errors about 50 percent
Dialogue: 0,0:08:47.77,0:08:50.49,Default,,0000,0000,0000,,of the time, whereas they make far fewer errors
Dialogue: 0,0:08:50.49,0:08:52.51,Default,,0000,0000,0000,,when there's no director present, when they just have
Dialogue: 0,0:08:52.51,0:08:55.60,Default,,0000,0000,0000,,to remember that rule of ignoring the gray background.
Dialogue: 0,0:08:55.60,0:08:58.26,Default,,0000,0000,0000,,Developmentally, these two conditions develop
Dialogue: 0,0:08:58.26,0:09:01.19,Default,,0000,0000,0000,,in exactly the same way. Between late childhood
Dialogue: 0,0:09:01.19,0:09:03.43,Default,,0000,0000,0000,,and mid-adolescence, there's an improvement,
Dialogue: 0,0:09:03.43,0:09:06.78,Default,,0000,0000,0000,,in other words a reduction of errors, in both of these trials,
Dialogue: 0,0:09:06.78,0:09:07.90,Default,,0000,0000,0000,,in both of these conditions.
Dialogue: 0,0:09:07.90,0:09:10.18,Default,,0000,0000,0000,,But it's when you compare the last two groups,
Dialogue: 0,0:09:10.18,0:09:12.14,Default,,0000,0000,0000,,the mid-adolescent group and the adult group
Dialogue: 0,0:09:12.14,0:09:15.30,Default,,0000,0000,0000,,where things get really interesting, because there, there is
Dialogue: 0,0:09:15.30,0:09:18.33,Default,,0000,0000,0000,,no continued improvement in the no-director condition.
Dialogue: 0,0:09:18.33,0:09:21.26,Default,,0000,0000,0000,,In other words, everything you need to do in order to
Dialogue: 0,0:09:21.26,0:09:23.97,Default,,0000,0000,0000,,remember the rule and apply it seems to be fully developed
Dialogue: 0,0:09:23.97,0:09:26.50,Default,,0000,0000,0000,,by mid-adolescence, whereas in contrast,
Dialogue: 0,0:09:26.50,0:09:28.90,Default,,0000,0000,0000,,if you look at the last two gray bars, there's still
Dialogue: 0,0:09:28.90,0:09:32.05,Default,,0000,0000,0000,,a significant improvement in the director condition
Dialogue: 0,0:09:32.05,0:09:34.49,Default,,0000,0000,0000,,between mid-adolescence and adulthood, and what
Dialogue: 0,0:09:34.49,0:09:37.86,Default,,0000,0000,0000,,this means is that the ability to take into account someone
Dialogue: 0,0:09:37.86,0:09:41.15,Default,,0000,0000,0000,,else's perspective in order to guide ongoing behavior,
Dialogue: 0,0:09:41.15,0:09:43.41,Default,,0000,0000,0000,,which is something, by the way, that we do in everyday life all
Dialogue: 0,0:09:43.41,0:09:48.01,Default,,0000,0000,0000,,the time, is still developing in mid-to-late adolescence.
Dialogue: 0,0:09:48.01,0:09:50.55,Default,,0000,0000,0000,,So if you have a teenage son or a daughter and you
Dialogue: 0,0:09:50.55,0:09:52.96,Default,,0000,0000,0000,,sometimes think they have problems taking other people's
Dialogue: 0,0:09:52.96,0:09:56.72,Default,,0000,0000,0000,,perspectives, you're right. They do. And this is why.
Dialogue: 0,0:09:56.72,0:10:00.23,Default,,0000,0000,0000,,So we sometimes laugh about teenagers.
Dialogue: 0,0:10:00.23,0:10:04.10,Default,,0000,0000,0000,,They're parodied, sometimes even demonized in the media
Dialogue: 0,0:10:04.10,0:10:07.62,Default,,0000,0000,0000,,for their kind of typical teenage behavior. They take risks,
Dialogue: 0,0:10:07.62,0:10:10.39,Default,,0000,0000,0000,,they're sometimes moody, they're very self-conscious.
Dialogue: 0,0:10:10.39,0:10:12.89,Default,,0000,0000,0000,,I have a really nice anecdote from a friend of mine
Dialogue: 0,0:10:12.89,0:10:15.37,Default,,0000,0000,0000,,who said that the thing he noticed most
Dialogue: 0,0:10:15.37,0:10:18.35,Default,,0000,0000,0000,,about his teenage daughters before and after puberty
Dialogue: 0,0:10:18.35,0:10:20.60,Default,,0000,0000,0000,,was their level of embarrassment in front of him.
Dialogue: 0,0:10:20.61,0:10:23.10,Default,,0000,0000,0000,,So, he said, "Before puberty, if my two daughters
Dialogue: 0,0:10:23.10,0:10:25.36,Default,,0000,0000,0000,,were messing around in a shop, I'd say, 'Hey,
Dialogue: 0,0:10:25.36,0:10:27.11,Default,,0000,0000,0000,,stop messing around and I'll sing your favorite song,'
Dialogue: 0,0:10:27.11,0:10:29.01,Default,,0000,0000,0000,,and instantly they'd stop messing around and he'd sing
Dialogue: 0,0:10:29.01,0:10:32.48,Default,,0000,0000,0000,,their favorite song. After puberty, that became the threat.
Dialogue: 0,0:10:32.48,0:10:34.30,Default,,0000,0000,0000,,(Laughter)
Dialogue: 0,0:10:34.30,0:10:37.77,Default,,0000,0000,0000,,The very notion of their dad singing in public
Dialogue: 0,0:10:37.77,0:10:40.14,Default,,0000,0000,0000,,was enough to make them behave.
Dialogue: 0,0:10:40.14,0:10:41.56,Default,,0000,0000,0000,,So people often ask,
Dialogue: 0,0:10:41.56,0:10:44.20,Default,,0000,0000,0000,,"Well, is adolescence a kind of recent phenomenon?
Dialogue: 0,0:10:44.20,0:10:46.32,Default,,0000,0000,0000,,Is it something we've invented recently in the West?"
Dialogue: 0,0:10:46.32,0:10:48.99,Default,,0000,0000,0000,,And actually, the answer is probably not. There are lots
Dialogue: 0,0:10:48.99,0:10:52.41,Default,,0000,0000,0000,,of descriptions of adolescence in history that sound
Dialogue: 0,0:10:52.41,0:10:54.57,Default,,0000,0000,0000,,very similar to the descriptions we use today.
Dialogue: 0,0:10:54.57,0:10:58.80,Default,,0000,0000,0000,,So there's a famous quote by Shakespeare from "The Winter's Tale"
Dialogue: 0,0:10:58.80,0:11:01.57,Default,,0000,0000,0000,,where he describes adolescence as follows:
Dialogue: 0,0:11:01.57,0:11:04.42,Default,,0000,0000,0000,,"I would there were no age between ten and
Dialogue: 0,0:11:04.42,0:11:07.66,Default,,0000,0000,0000,,three-and-twenty, or that youth would sleep out the rest;
Dialogue: 0,0:11:07.66,0:11:09.75,Default,,0000,0000,0000,,for there is nothing in the between but getting wenches
Dialogue: 0,0:11:09.75,0:11:15.97,Default,,0000,0000,0000,,with child, wronging the ancientry, stealing, fighting." (Laughter)
Dialogue: 0,0:11:15.97,0:11:20.51,Default,,0000,0000,0000,,He then goes on to say, "Having said that, would any
Dialogue: 0,0:11:20.51,0:11:23.65,Default,,0000,0000,0000,,but these boiled brains of nineteen and two-and-twenty
Dialogue: 0,0:11:23.65,0:11:26.15,Default,,0000,0000,0000,,hunt in this weather?" (Laughter)
Dialogue: 0,0:11:26.15,0:11:29.08,Default,,0000,0000,0000,,So almost 400 years ago, Shakespeare was portraying
Dialogue: 0,0:11:29.08,0:11:31.80,Default,,0000,0000,0000,,adolescents in a very similar light to the light that we
Dialogue: 0,0:11:31.80,0:11:35.26,Default,,0000,0000,0000,,portray them in today, but today we try to understand
Dialogue: 0,0:11:35.26,0:11:38.35,Default,,0000,0000,0000,,their behavior in terms of the underlying changes
Dialogue: 0,0:11:38.35,0:11:40.28,Default,,0000,0000,0000,,that are going on in their brain.
Dialogue: 0,0:11:40.28,0:11:43.89,Default,,0000,0000,0000,,So for example, take risk-taking. We know that adolescents
Dialogue: 0,0:11:43.89,0:11:46.22,Default,,0000,0000,0000,,have a tendency to take risks. They do.
Dialogue: 0,0:11:46.22,0:11:48.85,Default,,0000,0000,0000,,They take more risks than children or adults,
Dialogue: 0,0:11:48.85,0:11:51.31,Default,,0000,0000,0000,,and they are particularly prone to taking risks
Dialogue: 0,0:11:51.31,0:11:54.28,Default,,0000,0000,0000,,when they're with their friends. There's an important drive
Dialogue: 0,0:11:54.28,0:11:56.76,Default,,0000,0000,0000,,to become independent from one's parents
Dialogue: 0,0:11:56.76,0:11:59.59,Default,,0000,0000,0000,,and to impress one's friends in adolescence.
Dialogue: 0,0:11:59.59,0:12:02.19,Default,,0000,0000,0000,,But now we try to understand that in terms of
Dialogue: 0,0:12:02.19,0:12:05.18,Default,,0000,0000,0000,,the development of a part of their brain called the limbic system,
Dialogue: 0,0:12:05.18,0:12:07.72,Default,,0000,0000,0000,,so I'm going to show you the limbic system in red
Dialogue: 0,0:12:07.72,0:12:09.59,Default,,0000,0000,0000,,in the slide behind me, and also on this brain.
Dialogue: 0,0:12:09.59,0:12:12.70,Default,,0000,0000,0000,,So the limbic system is right deep inside the brain,
Dialogue: 0,0:12:12.70,0:12:16.43,Default,,0000,0000,0000,,and it's involved in things like emotion processing
Dialogue: 0,0:12:16.43,0:12:19.58,Default,,0000,0000,0000,,and reward processing. It gives you the rewarding feeling
Dialogue: 0,0:12:19.58,0:12:22.88,Default,,0000,0000,0000,,out of doing fun things, including taking risks.
Dialogue: 0,0:12:22.88,0:12:25.24,Default,,0000,0000,0000,,It gives you the kick out of taking risks.
Dialogue: 0,0:12:25.24,0:12:28.29,Default,,0000,0000,0000,,And this region, the regions within the limbic system,
Dialogue: 0,0:12:28.29,0:12:31.71,Default,,0000,0000,0000,,have been found to be hypersensitive to the rewarding
Dialogue: 0,0:12:31.71,0:12:35.48,Default,,0000,0000,0000,,feeling of risk-taking in adolescents compared with adults,
Dialogue: 0,0:12:35.48,0:12:39.18,Default,,0000,0000,0000,,and at the very same time, the prefrontal cortex,
Dialogue: 0,0:12:39.18,0:12:41.45,Default,,0000,0000,0000,,which you can see in blue in the slide here,
Dialogue: 0,0:12:41.45,0:12:44.32,Default,,0000,0000,0000,,which stops us taking excessive risks,
Dialogue: 0,0:12:44.32,0:12:47.72,Default,,0000,0000,0000,,is still very much in development in adolescents.
Dialogue: 0,0:12:47.72,0:12:51.38,Default,,0000,0000,0000,,So brain research has shown that the adolescent brain
Dialogue: 0,0:12:51.38,0:12:54.73,Default,,0000,0000,0000,,undergoes really quite profound development,
Dialogue: 0,0:12:54.73,0:12:58.68,Default,,0000,0000,0000,,and this has implications for education, for rehabilitation,
Dialogue: 0,0:12:58.68,0:13:02.70,Default,,0000,0000,0000,,and intervention. The environment, including teaching,
Dialogue: 0,0:13:02.70,0:13:06.11,Default,,0000,0000,0000,,can and does shape the developing adolescent brain,
Dialogue: 0,0:13:06.11,0:13:08.91,Default,,0000,0000,0000,,and yet it's only relatively recently that we have been
Dialogue: 0,0:13:08.91,0:13:11.42,Default,,0000,0000,0000,,routinely educating teenagers in the West.
Dialogue: 0,0:13:11.42,0:13:15.17,Default,,0000,0000,0000,,All four of my grandparents, for example, left school
Dialogue: 0,0:13:15.17,0:13:19.01,Default,,0000,0000,0000,,in their early adolescence. They had no choice.
Dialogue: 0,0:13:19.01,0:13:21.78,Default,,0000,0000,0000,,And that's still the case for many, many teenagers
Dialogue: 0,0:13:21.78,0:13:24.95,Default,,0000,0000,0000,,around the world today. Forty percent of teenagers
Dialogue: 0,0:13:24.95,0:13:29.17,Default,,0000,0000,0000,,don't have access to secondary school education.
Dialogue: 0,0:13:29.17,0:13:31.81,Default,,0000,0000,0000,,And yet, this is a period of life where the brain is
Dialogue: 0,0:13:31.81,0:13:34.66,Default,,0000,0000,0000,,particularly adaptable and malleable.
Dialogue: 0,0:13:34.66,0:13:38.42,Default,,0000,0000,0000,,It's a fantastic opportunity for learning and creativity.
Dialogue: 0,0:13:38.42,0:13:40.66,Default,,0000,0000,0000,,So what's sometimes seen as the problem
Dialogue: 0,0:13:40.66,0:13:43.13,Default,,0000,0000,0000,,with adolescents — heightened risk-taking, poor impulse
Dialogue: 0,0:13:43.13,0:13:47.08,Default,,0000,0000,0000,,control, self-consciousness — shouldn't be stigmatized.
Dialogue: 0,0:13:47.08,0:13:49.91,Default,,0000,0000,0000,,It actually reflects changes in the brain that provide
Dialogue: 0,0:13:49.91,0:13:52.83,Default,,0000,0000,0000,,an excellent opportunity for education
Dialogue: 0,0:13:52.83,0:13:57.26,Default,,0000,0000,0000,,and social development. Thank you. (Applause)
Dialogue: 0,0:13:57.26,0:14:05.03,Default,,0000,0000,0000,,(Applause)