发布者: 千缘 | 发布时间: 2020-7-15 00:51| 查看数: 95| 评论数: 0|


Fifteen years ago, it was widely assumed that the vast majority of brain development takes place in the first few years of life. Back then, 15 years ago, we didn't have the ability to look inside the living human brain and track development across the lifespan. 15年前,大多数人认为人类大脑最重要的发育阶段是在生命开始的头几年进行的。在过去,15年前,我们还做不到探究人脑的内部活动的情况以及追踪它在生命中的发育过程。

In the past decade or so, mainly due to advances in brain imaging technology such as magnetic resonance imaging, or MRI, neuroscientists have started to look inside the living human brain of all ages, and to track changes in brain structure and brain function, 在过去10年左右,主要是依靠脑成像技术的发展像磁共振成象,简称MRI,神经科学家已经开始了探究不同年龄的人脑内部情况,并记录下大脑结构和功能的不同变化,

so we use structural MRI if you'd like to take a snapshot, a photograph, at really high resolution of the inside of the living human brain, and we can ask questions like, how much gray matter does the brain contain, and how does that change with age?如果需要生成影像,我们可以使用结构磁共振成像,可以拍出高分辨率的人脑内部图。这样我们就可以提出一些问题了,例如大脑里有多少脑灰质会随着年龄变化而变化吗?

And we also use functional MRI, called fMRI, to take a video, a movie, of brain activity when participants are taking part in some kind of task like thinking or feeling or perceiving something.我们也可以使用功能磁共振成像,简称fMRI它可以拍摄视频,这样就可以在试验者进行某项活动中,比如思考或感受某些东西时记录拍摄下大脑的活动情况。

So many labs around the world are involved in this kind of research, and we now have a really rich and detailed picture of how the living human brain develops, and this picture has radically changed the way we think about human brain development by revealing that it's not all over in early childhood, 现在世界上很多实验室都参与了这项研究,所以我们就得出了很丰富很详尽的图片解密了人脑的发育情况,同时这张照片从根本上颠覆了我们以往对人脑发育的观念,通过告诉我们发育的过程不完全都在幼儿阶段。

and instead, the brain continues to develop right throughout adolescence and into the '20s and '30s.相反,大脑会继续发育贯穿整个青春期,一直到20多岁甚至30多岁。

So adolescence is defined as the period of life that starts with the biological, hormonal, physical changes of puberty and ends at the age at which an individual attains a stable, independent role in society.It can go on a long time.所以青春期也被定义为生命中生理和荷尔蒙转变的开端,当人们在社会中获得一个稳定和独立的身份时也就标志这青春期的结束了。有时青春期会持续很久很久。

One of the brain regions that changes most dramatically during adolescence is called prefrontal cortex. So this is a model of the human brain, and this is prefrontal cortex, right at the front. Prefrontal cortex is an interesting brain area. 大脑其中的一个区域,叫前额叶皮层,它在青春期阶段是最活跃的。这个是人脑的一个模型。这里是前额叶皮层,就在前面这里前额叶皮层是非常有意思的一个大脑区域。

It's proportionally much bigger in humans than in any other species, and it's involved in a whole range of high level cognitive functions, things like decision-making, planning, planning what you're going to do tomorrow or next week or next year, 相对其他物种而言人类的前额叶皮层是大很多的,它涉及到大量的高级认知功能,例如决策计划,计划明天要做的事情或者下周或明年的 。

inhibiting inappropriate behavior, so stopping yourself saying something really rude or doing something really stupid. It's also involved in social interaction, understanding other people, and self-awareness.对不恰当行为的抑制,像阻止你说一些粗鲁的话或做一些傻事,它还涉及到社交方面包括理解他人和自我意识。

So MRI studies looking at the development of this region have shown that it really undergoes dramatic development during the period of adolescence. So if you look at gray matter volume, for example, gray matter volume across age from age four to 22 years increases during childhood, which is what you can see on this graph. 所以MRI对前额叶皮层的发育的研究揭示了它确实在青春期阶段有着非同寻常的发育情况。举个例子,如果你去看大脑灰质,从4岁起到22岁的大脑灰质会在童年时期会增加,也就是现在在图表上你能看到的。

It peaks in early adolescence. The arrows indicate peak gray matter volume in prefrontal cortex. You can see that that peak happens a couple of years later in boys relative to girls, and that's probably because boys go through puberty a couple of years later than girls on average, 在早期的青春期会到达顶峰,箭头指的就是大脑灰质在前额叶皮质达到的锋点,你会发现要达到这个锋点,男孩会相对比女孩要慢几年

and then during adolescence, there's a significant decline in gray matter volume in prefrontal cortex. Now that might sound bad, but actually this is a really important developmental process, because gray matter contains cell bodies and connections between cells, 这大概是因为男孩平均要比女孩晚那么几年经历青春期。在青春期阶段,大脑灰质在前额叶皮层会出现一个明显的下降。听起来似乎有些不安,但这确实一个极其重要的发育阶段。因为大脑灰质包涵了细胞体,还有细胞之间的联系,

the synapses, and this decline in gray matter volume during prefrontal cortex is thought to correspond to synaptic pruning, the elimination of unwanted synapses. This is a really important process. It's partly dependent on the environment that the animal or the human is in, and the synapses that are being used are strengthened, 也就是突触在前额叶皮层到了一个需要对突触进行修剪,去除掉一些不必要的突触的这一阶段。大脑灰质也就会减少。这是非常关键的阶段,一部分取决于动物或人类居住的环境,那些有价值的突触会茁壮发育,

and synapses that aren't being used in that particular environment are pruned away. You can think of it a bit like pruning a rosebush. You prune away the weaker branches so that the remaining, important branches, can grow stronger, 而在那个特定的环境里,那些没什么存在必要的突触则会被剔除掉,你可以把它当成是修剪盆栽,把那些奄奄一息的枯枝败叶修剪掉,这样那些剩下的,重要的枝干,就会茁壮成长。

and this process, which effectively fine-tunes brain tissue according to the species-specific environment, is happening in prefrontal cortex and in other brain regions during the period of human adolescence.这个会根据物种及环境不同而高效调整大脑组织的过程。就是在人类的青春期阶段 在前额叶皮层和其他大脑区域进行的。

So a second line of inquiry that we use to track changes in the adolescent brain is using functional MRI to look at changes in brain activity across age. So I'll just give you an example from my lab. 我们用来记录青春期大脑变化的第二轮调查,就是用功能磁共振成来探究不同年龄大脑活动的变化情况,这里我举个发生在我实验室里的例子。

So in my lab, we're interested in the social brain, that is the network of brain regions that we use to understand other people and to interact with other people. So I like to show a photograph of a soccer game to illustrate two aspects of how your social brains work. So this is a soccer game.在我的实验室里,我们对社会大脑很感兴趣,就是我们与他人沟通交流的大脑区域网络。我会给你们看一张足球赛的图片,跟你们分析下社会性大脑工作时的两个方面,这就是一场足球赛。

Michael Owen has just missed a goal, and he's lying on the ground, and the first aspect of the social brain that this picture really nicely illustrates is how automatic and instinctive social emotional responses are, so within a split second of Michael Owen missing this goal, 迈克尔欧文刚刚的射门没有命中,所以他躺在地上,这张图片诠释了社交情绪反应是多么自动自觉的。这是社会脑的第一个层面,所以就在欧文没射中球门的那一瞬间,

everyone is doing the same thing with their arms and the same thing with their face, even Michael Owen as he slides along the grass, is doing the same thing with his arms, and presumably has a similar facial expression, and the only people who don't are the guys in yellow at the back--每个人的手都是同样的动作,同样的表情,甚至欧文也是这样,在他划过草地时,他也是同样的手势;估计他的面部表情也差不多,而唯一不为所动的那个人,就是背后穿黄色球衣的了

and I think they're on the wrong end of the stadium, and they're doing another social emotional response that we all instantly recognize, and that's the second aspect of the social brain that this picture really nicely illustrates, 我觉得他们是场上占不到什么优势的人,他们有着不一样的社交情绪反应,我们能马上认出来,这就是社会脑的第二个层面也在图片上很好地表现出来。

how good we are at reading other people's behavior, their actions, their gestures, their facial expressions, in terms of their underlying emotions and mental states. So you don't have to ask any of these guys.它揭示了我们对他人行为的理解程度,按照潜在的情绪和精神状态解读他人的举动,他人的手势,还有他们的面部表情,所以你不用去问他们中的任何一人。

You have a pretty good idea of what they're feeling and thinking at this precise moment in time.So that's what we're interested in looking at in my lab.  就能对这个时候他们的情感和思想有一个颇为准确的理解。这就是我的实验室所感兴趣的事。

So in my lab, we bring adolescents and adults into the lab to have a brain scan, we give them some kind of task that involves thinking about other people, their minds, their mental states, their emotions, 在实验室里,我们召集了青少年和成年人进行大脑扫描,我们给他们分配任务涉及了他们对他人,自己的思想,自己的精神状态,以及对自己的情绪的思考

and one of the findings that we've found several times now, as have other labs around the world, is part of the prefrontal cortex called medial prefrontal cortex, which is shown in blue on the slide, and it's right in the middle of prefrontal cortex in the midline of your head. 和其他实验室一样,目前我们多次发现的一点是 前额叶皮层的一个部分 叫做内侧前额叶皮质,就是蓝色那部分, 就在前额叶皮质的正中间 在脑袋的正中央。

This region is more active in adolescents when they make these social decisions and think about other people than it is in adults, and this is actually a meta-analysis of nine different studies in this area from labs around the world, and they all show the same thing, that activity in this medial prefrontal cortex area decreases during the period of adolescence. 当青少年在做社交决定以及考虑他人时 他们大脑的这个区域 要比成年人还要活跃,这其实是世界上其他实验室 在这个方面的九个不同研究的荟萃分析 他们都表明了一样的结果, 就是内侧前额叶皮质的活跃度, 会在青春期阶段逐渐减小。

And we think that might be because adolescents and adults use a different mental approach, a different cognitive strategy, to make social decisions, and one way of looking at that is to do behavioral studies where by we bring people into the lab and we give them some kind of behavioral task, and I'll just give you another example of the kind of task that we use in my lab.


So imagine that you're the participant in one of our experiments. You come into the lab, you see this computerized task. In this task, you see a set of shelves. Now, there are objects on these shelves, on some of them, and you'll notice there's a guy standing behind the set of shelves, and there are some objects that he can't see. They're occluded, from his point of view, with a kind of gray piece of wood. This is the same set of shelves from his point of view. 想象一下你是我们实验的参与人员之一,你进到这个实验室,你看到这个电脑程序任务。在这个任务中,你看到几排的架子。现在架子上有些摆上了物品,你会发现有个人站在架子后面,而且有些物品他是看不到的。他们被遮住了,从这个角度看被灰色的木板遮住了。从他的角度看,这是同样的架子。

Notice that there are only some objects that he can see, whereas there are many more objects that you can see. Now your task is to move objects around. The director, standing behind the set of shelves, is going to direct you to move objects around, but remember, he's not going to ask you to move objects that he can't see. This introduces a really interesting condition whereby there's a kind of conflict between your perspective and the director's perspective. So imagine he tells you to move the top truck left. 但要注意,他只看得到一些物品,但你却能看到更多的。你的任务就是去移动这些物品。引导人员,将站在架子后面,引导你去移动这些物品,但是要记住,他不会叫你去移动那些他看不到的物品。这就引出了一个很有意思的情况,在你的角度和引导员的角度之间会有一种冲突。假设他叫你去把上面的火车往左移。

There are three trucks there. You're going to instinctively go for the white truck, because that's the top truck from your perspective, but then you have to remember, "Oh, he can't see that truck, so he must mean me to move the blue truck," which is the top truck from his perspective. Now believe it or not, normal, healthy, intelligent adults like you make errors about 50 percent of the time on that kind of trial. They move the white truck instead of the blue truck. 但那儿有三辆火车,你会很自然地去移动白色那辆,因为从你的角度看它就是上面的火车,但你得知道 “噢,他看不见那辆火车,所以他是想我去移动蓝色的,”就是他的角度,最上面的那辆。现在信不信由你,像你们一样正常健康聪明的成年人都会犯错。在这种试验中,犯错几率高达50%。他们会移动白色那辆,而不是蓝色那辆。

So we give this kind of task to adolescents and adults, and we also have a control condition where there's no director and instead we give people a rule. We tell them, okay, we're going to do exactly the same thing but this time there's no director. Instead you've got to ignore objects with the dark gray background. You'll see that this is exactly the same condition, only in the no-director condition they just have to remember to apply this somewhat arbitrary rule, whereas in the director condition, they have to remember to take into account the director's perspective in order to guide their ongoing behavior.话说我们给青少年还有成年人分配了这种任务 我们有条件控制一个是没有引导员,另一个是给他们定规则。我们告诉他们,好吧,我们会做一样的事情。这次没有引导员。相反,你得忽略那些灰色格子。你会发现其实条件是完全一样的,要记住没有引导员这一情况,只有规定的要求,但在有引导员的情况下,他们则需要考虑引导员的视野角度,这样才能理解引导员的指令。

Okay, so if I just show you the percentage errors in a large developmental study we did, this is in a study ranging from age seven to adulthood, and what you're going to see is the percentage errors in the adult group in both conditions, 这个就是在我们较大规模的研究中得出的犯错比率,这是从七岁到成年的一个研究,你们接下来会看到的就是成人组在两种条件下的错误比率,

so the gray is the director condition, and you see that our intelligent adults are making errors about 50 percent of the time, whereas they make far fewer errors when there's no director present, when they just have to remember that rule of ignoring the gray back ground. 灰色的就是有引导员的情况,你会发现我们聪明的成年人的错误率约是50%,但是他们在没有引导员在场的情况下。错误率会低很多,他们只需记住去忽略灰色格子这一规定。

Developmentally, these two conditions develop in exactly the same way. Between late childhood and mid-adolescence, there's an improvement, in other words a reduction of errors, in both of these trials, in both of these conditions. 相应地,这两种条件的情况发展几乎是一样的,在后儿童期还有中青春期,都是有所提升,换句话说,就是在这些试验中,在这些条件下,错误的几率会随年龄增加而减少。

But it's when you compare the last two groups, the mid-adolescent group and the adult group where things get really interesting, because there, there is no continued improvement in the no-director condition. 但当你比较最后两组实验时,中青春期组和成年组事情会变得有趣很多,因为在没有引导员的情况下,也没有提升的趋势。

In other words, everything you need to do in order to remember the rule and apply it seems to be fully developed by mid-adolescence, whereas in contrast, if you look at the last two gray bars, there's still a significant improvement in the director condition between mid-adolescence and adulthood, 也就是说,涉及到记住规则并应用它所需要的一切似乎都在中青春期已经尘埃落定了。但是相反地,如果你去看两条灰色的图柱,在有引导员的条件下,在中青春期和成年组之间还是有明显的提升的

and what this means is that the ability to take into account someone else's perspective in order to guide ongoing behavior, which is something, by the way, that we do in everyday life all the time, is still developing in mid-to-late adolescence. 这就意味着,从他人角度考虑出发从而运用到实践中的能力,而这也是我们日常生活随处可见的,这一能力,在青春期的中后期仍在发育中。

So if you have a teenage son or a daughter and you sometimes think they have problems taking other people's perspectives, you're right. They do. And this is why.所以如果你有一个儿子或女儿出于青春期,你有时觉得他们在考虑他人感受时做得不够好,那么你是对的,的确是这样,这就是原因。

So we sometimes laugh about teenagers. They're parodied, sometimes even demonized in the media for their kind of typical teenage behavior. They take risks, they're sometimes moody, they're very self-conscious. 所以我们有时会讽刺青少年。说他们没什么大脑,有时会在媒体上丑化他们那种典型的青春期行为,他们爱冒险,情绪阴晴不定,非常自我。

I have a really nice anecdote from a friend of mine who said that the thing he noticed most about his teenage daughters before and after puberty was their level of embarrassment in front of him. 我从我朋友那儿听到一个很有趣的故事,他说这是他在女儿们青春期前后经常见到的事,就是在他面前的尴尬程度。

So, he said, "Before puberty, if my two daughters were messing around in a shop, I'd say, 'Hey, stop messing around and I'll sing your favorite song,' and instantly they'd stop messing around and he'd sing their favorite song. 她说,“青春期前,如果我的两个女儿在商店里胡闹,我会说,嘿,别闹了,我给你们唱你们最喜欢的歌,”然后她们立即安分守己,听他唱歌

After puberty, that became the threat.The very notion of their dad singing in public was enough to make them behave.但青春期过后,唱歌成了威胁。他们爸爸在公众场合唱歌这一举动足以震慑他们的调皮。

So people often ask, "Well, is adolescence a kind of recent phenomenon? Is it something we've invented recently in the West?" And actually, the answer is probably not. 所以人们经常问,“那么,青春期是一种新生的现象吗?是西方国家近几年才发现的吗?”其实,答案不然。

There are lots of descriptions of adolescence in history that sound very similar to the descriptions we use today.历史上,有过很多青春期的描写与今天那些描述十分相似。

So there's a famous quote by Shakespeare from "The Winter's Tale" where he describes adolescence as follows: "I would there were no age between ten and three-and-twenty, or that youth would sleep out the rest; for there is nothing in the between but getting wenches with child, wronging the ancientry, stealing, fighting."莎士比亚的《冬天的故事》里有这么一段 他是这么描述青春期的: “孩子与成人之间不再有差别,年轻人要么就去安眠;因为他们会空虚到与孩子滥交、做出伤风败俗的偷窃和斗殴。”

He then goes on to say, "Having said that, would any but these boiled brains of nineteen and two-and-twenty hunt in this weather?"So almost 400 years ago, Shakespeare was portraying adolescents in a very similar light to the light that we portray them in today, 他接着说,“话虽如此,但除了那些十几二十岁的脑残少年,还有谁会在这种天气出来打猎啊?”所以约在400年前,莎士比亚描述的青少年就十分类似我们今天所指的青少年,

but today we try to understand their behavior in terms of the underlying changes that are going on in their brain.So for example, take risk-taking. We know that adolescents have a tendency to take risks. They do. 但如今我们尝试根据他们,大脑那些看不到的变化去理解他们的行为。举个例子,爱冒险。我们知道青少年有爱冒险的倾向,真的有的。

They take more risks than children or adults, and they are particularly prone to taking risks when they're with their friends. There's an important drive to become independent from one's parents and to impress one's friends in adolescence. 他们会比儿童或成人更爱冒险,而且在和朋友在一起的时候会更有冒险倾向,在青春期会有个明显的驱动力就是远离父母争取独立和在朋友间出类拔萃。

But now we try to understand that in terms of the development of a part of their brain called the limbic system, so I'm going to show you the limbic system in red in the slide behind me, and also on this brain. 但现在我们根据他们大脑某部分叫边缘系统的发育尝试去理解他们,我会在背后的幻灯片里给你们看下红色的边缘系统,这个大脑里也有。

So the limbic system is right deep inside the brain, and it's involved in things like emotion processing and reward processing. It gives you the rewarding feeling out of doing fun things, including taking risks. It gives you the kick out of taking risks. 边缘系统就在大脑的深处,它涉及了情感处理还有奖励感处理,在你做有趣的事情时,像冒险它会产生一种收获的感觉。它让你在冒险中产生快感。

And this region, the regions within the limbic system, have been found to be hypersensitive to the rewarding feeling of risk-taking in adolescents compared with adults, and at the very same time, the prefrontal cortex, which you can see in blue in the slide here, which stops us taking excessive risks, is still very much in development in adolescents.这部分区域,在边缘系统里的区域, 相比成年人,对青少年的冒险产生的收获感 具有很高的敏感性, 与此同时,前额叶皮层, 在幻灯片显示蓝色的地方, 会阻止我们过多地参与冒险, 但在青春期还是出于发育阶段。

So brain research has shown that the adolescent brain undergoes really quite profound development, and this has implications for education, for rehabilitation, and intervention. 关于大脑的研究表明青少年的大脑经历了意义深远的的发育,这对教育,康复和介入治疗方面,就有所启示了,环境,包括教学,

The environment, including teaching, can and does shape the developing adolescent brain, and yet it's only relatively recently that we have been routinely educating teenagers in the West. 能塑造青少年大脑的发育,而且是到相当近的一段时期在西方才对青少年有常规的教育。

All four of my grandparents, for example, left school in their early adolescence. They had no choice. And that's still the case for many, many teenagers around the world today. Forty percent of teenagers don't have access to secondary school education. 就像,我的四个祖父母在青春期早期就辍学了,他们也是没办法的。目前世界上很多地方还是存在这样的情况,百分之四十的青少年没有机会进入学校接受初中教育。

And yet, this is a period of life where the brain is particularly adaptable and malleable. It's a fantastic opportunity for learning and creativity.而且,这个时期,是大脑处于特别有可塑性的时期。是学习和培养创新的绝好时机。

So what's sometimes seen as the problem with adolescents — heightened risk-taking, poor impulse control, self-consciousness — shouldn't be stigmatized. 所以那些常被认为是青少年的问题的情况高度爱冒险,易冲动不受控制,自我为中心,这些都不应受到指责。

It actually reflects changes in the brain that provide an excellent opportunity for education and social development. Thank you. 它实际是反映了大脑的变化为教育,社会发展提供了很好的机遇。谢谢。


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