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迷你大脑 – 译学馆
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迷你大脑

What are mini brains? - Madeline Lancaster

这个橡皮擦大小的细胞块叫做大脑类器官
This pencil-eraser-sized mass of cellsis something called a brain organoid.
它是一些实验室培养的神经细胞和其它脑组织的集合体
It’s a collection of lab-grown neuronsand other brain tissue
科学家用它来学习发育完全的人类大脑
that scientists can use tolearn about full-grown human brains.
它能够从你皮肤细胞的样本中培养出来
And it can be grown from a sample of your skin cells.
为什么我们需要这个东西?
Why would we need such a thing?
神经学家面临一个挑战:
Neuroscientists face a challenge:
人类的大脑被厚厚的颅骨隔离
shielded by our thick skulls and swaddled
被层层的组织包裹
in layers of protective tissue,
人脑很难在活动上被观测到
the human brain isextremely difficult to observe in action.
几个世纪以来 科学家试图通过尸检
For centuries, scientists have tried tounderstand them using autopsies,
动物模型以及近几年来出现的影像技术去理解它
animal models, and, in recent years, imaging techniques.
我们已经通过这些方式已经了解到很多
We’ve learned a lot throughall these methods,
但仍有很多局限性
but they have limitations.
比如像阿尔茨海默病和精神分裂症
Conditions like Alzheimer’sand schizophrenia,
以及一些疾病如塞卡病毒对大脑的影响
and the effect onthe human brain of diseases like Zika,
依然是隐秘和未知的
continue to hide beyond our view,and our understanding.
进入大脑类器官 其功能类似于人类大脑
Enter brain organoids,which function like human brains
而不是有机体的一部分
but aren’t part of an organism.
每一个都来自于一个未分化的干细胞
Each one comes froman undifferentiated stem cell,
干细胞能生长发育成
which is a cell that can develop
身体里的任何组织
into any tissue in the body,
从骨头到大脑
from bone to brain.
科学家可以从皮肤细胞里获取未分化的干细胞
Scientists can make undifferentiatedstem cells from skin cells.
这意味着他们可以
That means they can take a skin sample
从某些特定疾病的人身上获得一块皮肤样本
from a person with a particular condition
并制成大脑类器官
and generate brain organoidsfrom that person.
培养一个大脑类器官最困难的部分
The hardest part of growinga brain organoid,
困扰了科学家很多年
which stumped scientists for years,
是找到糖 蛋白质 维生素和矿物质的最佳配比
was finding the perfect combination of sugars, proteins, vitamins, and minerals
使其能诱导干细胞发育成为具有神经系统特性的细胞
that would induce the stem cellto develop a neural identity.
这种配比一直到2013年才被发现
That was only discovered recently,in 2013.
而制作过程的其余部分确是出人意料的简单
The rest of the processis surprisingly easy.
一个神经系统的干细胞基本会自己生长
A neural stem cell essentiallygrows itself,
有点像一颗种子发育成植物
similar to how a seed grows into a plant,
它所需要的全部条件就相当于大脑的土壤、水
all it needs are the brain ’ s equivalents of soil, water,
和阳光
and sunlight.
一种特别的凝胶用来模仿胚胎组织
A special gel to simulateembryonic tissue,
一个设定为人体温度的暖孵化器
a warm incubator set at body temperature,
以及轻微的活动来模拟血液的流动
and a bit of motion to mimic blood flow.
这个干细胞会生长成一个非常小版本的
The stem cell grows intoa very small version
早期发育的人类大脑
of an early-developing human brain,
互相联接的神经元
complete with neurons that can connectto one another
组成简化的神经网络
and make simplified neural networks.
当这个迷你大脑生长的时候 它符合所有胎儿大脑生长的步骤
As mini brains grow, they follow all the steps of fetal brain development.
通过观察这个过程 我们可以认识到我们的神经细胞如何生长
By observing this process,we can learn how our neurons develop,
并且我们在大脑皮质中
as well as how we end up with so many more
积聚那么多细胞的方式
of them in our cortex,
皮质是我们大脑中负责更高级认知功能的部分 比如逻辑推理
the part responsible for higher cognitionlike logic and reasoning,
这部分的功能远超其它物种
than other species.
在实验室里培养脑组织 即使是很小一块
Being able to grow brains in the lab,even tiny ones,
也会引发出一些道德问题
raises ethical questions, like:
比如 它们是否能思考或者产生意识?
Can they think for themselves,or develop consciousness?
基于几个原因 答案是否定的
And the answer is no, for several reasons.
一个大脑类器官和
A brain organoid has the same tissue types
一个真实大小的大脑虽然属于相同的组织类型
as a full-sized brain,
但并非以相同的方法被组织起来
but isn’t organized the same way.
类器官有点像一架飞机
The organoid is similar to an airplane that
被肢解后又随机的重新组装起来
’ s been taken apart and reassembled at random;
你仍然能研究翅膀 引擎和其它部分
you could still study the wings,the engine, and other parts,
但这架飞机不可能再飞起来
but the plane could never fly. Similarly,
同样的 一个大脑类器官
a brain organoid allows
可以让我们去研究脑组织的不同类型 但无法思考
us to study different types of brain tissue, but can’t think.
并且即使微型脑能够像真实的大脑一样组织起来
And even if mini brains were organizedlike a real brain,
它们仍然不能推理或产生意识
they still wouldn’t be ableto reason or develop consciousness.
使我们的大脑有如此智慧最主要的一点在于 它的尺寸
A big part of what makes our brains so smart is their size,
迷你大脑仅有大约十万个神经细胞
and mini brains have onlyabout 100,000 neurons
而真实尺寸的大脑拥有860亿个神经细胞
compared to the 86 billionin a full-sized brain.
科学家们在短时间内不太可能会培养出更大的大脑类器官
Scientists aren’t likely to grow largerbrain organoids anytime soon.
在缺乏血管系统支持的情况下
Without blood vessels to feed them,
它们的尺寸被限制在最多一厘米大小
their size is limited to one centimeter at most. Finally,
最终 迷你大脑无法和外部世界有交互作用
mini brains aren’t ableto interact with the outside world.
我们通过与环境的交互作用
We learn by interactingwith our environments: receiving inputs
通过我们的眼睛 耳朵和其它的感觉器官接收输入信息
through our eyes, ears, and other sensory organs,
并反过来作出反应
and reacting in turn.
具有意识性思维和动作的复杂神经网络
The complex neural networks that underlieconscious thoughts and actions
可以发展出反馈回路
develop from this feedback loop.
没有这个 这个类器官无法组成一个功能性的网络
Without it, the organoidscan never form a functional network.
也无法变得像实际的人类大脑一样了
There’s nothing quite likethe actual human brain,
但迷你大脑依然是一个史无前例的工具
but mini brains are an unprecedented tool
可以让我们研究很多东西 从发育到疾病
for studying everythingfrom development to disease.
幸运的话 这些简陋的类器官可以帮助我们
With luck, these humbleorganoids can help us discover
发现是什么让人类的大脑如何独特
what makes the human brain unique,
也许能让我们离回答那个古老的问题更近一步
and maybe bring us closerto answering the age-old question:
那就是:什么造就了我们人类?
what makes us human?

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迷你大脑的价值和它的道德问题

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视频来源

https://www.youtube.com/watch?v=s_LxZx42sIk

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