美国国家公共电台 NPR--The first wiring map of an insect's brain hints at incredible complexity

The first wiring map of an insect's brain hints at incredible complexity¹

Transcript²

Scientists mapped the 548,000 connections in the brain of a fruit fly larva, but they're far from repeating the feat³ with a grown fruit fly. (Story aired on All Things Considered on Feb. 9, 2023.)

LEILA FADEL, HOST:

Scientists hoping to map the trillions of connections in the human brain are starting a lot smaller with fruit flies. NPR's Jon Hamilton reports on an effort to trace every connection in the brain of a fruit fly larva.

JON HAMILTON, BYLINE⁴: A brain is more than just a collection of cells. Joshua Vogelstein of Johns Hopkins University puts it this way.

JOSHUA VOGELSTEIN: The brain is the physical object that makes us who we are.

HAMILTON: To understand that object, you need to know how it's wired, what scientists call its connectome. But Vogelstein says that's hard in a human brain, which has more than 80 billion nerve cells.

VOGELSTEIN: And each one has about 10,000 connections.

HAMILTON: So in the 1970s, scientists began mapping the connections in worms and tadpoles⁵ with just a few hundred neurons. Now, Vogelstein and an international team have mapped a brain with more than 3,000 neurons and more than 500,000 connections. It's from the larva of a fruit fly or drosophila.

VOGELSTEIN: The larval drosophila is closer in many regards to a human brain than the other ones. There's regions that correspond to decision-making. There's regions that correspond to learning. There's regions that correspond to navigation.

HAMILTON: Vogelstein says that, like a human, this insect has a brain with a left side and a right side.

VOGELSTEIN: One surprise that led to actually a follow-up paper that we've already written is how similar the left and the right sides are.

HAMILTON: In human brains, the right and left sides can have very different wiring. For example, the circuits involved in speech and language tend to be on the left, while circuits that recognize faces tend to be on the right. Vogelstein says the larval fruit fly connectome will help scientists study things like learning and memory.

VOGELSTEIN: Or look at differences across gender⁶ or differences across species or differences across developmental stages. This is the landmark⁷ first reference that we can use to compare everything else.

HAMILTON: The finding, which appears in the journal Science, shows how hard it is to map an entire brain, even in an insect. Vogelstein says the team began by slicing a single tiny brain into thousands of very thin sections.

VOGELSTEIN: You don't screw it up at all because if you make one mistake, you have to basically throw out the entire brain and start over again.

HAMILTON: The team used an electron microscope to capture an image of each slice. Vogelstein says tracing the connections took powerful computers and specialized⁸ analytical⁹ tools.

VOGELSTEIN: They'll work on thousands or millions or maybe 100 million connections but not 10,000 trillion connections.

HAMILTON: Roughly the number of connections in a human brain. Nuno Macarico da Costa of the Allen Institute in Seattle is part of a team working on a mouse connectome.

NUNO MACARICO DA COSTA: We started by trying to map the connectivity of a millimeter cube of mouse cortex, which is kind of a grain of sand but has 1 billion connections, 100,000 neurons and 4 kilometers of cable.

HAMILTON: Da Costa says it took 12 days just to slice up that one tiny cube, which represents only about 1/500 of a complete mouse brain. Even so, da Costa says mapping more complex brains is worth the effort. Eventually, he says, it should help scientists understand how a human brain can be affected¹⁰ by disorders¹¹ like schizophrenia.

DA COSTA: If your radio breaks, if someone has a wiring diagram of your radio, they'll be in a better position to fix it.

HAMILTON: Da Costa says mapping the human connectome will also help scientists answer basic questions like how we learn and why we behave the way we do.

DA COSTA: Every idea, every memory, every movement, every decision you ever made comes from the activity of neurons in your brain. And this activity is an expression of the structure.

HAMILTON: In other words, the wiring diagram that makes us who we are.

Jon Hamilton, NPR News.

(SOUNDBITE OF FRAMEWORK AND MURGE'S "CUSP")

1 complexity   

n.复杂(性)，复杂的事物

参考例句：

• Only now did he understand the full complexity of the problem.直到现在他才明白这一问题的全部复杂性。
• The complexity of the road map puzzled me.错综复杂的公路图把我搞糊涂了。

2 transcript   

n.抄本，誊本，副本，肄业证书

参考例句：

• A transcript of the tapes was presented as evidence in court.一份录音带的文字本作为证据被呈交法庭。
• They wouldn't let me have a transcript of the interview.他们拒绝给我一份采访的文字整理稿。

3 feat   

n.功绩；武艺，技艺；adj.灵巧的，漂亮的，合适的

参考例句：

• Man's first landing on the moon was a feat of great daring.人类首次登月是一个勇敢的壮举。
• He received a medal for his heroic feat.他因其英雄业绩而获得一枚勋章。

4 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

5 tadpoles   

n.蝌蚪( tadpole的名词复数 )

参考例句：

• The pond teemed with tadpoles. 池子里有很多蝌蚪。 来自《简明英汉词典》
• Both fish and tadpoles have gills. 鱼和蝌蚪都有鳃。 来自《现代汉英综合大词典》

6 gender   

n.（生理上的）性，（名词、代词等的）性

参考例句：

• French differs from English in having gender for all nouns.法语不同于英语，所有的名词都有性。
• Women are sometimes denied opportunities solely because of their gender.妇女有时仅仅因为性别而无法获得种种机会。

7 landmark   

n.陆标，划时代的事，地界标

参考例句：

• The Russian Revolution represents a landmark in world history.俄国革命是世界历史上的一个里程碑。
• The tower was once a landmark for ships.这座塔曾是船只的陆标。

8 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

9 analytical   

adj.分析的；用分析法的

参考例句：

• I have an analytical approach to every survey.对每项调查我都采用分析方法。
• As a result,analytical data obtained by analysts were often in disagreement.结果各个分析家所得的分析数据常常不一致。

10 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

11 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》