在一座可以俯瞰東河的八層實(shí)驗(yàn)室里，科妮莉亞·I·巴格曼正觀察兩位同事熟練操縱著顯微鏡下的蛔蟲(chóng)。 他們把它夾到透明玻璃片的小槽上，使它的鼻子正好陷進(jìn)溝槽里。信息激素——其它蛔蟲(chóng)發(fā)出的化學(xué)信號(hào)，被輸進(jìn)溝槽中，如果蛔蟲(chóng)腦中的一個(gè)神經(jīng)元產(chǎn)生反應(yīng)，神經(jīng)元研究人員就改變兩個(gè)神經(jīng)元的基因使它們發(fā)出亮綠色的光。
These ingenious techniques for exploring a tiny animal’s behavior are the fruit of many years’ work by Dr. Bargmann’s and other labs. Despite the roundworm’s lowliness on the scale of intellectual achievement, the study of its nervous system offers one of the most promising approaches for understanding the human brain, since it uses much the same working parts but is around a million times less complex.
這些發(fā)掘小生物行為的獨(dú)特技術(shù)是巴格曼實(shí)驗(yàn)室和其他實(shí)驗(yàn)室的成果。盡管蛔蟲(chóng)的智力等級(jí)低下，但是對(duì)其神經(jīng)系統(tǒng)的研究提供了對(duì)人類大腦研究最理想的途徑，因?yàn)樗蜆?gòu)成人腦運(yùn)作的部分大多相同，卻要簡(jiǎn)單大約一萬(wàn)倍。
Caenorhabditis elegans, as the roundworm is properly known, is a tiny, transparent animal just a millimeter long. In nature, it feeds on the bacteria that thrive in rotting plants and animals. It is a favorite laboratory organism for several reasons, including the comparative simplicity of its brain, which has just 302 neurons and 8,000 synapses, or neuron-to-neuron connections. These connections are pretty much the same from one individual to another, meaning that in all worms the brain is wired up in essentially the same way. Such a system should be considerably easier to understand than the human brain, a structure with billions of neurons, 100,000 miles of biological wiring and 100 trillion synapses.
秀麗隱桿線蟲(chóng)是蛔蟲(chóng)的學(xué)名，是一種只有1毫米長(zhǎng)的透明小生物。自然界里，它靠食用腐爛動(dòng)植物身上的細(xì)菌為生。它作為實(shí)驗(yàn)室首選的生物原因在于它的大腦構(gòu)造相對(duì)簡(jiǎn)單，只有302個(gè)神經(jīng)元和8000個(gè)（神經(jīng)元的）突觸，就是神經(jīng)元之間的鏈接。這些鏈接個(gè)個(gè)都非常相似，也就是說(shuō)所有的蛔蟲(chóng)腦內(nèi)回路構(gòu)造都是類似的。用這樣的系統(tǒng)研究人腦的數(shù)十億個(gè)神經(jīng)元、十萬(wàn)英里的生物線和一百萬(wàn)億的突觸就相對(duì)容易了。
The biologist Sydney Brenner chose the roundworm as an experimental animal in 1974 with this goal in mind. He figured that once someone provided him with the wiring diagram of how 302 neurons were connected, he could then compute the worm’s behavior.
1974年生物學(xué)家西德尼·布雷納把蛔蟲(chóng)選作實(shí)驗(yàn)對(duì)象時(shí)就有這個(gè)目標(biāo)。他認(rèn)為某次別人給他302個(gè)神經(jīng)元的連接圖后，他能計(jì)算出蛔蟲(chóng)的行為。
The task of reconstructing the worm’s wiring system fell on John G. White, now at the University of Wisconsin. After more than a decade’s labor, which required examining 20,000 electron microscope cross sections of the worm’s anatomy, Dr. White worked out exactly how the 302 neurons were interconnected.
重建蛔蟲(chóng)回路系統(tǒng)的重任目前落到了威斯康星大學(xué)的約翰·G·懷特身上。經(jīng)過(guò)十多年的努力，研究了2萬(wàn)個(gè)電子顯微鏡下蛔蟲(chóng)的解剖結(jié)構(gòu)橫截面，懷特博士精準(zhǔn)計(jì)算出了302個(gè)神經(jīng)元是怎樣連接起來(lái)的。
But the wiring diagram of even the worm’s brain proved too complex for Dr. Brenner’s computational approach to work. Dr. Bargmann was one of the first biologists to take Dr. White’s wiring diagram and see if it could be understood in other ways.
但是，甚至是蛔蟲(chóng)鬧內(nèi)的接線圖也足以復(fù)雜到讓布雷納博士的計(jì)算法難以運(yùn)行。巴格曼博士是第一個(gè)接過(guò)懷特博士接線圖并用其他方法去嘗試研究的生物學(xué)家。
Cori Bargmann grew up in Athens, Ga., a small college town in the Deep South where her father taught statistics at the University of Georgia. Both her parents had been translators and met while Rolf Bargmann was working at the Nuremberg trials. Her mother, Ilse, would read to her in German the works of the Austrian animal behaviorists Konrad Lorenz and Karl von Frisch, planting the seeds of an interest in neuroscience.
格里·巴格曼在美國(guó)南部雅典城長(zhǎng)大，她父親在佐治亞大學(xué)教統(tǒng)計(jì)學(xué)。她雙親都當(dāng)做翻譯，當(dāng)羅爾夫·巴格曼在紐倫堡大審工作時(shí)相遇了。她母親伊爾澤會(huì)用德語(yǔ)讀給她聽(tīng)奧地利動(dòng)物行為學(xué)家洛倫茲和弗利希和著作，引發(fā)了她對(duì)神經(jīng)系統(tǒng)學(xué)的興趣。
“I went into science because I loved the labs,” Dr. Bargmann says. She liked the machines and instruments, the fun of building things with one’s own hands, of learning what no one else knew. An outstanding student, she chose for her Ph.D. degree to work in the M.I.T. lab of Robert A. Weinberg, a leading cancer biologist. The first mutated genes capable of causing cancer were being isolated. “It was an incredibly exciting time,” she says.
“我踏入科學(xué)殿堂是因?yàn)槲覑?ài)實(shí)驗(yàn)室。”巴格曼博士說(shuō)。她喜歡機(jī)器和儀器，喜歡用自己的雙手創(chuàng)造東西，探索別人不知道的一切。作為一名出色的學(xué)生，她在博士階段選擇了在馬薩諸塞州理工學(xué)院羅伯特A·溫伯格的實(shí)驗(yàn)室工作，他是一位杰出的癌癥生物學(xué)家。第一次分離出能致癌的變異基因。她說(shuō)：“實(shí)在是激動(dòng)人心的一刻。”
Her task was to clone a rat gene called neu. When mutated, the gene causes a tumor, but one that the rat’s immune system can attack and destroy. Several years later, the human version of neu, called HER-2, was found to be amplified in breast cancer, and its receptor protein product is the target of the artificial antibody known as Herceptin, a leading breast cancer drug.
她的任務(wù)是克隆出一個(gè)老鼠的神經(jīng)鞘基因?；蛲蛔儠r(shí)會(huì)引發(fā)腫瘤，但是是一個(gè)老鼠的免疫系統(tǒng)能攻擊和摧毀的。幾年后，神經(jīng)鞘人用版本HER-2在乳腺癌內(nèi)被放大，它的受體蛋白質(zhì)會(huì)產(chǎn)生名為赫賽汀的人工抗體，對(duì)治療乳腺癌非常有效。
For her postdoctoral work, Dr. Bargmann decided to work on animal behavior. The mouse is a standard organism for such studies, but she did not like hurting furry animals. “In Weinberg’s lab I would start to cry every time I had to do anything with a mouse,” she says. A nonfurry alternative was the fruit fly. She interviewed with a leading laboratory in California, but her husband at the time did not wish to move there.
博士后時(shí)候巴格曼決定從事動(dòng)物行為學(xué)的研究。老鼠很適用于這樣的研究，但她不忍心傷害毛茸茸的小動(dòng)物。她是：“我凡是在溫伯格的實(shí)驗(yàn)室里對(duì)老鼠做了什么每次都會(huì)哭。”另一種不長(zhǎng)毛的替代物是果蠅。她訪問(wèn)了加利福尼亞一流的實(shí)驗(yàn)室，但當(dāng)時(shí)他丈夫不愿搬去那邊。
That left the roundworm. There are now several hundred worm labs around the world, of which perhaps 30 or so, like Dr. Bargmann’s, focus on the worm’s nervous system. In 1987, “worms weren’t entirely respectable,” Dr. Bargmann says. But right there at M.I.T., H. Robert Horvitz had established one of the first serious worm labs in the United States. She joined his lab and read everything written on the worm, including all the back copies of the little field’s informal journal, The Worm Breeder’s Gazette.
余下的就是蛔蟲(chóng)的研究。世界上目前有幾百所蛔蟲(chóng)實(shí)驗(yàn)室，其中約30所像巴格曼的實(shí)驗(yàn)室一樣主要研究蛔蟲(chóng)的神經(jīng)系統(tǒng)。1987年時(shí)，“蛔蟲(chóng)一點(diǎn)也不受注重。”巴格曼說(shuō)。但同時(shí)在馬薩諸塞州理工學(xué)院，H·羅伯特·霍維茨已經(jīng)建立起美國(guó)第一所重量級(jí)的蛔蟲(chóng)實(shí)驗(yàn)室。她加入了他的實(shí)驗(yàn)室，看取了每篇關(guān)于蛔蟲(chóng)的報(bào)告，以及該領(lǐng)域的期刊《蛔蟲(chóng)飼養(yǎng)員憲報(bào)》的所有備份。
She noticed that a particular behavior of C. elegans had been described but not well explored: it can taste waterborne chemicals and move toward those it finds attractive. Dr. White’s wiring diagram had been published the year before, in 1986. With this in hand, she told Dr. Horvitz she planned to identify which of the worm’s 302 neurons controlled its chemical-tracking behavior.
她注意到秀麗線蟲(chóng)的某個(gè)特定行為沒(méi)有被好好研究過(guò)：它能辨別并移動(dòng)到吸引它的化學(xué)試劑旁。懷特博士的接線圖在前一年發(fā)表了，也就是1986年。有了圖在手，她告訴霍維茨博士她要找出蛔蟲(chóng)的302個(gè)神經(jīng)元中哪個(gè)控制了它追蹤化學(xué)試劑的行為。
He thought the project was too ambitious, but said she could spend six months on the attempt. Each neuron in the worm’s brain is known, and is assigned a three letter name. Specific neurons can be identified under a microscope and zapped with a laser beam, allowing the neuron’s role to be deduced from whatever function the worm may seem to have lost.
他認(rèn)為這個(gè)計(jì)劃頗具野心，但說(shuō)她能為此花費(fèi)半年時(shí)間。每個(gè)蛔蟲(chóng)腦內(nèi)的神經(jīng)元都是已知的，都被編成三個(gè)字母的名稱。顯微鏡下能辨認(rèn)出被鐳射殺滅的特定神經(jīng)元，通過(guò)損失的神經(jīng)元的用途來(lái)判斷蛔蟲(chóng)可能會(huì)失去哪些行為。
Dr. Bargmann slogged her way through the task of killing each neuron one by one. Telling one neuron from another under the microscope is not easy. “It’s like knowing each grape in a bunch is different, but not quite being able to see it,” Dr. Horvitz said. “The first thing she had to do was learn the worm’s neuroanatomy, and she did so in a way only one other person has ever done.” (He was referring to John E. Sulston, who traced the lineage from the egg of all 959 cells in the adult worm’s body).
巴格曼博士堅(jiān)持不懈地完成任務(wù)，破壞了一個(gè)又一個(gè)神經(jīng)元。在顯微鏡下區(qū)分神經(jīng)元的不同之處是件難事。“就好比分辨一串葡萄上的每一個(gè)，細(xì)微之處很難看出。”霍維茨博士說(shuō)。"T她先要學(xué)習(xí)蛔蟲(chóng)的神經(jīng)解剖學(xué)，她做到了只有另一個(gè)人做過(guò)的事。“（這里提到的就是約翰·E·薩爾斯頓，他從成年蛔蟲(chóng)身體里的959個(gè)卵細(xì)胞開(kāi)始追逐蛔蟲(chóng)的血統(tǒng)。）
She discovered, by accident, the neurons that control the worm’s switch into hibernation, a survival strategy for when food is scarce or neighbors too many. Finally, she found the neurons that control taste, showing that without them the worm could not track chemicals, and that it retained this ability even if she killed all the other neurons in the worm’s body.
她偶然發(fā)現(xiàn)了神經(jīng)會(huì)在食物短缺或是周圍蛔蟲(chóng)太多時(shí)控制其進(jìn)入冬眠。最后，她發(fā)現(xiàn)蛔蟲(chóng)失去控制味覺(jué)的神經(jīng)將無(wú)法找到化學(xué)試劑，就算殺滅蛔蟲(chóng)體內(nèi)其他神經(jīng)，這個(gè)能力依然能夠保留。
She also discovered that the worms have a sense of smell — the ability to detect airborne chemicals — as well as a sense of taste. Since worms eat bacteria that feed on decaying plants and carcasses, she figured they should be able to detect and home in on the aromas of putrefaction. The redolent draft from these experiments caused a certain degree of complaint in Dr. Horvitz’s lab. After she succeeded, she says, “Horvitz told me that my great strength as a scientist was that I could think like a worm.”
她也發(fā)現(xiàn)蛔蟲(chóng)有味覺(jué)，同樣也有嗅覺(jué)——它們能辨別化學(xué)氣體。自打蛔蟲(chóng)靠腐爛動(dòng)植物身上的細(xì)菌為生起，她認(rèn)為它們能辨認(rèn)和追蹤腐爛的氣味。實(shí)驗(yàn)發(fā)出的濃烈氣味使霍維茨博士的實(shí)驗(yàn)室遭到了不少抱怨。她成功以后說(shuō)道：“霍維茨告訴我，我作為科學(xué)家的鉆勁是因?yàn)槲夷芟窕紫x(chóng)一樣思考。”
“Cori is talented beyond thinking like a worm,” Dr. Horvitz now says. “She can think like very few other people in a rigorous and creative way, and so has repeatedly developed new kinds of approaches.”
“葛利不僅愛(ài)思考，更是才華橫溢。”霍維茨博士現(xiàn)在說(shuō)：“很少有人像她一樣有慎密和創(chuàng)造性的思維，正因如此她不斷創(chuàng)造出各種成果。”
Dr. Bargmann moved in 1991 to the University of California, San Francisco, to start her own lab. She began by following up her finding that worms have a sense of smell. In 1991, Richard Axel and Linda Buck discovered the molecular basis for the sense of smell: there are about a thousand genes, at least in rats, that make odorant receptors, proteins that stud the olfactory nerves’ endings in the nose and respond to specific odors.
巴格曼博士1991年轉(zhuǎn)移到舊金山的加州大學(xué)開(kāi)始創(chuàng)立自己的實(shí)驗(yàn)室。她繼續(xù)蛔蟲(chóng)嗅覺(jué)的研究。1991年，理查德·阿克塞爾和琳達(dá)·巴克發(fā)現(xiàn)了分子性是嗅覺(jué)的基礎(chǔ)：至少在老鼠身上大約有1000個(gè)基因，就是附在鼻子內(nèi)嗅覺(jué)神經(jīng)末梢上的蛋白質(zhì)，接收氣味信號(hào)并對(duì)特定的產(chǎn)生反應(yīng)。
The C. elegans genome had just been decoded, and Dr. Bargmann was able to identify the worm’s odorant receptor genes. In fact, they have 2,000 of them, twice as many as the rat.
秀麗線蟲(chóng)的基因組剛剛被破解，巴格曼博士證實(shí)了蛔蟲(chóng)接收氣味的基因。實(shí)際上，它們有2000個(gè)這樣的基因，是老鼠的兩倍。
“This is what they do,” Dr. Bargmann says. The worm cannot see. Its world is one of smells, not sights. It needs to scent the soil bacteria that are its prey, while avoiding those that are poisonous to it. Ten percent of its genes are dedicated to making it a champion connoisseur of odors, mostly unpleasant.
“它們就是這樣接收氣味的。”巴格曼博士說(shuō)。蛔蟲(chóng)沒(méi)有視力。它的世界由氣味構(gòu)成的，并非視覺(jué)。它需要在嗅出作為食物的土壤細(xì)菌的同時(shí)避開(kāi)對(duì)它有毒有害的物質(zhì)。它有百分之十的專用基因是鑒別氣味的好手，特別是針對(duì)不愉快的氣味。
With the odorant genes in hand, Dr. Bargmann could apply genetics to figuring out how the worm’s sense of smell worked. By working with mutant worms, she showed that a specific odor receptor recognizes a specific odor, a finding that was implied by the Axel-Buck discovery but that no one had managed to nail down.
有氣味基因在手，巴格曼博士就能把遺傳學(xué)應(yīng)用到蛔蟲(chóng)嗅覺(jué)是怎樣運(yùn)作的問(wèn)題上。從事變異蛔蟲(chóng)的研究過(guò)程中，她表示蛔蟲(chóng)有辨識(shí)特殊氣味的特殊接收器，這是從阿克塞爾·巴克那里得到的啟示，但是還沒(méi)有人下定論。
She found that worms with a mutation in a gene called odr-10 could not smell diacetyl, a chemical that gives butter its odor and is also produced by a bacterium that is a favorite worm food. The odr-10 gene, which makes the odor receptor protein that detects diacetyl, is active in neurons that guide the worm toward a scent.
她發(fā)現(xiàn)含有變異基因ord-10的蛔蟲(chóng)聞不出聯(lián)乙醯，聯(lián)乙醯是一種細(xì)菌散發(fā)出的黃油味化學(xué)物質(zhì)，是蛔蟲(chóng)最愛(ài)的食物之一。odr-10基因使接收氣味的蛋白質(zhì)能辨識(shí)聯(lián)乙醯，是神經(jīng)元中引導(dǎo)蛔蟲(chóng)追蹤氣味的活躍部分。
Dr. Bargmann switched things around so that odr-10 was expressed only in a neuron that detected scents repulsive to the worm. These worms backed away from the buttery odor, showing that it is not the odor receptors but the wiring of the nervous system itself that determines whether the worm deems an odor delicious or detestable.
巴格曼博士調(diào)整了位置，傳播給有odr-10的神經(jīng)元蛔蟲(chóng)討厭的味道。蛔蟲(chóng)們遠(yuǎn)離了黃油氣味，這表示蛔蟲(chóng)判斷氣味好壞是靠神經(jīng)系統(tǒng)回路本身決定的而不是氣味接收器。
This was a surprising result because most people thought that sensory information was perceived as neutral, with the brain deciding later from the context whether it was good or bad. Some scientists said that only worms behave this way, but the same result was later obtained in mice.
這是個(gè)令人驚訝的結(jié)果，因?yàn)槎鄶?shù)人覺(jué)得感知信息是沒(méi)有傾向性的，好壞是由大腦隨環(huán)境而決定的。一些科學(xué)家說(shuō)只有蛔蟲(chóng)表現(xiàn)出這種行為，但后來(lái)在老鼠身上也得出這樣的結(jié)果。
Dr. Bargmann sees the arrangement in evolutionary terms. “The more reliable a piece of information is, the more it will be shifted into the genome,” she says. That way, an organism does not have to risk learning what is good or bad; the genes will dictate the right behavior by wiring it into the nervous system. Worms are wired up to know that diacetyl means good eating.
巴格曼博士認(rèn)為這是一種進(jìn)化方式。“越是可靠的信息，越會(huì)被轉(zhuǎn)換到基因組里。”她說(shuō)。那樣生物就不用冒著風(fēng)險(xiǎn)去學(xué)會(huì)分辨好壞。蛔蟲(chóng)通過(guò)回路知道聯(lián)乙醯代表了美味。
Having studied the worm by mutating its genes, Dr. Bargmann then looked at natural variation in the genetic basis of worm behavior. Most worms in nature like to congregate in clumps, but the laboratory version of C. elegans has developed an unusual liking for being on its own. She linked this difference in behavior to the switch of a single amino acid unit in a protein called npr-1 (for neuropeptide Y receptor-1).
通過(guò)改變其基因研究了蛔蟲(chóng)后，接著巴格曼博士專注于蛔蟲(chóng)基因?yàn)榛A(chǔ)的行為中的自然變異。自然界大多數(shù)蛔蟲(chóng)喜歡簇?fù)沓蓤F(tuán)，但實(shí)驗(yàn)室里的秀麗線蟲(chóng)卻養(yǎng)成了獨(dú)來(lái)獨(dú)往的喜好。她把這種行為的不同與蛋白質(zhì)內(nèi)一個(gè)氨基酸單位中性蛋白酶-1的改變聯(lián)系起來(lái)。（用于神經(jīng)肽Y的接收器1號(hào)）。
It took several more years to learn how the system worked. It turns out that social behavior in the worm is controlled by a pair of neurons called RMG. The two RMG neurons receive input from various sensory neurons that detect the several environmental cues that make worms aggregate. RMG integrates this information and sends signals to the worm’s muscles.
研究系統(tǒng)運(yùn)作又花費(fèi)了數(shù)年時(shí)間。結(jié)論得出蛔蟲(chóng)的社交習(xí)性是由一對(duì)叫做RMG的神經(jīng)元控制的。兩個(gè)RMG神經(jīng)元收到來(lái)自感覺(jué)神經(jīng)元的各種環(huán)境信號(hào)，使蛔蟲(chóng)們聚集起來(lái)。RMG集成信息并對(duì)蛔蟲(chóng)肌肉發(fā)出信號(hào)。
The usual role of the RMG neurons is to promote social behavior, but when the npr-1 gene is active, the RMG neurons cannot receive input from their sensory neurons, and the worms switch to solitary behavior.
RMG神經(jīng)元的特別用處在于它促進(jìn)了社交習(xí)性，但當(dāng)基因中性蛋白酶-1活躍時(shí)，RMG神經(jīng)元無(wú)法收到來(lái)自感覺(jué)神經(jīng)元的信號(hào)，蛔蟲(chóng)變得獨(dú)來(lái)獨(dú)往。
While working out the worm’s sense of smell, Dr. Bargmann fell in love with another olfactory researcher, Richard Axel. Dr. Axel works at Columbia University, and she was able to join him in New York by finding a place at Rockefeller University. Dr. Axel was helping her clear out her apartment in San Francisco when he heard he had won the Nobel Prize.
了解蛔蟲(chóng)的嗅覺(jué)后，巴格曼博士與同樣研究嗅覺(jué)的理查德·阿克塞爾墜入了愛(ài)河。阿克塞爾博士在哥倫比亞大學(xué)工作，她可以在洛克菲勒大學(xué)找到職位與他在紐約會(huì)合。阿克塞爾得知自己獲得諾貝爾獎(jiǎng)后幫助她清空了舊金山的公寓。
Right after that pleasant news, he had to drive to the local Goodwill store to drop off the stuff to be given away. “People think that if you’re married to a scientist you talk about science all the time,” Dr. Bargmann says. They read each other’s papers before publication, but they don’t plan experiments together. Dr. Axel works on how olfactory information is handled in the cortex, the highest level of human and mouse brains.
剛得知喜訊后，他得把要分發(fā)掉的行李開(kāi)車送去當(dāng)?shù)氐拇壬粕痰?。巴格曼博士說(shuō)：“人們覺(jué)得你和科學(xué)家結(jié)婚后就會(huì)無(wú)時(shí)不刻探討科學(xué)。”他們?cè)诎l(fā)表前互相閱讀對(duì)方的論文，但他們不會(huì)一起準(zhǔn)備實(shí)驗(yàn)計(jì)劃。阿克塞爾博士致力于嗅覺(jué)信息在大腦皮層內(nèi)的處理，這是人腦和鼠腦的最高等級(jí)研究。
“Probably once or twice a week we are sitting at dinner and Richard says, ‘The cortex is hopeless,’ and I say, ‘That’s why I work on the worm.’ ” Dr. Bargmann said.
“有可能一周或兩周一次我們吃飯時(shí)理查德會(huì)說(shuō)：‘大腦皮層沒(méi)希望了。’我會(huì)說(shuō)：‘那正是我為何要研究蛔蟲(chóng)。’”巴格曼博士說(shuō)。
After studying the little animal for 24 years, she believes she is closer to understanding how its nervous system works.
研究這小動(dòng)物24年后，她相信她對(duì)其神經(jīng)系統(tǒng)運(yùn)作的理解又加深了
Why is the wiring diagram produced by Dr. White so hard to interpret? She pulls down from her shelves a dog-eared copy of the journal in which the wiring was first described. The diagram shows the electrical connections that each of the 302 neurons makes to others in the system. These are the same kind of connections as those made by human neurons. But worms have another kind of connection.
為什么懷特博士制造的線路圖如此難破譯？她從書(shū)架上取下一本折角的雜志，上面第一次描述了回路。圖表顯示系統(tǒng)中302個(gè)神經(jīng)元每個(gè)都和其他的形成電連接。這和人腦神經(jīng)元的連接類似。但蛔蟲(chóng)有另外一種連接方式。
Besides the synapses that mediate electrical signals, there are also so-called gap junctions that allow direct chemical communication between neurons. The wiring diagram for the gap junctions is quite different from that of the synapses.
除了形成電子信號(hào)的突觸以外，還有使得神經(jīng)元之間產(chǎn)生直接化學(xué)通信的縫隙連接?？p隙連接的接線圖和突觸的接線圖非常不同。
Not only does the worm’s connectome, as Dr. Bargmann calls it, have two separate wiring diagrams superimposed on each other, but there is a third system that keeps rewiring the wiring diagrams. This is based on neuropeptides, hormonelike chemicals that are released by neurons to affect other neurons.
不光巴格曼博士口中的蛔蟲(chóng)連接體有兩個(gè)分別重疊于各自的接線圖，還有第三個(gè)重新連接接線圖的系統(tǒng)。這是基于神經(jīng)肽，神經(jīng)元影響其他神經(jīng)元后散發(fā)出的類似激素的化學(xué)物質(zhì)。
The neuropeptides probably help control the brain’s general status, or mood. A strong hint of how they work comes from the npr-1 gene, which makes a protein that responds to neuropeptides. When the npr-1 gene is active, its neuron becomes unavailable to its local circuit.
神經(jīng)肽很可能幫助控制了大腦的一般狀態(tài)，或是情緒。中性蛋白酶-1基因發(fā)出的強(qiáng)烈工作暗示使得蛋白質(zhì)對(duì)神經(jīng)肽產(chǎn)生反應(yīng)。中性蛋白酶-1活躍時(shí)，神經(jīng)元無(wú)法控制其局部回路。
That may be a reason why the worm’s behavior cannot be computed from the wiring diagram: the pattern of connections is changing all the time under the influence of the worm’s 250 neuropeptides.
這就是蛔蟲(chóng)的行為為何無(wú)法通過(guò)接線圖計(jì)算得出：在蛔蟲(chóng)250個(gè)神經(jīng)肽的影響下，連接的形式時(shí)刻在變化著
The connectome shows the electrical connections, and hence the quickest paths for information to move through the worm’s brain. “But if only a subset of neurons are available at any time, the connectome is ambiguous,” she says.
連接體顯示出電子連接，也因此是信息傳輸?shù)交紫x(chóng)腦內(nèi)的最快途徑。她說(shuō)：“但如果只有一個(gè)子集的神經(jīng)元是時(shí)刻有效的，連接體就會(huì)發(fā)生分歧。”
The human brain, too, has neuropeptides that set mood and modify behavior. Neuropeptides are probably at work when the pain pathways are cut off in acute crises, allowing people to function despite serious wounds.
人腦同樣有調(diào)節(jié)心情和調(diào)整行為的神經(jīng)肽。神經(jīng)肽任憑在重傷時(shí)痛覺(jué)通路被切斷的緊急情況下也可以調(diào)節(jié)人體。
The human brain, though vastly more complex than the worm’s, uses many of the same components, from neuropeptides to transmitters. So everything that can be learned about the worm’s nervous system is likely to help with the human system.
盡管人腦比蛔蟲(chóng)大腦復(fù)雜多了，但是從神經(jīng)肽到發(fā)射器的成分都相似。所以從研究蛔蟲(chóng)大腦得出的知識(shí)都對(duì)研究人體系統(tǒng)有幫助。
Though the worm’s nervous system is routinely described as simple, that is true only in comparison with the human brain. The worm has 22,000 genes, almost as many as a person, and its brain is a highly complex piece of biological machinery. The work of Dr. Bargmann’s and other labs has deconstructed many of its operational mechanisms.
盡管蛔蟲(chóng)的神經(jīng)系統(tǒng)通常被描述得很簡(jiǎn)單，但那只是和人腦比較的情況下。蛔蟲(chóng)有2萬(wàn)2千個(gè)基因，幾乎和一個(gè)成人一樣多，蛔蟲(chóng)大腦是生物體系中非常復(fù)雜的部分。巴格曼博士和其他實(shí)驗(yàn)室的研究解構(gòu)出了很多它的運(yùn)行機(jī)制。
What would be required to say that the worm’s nervous system was fully understood? “You would want to understand a behavior all the way through, and then how the behavior can change,” Dr. Bargmann says.
怎樣才能說(shuō)明蛔蟲(chóng)的神經(jīng)系統(tǒng)已經(jīng)完全研究清楚了呢？巴格曼博士說(shuō)：“你會(huì)通過(guò)所有方式了解一種行為，然后看這項(xiàng)行為會(huì)怎樣改變。”
“That goal is not unattainable,” she adds.
“這一目標(biāo)并非高不可攀。”她補(bǔ)充道。
聯(lián)系客服
