圖1.在求偶期間，雄性果蠅(藍色)尾隨雌性果蠅(紅色)。有色線條使用SLEAP(Social LEAP Estimates Animal Poses：社交的LEAP判斷動物姿態，是一種深度學習軟體框架。用於從影片中，進行通用的多動物肢體追蹤)追蹤每個肢體及身體部位的每一個動作。SLEAP是由，2021年博士生Talmo Pereira及其於Murthy實驗室之同事們設計的一種動作捕捉程式。
A male fruit fly (blue) follows a female (red) during their courtship. The colored lines track every movement of each limb and body segment using SLEAP, a motion-capture program designed by Talmo Pereira, a 2021 Ph.D. graduate of Princeton, and his colleagues in the Murthy lab.
Love songs are at least as popular in the animal kingdom as on the radio. The importance of musically serenading your true love has driven plotlines from Twelfth Night to The Trumpet of the Swan to Happy Feet.
情歌在動物王國中，至少與在電台中一樣普遍。用音樂為真愛唱小夜曲的重要性，曾推動從《第十二夜》到《天鵝號角》再到《快樂的大腳》的主要情節。
The latest exploration of music in the natural world is taking place in Mala Murthy’s lab at the Princeton Neuroscience Institute, where Murthy and her research group have used neural imaging, optogenetics, motion capture, modeling and artificial intelligence to pinpoint precisely where and how a fruit fly’s brain toggles between its standard solo and its mating serenade. Their research appears in the current issue of the journal Nature.
有關自然界中之音樂的最新探索，正在美國普林斯頓大學神經科學研究所，Mala Murthy的實驗室進行。在那裡，Murthy及其研究團隊已經使用，神經造影、光遺傳學、動作捕捉、模型製作及人工智慧，來精確找出果蠅大腦，在其標準獨奏與交配小夜曲之間，反復觸發的位置及方式。他們的研究發表於，最新一期(2023年10月12日)的《自然》期刊。
“For me it is very rewarding that, in a team of exceptional scientists coming from different backgrounds, we joined forces and methodologies to figure out the key characteristics of a neural circuit that can explain a complex behavior — the patterning of courtship song,” said Frederic Römschied, first author on this paper and a former postdoctoral fellow in Murthy’s lab. He is now a group leader at the European Neuroscience Institute in Göttingen, Germany.
該論文首要撰文人，目前是歐洲神經科學研究所(位於德國哥廷根市)，一支團隊領導人，Frederic Römschied宣稱：「對我來說，參與一支由來自不同背景之傑出科學家團隊，這是非常值得的。我們結合了，諸多力量及方法論來找出，能解釋複雜行為之神經迴路的關鍵特徵。也就是，求愛歌曲的模式。」
“It might be a surprise to discover that the fruit flies buzzing around your banana can sing, but it’s more than music, it’s communication,” said Murthy, the Karol and Marnie Marcin ’96 Professor and the director of the Princeton Neuroscience Institute.
Karol and Marnie Marcin ’96的教授兼普林斯頓神經科學研究所所長，Murthy宣稱：「發現在香蕉周圍嗡嗡作響的果蠅會唱歌，這或許是件令人驚訝的事。不過，這不僅僅是音樂，它是溝通。
It’s a conversation, with a back and forth. He sings, and she slows down, and she turns, and then he sings more. He’s constantly assessing her behavior to decide exactly how to sing. They’re exchanging information in this way. Unlike a songbird, belting out his song from his perch, he tunes everything into what she’s doing. It’s a dialogue.”
這是一種具有來、回的溝通。雄果蠅唱歌，䧳果蠅放慢速度、轉身，然後雄果蠅唱得更多。雄果蠅不斷評估䧳果蠅的行為，以決定究竟如何唱歌。它們以此方式交換信息。與鳴鳥不同，雄果蠅從其棲息處，大聲唱出它的歌聲，雄果蠅將一切都調整到，䧳果蠅在做的事情上。這是一種對話。」
By studying how these tiny brains work, researchers hope to develop insights that will prove useful in the larger and more complex brains that are millions of times harder to study. In particular, Murthy’s team is trying to determine how the brain decides what behavior is appropriate in which context.
藉由研究此些微小大腦如何運作，研究人員們希望獲得，能在研究難度數百萬倍之更大、更複雜大腦中，證實有用的洞察力。特別是，Murthy的團隊正嘗試確認，大腦如何決定，在哪種情況下、哪種行為是適當的。
“One of the brain’s most impressive abilities is its capacity to generate patterns of behavior that are appropriate in particular contexts,” said Max Aragon, a fifth-year graduate student in Murthy’s lab. “For example, the way you speak to a group of close friends in a coffee shop is likely very different from the way you speak to relatives at dinner. What is happening in the brain that allows us to generate this behavioral flexibility?”
於Murthy實驗室的五年級研究生，Max Aragon宣稱：「大腦最令人印象深刻的能力之一，是在特定環境中，它能產生適當的行為模式。譬如，在咖啡店與一群親密朋友交談的方式，可能與在晚餐時與親戚交談的方式，截然不同。於大腦中，發生了什麼事情，使我們得以產生這種行為靈活性？」
圖2. Murthy及其同事們已經繪製出，第一個全腦連結體：於Drosophila melanogaster(果蠅)大腦中的全部神經元及其連結。
Murthy and her colleagues have mapped out the first whole brain connectome: the total set of neurons and their connections in a Drosophila melanogaster (fruit fly) brain.
Similar to crickets and grasshoppers, fruit flies also use their wings to sing, but they extend and vibrate one wing at a time. For Drosophila melanogaster, only the male fruit flies sing. The females respond by moving away or slowing down to allow the male to approach. Male fruit flies can’t force mating; he has to woo her.
類似蟋蟀及蚱蜢，果蠅也使用翅膀唱歌。不過，它們一次伸展、振動一隻翅膀。就Drosophila melanogaster而言，僅有雄性果蠅會唱歌。雌性藉由作出走開或放慢速度的反應，來使雄性得以接近。雄性果蠅不會強行交配； 他必須對她求愛。
“He chases her and sings to her, and she chooses whether or not to slow down for him,” Murthy said. “They’ll go through this dance for 20 minutes or so, until she slows down enough to mate. He’ll sing hundreds of the ‘song bouts’ to her during their courtship.”
Murthy宣稱：「他追著對她唱歌，她選擇是否為他放慢腳步。他們會跳這種舞蹈大約20分鐘，直到她放慢速度足以進行交配。在他們求愛期間，他會對她唱數百次‘歌曲回合’。」
The simplest song bouts last only a fraction of a second, and the complex bouts can go on for several seconds. In an audio clip of the fruit fly serenade, amplified thousands of times, you can hear a series of pulses intermixed with more musical tones.
最簡單的歌曲回合持續僅幾分之一秒，而複雜的回合能持續達幾秒鐘。在放大數千倍之果蠅小夜曲的音訊片段中，能聽到一系列與更多音樂聲調交雜的脈衝。
“That’s the real song. It’s not slowed down or sped up,” Murthy said. “It’s just so quiet that even if the fruit fly landed in your ear, you wouldn’t hear it. You need to amplify it, because fruit flies have tiny little wings, but that’s it. That’s actually what he’s singing to her.”
Murthy宣稱：「那是真正的歌曲。它沒有被減慢或加速。只不過這很平穩，即使果蠅處在耳邊，也不會聽到。需要將它放大，因為果蠅具有很細小的翅膀，不過僅此而已。實際上，那是他正對她唱歌。」
短片網址：https://youtu.be/m5qasVB3tXs
The “pulses” are the sounds that the male makes when he’s further away, to get the female’s attention, and the more tuneful serenading that he does up close is the “sine” song. There’s a third mode, “complex,” which flips back and forth between pulse and sine songs.
此些“脈衝”是雄性離雌性較遠時，所發出以引起雌性注意的聲音。而在近距離時，所發出旋律更優美的小夜曲，是“正弦”歌曲。還有第三種，在脈衝與正弦歌曲之間，來、回翻轉的複雜模式。
As he chases and she evades or encourages his approach, the song flickers back and forth between simple pulse-only songs and complex pulse and sine serenades. She seems to like the alternating pattern as well. In the clinical language of academia, the paper says, “Songbout complexity may be desirable to the female, as the majority of bouts immediately preceding copulation are complex.”
當他追求而她躲避或鼓勵他接近時，此種歌曲在只是脈衝的歌曲與複雜的脈衝及正弦小夜曲之間，來、回擺盪。她似乎也喜歡交替的模式。該項論文表示，在學術界的臨床語言中，「歌曲回合(Songbout)的複雜性，或許是䧳性所期望的。因為在交配前，緊接的回合大多數是複雜的。」
Several Princeton resources contributed to answering the question of how the fruit fly brain signals the right song for the right context.
若干普林斯頓大學的資源，有助於回答果蠅大腦，如何就正確的背景，發出正確歌曲信號的問題。
The team used LEAP (LEAP Estimates Animal Pose) and its next generation SLEAP (Social LEAP Estimates Animal Poses), both deep-learning-based motion-capture tools developed by a previous Princeton collaboration, that quantified exactly how the flies are moving and where they are in relation to each other.
該團隊使用了，LEAP(LEAP判斷動物姿態)及其下一代的SLEAP(社交的LEAP判斷動物姿態)。這兩種是由先前普林斯頓大學一項合作所開發，以深度學習為基礎，經準確量化此些果蠅，正如何移動及它們彼此關係位置之捕捉動作的工具。
In addition, the neural imaging of the flies was performed at the endowment-funded Bezos Center for Neural Circuit Dynamics.
此外，這些果蠅的神經造影，是在捐贈基金資助的貝佐斯神經迴路動態中心進行的。
“Princeton is a special place that encourages collaboration between scientists with diverse expertise, from computational neuroscience to physics and beyond,” Aragon said. “PNI in particular is a relatively small institute, so there’s a good chance of running into someone with a great idea that happens to exactly solve a problem you’ve been facing in your work.”
Aragon宣稱：「普林斯頓大學是一處，鼓勵從計算神經科學到物理學等，具有不同專業知識科學家們之間合作的特殊地方。普林斯頓大學神經科學研究所(PNI：Princeton Neuroscience Institute)特別是個相對小的機構，因此有偶然遇到某個具有，碰恰確切解決，於研究上一直面臨之問題的人。」
“Being at Princeton, working with Mala Murthy, created an extremely supportive atmosphere, where novel ideas were always encouraged, and the path from idea to experiment was free from bureaucratic hurdles,” agreed Römschied.
Using SLEAP, the researchers showed that the key cause for the switch between solo mode and serenade mode was proximity — how close together the male and female fruit flies were.
Römschied認同：「在普林斯頓大學，與Mala Murthy進行研究，創造了一種極度有支持力的氛圍，新穎的構想總是受到鼓勵，從構想到實驗的道路，沒有官僚障礙。」使用SLEAP，此些研究人員證實了，有關獨奏模式與小夜曲模式之間切換的關鍵原因，是距離。也就是，雄性與雌性果蠅在一起，有多接近。
“Our work uncovered a toggle switch in his brain,” Murthy said. “When the switch is engaged, he can sing a beautiful, long song, and then immediately, as he separates from her just a little bit, the switch disengages, and he’s just singing one simple song. We showed that this one neural circuit operates in two regimes via the switch. You don’t need a separate circuit to generate a different song. This had not been shown before. ”
Murthy宣稱：「我們的研究揭露了，於其大腦中的一個來回開關。當此開關開啟時，他能唱一首優美、長的歌曲。然後，當他與她稍微分開時，此開關立即關閉，因此他只唱一首簡單的歌曲。我們證實了，這條神經迴路經由此開關，以兩種型式運作。無需不同的迴路，來產生不同的歌曲。這先前一直未經證實。」
“I love the idea of a circuit that toggles between regimes,” she continued. “It’s just so simple. You don’t have to keep making new circuits for every new behavior. It’s such a nice, elegant solution.”
她續言：「我喜歡一種，來回於兩型式間之迴路的構想。這就是這麼簡單。無需為每一個新行為，不斷產生新迴路。這是一種如此美好、優雅的解決方案。」
網址：https://www.princeton.edu/news/2023/10/12/fruit-fly-serenade-princeton-neuroscientists-decode-tiny-creatures-mating-song
翻譯：許東榮
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