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今天，我想和大家談論人類大腦的奧秘，這是我們在加州大學所做的研究。試著思考一下這個問題，這裡有一堆肉，大約三磅重，可用一隻手掌握住，但它卻可以探究浩瀚的星際空間，可以探究無限的意義，可以探究自身存在的意義，可以探究上帝的本質。
這是世界上最不可思議之事，這是人類面臨的最大謎題之一：這一切是怎麼來的？正如你們所知，大腦是由神經元所組成，這就是神經元，成人大腦裡含有一千億個神經元，在大腦中，每個神經元與其他神經元的交接點約有一千至一萬處。基於這一點，人們計算出大腦活動的排列組合，總數超過了宇宙中基本粒子的數量。
所以，我們應該如何研究大腦？一種方法是，觀察那些在大腦不同部位受到損傷的病人，並研究他們行為的變化，這是我於上次TED大會上演講的內容。今天我將講述另一種不同的方法，就是將電極放在大腦的不同的部位，並記錄大腦中個別神經細胞的活動情形，類似於竊聽神經細胞在大腦內的活動。
最近，義大利Parma的研究人員，就是Giacomo Rizzolatti與其同事們，在大腦前方的額葉發現一組神經元，稱之為鏡像神經元。此外，大腦前方還有一組神經元，稱之為運動神經元，在50年前就已被發現。當人們做某種動作時這組神經元會發射訊號，例如，如果我這麼做，伸手抓住一顆蘋果，一個位於我大腦前方的運動神經元就會發射訊號；如果我伸手拉一個物體，另一個神經元會發射訊號，控制我拉那個物體，我們很久以前就發現了這些被稱之為運動神經元的東西。
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以下為系統擷取之英文原文
I'd like to talk to you today about the human brain, which is what we do research on at the University of California. Just think about this problem for a second. Here is a lump of flesh, about three pounds, which you can hold in the palm of your hand. But it can contemplate the vastness of interstellar space. It can contemplate the meaning of infinity, ask questions about the meaning of its own existence, about the nature of God.
And this is truly the most amazing thing in the world. It's the greatest mystery confronting human beings: How does this all come about? Well, the brain, as you know, is made up of neurons. We're looking at neurons here. There are 100 billion neurons in the adult human brain. And each neuron makes something like 1,000 to 10,000 contacts with other neurons in the brain. And based on this, people have calculated that the number of permutations and combinations of brain activity exceeds the number of elementary particles in the universe.
So, how do you go about studying the brain? One approach is to look at patients who had lesions in different part of the brain, and study changes in their behavior. This is what I spoke about in the last TED. Today I'll talk about a different approach which is to put electrodes in different parts of the brain, and actually record the activity of individual nerve cells in the brain. Sort of eavesdrop on the activity of nerve cells in the brain.
Now, one recent discovery that has been made by researchers in Italy, in Parma, by Giacomo Rizzolatti and his colleagues, is a group of neurons called mirror neurons, which are on the front of the brain in the frontal lobes. Now, it turns out there are neurons which are called ordinary motor command neurons in the front of the brain, which have been known for over 50 years. These neurons will fire when a person performs a specific action. For example, if I do that, and reach and grab an apple, a motor command neuron in the front of my brain will fire. If I reach out and pull an object, another neuron will fire, commanding me to pull that object. These are called motor command neurons that have been known for a long time.
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但Rizzolatti發現這組神經元中，有百分之二十的神經元，當我觀看他人做同樣動作時，也會發射訊號。因此，當我伸手抓某物時，這個神經元會發射訊號，但當我觀看Joe伸手抓某物時，它也會發射訊號。這實在是令人震驚，因為這就像是這個神經元會採用他人的觀點，幾乎就像是虛擬實境般模仿他人的動作。
那麼，這些鏡像神經元的存在有何意義？其中必定包含模仿和仿真等行為。因為如果要模仿一個複雜的行為，我的大腦必須採用他人的觀點，因此模仿和仿真非常重要。好，它們為什麼重要呢？讓我們看看下一張幻燈片。要如何進行模仿？為什麼模仿是重要的？鏡像神經元、模仿、仿真。
現在，讓我們來看看人類文化的各種現象。如果我們回到約七萬五千至十萬年前，觀察人類演化過程，結果發現，大約在七萬五千年前，一件非常重要的事發生了，那就是各種「人類」獨有的技巧突然出現並迅速傳播，像是工具的使用、火的使用、房屋的出現，當然還有語言，以及讀取他人心思和理解他人行為的能力。與之前相較之下，這一切發生的相當迅速。
雖然人類大腦容量在大約三、四十萬年前就已發展成目前的大小，但這些事件在十萬年前才相當迅速地發生。我認為這些事件的產生，源於複雜的鏡像神經元系統突然出現，讓你能模仿他人的行為。舉例來說，當族群中某一成員意外發現火的使用或某種特殊工具，這些方法並沒有失傳，而是迅速地在族群中橫向傳播，或縱向地代代相傳。
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But what Rizzolatti found was a subset of these neurons, maybe about 20 percent of them, will also fire when I'm looking at somebody else performing the same action. So, here is a neuron that fires when I reach and grab something, but it also fires when I watch Joe reaching and grabbing something. And this is truly astonishing. Because it's as though this neuron is adopting the other person's point of view. It's almost as though it's performing a virtual reality simulation of the other person's action.
Now, what is the significance of these mirror neurons? For one thing they must be involved in things like imitation and emulation. Because to imitate a complex act requires my brain to adopt the other person's point of view. So, this is important of imitation and emulation. Well, why is that important? Well, let's take a look at the next slide. So, how do you do imitation? Why is imitation important? Mirror neurons and imitation, emulation.
Now, let's look at culture, the phenomenon of human culture. If you go back in time about [75,000] to 100,000 years ago, let's look at human evolution, it turns out that something very important happened around 75,000 years ago. And that is, there is a sudden emergence and rapid spread of a number of skills that are unique to human beings like tool use, the use of fire, the use of shelters, and, of course, language, and the ability to read somebody else's mind and interpret that person's behavior. All of that happened relatively quickly.
Even though the human brain had achieved its present size almost three or four hundred thousand years ago, 100,000 years ago all of this happened very very quickly. And I claim that what happened was the sudden emergence of a sophisticated mirror neuron system, which allowed you to emulate and imitate other people's actions. So that when there was a sudden accidental discovery by one member of the group, say the use of fire, or a particular type of tool, instead of dying out this spread rapidly, horizontally across the population, or was transmitted vertically, down the generations.
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所以這是一種拉馬克式，而非達爾文式演化。達爾文式演化是緩慢的，需耗時數十萬年。一隻北極熊要進化出一身毛皮需歷經數千代，或許得耗時十萬年；一個人類小孩只需觀看父母如何屠殺另一隻北極熊，將其剝皮，並將毛皮披在身上當作外衣，很快就能學會這個方法。北極熊需十萬年才能進化出的毛皮，人類僅需五或十分鐘就能經學習而擁有。當他們學會之後，這項技能將以燎原之勢在族群中傳播。
這就是本源，所謂文化就是模仿複雜的技能，這就是文明的基礎。我現在要談另一種具有相當不同功能的鏡像神經元。如同擁有掌管動作的鏡像神經元一樣，人體也擁有掌管碰觸的鏡像神經元。換句話說，如果某人觸碰了我，碰觸我的手，大腦內感測區域中的軀體感覺皮質神經元會發射訊號，但同一個神經元，在某些情況下，當我觀看他人被觸碰時，也會發射訊號，因此，它會對他人被觸碰產生共鳴。
因此，當我身上不同部位被觸碰時，大多數神經元會發射訊號，不同神經元負責身體上不同的區域。但有部份神經元即使在我觀看他人於同一位置被觸碰時，也會發射訊號，因此，同樣的，有一些神經元參與了你與他人之間的共鳴。現在問題來了：如果我只是觀看他人被觸碰，為什麼我不會感到困惑，並確實產生被觸碰的感覺呢？我的意思是，我與那個人產生共鳴，但我並未真正產生觸碰感。那是因為我們皮膚上有感受器，有觸感和痛感受器，它會向大腦回覆，「別擔心，你並沒有被觸碰，所以，當然，你與他人產生共鳴，但並非真正歷經被碰觸的過程，否則你會感到困惑並產生混淆。」
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So, this made evolution suddenly Lamarckian, instead of Darwinian. Darwinian evolution is slow; it takes hundreds of thousands of years. A polar bear, to evolve a coat, will take thousands of generations, maybe 100,000 years. A human being, a child, can just watch its parent kill another polar bear, and skin it and put the skin on its body, fur on the body, and learn it in one step. What the polar bear took 100,000 years to learn, it can learn in five minutes, maybe 10 minutes. And then once it's learned this it spreads in geometric proportion across a population.
This is the basis. The imitation of complex skills is what we call culture and is the basis of civilization. Now there is another kind of mirror neuron, which is involved in something quite different. And that is, there are mirror neurons, just as there are mirror neurons for action, there are mirror neurons for touch. In other words, if somebody touches me, my hand, neuron in the somatosensory cortex in the sensory region of the brain fires. But the same neuron, in some cases will fire when I simply watch another person being touched. So, it's empathizing the other person being touched.
So, most of them will fire when I'm touched in different locations. Different neurons for different locations. But a subset of them will fire even when I watch somebody else being touched in the same location. So, here again you have neurons which are enrolled in empathy. Now, the question then arises: If I simply watch another person being touched, why do I not get confused and literally feel that touch sensation merely by watching somebody being touched? I mean, I empathize with that person but I don't literally feel the touch. Well, that's because you've got receptors in your skin, touch and pain receptors, going back into your brain and saying "Don't worry, you're not being touched. So, empathize, by all means, with the other person, but do not actually experience the touch otherwise you'll get confused and muddled."
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好，所以這裡有一種回饋信號，否決鏡像神經元所發出的信號，使你不會在意識上歷經被觸碰的感覺。但如果你將手臂移除，或向我的手臂注射，將它麻醉，麻醉臂神經叢，使手臂麻木，不會再有任何感覺時，現在，如果我觀看你被觸碰，事實上我腦海裡能產生被觸碰的感覺。換句話說，你將你與他人之間的隔膜溶解了，因此，我稱它們為甘地神經元，或共鳴神經元。(笑聲)
這並不是某種抽象的隱喻，將你與他人隔開的就只有你的皮膚，移除你的皮膚，你將能感同身受地體驗他人被觸碰，你將你與他人之間的隔膜溶解了，這當然就是許多東方哲學的基礎，就是並沒有真實獨立的自我將你與他人隔開，並以此審視這個世界，審視他人。事實上，你並不只是藉由Facebook或網路與他人產生聯繫，而是藉由各式各樣的神經元。在這間大廳裡，有一群神經元正互相交談，你與他人的意識並沒有任何真正的差異。
這並非晦澀難懂的哲學，而是起源於我們對基礎神經學的瞭解。假設有位病人有幻肢症，如果你被截肢，而有幻肢症，當看到他人被觸碰時，你的幻肢也會產生同樣感覺。令人震驚的是，若你患有幻肢痛，當你捏他人的手，按摩他人的手時，你幻肢痛的症狀就會減輕，彷彿僅僅藉由觀看他人被按摩，神經元就能獲得放鬆的舒適感。
這是最後一張幻燈片。長期以來，人們都將科學與人文視為截然不同的領域。C.P. Snow說，這兩種文化，一邊是科學，一邊是人文，永遠不會有交集。而我認為，鏡像神經元系統將成為這個交集的基礎，讓你重新思考一些問題，例如什麼是意識，什麼展現了你的自我，什麼將你與其他人隔開，什麼使你與他人產生共鳴，甚至關於文化與文明產生之類的議題，以及什麼才是人類獨一無二之處，謝謝。(掌聲)
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Okay, so there is a feedback signal that vetos the signal of the mirror neuron preventing you from consciously experiencing that touch. But if you remove the arm, you simply anesthetize my arm, so you put an injection into my arm, anesthetize the brachial plexus, so the arm is numb, and there is no sensations coming in, if I now watch you being touched, I literally feel it in my hand. In other words, you have dissolved the barrier between you and other human beings. So, I call them Gandhi neurons, or empathy neurons. (Laughter)
And this is not in some abstract metaphorical sense, all that's separating you from him, from the other person, is your skin. Remove the skin, you experience that person's touch in your mind. You've dissolved the barrier between you and other human beings. And this, of course is the basis of much of Eastern philosophy, And that is there is no real independent self, aloof from other human beings, inspecting the world, inspecting other people. You are in fact, connected not just via Facebook, and Internet, you're actually quite literally connected by your neurons. And there is whole chains of neurons around this room, talking to each other. And there is no real distinctiveness of your consciousness from somebody else's consciousness.
And this is not mumbo-jumbo philosophy. It emerges from our understanding of basic neuroscience. So, you have a patient with a phantom limb. If the arm has been removed and you have a phantom, and you watch somebody else being touched, you feel it in your phantom. Now the astonishing thing is, if you have pain in your phantom limb, you squeeze the other person's hand, massage the other person's hand, that relieves the pain in your phantom hand, almost as though the neuron were obtaining relief from merely watching somebody else being massaged.
So, here you have my last slide. For the longest time people have regarded science and humanities as being distinct. C.P. Snow spoke of the two cultures: science on the one hand, humanities on the other; never the twain shall meet. So, I'm saying the mirror neuron system underlies the interface allowing you to rethink about issues like consciousness, representation of self, what separates you from other human beings, what allows you to empathize with other human beings, and also even things like the emergence of culture and civilization, which is unique to human beings. Thank you.
