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This is Scientific American's 60-second Science, I'm Christopher Intagliata.

There's a scene in the Matrix where the character Cypher talks about the illusory experience of eating a fine meal:

CARLOS RIBEIRO: "And then he eats from the steak and says:"

(FILM CLIP: "I know this steak doesn't exist. I know that when I put it in my mouth, the Matrix is telling my brain that it is juicy and delicious.")

CARLOS RIBEIRO: "It tastes so good, I prefer this virtual reality to the cruelty of the world."

(FILM CLIP: "Ignorance is bliss¹.")

Recounting that scene is Carlos Ribeiro, a neuroscientist at the Champalimaud Foundation in Portugal. He has a special interest in that scene because he has essentially² recreated that phenomenon—in fruit flies. "This is exactly what we're doing to the flies."

Here's how it works. He and his team raised genetically⁴ engineered flies with taste neurons that can be turned on and off with red and green light. That kind of process is known as optogenetics.

His team fed the flies bland⁵ food, which they understandably disliked. But then the researchers bathed the flies in light to turn on sweetness-perceiving neurons, and the flies gobbled up the food, which to them now tasted sweet. The team was also able to do the same with bitter neurons. The flies got bitter food, which they avoided—but the scientists then turned off the bitter neurons, and all of a sudden the flies changed their minds. "And so we have used this to create completely virtual taste realities for our flies."

The experimental details are in the journal eLife.

So, why do this? "We really want to understand how the brain uses sensory⁶ taste information to make feeding decisions—and also what goes wrong in obese⁷ people, for example, or when there are other diseases related to nutrition."

He also imagines we could someday use gene³ therapy techniques to plug senses back into the noses or tongues of people who've lost the ability to smell or taste. But for now, that is, like the Matrix, firmly the realm of science fiction.

(FILM CLIP: "I know kongfu." "Show me.")

Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.

这里是科学美国人——60秒科学系列，我是克里斯托弗·因塔格里塔。

电影《黑客帝国》中有一个场景，片中角色塞弗谈论吃美味佳肴的虚幻体验：

卡洛斯·里贝罗：“然后他吃了牛排并说：”

（电影剪辑：“我知道这块牛排并不存在。我知道当我把它放进嘴里时，矩阵告诉我的大脑它多汁且美味。”）

卡洛斯·里贝罗：“味道真是太棒了，比起残酷的世界，我更喜欢这种虚拟现实。”

（电影剪辑：“无知是福。”）

描述这一场景的是葡萄牙查姆帕利莫德基金会的神经学家卡洛斯·里贝罗。他对那个场景特别感兴趣，因为他基本上在果蝇身上重现了那个现象。“这正是我们对果蝇所做的事。”

以下是具体操作方式。他和团队饲养转基因果蝇，使其神经元可以在红绿光下开关。这种过程被称为“光遗传学”。

他的团队给果蝇喂食清淡食物，它们当然不喜欢这种食物。但之后，研究人员用光照射果蝇，打开其感知甜味的神经元，然后果蝇便狼吞虎咽地吞下食物，现在对它们来说这种食物是甜的。团队对苦味神经元进行了同样的操作。果蝇得到了它们会避开的苦味食物，但在科学家关闭了苦味神经元后，果蝇马上改变了主意。“因此，我们用这种方法为果蝇创造了完全虚拟的味觉现实。”

实验细节发表在《eLife》期刊上。

那为什么要这样做？“我们真的想了解大脑如何利用感官味觉信息来做出进食决定，我们还想知道比如肥胖人群的问题出在哪里，或者何时会产生与营养有关的其它疾病。”

他还想象有一天我们能利用基因治疗技术，让失去嗅觉或味觉能力的人的鼻子或舌头恢复感知。但就目前而言，这就像《黑客帝国》一样，完全属于科幻小说的范畴。

（电影剪辑：“我会功夫。”“练练看”）

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。