Level 5 Reading 7A

Reading 7A

阅读7A

SECRETS OF THE BRAIN New technologies are helping researchers solve a great biological mystery: how the brain really works. Carl Zimmer takes a journey into his own head to see what it's all about. My Contribution to Science In a scanning room at the Martinos Center for Biomedical Imaging in Boston, Massachusetts, I lay on my back on a slab, my head resting in an open plastic box. I had offered myself as a guinea pig to neuroscientist Van Wedeen and his colleagues who were now going to scan my brain. A white plastic helmet was lowered over my face, and the slab slowly glided into the scanner tube. The magnets that surrounded me began to rumble and beep. For an hour I lay still, eyes closed, and tried to remain calm in the narrow scanner—it wasn't easy. To suppress feelings of panic, I breathed smoothly and transported myself to places in my memory. At one point I recalled walking my nine-year-old daughter to school through the snow. And as I lay there, I reflected on the fact that all my thoughts and emotions were the creation of the 1.3-kilo loaf of flesh that was being scrutinized: my brain. Submitting to this uncomfortable scanning procedure was part of reporting on the stunning advances in understanding the human brain. Wedeen, who is at the forefront of brain imaging, creates in unprecedented detail representations of the brain's wiring. My brain scan was the first step in creating an image of my own brain, but I would have to make a second appointment to see the final product. On my return trip to his lab, Wedeen opened up the image on a computer screen. His technique—called diffusion spectrum imaging— translates radio signals given off by the brain. What I saw was a map of the nerve fibers that form hundreds of thousands of pathways, carrying information from one part of my brain to another. Wedeen had painted each path a rainbow of colors so that my brain appeared as an explosion of colorful fur, like a psychedelic Persian cat.

大脑的秘密 新技术正在帮助研究人员解决一个巨大的生物学谜团： 大脑是如何真正工作的。 卡尔·齐默（Carl Zimmer）走进自己的脑海，看看这是怎么回事。 我对科学的贡献 在马萨诸塞州波士顿Martinos生物医学成像中心的扫描室里， 我仰面躺在一块石板上，头枕在一个打开的塑料盒子里。 我把自己当成了神经科学家Van Wedeen的实验品 还有他的同事们，他们现在要扫描我的大脑。 一顶白色的塑料头盔被放在我脸上， 平板缓缓滑入扫描管。 我周围的磁铁开始发出隆隆声和嘟嘟声。 我闭着眼睛静静地躺了一个小时， 并试图在狭窄的扫描仪中保持冷静——这并不容易。 为了抑制恐慌感， 我呼吸顺畅，把自己带到了记忆中的地方。 有一次，我记得带着九岁的女儿在雪地里上学。 当我躺在那里时，我反思了这样一个事实，即我所有的想法和情绪 被仔细检查的1.3公斤肉是我的大脑。 接受这种令人不舒服的扫描程序 是关于理解人类大脑的惊人进展的报道的一部分。 Wedeen处于脑成像的前沿， 创造了前所未有的大脑线路细节表示。 我的脑部扫描是创建自己大脑图像的第一步， 但我必须再次预约才能看到最终产品。 在我回他的实验室的路上，Wedeen打开了电脑屏幕上的图像。 他的技术被称为扩散光谱成像-- 翻译大脑发出的无线电信号。 我看到的是形成数十万条通路的神经纤维图， 将信息从大脑的一个部分传递到另一个部分。 韦登把每条路都漆成了彩虹 所以我的大脑看起来就像一堆五颜六色的皮毛，就像一只迷幻的波斯猫。

Mapping the Brain Cutting-edge techniques for mapping the brain are giving researchers greater access to that organ than ever before. Some neuroscientists focus in on the structure of individual nerve cells, or neurons. Others chart genes that interact with those neurons. Still others—Wedeen among them— work on revealing as much of the brain's vast neural network as they can. Jeff Lichtman and his colleagues at Harvard University are creating extremely detailed three-dimensional images of neurons, revealing every bump and stalk branching from them. They begin by slicing preserved mouse brains into thin layers of tissue, each less than a thousandth the thickness of a human hair. An electron microscope is then used to take a picture of each layer, and the images are put in order using a computer. Slowly a three-dimensional image is built— one that the scientists can explore as if they were in a tiny submarine. "Everything is revealed," says Lichtman. The problem is that even a mouse brain is unbelievably complex. Lichtman and his colleagues have managed to recreate a piece about the size of a grain of salt. Its data alone is equal to the amount of data in about 25,000 high-definition movies. "It's a wake-up call to how much more complicated brains are than the way we think about them," says Lichtman. When asked if his method could be used to scan an entire human brain, which contains a thousand times more neurons than a mouse brain, Lichtman says with a laugh, "I don't dwell on that—it's too painful." When and if Lichtman completes his 3-D portrait of the brain, it will reveal much—but it will still be only an exquisitely detailed sculpture. Living neurons, on the other hand, are full of active genes that are integral to brian function. Researchers at the Allen Institute in Seattle, Washington, have developed a method for mapping these genes—the Allen Brain Atlas. First, the donated brains of recently deceased people are scanned using a powerful MRI scanner. This scan is used for reference as a kind of 3-D road map. The brain is then sliced into sections so thin that they are nearly invisible, and the slices are mounted on glass. Finally, chemicals are applied to reveal the active genes in the neurons. So far, the researchers have mapped the brain of six people. It's a huge amount of data, and they've only just begun to understand the genetic landscape of the brain. The scientists estimate that 84 percent of all the genes in our DNA become active in the adult brain. Certain combinations of genes are activated by neurons to carry out important tasks in different locations. The secret to certain disorders may be hiding in these complex networks, as certain genes shut down or switch on abnormally. Of all the new ways of visualizing the brain, perhaps the most remarkable is one invented by neuroscientist Karl Deisseroth and colleagues at Stanford University. They have found a way to make a mouse brain as transparent as glass, allowing researchers to see inside the brain while it is still intact. The technique involves replacing the naturally occurring substances in the brain with transparent ones. They can then color the brain with chemicals that show different pathways of connecting neurons. "You don't have to take it apart to show the wiring," says Deisseroth. It's not easy to dazzle neuroscientists, but Deisseroth's method, called CLARITY, has left his colleagues awestruck. Wedeen has called the research "spectacular ... unlike anything else in the field." Deisseroth's ultimate goal is to make a human brain transparent—a far more difficult task, not least because a human brain is 3,000 times larger than that of a mouse. He anticipates that CLARITY may someday help patients with autism or depression, but for now he's keeping those hopes in check. "We have so far to go before we can affect treatments that I tell people, 'Don't even think about that yet.' It's just a voyage of discovery for now."

绘制大脑地图 绘制大脑图谱的尖端技术 研究人员比以往任何时候都更容易接触到这种器官。 一些神经科学家专注于单个神经细胞或神经元的结构。 其他人绘制了与这些神经元相互作用的基因图。 还有其他人——Wedeen也在其中-- 尽可能多地揭示大脑庞大的神经网络。 哈佛大学的Jeff Lichtman和他的同事们 正在创建神经元的极其详细的三维图像， 露出它们身上的每一个凸起和分枝。 他们首先将保存的小鼠大脑切成薄层组织， 每根头发的厚度都不到人类头发的千分之一。 然后使用电子显微镜拍摄每一层的照片， 并且使用计算机对图像进行排序。 慢慢地，一个三维图像被建立起来-- 科学家们可以像在一艘小型潜艇上一样探索它。 利希特曼说：“一切都暴露了。”。 问题是，即使是老鼠的大脑也非常复杂。 利希特曼和他的同事们设法重新制作了一块大约一粒盐大小的碎片。 仅其数据量就相当于约25000部高清电影的数据量。 “这是一个警钟，提醒我们大脑有多么复杂 利希特曼说：“这比我们看待它们的方式更重要。”。 当被问及他的方法是否可用于扫描整个人脑时， 其含有比小鼠大脑多千倍的神经元， 利希特曼笑着说：“我不想纠缠于此——这太痛苦了。” 当Lichtman完成他的大脑3D肖像时， 它将揭示很多东西，但它仍然只是一个细节精美的雕塑。 另一方面，活神经元充满了对大脑功能不可或缺的活性基因。 华盛顿州西雅图艾伦研究所的研究人员， 开发了一种绘制这些基因的方法——艾伦脑图谱。 首先，使用功能强大的MRI扫描仪对最近去世的人的捐赠大脑进行扫描。 这种扫描作为一种三维路线图作为参考。 然后将大脑切成几乎看不见的薄片， 切片被固定在玻璃上。 最后，应用化学物质来揭示神经元中的活性基因。 到目前为止，研究人员已经绘制了六个人的大脑图谱。 这是一个巨大的数据量， 他们才刚刚开始了解大脑的遗传景观。 科学家估计，我们DNA中84%的基因 在成人大脑中变得活跃。 某些基因组合被神经元激活 在不同地点执行重要任务。 某些疾病的秘密可能隐藏在这些复杂的网络中， 因为某些基因异常关闭或开启。 在所有可视化大脑的新方法中， 也许最引人注目的是斯坦福大学的神经科学家Karl Deisseroth及其同事发明的。 他们已经找到了一种方法，可以使小鼠的大脑像玻璃一样透明， 使研究人员能够在大脑完好无损的情况下看到大脑内部。 该技术涉及用透明物质替代大脑中天然存在的物质。 然后，他们可以用化学物质给大脑上色 显示了连接神经元的不同途径。 Deisseroth说：“你不必把它拆开来显示接线。”。 让神经科学家眼花缭乱并不容易， 但Deisseroth的方法“CLARITY”让他的同事们惊叹不已。 Wedeen称这项研究“壮观……不同于该领域的其他任何研究。” Deisseroth的最终目标是让人类大脑透明化——这是一项更困难的任务， 尤其是因为人脑比老鼠大3000倍。 他预计，CLARITY有朝一日可能会帮助自闭症或抑郁症患者， 但目前，他正在控制这些希望。 “我们还有很长的路要走，才能影响我告诉人们的治疗方法， “现在连想都不要想。” 目前，这只是一次探索之旅。"

Connecting Brain with Machine For the most part, brain research has yet to change how doctors treat patients. But there is one line of research—brain-machine interfaces— where the mapping of the brain has started to change peoples lives. At 43 years old, Cathy Hutchinson suffered a massive stroke, leaving her unable to move or speak. Lying in her bed in Massachusetts General Hospital, she gradually figured out that her doctors didn't know if she was brain-dead or still aware. Her sister asked Hutchinson if she could understand her, and she managed to answer by moving her eyes up as a signal. "It gave me such a relief," Hutchinson tells me 17 years later, "because everybody talked about me as if I was dying." Still almost completely unable to move or speak, she communicates by looking at letters on a computer screen. A camera tracks the movement of a tiny metal disk attached to the center of her eyeglasses, thanks to a system developed by Brown University neuroscientist John Donoghue. Donoghue wanted to find a way to help people with paralysis by using signals from the brain's motor cortex— the area where signals to move muscles originate. He spent years developing such a device, testing it on monkeys. Once he and his colleagues knew it was safe, they were ready to start working with human patients. Surgeons inserted the device into Hutchinson's motor cortex. After she had healed from her surgery, the researchers plugged in wires to send signals from her brain to nearby computers. The computers recognize the signals and use them to move a computer cursor around a screen. Two years later, they attached a robot arm with a hand to the computers, and Hutchinson quickly learned to use it. "It felt natural," she says. So natural that one day she reached out for a cup of coffee, grabbed it, and brought it to her lips to drink. "Cathy's smile when she put down that drink that's everything," Donoghue says. Today Donoghue and other scientists are building on that success, hoping to create human-machine interfaces that will be powerful, safe, and easy. At Duke University, Miguel Nicolelis has gotten monkeys to control full-body exoskeletons using methods similar to those that helped Hutchinson. "Eventually brain implants will become as common as heart implants," says Nicolelis. Predicting the future is a tricky game, however, and advances in the past have inspired expectations that have not been met. But it is clear that current research is moving ncuroscience to a remarkable new stage.

将大脑与机器连接起来 在大多数情况下，大脑研究尚未改变医生治疗患者的方式。 但有一条研究路线——脑机接口-- 大脑图谱已经开始改变人们的生活。 43岁的Cathy Hutchinson遭受了严重的中风， 使她无法移动或说话。 躺在马萨诸塞州总医院的病床上， 她逐渐意识到，她的医生不知道她是脑死亡还是仍然清醒。 她姐姐问哈钦森是否能听懂她的话， 她设法通过抬起眼睛作为信号来回答。 17年后，告诉告诉我：“这让我松了一口气。”， “因为每个人都在谈论我，好像我快死了一样。” 仍然几乎完全无法移动或说话， 她通过看电脑屏幕上的字母进行交流。 一个摄像头追踪着她眼镜中心的一个小金属盘的运动， 这要归功于布朗大学神经科学家约翰·多诺霍开发的一个系统。 多诺霍想找到一种方法来帮助瘫痪的人 通过使用来自大脑运动皮层的信号-- 肌肉运动信号产生的区域。 他花了数年时间开发这种设备，并在猴子身上进行了测试。 一旦他和他的同事们知道这是安全的， 他们准备开始与人类患者合作。 外科医生将该装置插入哈钦森的运动皮层。 在她手术痊愈后， 研究人员插上电线，将信号从她的大脑发送到附近的电脑。 计算机识别信号并使用它们在屏幕上移动计算机光标。 两年后，他们用一只手把机器人手臂连接到电脑上， 哈钦森很快学会了使用它。 “感觉很自然，”她说。 如此自然，以至于有一天她伸手去拿一杯咖啡， 然后把它端到嘴边喝。 多诺霍说：“凯西放下饮料时的笑容就是一切。”。 如今，多诺霍和其他科学家正在这一成功的基础上再接再厉， 希望创建强大、安全、简单的人机界面。 在杜克大学，Miguel Nicolelis已经让猴子控制了全身外骨骼 使用类似于帮助哈钦森的方法。 Nicolelis说：“最终，大脑植入物将变得和心脏植入物一样普遍。”。 然而，预测未来是一场棘手的游戏， 过去的进步激发了人们的期望，但这些期望并没有得到满足。 但很明显，目前的研究正在将神经科学推向一个非凡的新阶段。

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