雅思阅读材料盘点：脑机连接的世界

　　Kernel的工程师希望首先能打造出用于治疗中风及阿尔茨海默症等神经系统疾病的设备。不过，他们最终想创造的是能够强化认知能力、任何人也许都想买的植入物。Kernel由企业家布莱恩·约翰逊(Bryan Johnson)于2016年10月创立。和马斯克一样，他也是因提供在线支付的处理服务而致富(马斯克参与创办的Paypal在2013年收购了约翰逊的公司Braintree)。约翰逊自掏腰包向Kernel投入一亿美元，并称“解开我们大脑的秘密是有史以来最为重要、意义最为重大的一个机会。”

　　In some ways, Mr Johnson and Mr Musk are merely the new boys in what is quite an old field. The first brain implants, carried out in the 1970s, were prosthetic visual systems, though they did not work well. Cochlear implants, to restore hearing, have done much better. Hundreds of thousands of people now have them—though, strictly speaking, they talk to auditory nerves rather than to the brain directly, which simplifies the task. For some people, the symptoms of Parkinson’s disease can be kept in check by electrodes the diameter of a strand of spaghetti inserted deep into the brain. And one of the latest ideas in the field is to read and interpret brain activity, in order to restore movement to the limbs of the paralysed.

　　从某些方面来看，约翰逊和马斯克仅仅是新步入一片久经耕耘的领域的毛头小伙。最早的脑植入物是人工视觉系统，于上世纪70年代植入人脑，不过效果并不太好。用于恢复听力的人工耳蜗表现则要好得多。如今已有几十万人植入了人工耳蜗——不过严格说来，它们并不是直接同大脑对话，而是连接听觉神经，这使任务得以简化。在有些人那里，将一根意面粗细的电极植入其大脑深处，便可抑制帕金森氏症的某些症状。该领域最新的想法之一是读取并解读大脑的活动，以使瘫痪之人的四肢恢复活动能力。

　　In one important way, however, Kernel and Neuralink are different from previous efforts. Though aimed initially at medical applications, they also explicitly nod to the possible non-medical uses of this kind of implant technology. In February Mr Musk said that he thought “meaningful” interfaces between the brain and computation were five years away. The creation of Neuralink suggests that he, like Mr Johnson, is putting his money where his mouth is.

　　不过，Kernel和Neuralink在一个重要的方面有别于前人的工作。虽然它们最初的计划是将这类植入技术应用于医疗，但也明确表示可能将它们应用于医疗之外的目的。马斯克在2月称，他认为要实现人脑和计算机之间“有意义”的连接需要五年的时间。Neuralink的创立表明他和约翰逊一样，是个会为自己倡导的东西投资的人。

　　Most neuroscientists would, it must be acknowledged, regard all this as heroically optimistic. In a review of the field, published in January in Nature Reviews Materials, Polina Anikeeva and her colleagues at the Massachusetts Institute of Technology (MIT) wrote that, although Moore’s Law and the miniaturization of electronics have brought devices down to a size where their insertion into the brain can be considered, big challenges lie ahead.

　　必须得承认，多数神经科学家都会认为这些计划乐观中却也透着逞强。在发表于1月《自然综述：材料》(Nature Reviews Materials)上的一篇对该领域的综述中，麻省理工学院的波琳娜·安尼基娃(Polina Anikeeva)及其同事写道，虽然摩尔定律及电子元件的微型化已使各种装置缩小到可以考虑将之置入大脑的程度，但未来仍存在着重大挑战。

　　The brain’s complexity, and researchers’ present lack of understanding of how that organ’s component cells work together to do what they do, makes designing interfaces between brain and machine hard. But, even were it simple in principle, the rigid, silicon-based tools of modern computing do not mesh easily with the squishy soft-tissue of biology. Implants often generate scars around themselves. And the surgery needed to put them in place carries risks of its own.

　　由于人脑的复杂性，以及研究人员目前对组成人脑的细胞协同工作的原理理解得并不充分，要设计人机接口并不容易。不过，就算这在理论上变得简单易行，要让硬质的现代化计算硅片跟生物学中黏湿的软组织相融合也不会很容易。植入物经常会对周围的组织造成创伤，将它们放入相应位置的手术本身也存在风险。

　　There may, though, be alternative approaches. One such is being tested by a group at Florida International University, in Miami, led by Sakhrat Khizroev. Dr Khizroev and his team use magnetoelectric particles so tiny that they can interact with the electric field generated by an individual nerve cell. The team inject these particles, tens of billions at a time, into a vein in a rat’s tail, then drag them into the animal’s brain using magnets. Each particle produces an electric field when stimulated by an external magnetic field. This may, in principle, permit a researcher to use such a particle to influence the electrical states of nearby nerve cells—and thus, in essence, reprogram them. How that would be done in practice, though, is obscure.

　　不过，或许还有其他的办法。迈阿密佛罗里达国际大学(Florida International University)的萨克拉特·齐兹洛夫博士(Sakhrat Khizroev)所领导的团队便在测试其中的一种。他们使用的磁电粒子十分微小，能够与单个神经细胞产生的电场相互作用。该团队将数百亿这种粒子一次性注射进小鼠尾部的血管中，然后用磁铁将它们引至小鼠的大脑。每个粒子都会在外部磁场的刺激下产生电场。这在理论上或许可令研究人员利用这种粒子来影响附近神经细胞的电位状态——实质上就是重新编排这些细胞。但这在实践中能如何实现就不得而知了。

　　Another approach, being pioneered by Jose Carmena of the University of California, Berkeley, and his colleagues, uses devices the size of a grain of rice to convert ultrasonic energy beamed towards them into electricity that can stimulate nerve or muscle cells. Ultrasound travels through the body, so can power and control such devices without wires.

　　加州大学伯克利分校的何塞·卡梅纳(Jose Carmena)及其同事正在开创另外一种替代办法。他们所使用的装置有一粒米那么大，可将射向它们的超声波能量转化为电能来刺激神经或肌肉细胞。超声波能穿透身体，因而无需电线就可驱动和控制这种装置。