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  3. Scientists sent patterns of electricity coursing across people’s brains, coaxing their brains to see letters that weren’t there.

Scientists sent patterns of electricity coursing across people’s brains, coaxing their brains to see letters that weren’t there.

admin2022-11-16  158
问题     Scientists sent patterns of electricity coursing across people’s brains, coaxing their brains to see letters that weren’t there. The experiment worked in participants who had lost their sight in adulthood, according to the study published in the journal Cell by neuroscientist Michael Beauchamp and neurosurgeon Dr. Daniel Yoshor, both at the Baylor College of Medicine.
    Known as artificial visual devices, the implants were placed on the visual cortex—a brain region that processes incoming information from the eyes—and then stimulated in a pattern to "trace" out shapes that the participants could then "see." The study authors crafted the letters by stimulating the brain with electrical currents, causing it to generate so-called phosphenes— tiny spots of light that people sometimes perceive without any actual light entering their eyes, unlike when light bounces off an object in the room and enters your eyes.
    The team laid an array of electrodes over the region of the brain known as VI, where information from the eyes gets transmitted for early processing. VI works like a map, where different regions of the map correspond to the different zones of our visual field. The authors found that, if they activated one electrode at a time, participants reliably saw a phosphene appear in its predicted zone. But if multiple electrodes came online simultaneously, the individual phosphenes still appeared but did not come together as coherent shapes. So the authors hypothesized that by "sweeping an electrical current across" several electrodes, they could trace patterns onto the surface of the brain and thus generate recognizable shapes.
    "The brain is uniquely tuned to detect changes in our environment, and the organ should track a pattern of phosphenes presented one after the other," the authors said. With this assumption, they generated phosphenes between the locations of two separate electrodes, thus connecting the dots between them, and, surprisingly, the study participants could see the traced shapes and accurately recreate them on a touch screen. When participants in the study began seeing letters form in their minds’ eyes, "I think they were at least as excited as we were, probably more!" Beauchamp and Yoshor said.
    In the future, "these electrodes may be designed to penetrate the cortex so that the electrode tips are closer to the neurons that lie several hundred microns below the cortical surface," they added. "For certain patients, however, surface electrodes may work best, depending on the risks associated with implanting electrodes deeper in their brains," Yoshor said, "There are so many different causes of blindness that some patients may benefit most from deeply implanted electrodes, others from surface electrodes and still others from devices implanted directly into the retinas, which only require eye surgery to implant."
Which of the following is true according to the words of Yoshor?
选项 A、It is desirable to get the electrode tips closer to the neurons of patients.
B、It may be dangerous for some patients to get deeper electrode implants.
C、Electrodes may directly reach the cortex of the patients by eye surgery.
D、Penetrated implants probably can be beneficial to most of the patients.
答案B
解析 通读全文可知，Yoshor说话的内容集中在第五段后半部分。其中第一句For certain patients, however, surface electrodes may work best, depending on the risks associated with implanting electrodes deeper in their brains(然而，对于某些病人来说，在他们脑皮层表面植入电极效果最佳，因为电极植入大脑越深，风险就越高)可知，对于某些病人来讲，并不是植入电极越深越好。B项It may be dangerous for some patients to get deeper electrode implants句意与原文是同义替换，故为正确答案。由第五段第一句“these electrodes may be designed to penetrate the cortex so that the electrode tips are closer to the neurons that lie several hundred microns below the cortical surface”(“或许我们还可以将这些电极设计成能够深入脑皮层中去，这样电极的端片就可以更加贴近皮层之下数百微米处的神经元”)可知，这种操作还处于设想层面，可行性尚不明了，且通过后文的转折可知，并不是所有的病人都适合把电极深度植入大脑，故排除选项A。第二句提到still others from devices implanted directly into the retinas. which only require eye surgery to implant(而有些病人只需要做个眼科手术，把设备植入视网膜就足够了)，但并未指出电极可以通过眼部手术直达脑皮层，故排除选项C。原文只提到有些病人适合深度植入，有些病人适合表层植入，还有一些病人适合眼科手术，并没有表述大多数病人都适合深度植入，故排除选项D。
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