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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  193
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."
The reason why the authors failed to generate recognizable visual shapes at first was that________.
选项 A、there was a lack of connection between each two separate electrodes
B、the phosphenes didn’t appear in their assumed zones of the brain
C、the participants couldn’t accurately retell the shapes on the touch screen
D、the brain wasn’t tuned enough to detect changes in the environment
答案A
解析 根据题文同序原则可以推测，本题最有可能设在第三段。该段第四句提到But if multiple electrodes came online simultaneously, the individual phosphenes still appeared but did not come together as coherent shapes. (但如果同时激活多个电极，参与者虽然也能看见幻视光点，但这些光点并没有构成连贯的图形)，既然没有形成连贯的图形，那么参与者有可能“看不到”图案。题干中的recognizable visual shapes对应原文中的coherent shapes。但下文中第四段第二句提到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 (在两个间隔的电极之间又制作了一些幻视光点，这样就可以连接两个电极之间的断点……参与实验的盲人看见了科学家所描绘的图形，而且还可以在触屏上精确地再现这些图形)，由此可知，既然科学家将断点连接在一起后便获得了成功，那么最初失败的原因可逆推为“电极之间缺乏连接”，故选项A为正确答案。第三段第四句提到the individual phosphenes still appeared but did not come together as coherent shapes(参与者虽然也能看见幻视光点，但这些光点并没有构成连贯的图形)。由此可见，实验失败并不是因为幻视光点没有出现在目标区域，而是没有连在一起，故排除选项B。第四段第二句提到the study participants could see the traced shapes and accurately recreate them on a touch screen(参与实验的盲人看见了科学家所描绘的图形，而且还可以在触屏上精确地再现这些图形)，由此可知，他们再现出图形是实验成功后的结果。并不是决定实验成败的因素，故排除选项C。第四段首句提到The brain is uniquely tuned to detect changes in our environment(人脑非常独特，它天生就有一种调节能力，可以察觉环境中的变化)，由此可知该项与原文表述不符，故排除选项D。
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