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根据以下材料，回答题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 V1, where information from the eyes gets transmitted for early processing.V1 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 maybe 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."
According to the first two paragraphs, how does the artificial visual device work? A．By crafting artificial shapes and patterns into the eyes of the blind with visual device.
B．By stimulating device in the visual cortex of the blind with certain electrical currents.
C．By implanting phosphenes into the brains of the participants who are blind in adulthood.
D．By tracing out shapes when light reflects off an object and enters the eyes of the blind.
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