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翻譯資格考試輔導：時事口譯筆譯6

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Inside Avatar's Brain Science

Now the highest-grossing film ever, "Avatar," has captivated millions of viewers with its picturesque scenery, extraterrestrial battles, and nature-loving, blue-skinned aliens.

A high-tech interfacing mechanism allows a human to remain inert while controlling one of these avatar hybrids just by thinking.

Not only does the human manipulate the avatar's movements and speech, but he or she also experiences life -- every sensation, feeling and emotion -- through the eyes of the hybrid, as if consciousness were transferred.

Scientists say we are many decades, even centuries, away from making this kind of sophisticated interaction possible, if it can be done at all. But the fundamentals of components required to create this complicated system of mind-controlled avatars are already in the works, and have useful applications in medicine.

"We're starting to understand the basic building blocks, but the biggest challenges will be emotion and thought -- how to make another organism think what you think, to feel what you feel -- because those networks are much more difficult to sort out," said Dr. Brian Litt, associate professor of neurology and bioengineering at the University of Pennsylvania.

Although nothing as complex as manipulating a creature through thought has been done, scientists working on allowing handicapped people to move prosthetic limbs with their minds are making headway. This idea actually played a role in the movie: Protagonist Jake Sully was in a wheelchair in his human body, but could walk, run and jump as his avatar.

One demonstration has been shown by Miguel Nicolelis, a neuroscientist at Duke University, who is working on robotic leg braces. In 2008, his group got a monkey in North Carolina to mentally control the walking patterns of a robot in Japan.

This was done by implanting electrodes in the brains of two rhesus monkeys. The electrodes recorded how cells in the brain's motor and sensory cortex responded to walking on the treadmill at various speeds. The monkeys' legs also had sensors to record walking patterns.

Researchers used all this information to predict the exact speed of movement and stride length of the legs, and uploaded that information to a robot in Japan, getting the robot to move in synch with a monkey thousands of miles away in real time. Even when the treadmill was turned off, a monkey continued making the robot walk just by thinking for a few minutes.

Another arena is one of virtual reality: controlling an avatar in a video game with your mind. Jaime Pineda, cognitive neuroscientist at the University of California, San Diego, is working with a brain-computer interface that allows participants to move a car around a racetrack, fly a plane and do other virtual tasks on a screen, simply by thinking. The mental training for this takes about four to six hours, he said.

Apart from the entertainment value, Pineda sees this as a future therapy for autistic children. The theory is that because people with autism have less conductivity between various parts of the brain, participating in mind-controlled video games may normalize those circuits. Results from his lab show improvement in social interaction and other behaviors after 10 or 20 weeks of playing the game in the lab.

Here's what's possible now: Scientists such as Gerwin Schalk at the New York State Department of Health's Wadsworth Center have harnessed the brain's electrical impulses to have people mentally type their thoughts using electrodes on the surface of the head. The rate is typically seven words per minute. In one epileptic patient who had electrodes already on the brain for clinical purposes, the record was 20 words per minute.

This kind of technology is useful for people who are paralyzed and cannot communicate, Schalk said. His research group also works on using electrodes to extract specific information from the brain such as people's actual actions, imagined actions and intended actions -- even how they move individual fingers.

Today there are auditory prostheses called cochlear implants that encode signals that allow people to hear who could not otherwise, as well as rudimentary visual aids. It is also possible to stick a pin in a particular part of someone's brain and induce sensations of various temperatures, pressures and even pain levels, just by stimulating certain neural circuits.