[彭蒙惠英语] 人类心思看得更透(2)
A Clearer View of the Human Mind (2/3)
Mind reading has become a serious scientific endeavor. How is it done? With a gigantic magnet!
A huge magnet
To look at how the brain works in fine detail, from neuron to neuron, a huge magnet is needed. The one at the University of Illinois at Chicago is 9-4 tesla.
At 100,000 times the strength of the Earth's magnetic field , the university's magnet is so strong it pulls on the steel shanks in the shoes of people who come near it. If it weren't for a 520-ton steel shield encasing the magnet, people would be able to feel its fringe magnetic field a couple of blocks away.
How it works
The magnet's hollow core holds the targets. In comparison to the machine, they are much smaller: They are the sodium ions in the brain that generate the electrical charges powering our thoughts.
The machine is the first to be able to follow the flow of sodium, allowing it to see the firing of individual brain cells instantaneously. Instead of looking at the flow of blood as a marker of brain activity, it will look directly at the biochemistry that underlies thought. Other brain imaging machines follow water-the main ingredient in blood-and that means a time lag.
Neurons will register a flash of light in 100 milliseconds, for instance, but the flow of blood that accompanies this activity is comparatively slow, taking two to five seconds.
Pass the test
Thulborn was the first person to have his brain imaged in the new machine. "It was very satisfying," he said. "What people said couldn't be done was actually done." He could see that billions and billions of neurons were working busily in his brain.
Now that the machine is running and going through safety tests, Thulborn anticipates that in time, it will reveal some of the mind's deepest secrets: how we make decisions, how we perceive things, how we process language.
Vocabulary Focus
fringe (n) ---the outer or less important part of an area, group or activity
instantaneously (adv) ---something that takes place immediately, without any delay
lag (n) ---a delay between two things happening
Specialized Terms
magnetic field (n phr) --- 磁场 an area around a magnet or something magnetic, in which its power to attract objects to itself can be felt
shank (n) --- （鞋子底部的）铁心 the narrowest part of the bottom of a shoe, beneath the arch of the foot
marker (n) --- 标记 a symbol or object that gives information or indicates the presence of something
