formed well above chance when they were made to rank the 1,001 words according to how well they matched the pattern. The results are reported in Science 1.
The idea is similar to another ‘brain-reading' technique, reported in Nature earlier this year2, that can predict what picture a person is seeing from a selection of more than 100. The new model is different in that it has to look at the meanings of the words, rather than just lower-level visual features of a picture.
活动关联
研究小组给9为志愿者出示了一些名词的图片，并使用机能性磁共振成像技术（fMRI）扫描了他们的大脑。然后研究人员给电脑输入了60个名词中的58个来训练它。计算机会在一个有一万亿单词的文本中进行检索，就为找到每个名词是如何与那25个动词相关联的，并且找到这种关联与哪种大脑活动相关。
训练结束，进入测试阶段。电脑的任务就是找到那2个没有被输入单词所对应的大脑活动类型，并且推算出那2个单词。一般来说，电脑的正确率超过75%。
接下来的实验更深一步，这次给电脑输入59个单词用于训练，然后给它一个新的大脑活动类型，让它在1001个单词中选择一个与之配对。根据这1001个单词与脑活动的配比程度，电脑将它们排序，它的表现依然良好。这项结果已经发表于《科学》杂志。
另一种"读脑"技术与此想法类似，它可以从100多幅图片中找到人看过的那一张，这项技术于今年早些时候发表于《自然》杂志。两种技术不同之处在于，本文介绍的新模型着眼于词语的意思，而不仅仅是较低等级的图片的视觉特征。

Mind readers
It shouldn't be too difficult to get the model to choose accurately between a larger number of words, says John-Dylan Haynes, who also works on models of brain decoding at the Bernstein Center for Computational Neuroscience Berlin in Germany. "This study shows a method that allows one to read out a large number of different thoughts from brain activity, even with only a few calibration measurements," he says.
An average English speaker knows 50,000 words, Mitchell says, so the model could in theory be used to select any word a subject chooses to think of.
Even whole sentences might not be too distant a prospect for the model, says Mitchell. "Now that we can see individual words, it gives the scaffolding for starting to see what the brain does with multiple words as it assembles them," he says. This gives researchers the chance to understand the "mental chemistry" that the brain does when it processes such phrases, Mitchell suggests.
Models such as this one could also be useful in diagnosing disorders of language or helping students pick up a foreign language. In semantic dementia, for example, people lose the ability to remember the meanings of things - shown a picture of a chihuahua, they can only recall 'dog', for example - but little is known about what exactly goes wrong in the brain. "We could look at what the neural encoding is for this," says Mitchell.
读心者
"让电脑从更多的词语中精确挑选出一个并不是非常难的事"，John-Dylan Haynes如是说，他在柏林的计算神经科学Bernstein中心工作，同样致力于研发可以解码人脑的模型。他说，"这项研究指出了一种通过大脑活动阅读大量不同想法的方法，这种方法甚至只需要少量

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