Map of the brain's word filing system could help us read minds

Most English dictionaries list words alphabetically, but how do we store them in our head? Finding out could have an unexpected pay-off: being able to tell what someone is thinking from their brain activity. Although neuroscientists can already do this to a limited extent, the brain's internal filing system for words and concepts – an important step towards accurately reading a person's thoughts – remains murky. Now Jack Gallant at the University of California, Berkeley, and his team have charted the "semantic system" of the human brain. The resulting map reveals that we organise words according to their deeper meaning, in subcategories based around numbers, places, and other common themes. Previous "mind-reading" studies have shown that certain parts of the brain respond to particular words.