Brain Dictionary: Scientists create Atlas to decode inner thoughts
What if a map of the brain could help us decode people’s inner thoughts?
Scientists at the University of California, Berkeley, have taken a step in that direction by building a “semantic atlas” that shows in vivid colors and multiple dimensions how the human brain organizes language. The atlas identifies brain areas that respond to words that have similar meanings.
The findings, published in the journal Nature, are based on a brain imaging study that recorded neural activity while study volunteers listened to stories from the Moth Radio Hour, a U.S. Radio Show. They show that at least one-third of the brain’s cerebral cortex, including areas dedicated to high-level cognition, is involved in language processing.
“Our goal was to build a giant atlas that shows how one specific aspect of language is represented in the brain, in this case semantics, or the meanings of words,” said Jack Gallant, a neuroscientist at the University of California, Berkeley.
No single brain region holds one word or concept. A single brain spot is associated with a number of related words. And each single word lights up many different brain spots. Together they make up networks
that represent the meanings of each word we use: life and love; death and taxes; clouds, Florida and bra. All light up their own networks.“It is possible that this approach could be used to decode information about what words a person is hearing, reading, or possibly even thinking,” said Alexander Huth, the first author on the study. One potential use would be a language decoder that could allow people silenced by motor neuron disease or locked-in syndrome to speak through a computer.
Strikingly, the brain atlases were similar for all the participants, suggesting that their brains organized the meanings of words in the same way. The scientists only scanned five men and two women, however. All are native English speakers, and two are authors of the study published in Nature. It is highly possible that people from different backgrounds and cultures will have different semantic brain atlases.
Armed with the atlas, researchers can now piece together the brain networks that represent wildly different concepts, from numbers to murder and religion. “The idea of murder is represented a lot in the brain,” Gallant said.
Using the same haul of data, the group has begun work on new atlases that show how the brain holds information on other aspects of language, from phonemes to syntax. A brain atlas for narrative structure has so far proved elusive, however. “Every time we come up with a set of narrative features, we get told they aren’t the right set of narrative features,” said Gallant.
Lorraine Tyler, a cognitive neuroscientist and head of the Centre for Speech, Language and the Brain at Cambridge University said the research was a “tour de force in its scope and methods”. But the brain atlas in its current form does not capture fine differences in word meanings. Take the word “table”. It can be a member of many different groups, says Tyler. “It can be something to eat off, things made of wood, things that are heavy, things having four legs, non-animate objects, and so on. This kind of detailed semantic information that enables words to be used flexibly is lost in the analysis,” she said. “While this research is path-breaking in its scope, there is still a lot to learn about how semantics is represented in the brain.”
