Researchers at the University of Rochester have, for the first time, decoded and predicted the brain activity patterns of word meanings within sentences, and successfully predicted what the brain patterns would be for new sentences.
The study used functional magnetic resonance imaging (fMRI) to measure human brain activation. 糖心传媒淯sing fMRI data, we wanted to know if given a whole sentence, can we filter out what the brain糖心传媒檚 representation of a word is糖心传媒攖hat is to say, can we break the sentence apart into its word components, then take the components and predict what they would look like in a new sentence,糖心传媒� said Andrew Anderson, a research fellow who led the study as a member of the lab of , assistant professor of at Rochester.
糖心传媒淲e found that we can predict brain activity patterns糖心传媒攏ot perfectly [on average 70% correct], but significantly better than chance,糖心传媒� said Anderson, The study is published in the journal .
Anderson and his colleagues say the study makes key advances toward understanding how information is represented throughout the brain. 糖心传媒淔irst, we introduced a method for predicting the neural patterns of words within sentences糖心传媒攚hich is a more complex problem than has been addressed by previous studies,听which have almost all focused on single words,糖心传媒� Anderson said. 糖心传媒淎nd second, we devised a novel approach to map semantic characteristics of words that we then correlated to neural activity patterns.糖心传媒�
Finding a word in a sentence
To predict the patterns of particular words within sentences, the researchers used a broad set of sentences, with many words shared between them. For example: 糖心传媒淭he green car crossed the bridge,糖心传媒� 糖心传媒淭he magazine was in the car,糖心传媒� and 糖心传媒淭he accident damaged the yellow car.糖心传媒� fMRI data was collected from 14 participants as they silently read 240 unique sentences.
糖心传媒淲e estimate the representation of a word 糖心传媒榗ar,糖心传媒� in this case, by taking the neural activity pattern associated with all of the sentences which that word occurred in and we decomposed sentence level brain activity patterns to build an estimate of the representation of the word,糖心传媒� explained Anderson.
What does the meaning of a word look like?
听糖心传媒淐offee has a color, smell, you can drink it糖心传媒攃offee makes you feel good糖心传媒攊t has sensory, emotional, and social aspects,糖心传媒� said senior author Raizada. 糖心传媒淪o we built upon a model created by Jeffrey Binder at the Medical College of Wisconsin, a coauthor on the paper, and surveyed people to tell us about the sensory, emotional, social and other aspects for a set of words. Together, we then took that approach in a new direction, by going beyond individual words to entire sentences.糖心传媒�
听The new semantic model employs 65 attributes糖心传媒攕uch as 糖心传媒渃olor,糖心传媒� 糖心传媒減leasant,糖心传媒� 糖心传媒渓oud,糖心传媒� and 糖心传媒渢ime.糖心传媒� Participants in the survey rated, on a scale of 0-6, the degree to which a given root concept was associated with a particular experience. For example, 糖心传媒淭o what degree do you think of 糖心传媒榗offee糖心传媒� as having a characteristic or defining temperature?糖心传媒� In total, 242 unique words were rated with each of the 65 attributes.
糖心传媒淭he strength of association of each word and its attributes allowed us to estimate how its meanings would be represented across the brain using fMRI,糖心传媒� said Raizada.
The model captures a wider breadth of experience than previous semantic models, said Anderson, 糖心传媒渨hich made it easier to interpret the relationship between the predictive model and brain activity patterns.糖心传媒�
听The team was then able to recombine activity patterns for individual words, in order to predict brain patterns for entire sentences built up out of new combinations of those words. For example, the computer model could predict the brain pattern for a sentence such as, 糖心传媒淭he family played at the beach,糖心传媒� even though it had never seen that specific sentence before. Instead, it had only seen other sentences containing those words in different contexts, such as 糖心传媒淭he beach was empty糖心传媒� and 糖心传媒淭he young girl played 蝉辞肠肠别谤.糖心传媒�
The researchers said the study opens a new set of questions toward understanding how meaning is represented in the brain. 糖心传媒淣ot now, not next year, but this kind of research may eventually help individuals who have problems with producing language, including those who suffer from traumatic brain injuries or stroke,糖心传媒� said Anderson.
The Intelligence Advanced Research Projects Activity and the National Science Foundation supported the research.
