New research reveals how the brain arranges noun representations
Anthony Marrelli
Argus
In the 19th century, the discovery of the Rosetta Stone was used to understand the ancient Egyptian scrolls. Presently, a team of Carnegie Mellon University scientists have discovered the beginning of the neural Rosetta Stone.
Utilizing unique brain imaging and machine learning techniques, neuroscientists Marcel Just and Vladimir Cherkassky, and computer scientists Tom Mitchell and Sandesh Aryal determined how the brain arranges noun representations.
Just, a professor of Psychology and director of the Center for Cognitive Brain Imaging says they have “discovered how the brain’s dictionary is organized”.
As the researchers report, the three codes or factors that concern the development of basic human fundamental representation include how you physically interact with the object, how it is related to eating, and how it relates to shelter.
“It isn’t alphabetical or ordered by the sizes of objects or their colors. It’s through the three basic features that the brain uses to define common nouns like apartment, hammer and carrot,” says Just.
In the case of an item such as a hammer, the motor cortex was the brain area activated to code the physical interaction. “To the brain, a key part of the meaning of hammer is how you hold it, and it is the sensory-motor cortex that represents ‘hammer holding,’” said Cherkassky.
The research also showed that the noun meanings were coded similarly in all of the participants’ brains.
“This result demonstrates that when two people think about the word ‘hammer’ or ‘house,’ their brain activation patterns are very similar. But beyond that, our results show that these three discovered brain codes capture key building blocks also shared across people,” said Mitchell.
This study marked the first time thoughts stimulated by words alone were accurately identified using brain imaging, in contrast to earlier studies that used picture stimuli or pictures together with words.
The programs were able to identify the thought without benefit of a picture representation in the visual area of the brain, focusing instead on the semantic or conceptual representation of the objects.
Additionally, the team was able to predict where the activation would be for a previously unseen noun. A computer program assigned a score to each word for each of the three dimensions, and that score predicted how much brain activation there would be in each of 12 specified brain locations.
The theory generated a prediction of the activation for apartment based only on the patterns derived from the other 59 words.
To test the theory, the team used the word scores to identify which word a participant was thinking about, just by analyzing the person’s brain activation patterns.
The program was able to tell which of the 60 words a participant was thinking about, with an accuracy as high as 84 percent for two of the participants, and an average accuracy of 72 percent across all 10 participants.
The three factors, each coded in three to five different locations in the brain, were found by a computer algorithm that searched for commonalities among brain areas in how participants responded to 60 different nouns describing physical objects.
With psychiatric and neurological illnesses, the meanings of certain concepts are sometimes distorted,” Just said.
Another implication is in developing and testing domain expertise at the neural level. “We teach to the mind but we are shaping the brain, and now we can give the brain a test of how well it has learned a concept,” says Just.
The research can be found in the January 12th issue of the journal PLoS On, which is available open source and available at: http://www.plosone.org/home.action.