"We would give the study participants a brief scenario and ask them to complete it with what comes naturally," Wilson said. "For example, if I said to you, 'A man was walking along the railway tracks. He didn't hear the train coming. What happened to the man?' Usually, you would say, 'He was hit by the train,' or something along those lines."
"But a patient with damage to the upper pathway might say something like 'train, man, hit.' We found that the lower pathway has a completely different function, which is in the meaning of single words."
To test for comprehension of the meaning of a sentence, the researchers presented the patient with a sentence like, "The girl who is pushing the boy is green," and then ask which of the two pictures depicted that scenario accurately.
"One picture would show a green girl pushing a boy, and the other would show a girl pushing a green boy," Wilson said. "The colors will be the same, the agents will be the same, and the action is the same. The only difference is, which actor does the color apply to?"
"Those who have only lower pathway damage do really well on this, which shows that damage to that pathway doesn't interfere with your ability to use the little function words or the functional endings on words to figure out the relationships between the words in a sentence."
Wilson said that most previous studies linking neurodegeneration of specific regions with cognitive deficits have focused on damage to gray matter, rather than the white matter that connects regions to one another.
"Our study shows that the deficits in the ability to process sentences are above and beyond anything that could be explained by gray matter loss alone," Wilson added. "It is the first study to show that damage to one major pathway more t
|Contact: Daniel Stolte|
University of Arizona