A Rice University researcher has announced the identification of those parts of the brain that are involved in the process of choosing appropriate words during speech.
Tatiana Schnur, assistant professor of psychology at Rice, says that her team's findings may be helpful in gaining a deeper understanding of the speech problems that are often faced by stroke patients.
Describing the study in the Proceedings of the National Academy of Sciences, she and her colleagues revealed that they wanted to determine whether one particular part of the brain, the left inferior frontal gyrus (LIFG), was necessary for resolving the competition for choosing the correct word.
The researchers said that they compared brain images from 16 healthy volunteers and 12 volunteers who suffer from aphasia, an acquired language disorder as a result of stroke.
They observed that two parts of the brain, the LIFG and the left temporal cortex, responded to increased conflict among words competing for selection during speech.
However, according to them, only the LIFG was found to be necessary to resolve the competition for successful word production.
Tatiana revealed that the LIFG includes Broca's area, named after the 19th-century French scientist Paul Pierre Broca, which is responsible for aspects of speech production, language processing and language comprehension.
Her findings were based on two experiments where the subjects had to name a series of images, and conflict between words increased as more images were named.
In the first experiment, the researchers used functional magnetic resonance imaging to measure brain activations among healthy speakers, while in the second experiment, they mapped performance deficits to lesion locations in participants with aphasia.
Tatiana said that looking at direct parallels between the healthy and aphasic volunteers enabled her team to couple location in the brain with specific speech processes.
She and her colleagues found that the ability of aphasic speakers "to resolve competition that arises in the course of language processing appears to depend on the integrity of the LIFG."
The researchers believe that their findings may open an exciting line of research, as damage to this mechanism may explain the hesitant, non-fluent speech exhibited by those described as Broca's aphasics.