Resolving sentence ambiguity with planning and working memory resources: Evidence from fMRI

Area of Science:

• Cognitive Neuroscience
• Psycholinguistics
• Neuroimaging

Background:

• Understanding sentence structure and resolving ambiguity are fundamental aspects of language processing.
• The precise neural mechanisms underlying the resolution of temporary structural ambiguity and the role of executive functions remain debated.
• Previous research suggests involvement of prefrontal and parietal regions in complex language tasks.

Purpose of the Study:

• To investigate the neural correlates of executive resource recruitment during the disambiguation of syntactically ambiguous sentences.
• To differentiate the brain regions involved in strategic planning versus working memory demands in sentence processing.
• To test competing hypotheses regarding the role of executive functions in resolving temporary structural ambiguities.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to monitor brain activity in 19 healthy young adults.
• Participants read sentences with either a direct object (DO) or sentential complement (SC) structure, presented phrase-by-phrase.
• Sentences varied in verb-structure mapping consistency and working memory load, manipulated by including extra phrases.

Main Results:

• Sentences with less consistent verb-structure mappings elicited greater activation in the dorsolateral prefrontal cortex (dlPFC).
• Increased working memory load correlated with heightened activation in the left inferior parietal cortex (IPC).
• These findings implicate distinct neural resources for on-line planning and working memory during ambiguity resolution.

Conclusions:

• The brain utilizes a flexible, large-scale network for sentence processing, recruiting specific executive resources as needed.
• Dorsolateral prefrontal cortex (dlPFC) activation suggests a role in strategic planning for resolving structural ambiguities.
• Left inferior parietal cortex (IPC) activation highlights its involvement in managing working memory demands during complex sentence comprehension.