Semantic ambiguity processing in sentence context: Evidence from event-related fMRI

Area of Science:

• Cognitive Neuroscience
• Psycholinguistics
• Neuroimaging

Background:

• Lexical semantic ambiguity occurs when a word has multiple meanings, posing a challenge for language comprehension.
• Understanding how the brain resolves ambiguity is crucial for deciphering complex language processing.
• Previous research has explored various aspects of context processing and integrative tasks in the brain.

Purpose of the Study:

• To identify specific brain regions involved in resolving contextually driven lexical semantic ambiguity.
• To investigate the neural mechanisms underlying the selection and updating of word meanings based on sentence context.
• To examine the role of different brain hemispheres in semantic ambiguity resolution.

Main Methods:

• Event-related functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• Participants were presented with sentences containing ambiguous words, biased towards dominant or subordinate meanings by sentence-final context.
• Control sentences without ambiguous words were used for comparison; brain activity at the end of sentences was modeled.

Main Results:

• A bilaterally distributed network, including the inferior frontal gyri (BA 45/44, BA 47) and inferior/middle temporal gyri (BA 20/37, BA 20), supports semantic ambiguity resolution.
• Activation patterns suggest an initial frequency-based probabilistic selection of word meaning, followed by contextual updating.
• The findings indicate similar roles for both brain hemispheres in resolving semantic ambiguity, challenging earlier claims.

Conclusions:

• The brain utilizes a widespread bilateral network for comprehending context-dependent word meanings.
• Semantic ambiguity resolution involves a dynamic process of meaning selection and contextual refinement.
• Neuroimaging findings align with existing literature on integrative and contextual processing, highlighting bilateral hemispheric contributions.