Measuring brain sensitivity to semantic distance in spoken narrative comprehension

Area of Science:

• Neuroscience
• Cognitive Science
• Psycholinguistics

Background:

• Discourse comprehension involves integrating local word meanings and global story gist.
• The brain processes semantic information at multiple time scales and granularities.
• Limited understanding exists regarding the neural basis of processing local versus global semantic relationships.

Purpose of the Study:

• To investigate how semantic distance between a word and its prior context influences brain activity during naturalistic listening.
• To identify brain regions sensitive to varying semantic distances at different context window sizes.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) data from 79 participants listening to a podcast interview.
• Developed a novel method to estimate semantic distance at multiple grain sizes.
• Applied amplitude-modulated regression to identify brain regions responsive to semantic distance.

Main Results:

• Semantic distance significantly activates a frontotemporal network, including the superior and middle temporal gyri and inferior frontal gyrus, and the cerebellum.
• The right anterior superior temporal gyrus showed heightened sensitivity to larger context window sizes.
• Findings suggest a right hemisphere specialization for gist processing and anterior temporal lobe involvement in semantic integration.

Conclusions:

• Semantic distance is a crucial factor driving neural activity in language comprehension.
• The findings support distinct roles for brain regions in processing local and global semantic information.
• This study presents a novel methodology for exploring neural responses to semantic context in naturalistic settings.