The extended language network: Language-responsive brain areas whose contributions to language remain to be...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Imaging

Background:

• Traditional language neuroscience focuses on left frontal and temporal areas.
• Other brain regions are implicated in language, but their roles are unclear due to confounding factors in research paradigms.
• Existing evidence often mixes language processing with perceptual, motor, or general cognitive tasks.

Purpose of the Study:

• To identify a comprehensive set of brain areas reliably responding to language across modalities.
• To evaluate the selectivity of these areas for language processing compared to non-linguistic tasks.
• To map the extended language network beyond the core fronto-temporal regions.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) data from 772 participants.
• Employed a validated language localizer paradigm to isolate language processing.
• Compared brain activity during linguistic tasks with a demanding non-linguistic task.

Main Results:

• Identified 17 brain areas outside the core network that respond to both auditory and written language.
• Most of these identified areas demonstrated selectivity for language processing.
• Key areas in the extended network include the temporal poles, medial frontal cortex, hippocampus, and cerebellum.
• The extended language network constitutes a small fraction (<5%) of total grey matter volume.

Conclusions:

• Language processing involves an extended network beyond the canonical left fronto-temporal regions.
• These newly identified areas are selective for language, suggesting specific functional roles.
• The findings challenge the notion that the entire brain is dedicated to language processing.
• This study provides a foundation for further investigation into the functions of these non-canonical language areas.