Bidirectional Connectivity Between Broca's Area and Wernicke's Area During Interactive Verbal Communication

Area of Science:

• Neuroscience
• Social Neuroscience
• Cognitive Neuroscience

Background:

• Understanding neural dynamics in live human interaction is crucial.
• Previous studies show coupled neural mechanisms during dialogue.
• The role of within-brain long-range neural mechanisms in social functions remains unclear.

Purpose of the Study:

• To investigate how functional connectivity between speech areas is modulated by social interaction.
• To compare directional connectivity in Broca's and Wernicke's areas during interactive versus noninteractive spoken dialogue.
• To explore neural dynamics underlying natural two-person verbal interactions.

Main Methods:

• Applied Granger causality analysis to functional near-infrared spectroscopy (fNIRS) data from 33 participant pairs.
• Compared directional connectivity in Broca's and Wernicke's areas during interactive and noninteractive object naming/description tasks.
• Utilized hyperscanning to record brain activity from both participants simultaneously.

Main Results:

• Interactive communication featured bidirectional connectivity between Wernicke's and Broca's areas in the listener's brain.
• In contrast, the speaker's brain showed unidirectional connectivity during interaction.
• Noninteractive communication resulted in unidirectional top-down connectivity (Broca's to Wernicke's) in both speaker and listener brains.

Conclusions:

• Directional Granger causality analysis reveals bidirectional neural information flow during interactive dialogue, particularly during listening.
• Findings support the Interactive Brain Model, suggesting long-range neural mechanisms process spontaneous spoken social cues.
• Neural modulation of the receptive language system (Wernicke's area) is evident during live social interactions.