Brain connectivity in the left frontotemporal network dynamically modulated by processing difficulty: Evidence from...

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Science

Background:

• The left inferior frontal gyrus (LIFG) and left superior temporal gyrus (LSTG) are crucial for relative clause (RC) sentence comprehension.
• The precise interaction dynamics between LIFG and LSTG during Chinese RC processing, particularly concerning varying difficulty levels, remain underexplored.

Purpose of the Study:

• To investigate the interaction between the LIFG and LSTG during the comprehension of Chinese relative clauses.
• To examine how modifying position and extraction position influence brain activation and effective connectivity within these regions.

Main Methods:

• Utilized 2 × 2 factorial analyses examining modifying position and extraction position in Chinese RC sentences.
• Analyzed regional brain activation and directional connectivity between the LIFG and LSTG.

Main Results:

• Greater LIFG activation was observed for subject-extracted relative clauses (SRCs) with non-canonical word order compared to object-extracted relative clauses (ORCs) with canonical word order.
• Effective connectivity from LIFG to LSTG dominated when RCs were in the subject-modifying position.
• A feedback mechanism from LSTG to LIFG appeared more prominent for more difficult object-modifying position RCs.

Conclusions:

• LIFG activation is associated with ordering processes and integration demands in non-canonical Chinese sentences.
• The directional connectivity between LIFG and LSTG is dynamically modulated by the processing difficulty of RC sentences.
• These findings highlight specialized roles and extensive collaboration between LIFG and LSTG in sentence comprehension.