Neural mechanisms underlying dynamic manipulation of sequential information in working memory.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Cognitive Neuroscience

Background:

• Working memory is vital for complex cognition, including language and planning.
• Neural mechanisms for passive sequence maintenance are known, but sequence manipulation is less understood.

Purpose of the Study:

• To differentiate neural mechanisms of active sequence manipulation from passive maintenance using fMRI.
• To investigate large-scale brain network dynamics during working memory tasks.

Main Methods:

• fMRI study with 31 healthy adults performing digit-ordering tasks (pure recall vs. reorder & recall).
• Employed univariate analyses, multivariate pattern analysis (MVPA), and functional connectivity analysis.
• Examined network activation, pattern decodability, and inter-network communication.

Main Results:

• Sequence manipulation robustly activated the frontoparietal network (FPN) and deactivated the default mode network (DMN) compared to maintenance.
• MVPA showed manipulation-specific representations decodable in frontoparietal regions.
• Functional connectivity revealed strengthened FPN connectivity and FPN-DMN decoupling during manipulation.

Conclusions:

• Working memory manipulation requires large-scale, demand-driven brain network reconfiguration, not just localized activation.
• The FPN and DMN exhibit dynamic segregation and integration during manipulation.
• The anterior cingulate cortex and middle frontal gyrus act as key hubs in this network reorganization.