Dynamic Reorganization of the Frontal Parietal Network During Cognitive Control and Episodic Memory

Abstract

Higher cognitive functioning is supported by adaptive reconfiguration of large-scale functional brain networks. Cognitive control (CC), which plays a vital role in flexibly guiding cognition and behavior in accordance with our goals, supports a range of executive functions via distributed brain networks. These networks process information dynamically and can be represented as functional connectivity changes between network elements.\n\nUsing graph theory, we explored context-dependent network reorganization in 56 healthy adults performing fMRI tasks from two cognitive domains that varied in CC and episodic-memory demands. We examined whole-brain modular structure during the DPX task, which engages proactive CC in the frontal-parietal cognitive control network (FPN), and the RiSE task, which manipulates CC demands at encoding and retrieval during episodic-memory processing, and engages FPN, the medial-temporal lobe and other memory related networks in a context dependent manner.\n\nAnalyses revealed different levels of network integration and segregation. High CC conditions exhibited greater integration across tasks. Moreover, nodes associated with higher cognitive functioning displayed the greatest amount of dynamic module reorganization across tasks. Specifically, the FPN displayed a high level of segregation in the DPX task, where only demands for proactive control varied, and more complex network integration with default mode and salience networks in the RiSE task, where CC is differentially integrated during memory encoding and retrieval. These findings provide insight into how brain networks reorganize to support differing task contexts, suggesting that the FPN flexibly segregates during focused proactive control and integrates to support control in other domains such as episodic-memory.