Modularity Analysis of Intrinsic Connectivity Networks

Modularity Analysis of Brain Intrinsic Connectivity Networks in Frequency Domain

The brain generates a wide range of cognitive and behavioral states by balancing between integration and segregation processes. Different functional domains are represented in large-scale networks called intrinsic connectivity networks (ICNs).

Phase-based connectivity estimation was performed on resting state fMRI data of 98 subjects from Human Connectome Project in three frequency bands (0.011-0.038Hz, 0.043-0.071Hz, and 0.076-0.103Hz) in the BOLD signal during rest. We applied modularity analysis to connectivity matrices and investigated those areas, which we called integrative regions, that showed frequency-domain flexibility.  

Three large modules across frequency bands: one dominated by the visual network (VN), one by the somatomotor network (SMN), and a cognitive module that included the limbic network (LN), cognitive network (CN), and default mode network (DMN). Attention networks were distributed among these three main modules.  

Project Coordinator: Prof. Dr. Ahmet Ademoğlu & Prof. Dr. Tamer Demiralp (İstanbul University)
Researcher: Hüden Neşe

Project Summary: This study significantly advances our understanding of frequency-specific characteristics of ICNs as reflected in the BOLD signal. The findings underscore the importance of attention networks in maintaining integrative functions across different frequency bands, revealing their critical role in dynamic brain connectivity. The frequency-dependent flexibility of these networks aligns with their ability to adapt to changing cognitive demands and environmental stimuli. The consistent presence of hubs across frequencies suggests stable functional roles, while the dynamic nature of bridges indicates frequency-specific inter-network communication. Overall, this research highlights the complex and nuanced nature of brain connectivity, emphasizing the need for frequency-specific analysis to fully understand the brain's functional organization.

Funded by Bogazici University Scientific Research Project Council (2023-2025)