Human cerebral cortex organization characterized by functional PET-FDG "Metabolic Connectivity".
TL;DR
This study characterizes the spatiotemporal organizational principles of RSMC, deepening insight into the brain's energetic framework and providing a basis for future cognitive and clinical investigations of metabolic connectivity organization.
Abstract
Purpose
In this study, we characterize the spatiotemporal organization of resting-state metabolic connectivity (RSMC) in the human brain, as measured by [18F]-fluorodeoxyglucose (FDG) functional PET (fPET-FDG). We examine the relationship between RSMC organization and resting-state functional connectivity (RSFC) derived from functional magnetic resonance imaging and other known cortical organizational principles.
Methods
Resting-state fPET-FDG data from 24 individuals were obtained from a publicly available repository (Monash rsPET-MR Dataset). We characterized local metabolic organization using connectivity-based boundary mapping, with adaptations to account for the low signal-to-noise ratio of fPET-FDG data. We then estimated global metabolic organization through community detection-based network and principal gradient analyses. Furthermore, we examined how metabolic connectivity is shaped by temporal-frequency-specific components of fPET-FDG signal. Finally, we contextualized metabolic organization by relating metabolic gradients to anatomical, functional, and energetic reference measures.
Results
At the local scale, boundary mapping results revealed structured transitions shaped by a combination of both fast and slow fPET-FDG signals, partly overlapping with RSFC boundary maps. Globally, RSMC analyses revealed a robust metabolic structure organized along a superior-inferior cortical gradient. This pattern remained consistent across network community detection and principal gradient analyses and was primarily driven by low-frequency, minute-scale fPET-FDG dynamics. The identified large-scale metabolic profile aligns closely with several known anatomical and energetic constraints.
Conclusion
This study characterizes the spatiotemporal organizational principles of RSMC, deepening insight into the brain's energetic framework and providing a basis for future cognitive and clinical investigations of metabolic connectivity organization.