Task-evoked brain network architecture captured by the complementary integration of metabolic and functional connectivity.

Cognitive task performance relies on functional adaptations in brain network organization. While much research has focused on functional connectivity, less is known about how metabolic relationships contribute to cognition. The emerging concept of metabolic connectivity allows to investigate metabolic networks; however, this has not been assessed during task engagement. This study investigates both metabolic and functional adaptations on cognitive demands, highlighting the complementary insights gained from integrating these modalities. We simultaneously acquired functional PET/MRI data in 49 participants performing a cognitive task (Tetris®) at two difficulty levels. Euclidean-similarity metabolic and functional connectivity matrices were estimated during resting-state and both task conditions separately. Brain network reconfigurations were analyzed using network-based statistics. We then assessed how functional and metabolic adaptations, independently and in combination, relate to task performance. Although overlapping patterns emerged in task-relevant regions, metabolic and functional reconfigurations also revealed distinct characteristics. The dorsal attention network emerged as a key metabolic node, while the default mode network reconfigured its functional connectivity to meet task demands. Importantly, the multimodal approach outperformed single modalities in predictive task performance. These findings highlight PET-based connectivity as a valuable tool for investigating task-related brain network dynamics, offering new insights into the metabolic underpinnings of cognitive function.