Functional connectivity and brain activation: a synergistic approach. Cereb. Cortex 24, 2619–2629. doi: 10.1093/cercor/bht119

Traditional functional magnetic resonance imaging (fMRI) studies exploit endogenous brain activity for mapping brain activation during “periodic ” cognitive/emotional challenges or brain functional con-nectivity during the “resting state”. Previous studies demonstrated that these approaches provide a limited view of brain function which can be complemented by each other. We hypothesized that graph theory functional connectivity density (FCD) mapping would demon-strate regional FCD decreases between resting-state scan and a con-tinuous “task-state ” scan. Forty-five healthy volunteers underwent functional connectivity MRI during resting-state as well as a continu-ous visual attention task, and standard fMRI with a blocked version of the visual attention task. High-resolution data-driven FCD mapping was used to measure task-related connectivity changes without a priori hypotheses. Results demonstrate that task performance was associated with FCD decreases in brain regions weakly activated/de-activated by the task. Furthermore, a pronounced negative corre-lation between blood oxygen level-dependent-fMRI activation and task-related FCD decreases emerged across brain regions that also suggest the disconnection of task-irrelevant networks during task performance. The correlation between improved accuracy and stron-ger FCD decreases further suggests the disconnection of task-irrele-vant networks during task performance. Functional connectivity can potentiate traditional fMRI studies and offer a more complete picture of brain function