Astrocyte-Driven Modulation of Whole-Brain Functional Networks and BOLD Signals Revealed by Optogenetic-fMRI.

Astrocytes have long been considered passive players in brain function, yet emerging evidence suggests they actively modulate neural activity and signal transmission. This study combines chemogenetics and optogenetics approaches with functional magnetic resonance imaging (fMRI) to investigate the impact of astrocyte activation on local field potentials (LFPs) and downstream BOLD signals. Using a multimodal neuroimaging approach, we explore how astrocyte activation influences electrophysiological responses in different brain regions, particularly focusing on the prefrontal cortex (PFC) and its downstream targets. Our results reveal significant increases in LFP energy within specific frequency bands, such as Theta and Delta, in response to laser stimulation. These changes demonstrate the spatial specificity of astrocyte activity and its capacity to modulate local network dynamics. Furthermore, following chemogenetic inhibition of neuronal activity, optogenetic reactivation of astrocytes continued to evoke BOLD responses, supporting the notion that astrocytes have a pivotal role in the regulation of cerebral blood flow and metabolism. These findings challenge traditional views of BOLD signal origins and emphasize the need for a reevaluation of astrocyte involvement in neurovascular coupling. This study provides novel insights into astrocyte function, offering a new perspective on brain-wide connectivity and its implications for both normal brain function and neuropathological conditions.