Spatial Coordination of Ca 2+ Signaling by Astrocyte Morphology

Astrocytes exhibit spatially heterogeneous Ca 2+ signaling, yet how this activity is organized across subcellular compartments and branch domains remains unclear. We combined in vivo two‐photon imaging of the mouse primary somatosensory cortex under isoflurane anesthesia with Astrocyte Quantitative Analysis (AQuA) event detection and multimodal variational‐autoencoder–based coordination analysis to characterize 75,560 Ca 2+ events from 46 astrocytes in seven male mice. Events were assigned to manually delineated GCaMP‐positive masks representing the soma, primary branches, fine processes, and branch domains. Ca 2+ event features exhibited compartment‐dependent gradients extending from the soma through primary branches to fine processes, while coordination was strongest in primary branches, followed by fine processes and the soma. Within branch domains, intermediate‐sized events (10–100 μm 2 ) showed greater within‐domain than cross‐domain coordination in both primary and secondary branch domains and were relatively enriched within primary branch domains. These findings link astrocyte morphology to subcellular activity coordination and provide a quantitative framework for investigating astrocyte functions within neural circuits.