Research Question: The study shows SPP1 from perivascular cells drives microglial synaptic engulfment, but the specific receptors, signaling pathways, and molecular cascades linking SPP1 to phagocytic gene expression remain undefined. Understanding this mechanism is critical for developing targeted therapeutics that could modulate pathological synaptic loss. Gap type: unexplained_observation Source paper: Perivascular cells induce microglial phagocytic states and synaptic engulfment via SPP1 in mouse models of Al