 Synapses are the biochemical switchboards in our bodies that make perception of the external world possible. Over the past few decades, research has shown that throughout the central nervous system, synapse formation and function is closely regulated by astrocytes. Unfortunately, accessing the tiny regions where astrocytes interact most intimately with synapses has proven extremely difficult. Now, a new chemical tagging method is providing a window into this previously invisible world, revealing the molecular details of how astrocytes orchestrate synapse dynamics in live mice. The approach is called Split-TurboID. As the name suggests, the enzyme TurboID is split into two inactive fragments and injected into the cortex of mice. The complementary fragments attach independently to the surface of neurons and astrocytes. The areas between synapses where these fragments reunite ignite with enzymatic activity. These are the regions where astrocytes interact most closely with synapses. The proteins caught up in these bursts of enzyme activity can then be analyzed in their individual roles understood. In mice, Split-TurboID revealed more than 170 astrocytic proteins that participate in synaptic processes, including neuronal cell adhesion molecule or NR-CAM. Experiments showed that NR-CAM is expressed in cortical astrocytes, clusters in and around synapses, and is required to restrict infiltration by astrocytic processes. In fact, depletion of NR-CAM was found to significantly reduce numbers of inhibitory synapses and their function. That's important because astrocytes were previously believed to control the formation of inhibitory synapses through the secretion of proteins. That NR-CAM on astrocytes and neurons serves as a physical bridge between these cells suggests a new mechanism for how astrocytes modulate inhibitory synapses. Future studies will help researchers better understand how these microscopic components interact to produce the complex wiring of cells in the brain. And with the versatile Split-TurboID approach, researchers can begin to explore the roles of many other proteins that participate in not only astrocyte neuron interactions, but countless other interactions between cells within neuronal circuits.