Astrocytes, the most numerous cells in the brain, are increasingly implicated in neurodevelopment and disease. Our lab studies astrocyte-neuron interactions at the molecular level by identifying novel astrocyte-encoded genes and studying their functional role in circuit and synapse formation during development. The finding that astrocytes are heterogeneous based on their location in the central nervous system provides a powerful tool to begin to identify novel astrocyte-encoded genes based on regional heterogeneity, and explore their functions in the developing nervous system. Using circuits in the developing spinal cord and other CNS regions, we study the role of specific astrocyte-encoded proteins on neuronal positioning, neuronal survival, and synapse formation. We are also interested in how astrocytes communicate with microglia to regulate synapse number and circuit function, and may serve as regulators of the innate immune system in the brain. These types of molecular studies will help to elucidate the role of astrocytes in psychiatric diseases of neural circuit formation, including schizophrenia, autism, and others.