Microglia: Key players in neurodevelopment and neuronal plasticity.

Microglia are the primary innate immune cells in the CNS. Since their initial discovery and characterization, decades of research have revealed their unique roles not only in maintaining immune homeostasis, but also being indispensable to brain development and cognitive function. As such, microglia drive synaptogenesis, synaptic pruning, neurogenesis and neuronal activity. Microglia-specific mutations are implicated in several neurodevelopmental disorders, and dysregulation of microglial function is strongly linked to several pathologies, including cognitive decline and Alzheimer's disease. Importantly, developmental insults can lead to long-term changes in microglial function that may compromise the ability of the adult brain to fight infections and process cognitive information. Adult lifestyle or injury can also lastingly influence microglial morphology and function. Here we highlight key research on microglia's role in neuronal plasticity across the lifespan.