SYNAPTIC PRUNING BY MICROGLIA IS ESSENTIAL IN NORMAL BRAIN DEVELOPMENT

Microglia are highly motile phagocytic cells that infiltrate and take up residence in the developing brain where they are thought to provide a surveillance and scavenging function. However, although microglia have been shown to engulf and clear damaged cellular debris following brain insult, it remains less clear what role microglia play in the uninjured brain. Here we show that microglia actively engulf synaptic material and play a major role in synaptic pruning during postnatal development in mice. These findings provide a direct link between microglia surveillance and synaptic maturation and suggest that deficits in microglia function may contribute to synaptic alterations seen in some neurodevelopmental disorders.