The developing brain is exquisitely sensitive to both endogenous and exogenous signals which direct or significantly alter the developmental trajectory of cells, neural circuits, and associated behavioral outcomes for the life of the individual. Contrary to initial dogma that the brain is one of the few organs within the body that is immune-privileged, evidence indicates that the immune system has a critical role in brain function during development as well as during sickness and health in adulthood. Microglia are the primary immune cells within the brain, and they are in constant...