Research is increasingly revealing new roles for microglia in the developed brain beyond their well-known function in protecting it from pathogens and injury. 1,2 For example, recent work has demonstrated microglia are likely to be important for memory processing and executive function. [3][4][5][6] Microglial activity directed at pruning of synapses mediates memory degradation in a complement-dependent manner in a contextual fear conditioning task. 3 Likewise, spatial learning is impaired in animals that are unable to reduce their CA1 microglial density during task acquisition 7 and recognition memory is improved when microglia repopulate the brain after depletion. 8 Roles for microglia have also emerged for regulation of feeding and satiety, 9 and in modifying pain responses. 10,11