Microglia are thought to be key players in the refinement of neural circuits during development. However, Brown et al. now report that depleting these cells in mice had no notable effects on experience-dependent maturation of visual cortex circuitry.

The authors fed mouse pups (and their dams) a diet containing an inhibitor (PLX5622) of colony-stimulating factor 1 receptor from postnatal day 14 (P14) to P50 — approximately covering the period of experience-dependent maturation of visual cortex circuits after eye opening. Signalling through this receptor is necessary for the survival of microglia, and PLX5622 treatment has been previously used to deplete these cells in mice.