Microglia
Research has discovered dystrophic (defective development) human microglia. "These cells are characterized by abnormalities in their cytoplasmic structure, such as deramified, atrophic, fragmented or unusually tortuous processes, frequently bearing spheroidal or bulbous swellings." The incidence of dystrophic microglia increases with aging. Microglial degeneration and death have been reported in research on Prion disease, Schizophrenia and Alzheimer's disease, indicating that microglial deterioration might be involved in neurodegenerative diseases. A complication of this theory is the fact that it is difficult to distinguish between "activated" and "dystrophic" microglia in the human brain.
Beth Stevens
In 2012, Stevens’s team published evidence that microglia 'eat' synapses, especially those that are weak and unused. The findings pinned down a new role for microglia in wiring the brain, indicating that adult neural circuitry is determined not only by nerve cells but also by the brain’s immune cells; this helped to explain how the brain, which starts out with a surplus of neurons, trims some of the excess away. Neuron named the paper its most influential publication of 2012.