Illustration of activated and proliferating microglia (orange) in Alzheimers disease. Microglia are immune cells of the central nervous system. They detect and remove damaged neurons, plaques and other cellular debris from the brain. Here they can be seen surrounding neurotoxic amyloid beta plaques (tangles), which are found in the brains of Alzheimers patients. It is thought that activation of microglia in response to persistent plaques can lead to chronic inflammation, which contributes to neuronal damage and the progression of Alzheimers disease.