Little cells that normally sleep and get active when pathogens infiltrate the CNS
for example. Interferon activates them
for weeks. That makes them extremely sensitive towards noise, chemicals, food etc. and once the cascade activates themselves they start oxidative processes that attack the nerve tissue and lead to fatigue, "brain fog" etc. So, the goal is, how to calm down the microglia.
The microglia has a receptor called TLR4 or Toll Like Receptor 4.