Activated microglial cells are involved in the mechanism of neuronal damage in neurodegenerative diseases and release NF-κB, TNF-α, COX-2, IL-1β, and IL-6, and other neurotoxic proinflammatory cytokines that mediate secondary neuron loss and brain damage, which ultimately induce learning and memory dysfunction. The gene discussed is TNF; the disease is neurodegenerative disease.