Anecdotal evidence suggests that the brain stays conscious for a brief time after beheading. During the French Revolution the severed head of a Madame Pujol was lifted up by the hair by the executioner. It is said that the eyes opened and the mouth uttered a single word - "Merde" before finally lapsing into death. The assembled crowd panicked and 11 revolutionaries were killed in the ensuing stampede.

Source : La Teene, Guy. I've Seen London-I've Seen France, 1889.