Necrosis, particularly of the brain, occurs in such significance that Zombies can and have been
mistaken for dead. Brain damage is extreme in the
neocortex, which is responsible for higher-order brain functions.
[1][excerpt 1] As a result, sensory perception; cognition; motor skills, spatial reasoning, and language are either greatly limited or totally absent. Zombies, lacking human reasoning, rely entirely on basal urges and will wander in search of food.
[1] The mind is not entirely gone, however, as Zombies are thought to have a fixation with wandering around buildings they frequented before infection.
[1]