As far as we know, nobody has ever harvested the undead brain of a zombie to properly examine it, and get a better idea of what causes a person to turn into a walking flesh-eating virus. Furtunately, there are neuroscientists working on a theoretical model of not only the zombie brain, but an actual medical diagnosis of the zombie condition.
Bradley Voytek, PhD, and Timothy Verstynen, PhD, met in graduate school, and when they realized they had a shared interest in the undead, they began to apply their knowledge of brain chemistry and disorders to the creation of a zombie brain model. Neurology Today recently interviewed the duo about their findings.
My graduate advisor had always said how people with cerebellar ataxia had a “zombie walk”… So that was the next logical link-up to known diseases. We just kept going with that kind of “forensic neuroscience” logic and after a while, we identified several “symptoms” that we could link to known circuits.
Zombies suffer from a global impairment of several systems. First, they suffer from impulsive-reactive aggression disorder linked to a loss of the orbitofrontal control signals to the amygdala. Thus, they have a hyper-amygdala disorder… We also found they suffer from ataxic movements due to a loss of the cerebellum. Additionally, they have bilateral hippocampal damage, which explains the lack of long-term memory consolidation. Obviously, the whole arcuate language circuit is destroyed in the zombies, which explains their aphasias. In some cases, Broca’s circuit may be intact enough to allow limited communication abilities, such as moaning, but assuredly, the posterior language areas are all destroyed leading them to lack verbal comprehension. Their reduced pain response is due to damage to the secondary somatosensory cortex, although this may also be mediated by damage to ascending spinal pathways. They also have attentional locking problems, such as Balint’s syndrome, due to bilateral degeneration of the posterior parietal cortices, which also affects their coordination abilities… Dysfunction of the ventral striatal reward pathways leads to addictive behaviors, particularly a “flesh addiction.” Finally, they suffer from a completely lack of meta-consciousness thanks to an ablation of the claustrum.”