Decided to put together some coherent sentences from the notes I took at the Coolidge Corner Theater's Science on Screen event back in April. Before a screening of Night of the Living Dead, Dr. Steven Schlozman, psychiatrist and educator at Harvard Medical School, gave a truly enlightening talk on zombie neurobiology. As it turns out, zombies are just humans suffering from Ataxic Neurodegenerative Satiety Deficiency Syndrome. Read on.

Armed with a great PowerPoint presentation filled with pop culture references, he covered many areas of the human brain and their functions in order to point to specific neurological causes for several zombie traits.

But first let's be specific: we're talking about George Romero zombies, not the running, hyper, super-strong creatures from newer movies like 28 Days Later. This debate over which can officially be called "zombie" rages all over the Internet and I'm not going to weigh in with my opinion; just setting the parameters for what we're discussing here.

The frontal lobe, for starters, is responsible for planning, "executive functioning," abstract problem solving, staying on task, paying attention, and, most importantly controlling impulsivity. Schlozman describes impulsivity as something where "if you had a few more seconds, you might not have done it."

As a relevant example, he points to Phineas Gage, the guy who survived a big metal rod going through his head back in the mid-1800s. It's an interesting case, not just because he survived, but because the massive frontal lobe damage he sustained in the accident significantly changed his personality. He was, to relevantly summarize the changes, more impulsive.1

The amygdala is the source of our base emotions: fear, rage, and so on. Taking the impulses of the amygdala and processing them through other parts of the brain is, according to Schlozman, "what makes us human." We have animal instincts, but intellect to moderate them. A crocodile is, he says, "all amygdala." Getting mad at a zombie doing what zombies do is, thus, sort of like getting mad a crocodile for being a crocodile.

When the amygdala does go a little crazy, there's another part of the brain that gets involved in addition to the frontal lobe: the anterior cingulate cortex (ACC). It acts as a sort of emotional speed bump. It slows down impulses so the frontal lobe can swoop in and moderate the situation. People who suffer from posttraumatic stress disorder, he points out, have more amygdala activity and less anterior cingulate cortex activity (more base emotion with less slowing).2

The cerrebellum and basal ganglia are the parts of the brain responsible for balance and coordinated movement, respectively. Cerebellar atrophy and basal ganglia dysfunction can result in a poor coordination, severe tremors, and a wide-legged, unsteady lurching walk that looks an awful lot like the zombie gait. There are a number of YouTube videos showing this, but I don't really feel great about linking directly to people's personal recovery videos in this context.

The hunger can be explained by lesions to the ventromedial hypothalamus, which can cause obesity and hyperphagia (eating and eating because you never feel satiated).

So. To be a zombie may be to have an overactive amygdala, decreased frontal lobe and anterior cingulate cortex functioning, and damage to the cerebellum, basal ganglia, and ventromedia hypothalamus.

1. The skull and offending metal rod are both on display at the Warren Anatomical Museum at Harvard Medical School.

2. As a bit of trivia having nothing to do with zombies, the connection between the amygdala and ACC gets stronger with age, which is one reason why we're less likely to do something dumb on a dare when we're older.